BlackTopKing

iTrader: (1)

Hey guys,

Well I have decided on a Carb swap from TPI.
Mainly two reason, 1st: not a daily driver - weekend cruise and bruiser. 2nd: in order to get what I want from this particular car, changing over with new (clean used) parts will be more effective for my budget.

Of course I know the first 10 replies wil be "you idiot, stay efi", I like to mention now, the complete TPI unit is for sale!
Don't get me wrong TPI are cool, but they are a different animal. So are Carbs and for what I really want the most. Carb is this cars best application, so let not debate if I am making a decision you agree with.


Now "onward".
Current status:
87 Trans Am GTA
350 TPI with a T56 swap and 4thgen rear (3:42 I assume)

I have a friend with a 650cfm edlbrock electric chock with vacuum secondary new in box who isn't asking much for it to help get me started.

Was gonna get a Edlebrock Performer Intake to match.

I do have some thoughts or questions.
Mainly the manual transmission, I have read conflicting threads noting Manual transmission needing diuble pump carbs as the vacuum secondary don't surfice. True or False?

Stock heads, I was kicking the idea around about getting heads buts after inspection mine are in good shape and would like to just hold off until the spare motor gets rebuilt to do some higher performance upgrades, but if I changed my mind. Could I still change out cam and heads later before needing to upgrade carb....any rule of thumbs? When would I need a 750cfm?

Throttle cable brackes, auto trans....use the same?

Fuel, was hoping to find a pre made line kit that I could swap in with regulators (thinking Mallory) to keep my current pump which is faily new ....but an upgrade even for TPI, so I am consern that it will be too much to reg down effectively (areo stealth3000). Worth trying or save my mind now and just change out for something else.
Holley pump w/reg ?

Now for the one that just seems to have options galore. ?.Dizzy...lol...recomendations would be appreciated, but didn't want to drop a High Line MSD!
Could a TBI work?


Thanks for your thoughts in advance.
As I'm sure ill will return with more, but do intend to continue this thread and even post pics and info of swap as I go, since I couldnt find much at all when I was looking and searching. Guess thjs is the evil hidden swap on the forum.....lmao...

RedLeader289

iTrader: (2)

I've never heard of manual transmissions needing a double pumper carb(as in a VS carb wouldn't work), but I will recommend a double pumper over a vacuum secondary, if you want the most power out of your carb.

I have a holley 750 DP on my 350 (single plane air-gap, vortec heads, roller rockers, etc etc). It allows room for expansion but I also have it tuned so that I'm not draining the tank every time I goose the throttle. My advice would be-if you plan to see over 400 hp, you can tune the 750 to play nicely until the point that you need more of it's potential, if that makes sense.

midias

Performer RPM not regular performer. Get any HEI with vac advance and don't forget to memorize where all the gas stations are.

You would need a 750 when you are making over 400hp and spinning over 6k RPM.

pancherj

Run away from the Edelbrock carb. A 650DP or a quadrajet (I prefer the Holley style carbs myself only because I am familiar with them). For a distributor, I prefer the GM Performance HEI. It has a melonized gear (will work with a roller cam) and the advance curve is decent for a performance cam. I would also go for the Air Gap manifold. As for the heads...if you can swing it in your budget, I would look for a lightly used set of aftermarket heads. They pop up all of the time, so keep your eyes open.

BlackTopKing

iTrader: (1)

Thanks for the last 3 post and I really am going to enjoy this talk.

When I was a teenager, my first 3rdgen and first car was an 87, this being my only other 87 as I have had 88-89 and all TPI's. My first 87, was carb and was a 750 holly, but was also a hand me down motor that my uncle put in for me when I first got it. Although the car had issues here and there...starting and driving never was one and that car never left me anywere....

This is years ago...so I have spent the last 3days, reading, looking and searching. And for the most part, its all geared towards big HP full ground builds to you just shouldn't because its 2014.
Lol
If I had a monster budget, I do something different.

A lot of the discussion gear towards 650dp, because of trans (which I am glad I don't have to do either or although a DP, I understand is better) and 650 cfm, because of stock motor....which is yeh or neh...I like to complete this with in the next month, so I want to keep bottom stock until I find better later on.
I also agree, hunting on heads is the best way to do it, so with that said I don't want to...commit either way, my heads are good...so like to get swap going with stock heads, but be able to swap heads ouf once I find a set, vers....a torn apart car waiting on the righg deal.

Here is were I expected to get stuck with carb...650 now and then too small with heads later (180-190).

I thought of 750, tuned down for now ( this is were every thing is a conflict, 5 say yeah 5 say no) and adjusted with new heads then.

Not worried about gaskets....I have two complete rebuild sets now, which I'd probably use 1/2 anyway.

The dizzy, I saw a nice write up, in the sticky that said same thing, and agree with cam options good part to do, pn 1104067...as heads and cam should go hand and hand.

So really I'm only considering edlebrock cause its a now and cheap deal...question with the two holly and edlebrock, are yours under stock hood...I see cowl hood on yhe camaro.

Next question and maybe dumb...but are you guys keeping fuel line (factory stock hard lines and running off or cutting back closer to firewalk and running up.

RedLeader289

iTrader: (2)

For my application I couldn't make it fit under the stock ('83) hood, sadly (because it would have been an awesome sleeper, haha). I have this intake: http://www.summitracing.com/parts/nal-12496822 , a holley 750 DP, and a 14x3 air cleaner with a drop base. I had to get a 2" cowl induction hood to fit it all.

I've seen some people on here fit other intakes and carbs under the stock hoods though so it can be done.

I have the factory hardline up and into the engine bay and into my regulator (I've attached a pic). I may re-route it at some point but for now it hasn't caused any issues.

pancherj

I had an AirGap with a 750DP and a 3" air cleaner using an L88 reproduction drop base (and a crappy lid I found somewhere). The L88 base does a great job (with minor clearancing for the HEI). This all fit under my stock 1990 IROC hood.

A 750DP will work for now and for later. So will a 650. Lots of guys running well into the 10's with a 650DP. If the Edelbrock is cheap, throw it on. Just don't expect the best gas mileage or performance (the Holley style will win hands down).

You can get adapters that fit to the existing TPI fuel lines and adapt to AN lines. Run AN lines to the Mallory regulator and then to the carb. A good, stock fuel pump will be plenty for you now.

skinny z

A double pumper or more correctly a mechanical secondary carb is absolutely and completely unnecessary on a street engine or ANY other engine where power below peak is a concern. It IS entirely possible to make EXACTLY the same power with a vacuum secondary carb as it is with a mechanical secondary provided they flow the same cfm. Tuning however is a different animal. This is why many mistakenly select a mech carb. Because they can't tune or don't have the patience to.
What's more, power below peak torque will be enhanced (with vac sec) as the booster signal through the venturi is greater with only 2 barrels in operation. This is not to mention the better fuel economy that's seen with a vac carb compared to a mech carb.
About the ONLY application where a DP makes sense is a drag racing only engine with a stall speed or stick shift that allows the RPM up to peak torque at the launch. Then it's the tuning that's easier. It's not necessarily going to be any quicker. Some road racers prefer the mech sec for the same reasons but not having had a dedicated road racing car, I can't say one way or the other.
Anyone that says otherwise hasn't done enough testing and tuning.
As for cfm, consider the RPM point of maximum horsepower and the volumetric efficiency of your engine. Stock engines will tend to have lower VE and require less carb. The smallest carb that will do the job is the best carb for the job. In your case, a 600 cfm would do the job. If you plan on upgrading to better heads and a cam in the future then you may consider upgrading the carb as well. Putting a 750 DP on your stocker will not produce satisfying results. If someone says otherwise, I suggest THEY try a smaller carb and tune it properly.
I can't comment on the Edelbrock as I've never tuned one. I've heard mixed reviews on them.

As for your distributor, an HEI with a upgraded module and coil will provide all that you're looking for. A vacuum advance mechanism is an absolute must. Getting a vacuum can that's adjustable for both rate of application and the amount is even better. Then learn how to tune THAT.

BlackTopKing

iTrader: (1)

Ok, so combo play will determine a lot of the fitment issues as far as getting under stock hood.
What about the CAI version for carbs, the double airfilter looks kinda cool.
But I still have soft spot for a nice k&n top filter on the carbs...just somthing abiut it makes me feel like "the blackwhole" sucking in everything. If I have to mod, hood....fine, just if I can clear it, cool.

The 650edlebrock, like I said...new clean and really cheap $100 for it, and seemed like a good starting point for swap, I was just worried about the interaction with manual, so I appreciate the info on that. Yhing with 650 is I think its an 1806#...I have to ask, but I know its not a double pump and those two features is what had me concerned with the trans.

So for now, i have a pretty good list going and looking to buy next week, give myself a week for tge $ +/homework and of cours3 little hunting.

With that said, I have areo steakth in tank now...this was an upgrade for my TPI, but question is...is that too far over stock to regulate to carb or should I get a different pump (sell areo).
As for lines, you mentioned I can get the connection for swap, does jegs or summit sell the lines premade, I searched but didn't fint a forsure item.?

And finally bracket? I see tones of info on auto brackets, would I apply same as manual? My first 87 had 700r4 and I remeber that being adjusted....as I burnt up cable once, but never really had a reason to look at carb +/manuals before?

In meantime, thinking ill look at holly 750dp as suggested and see what's out there in my budget. May still grab 650vs while I can.

Thanks again for all your help and information, as well as picture (are you a vortex set up?)

RedLeader289

iTrader: (2)

You're welcome, there's a lot of smart folk on this board and a plethora of info. Yes, the engine is a GMPP 385 fastburn crate engine to be precise (350).

jwfirebird

iTrader: (2)

i have the dual plane, 750 mechanical dp holley and 14x3 drop base edelbrock air cleaner and it just fits under the hood. i wouldnt bother with the open top ones though the hood just about touches the top of the cleaner.

as far as vacuum vs mechanical secondary i havent had vacuum one but the car is now half drag and half street use and i dont feel like im losing anything either use. its very simple to tune it sounds like compared to the vacuum threads people put on here. and you dont have to worry about the compatibility with different transmissions. i do agree though learning to tune the ign is as important. i have a mallory 85 all in one and you can adjust everything. thats kind of the advantage of the holley over edelbrock too, on the 4150 i have you can adjust the primary side of things to keep good fuel economy and secondary for max power

pancherj

I shouldn't post this here, because it really has little value for the OP, but it may help others in the future who search their way into this thread. It is true that the engine doesn't care about how the air and fuel gets there. Whether it be vacuum carb, mechanical carb, EFI, etc. It just wants a certain mixture. And, of course, MPG depends on the tune. This is exactly what makes the double pumper, in my opinion, the better carb. Now, if Holley had decided to add a second pump and squirter setup to the back barrels on their vacuum carb, then this would be a different conversation. Depending on the air speed in the intake tract and the overall length of the runners and also the turns in the runners, the air stream will need a "squirt" of fuel to overcome the lean spots when the throttle blades open rapidly. To get the vacuum secondary carb to perform optimally, you want the secondaries to open as quickly as possible (without bogging). When you get that sorted, you need enough squirter to meet those needs. But there is only one squirter on the primary of a Holley vacuum secondary carb that you are asking to cover for four barrels. That means it needs to be big! Unfortunately, a properly adjusted pump should activate the squirter with minimal movement of the arm. So now, you are activating that one single, big squirter an awful lot even when the secondaries aren't coming into play. On a double pumper, with progressive linkage, you can avoid all this. In fact, I have seen better MPG with my Mighty Demon 750DP than I was getting with my miniram setup. I believe either setup would be shoulders above my 3310 Vacuum secondary Holley for the reasons I explained above.

Either carb choice does require work from the end user. There is no "bolt on and go" solution (at least if you are looking for the best from your combination of parts). It will take playing with timing, timing curves, IFRs, PVCR's, etc. In the end, you can do an awful lot with either carb (Holley...not the Edelbrock!) and you will also learn an awful lot about your engine.

PS...I wouldn't even take that Edlebrock carb if the owner attached a $100 bill to it!! When you start REALLY trying to tune it, the headaches will make you forget about the $100 real quick!

skinny z

I'll agree with the WOT tuning bit (unless you're leaving below peak torque rpm) but you're giving up part throttle drivability and fuel economy with the DP. No doubt about it. The booster signal is seriously diminished with a mechanical secondary (the math is simple) and every reasonable motion of the gas pedal operates TWO accelerator pumps as well. That's a lot of fuel.
For the OP, a 750 is overkill (IMHO) and if he were able to do an A to B comparison between a 600 vac sec verses a 750 DP (both properly tuned) I think his decision would be simple.
Something to consider if a 750 IS selected, is what 750. The booster style plays a significant role in how the carb behaves and how well the mixture is atomized (read that as throttle response). It's basic knowledge that a carb with straight leg boosters will perform nothing like one equipped with annular boosters. The latter being helpful when too large a carb has been selected. The style of manifold here also plays a significant role although nothing been mentioned about a single plane intake (thankfully). Too large a carb on a single plane spells disappointment from the everyday driving experience.

sootie007

" I couldnt find much at all when I was looking and searching. Guess thjs is the evil hidden swap on the forum.....lmao"

Alot of part numbers, brackets, fuel line, fuel regulator info, wiring etc you can use here ..even though mine was slightly different - a 305 TBI to Carb swap. Ebay has a ton of inexpensive HEI mechanical distributors with coils for usually under $80......

https://www.thirdgen.org/forums/carb...s-305-tbi.html

skinny z

You miss the most important point regarding a VS carb. The second pump ISN'T needed because the throttles are opened gradually. It's this gradual opening that makes the VS superior in most applications. Particulalry the street. What's more, at WOT there's no reason for a second pump. Manifold vacuum is zero (it's at atmospheric pressure) and the fuel is being carried in the airstream at that manifold pressure. There is no sudden pressure rise such as when the throttles are mashed open from idle (below atmospheric pressure) and consequently the fuel doesn't change from a vapour (as it is at say, 10" of vacuum) to a liqiuid (due to the pressure RISE) and condense on the manifold walls. When the vacuum secondaries start to open at WOT, manifold pressure doesn't change significantly so there's no need for the 2nd pump. That's science and that's why we need accelerator pump(s).
Absolutely, either choice will need work from the end user but the correct choice in the first place will make the process the much easier and the results more satisfying on ALL levels.
As for the MPG, the carb plays a huge role in that. Not just the tune, but the size and style of carb selected as well. A properly tuned VS carb will, in every aspect out-economy a DP every time.
It's difficult to compare the results of your DP vs your EFI because it's not apples to apples. The manifold styles alone make that difficult.
Yes this debate might be better carried in a place other than this thread but maybe it's an education for the OP.
There are plenty of great books out there. If you want a real eye opener on carbs, check out Vizard's latest on super tuning and modifying Holley carbs. Possibly the best I've read on a scientific level with tons of great info and tips.

five7kid

iTrader: (14)

The issue with a Holley-type vacuum secondary carb and manual transmission is the secondaries don't close instantly when you let off the throttle. Just as they open slower than mechanical secondaries, they also close slower than mechanical secondaries. So, during shifts, for instance, you may have backed off the accelerator pedal completely and the primaries are closed, but if the secondaries had opened in the previous gear, they will stay open until the vacuum "bleeds off" of the secondary diaphragm.

Maybe that doesn't seem like an issue to you, but the first time I thought I was backing off the throttle and the engine continued to pull (this happened to be an automatic application), it was an eye-opening experience for me.

As for street driving a mechanical secondary Holley, I found it to be just fine.

jwfirebird

iTrader: (2)

i would have to agree with the street driving being fine, once its tuned properly its not boggy or anything and tuning for a hobby type car isnt really about every last little efficency. or else they would have left the efi on.

i have that book its pretty good

skinny z

While I have no direct experience tuning with a manual shift trans and a vacuum secondary carb, I do know that my vacuum sec carb has a mechanical connection that closes the secondaries as quickly as the primaries. At least that's the way it functions on my Holley and BG VS carbs. Perhaps it's not as instantaneous as I understand. What I do know is that after closing the throttle quickly after a WOT high RPM blast, there's an enormous sucking sound from the carb that I asssociate with all of the barrels closing. After a lower RPM WOT run when the secondaries haven't opened (or opened fully) the sound isn't as pronounced.
Just an observation.
I suppose street driving a mechanical carb and what you associate with fine is a matter of personal preference. Lately, while performance is still my objective, fuel economy is right up there. The VS will win every time provided all the tuning has been done with the emphasis on a lean cruise AFR.
Also just relating my experiences.

skinny z

For me, if I can save a dime with some judicious tuning, then I will. It's VS all the way in that regard. With NO downside to the VS carb, why bother the mechanical carb in the first place? The mechanical carb will always suffer and most likely produce less torque (and horsepower) at mid throttle and mid RPMs. Power output for either carb is the same at WOT. Period.
Where do you drive your street car? WOT is seldom seen (for most people anyway).
However it's not an arguement I'm looking for in any of these posts. I'm just trying to lay out the facts. It's only science and science doesn't lie.
If opinions differ, well, that's why they're called opinions.

BlackTopKing

iTrader: (1)

Sootie007,

Thank you for the link and i will review your thread tomorrow when I havensome free time. I may of over looked it at first when searching as it was a TBI set up and really expected most of the TBI to be reuseable for a traditional carb swap, but now thinking about it more so your right. Information will be appreciated and am interested in the smaller parts. Like hoses....oh yeah, for got about that....lol

But as I said before, I like to get my shopping list together and ready so next week, I can gather and start thjs project.

Sidenote, with the consideration and thoughts of skinnyz and pancherj...you guys have really just made this thread excellent IMHO with the clean debate and information gjven on bith 650-750, VS vers DP application and configuration. That I have re-read the above twice and think with the gather experience the Holley really will be worth the extra.....
Especially since the tuning feature is a must, the advantages of tuning holley make the 750 more acceptable then the disadvantage edlebrock 650, which as agree...would work...but only so much so well.

So for me I think spending the extra now to get Holley750 and tuning correctly for mh motor as is, is better to do. Especially if heads and cams come into play on ghis motor later on...I would only be tuning back up verse buying an upgrade and re learning another carb.

*Demon carbs, are just cool looking carbs, don't know much about th3m other then, huge cfm carbs and my uncle had one on his mocho TA when I was a kid....maybe only cool because of that, but to me...it was bad! Did not know or ever seen a 750demon

So wise spent money and gain experience are worth the cash now.

Also, as a lot of the topic is gearing towards, useage of the TA. I'm in SC, all 1/8th tracks and have no intention on dragging this car....maybe some SCCA, but even then...car is just to have fun, cruise and take out on weekend day trips...of course, fun is some throttle play and enjoying the highways...but, I'm not out to hotrod the tkwn streets.

As pleasure, gotta pay to play, although I like some MPG 15-18 might be nice at same time its not daily driver, so hooefully I'm not sitting in traffic and stop go crap anyway, nor 1hr commutes to work and needing that 25mgp to keep some cash out of mu checks.

With that said....VS Holleys are more cost effective then the DP.

I was just worried about the shift behavor and the high rpm in high gears effect, but with the abkve information. Skinnyz does have some good poings of interest and the manual trans drive behavor really shouldn't change the carb physics and design....hopefully...lol

At same point, I'm interested in knowing, if the DP secondaries really would close slower then the primary during shifts.

I clutch everytime I touch breaks, habbit....so if so, it would def be an odd inticipation of breaking and car trying to pull because I clutched in.

As for intakes, by far...performer rpm have been ranked #1. How would it compare if at all to a weiand?

jwfirebird

iTrader: (2)

the performer rpm is better for street rpm, the weiand and most single plane intakes are higher rpm oriented.

i dont see why you wouldnt be able to achieve somewhere in that mileage goal with 3.42's and a t56. they have the .5 od so the car will just lope along just above idle like it does now i imagine.

i think the 750 dp is the way to go, like you say you are already set for the mods you anticipate. i had to go down on the jets and stuff with my 350 and i have mild heads and a cam already, you are going to have to go way down.

you dont have to worry about what the mechanical secondary does because it doesnt have anything to do with vacuum, thats one of the reasons i went that way.


skinny-mid throttle is never seen, at least by me. driving around town and by my house its maybe an eighth inch down, because i dont need to upset the neighbors or the wife riding with me on that rare occasion. at the track its wot obviously and i want consistency, i dont want to have to worry about if that thing is open or not. you know if you watch it open in the pits its going to open all the way.

BlackTopKing

iTrader: (1)

Jwfirebird,

Thanks that's what I was looking for. The rpm effect on intake combo.

Def want dual olane and I'm ok with performer rpm.
So that's what ill get.


I put my TPI on CL last night, got 3 who want to come see it. Its fairly cheap for litterly everything so hopefully it sells and that will go towards the carb.

I been looking at the modles all morning online new, but will look threw tge forum and CL as well for one.

RedLeader289

iTrader: (2)

If you know a little bit about carbs you can sometimes find good deals on ones that need rebuilding or a little work but are going for cheap. Don't know what route you plan on going or how confident you feel in that.

midias

Fairly often I find carbs that need a rebuild for 50-100 then a rebuild kit is usually 20-30 plus a little time.

Just helped my friend get rid of his 750 and got him a nice 600 really cheap that was great after a rebuild total cost was <$100.

BlackTopKing

iTrader: (1)

Well I'll explain a little better.
Since I have a week to kill in education and may in future get one to rebuild and learn on. I don't think I have the experience to rebuild a carb and troubleshoot if I made any mistakes. This is something I will be looking at learning though and have bookmarked some books to order.

I ment, hunt on intake used ect. Maybe look at carbs too....as I have seen ppl selling carbs (claim good) after making changes in their build or whatever....

Just my luck is. I don't find these when I'm wanting....only afterwards. But with TPI sold, I would rather not cut cost on carb aspect of this swap....my thinking is you can go cheap on a lot...just maybe not on other things.

This is what has geared me out of the edlebrock. I rather spend 400$ on something that will work on this motor and later upgrades then $100 now and $400 later....lol

But...I am looking

Shoot maybe I'll find a carb guy who wanna swap TPI...?! Lmao

midias

The edelbrock will work fine for your application. If it is a good deal go for it, there are many people who argue each way but get what you want then if you are disappointed later then you can always spend more and change it.

skinny z

If I can offer even the slightest bit of advice before you make a purchase and that would be to contact Holley and ask what their selection might be. You can give them both engine specs. What you have now and where you intend to be down the road. You may surprised at what they have to say. I'd certainly be interested in hearing it too.
The other bit, and I strongly recommend it, is to buy Vizards Holley book. You'll learn so much from a read through it that you'll be amazed. Seriously. I've been in this game a long time (Auto Technician 1979) and it filled in a lot of tuning mysteries and disspelled a lot of myths and BS.
The information on carb selection is very relevant to this thread.
Plus, when you do get a carb, it's has a step by step break down of what you're supposed to do and how to do it.
Reading that book before you consult Holley will arm with the information to ask intelligent questions as well.

http://www.amazon.com/Vizards-Modify.../dp/1934709654

skinny z

I suppose I should qualify that by saying part throttle response is ANY time the your not idling or WOT.
I understand your point of view regarding the ability to tune for the drag strip with a mechanical carb. That's the same reason the "magazines" always seem to have a DP when the engine is strapped to the dyno. They don't want (or need in their unique case because it's dyno only) to have to tune the secondary opening point. At the track, it takes some time and skill to get it right but in all reality, like I said, unless your stall speed is above peak torque or you dump the clutch up in the RPM range, the VS carb just may be quicker.
In the end though, it's go with what you know. If it works, then get out there and go racing.

five7kid

iTrader: (14)

The link from the primary to secondary throttle shaft doesn't pull the secondaries closed - it keeps them from opening more than the primaries.

VS vs DP fuel economy is a moot topic if you stay out of the secondaries. The primaries can be tuned identically.

I tuned my VS carb to death; bolted on a DP and picked up a tenth in the quarter, all due to improved 60' time. With an automatic car.

If your car is traction-limited, then a VS carb can be tuned to allow you to get off the line without instant tire spin. Popular in small tire classes.

skinny z

Fair enough and I'm mistaken on my observation. Not having experienced what your describing kind of leaves me scratching my head on that one. (I understand the operation of the linkage now that's I've had a second look).
I find it odd that under normal operating conditions, the secondaries would stay open long enough to have any effect, much less still powering the vehicle as you've described.

Kind of proves my point. I don't think it's possible to do that under every day driving conditions. The throttles are always be worked and despite the pump circuitry being inactive under minute changes in throttle postion, most if not everyone will suffer in the mpg department with a DP carb because throttle position changes are rarely minute. Especially with a manual trans. Our experiences with VS carbs show a decline in city driving fuel economy just from a change to a larger squirter size. Even the full volume of the shot doesn't change with the nozzle size, the amount discharged with smaller position changes results in more fuel being discharged earlier in the stroke. Double up the pumps and you can see where this is going.

What's your launch RPM? Do you leave off of a rev limiter? Which pair of carbs would you be talking about?

Don't get me wrong five7kid, I respect your experience a great deal, it's just that some of it contradicts what I've come to understand (through both experience and theory).
Perhaps this isn't the place to discuss it.

BlackTopKing

iTrader: (1)

Still could, if I didn't sell the TPI set up with in reason, I could fault to orignal plan.

With out getting to far into it, my TA fund is based on portions of side work and with car, in garage not running...kinda blocks side work....lol...sorta speak.

BlackTopKing

iTrader: (1)

Thank you sir, I had actually looked it up earlier from your post ealier in thread today at lunch and see the kindle app....thought that would be great buy eitherway. Might pick it up faster then expected with the book as an aid. I'm getting this tonightl...just mqy really want the paperback version (something about it....lol...makes ig feel real....idk, oldschool, I like turn pages)

BlackTopKing

iTrader: (1)

Call holley....simple enough ti make me really feel stupid, but think its a great idea. Will do

BlackTopKing

iTrader: (1)

Although I have nothing to add in this discussion, I very much welcome it and thew both parties getting a great picturd of the functions and its interactions...mainly because of my consern of a manual trans. The driving experiences and the carb behavor in both aspects....

Granted, most of mine will be cruises and day trips, but we all know the enjoy ment of getting on a nice countryside road and having some fun as well as joining in on the street night at the track.

I may not be an all drag car or a C class modified SCCA contender, but I do want to drive the Trans Am (if I didn't...I wouldn't even have it). But what's needed is an overall, flexible and reliable TA. In my signature is my link. I've spent 18months (20 now) building it. Which I mention to show commitment to this project ( I siad I was gonna do a lot of crazy stuff when I first started and most...said yeahhhhhh right) but I was brave, diligent and willing.

This is the same, just I'm getting to the section of the car little sooner then planned as I could use the pick me up, and positive morale booster of a nice ride wigh out a two truck fallowing me or with out a topdallor budget.

So this conversation, suggestion and information are booth helping me now, in achieving a nice practical and good structure swap to start off from.

The DP does sound like it would have some advantages, and maybe more of a carb for the (spare 5.7, this is the one I want to teardown, rebuild later so that when done, idea is to swap the current top on to from motor in car.) As the DP feature might be a fuel advantage for higher built performance motors....would it be too much of a carb for me now, considering my stock block, cam and heads? Vers the VS which maybe more friendly and perfectly capable of keeping up with the t56 and overall driving conditions?

When thread started and the topic was the 650edlebrock, my worrie was that with it being a VS that it would be troublesome with a manual...especially shifting ( maybe not so much on highway) but in normal driving conditions. I did enter this talk with the idea it had to be a DP in order too to keep up with a 4500rpm shift (upgear 1500-1800rpm for example).

From your talks I have a better understand and I don't really see the sudden rpm changes being as boggy (guess how to say) as I first forsaw.

Maybe just me...or maybe silly, but I have yet to relly find anyone go explain or compare a carb auto behavor towards a carb manual....just a lot of sbc with DP and 5spds....seems to be the thing....

I really just want to know, if it was....and little of why

So I really have enjoyed this talk and everyone's thoughts. And can't wait to get started and have some useful feedback.

BlackTopKing

iTrader: (1)

So fuel milage is going to be depending on the secondary tune? And on your VS set up, the secondary being vacuum controled onlh allowed that carb (even at max tune) achieve so much....were the DP carb set up was able to fill the blanks and get you more (same size carb)?

Sorry to re cap it, just asking so I can get exactly what your discribing....I def didn't think kf the trackion aspect of things....but really interesting point...as I'm starting to see carbs have this airsucking fuel dumping robot..when they are actually arnt!

I think I'm gonna really get inyo this more then I first expected.

BlackTopKing

iTrader: (1)

Great thread and a lot of information. Def appreciate bring that up as I am now on edge of my seat on how your new dizzy will intteract? Hopefully it resolves those issues and am looking forward to a post of you "cruising"

jwfirebird

iTrader: (2)

the fuel mileage is more based on your primary tune, because most times you dont open the secondaries while just cruising. the secondaries are more when you are "accelerating briskly" or however you want to put it. have you read the holley tuning sticky, its pretty good?

as far as the best setup for now and later, you are not gong to be able to have the best for two different setups. i wouldnt buy a edelbrock anything, have heard to many issues, but i would get 600-650 holley for a stock 350. but if you know you are changing it to a higher power stuff that would benefit from a 750 and the 750 isnt ideal but it can be leaned out to run "good enough" so to me sounds like you are buying new and it would be wasted money to buy a 650 or whatever and have to sell it at used money and get something else later.


as far as auto vs manual, i have a 400 but not real sure how any of it interacts. i have semi auto/manual valve body that has no vacuum to worry about like the 350, and got the mechanical secondaries so i didnt have to worry about vacuum issues. my cam is pretty big, have heard of issues with all that interacting so i got stuff that i wouldnt have to worry about

sootie007

The distributor fixed the abrupt dying issue ! It was probably the module inside . Still haven't been able to drive it yet and give final impressions as its still pouring rain here .

skinny z

Here's an article I came across today looking for more insight on the vacuum carb/manual trans combination. Nothing specifically mentioned about that there but it covers a lot of what's been discussed here.
http://www.hotrod.com/pitstop/1306_v...r/viewall.html

I still recommend the Vizard book as well as talking to Holley before you pull the trigger.

BlackTopKing

iTrader: (1)

Loved artical, between that and thread I am reassured and confident both in the swap and in the manual refection to carb.
I did order the book and should have mon Monday maybe Tuesday, I want to order some of the larger main parts this week...maybe by Thursday. So weekend I can take down TPI and get ready to install as the parts come.

RPM intake def, Mollory 4309 def and gauage at carb. And the Dizzy (still looking and comparing)
Ill get water neck and hoses and such, later this week locally.

Just coming down to carb. I have a guy coming this week to look at TPI. So if that sells, thatll cover carb. Still like to do the Holley, but if not ill probably take the Edlebrock to get strarted and save up for a nice Holley.

I imagine, changing the two isn't anything but bolt off bolt on...I don't have to change anything else....but hopefully TPI sells.

In mean time. Thank you everyone for all the help, I look forward to get started and make you guys proud (if my first carb tuning works well) if not , I know between book and thirdgen....well get it

BlackTopKing

iTrader: (1)

Would really like to get something like thishttp://pages.ebay.com/motors/link/?nav=item.view&id=121363731346&alt=web

skinny z

I highly recommend getting the crane fully adjustable vacuum advance kit as a replacement for whatever comes on the distributor you buy. It's adjustable for both amount of advance and the vacuum set point. There's an excellent and very detailed write-up in the Vizard book regarding tuning the vacuum mechanism as well as the timing curve in general.



http://www.summitracing.com/int/part...01-1/overview/
or
http://www.summitracing.com/int/part...00-1/overview/

skinny z

The reman stuff always makes me nervous. Great price mind you. You would have to get the list number off the choke horn before making a decision. It'll let you look up the vitals on that carb.

jwfirebird

iTrader: (2)

something seems fishy on that to me. ebay always makes me nervous. at best seems like the owner just put some new parts on it and they want professionally rebuilt money

I got this mallory 85. i am not a big fan of the not being able to take the wires off but besides that its much easier to change the weights and springs than stock hei, and the vacuum is adjustable already without the kit skinny posted.

http://www.summitracing.com/parts/ma...make/chevrolet

midias

And what motor would you be putting it on. Not a 350 hopefully, the 650dp will support over 400 NP.

BlackTopKing

iTrader: (1)

Awh no....
See that makes me nervous. I am not a big eBay person either but have been using it more in the past year and so far, good experience. But then again...haven't bought anything to substantial either.

Maybe I'm getting suckered into price...
So its suggest, buy from summit or jegs? Warrenty vers rebuild?

Guess that makes sense...

As for the 650cfm verse 750cfm.
I am still on the fence. As soon as I lean one way, something leans back. I do want Holley though...to bad I can get away with a 700cfm (compromise)...lol....I don't expect to see more then 400Hp on this motor (ever, lol)

I will check out the Mallory 85 this afternoon on lunch....

Truely a Shame could just get a complete carb noon kit...lol.

midias

Thats easy then, go ask holley

http://www.holley.com/data/TechServi...Carburetor.pdf

or use the interactive tool

http://www.holley.com/applications/C...bSelection.asp

Johnny Blaze

iTrader: (15)

Tuning the carb to not load ip and buck while cruising at speed in 6th gear will be the challange, that's where efi shines.

Qjet or vacume secondary carb will be much better for a cruiser than a mechanical secondary any day.

BlackTopKing

iTrader: (1)

Suggestion is
ChartsAppl:
670 CFM FOUR BARREL CARBURETOR PART #: 0-80670
Or
Interactive:
00 CFM FOUR BARREL STREET CARBURETOR PART #: 0-80457S

midias

Dont forget per the chart

So for me, 350, 6000 rpm max, on the chart is about 700 then figuring 85% VE 595 CFM. I may be figuring low but a 650 should be more than enough in any case without a supercharger.



CHART BASED ON
100% VOLUMETRIC
EFFICIENCY

and

Use the following examples as a
guide to estimate the volumetric effi-
ciency of your engine.
(A) An ordinary low-performance
engine has a volumetric efficiency
of about 80% at maximum torque.
(B) A high-performance engine has
a volumetric efficiency of about 85%
at maximum torque.
(C) An all-out racing engine has a
volumetric efficiency of about 95%
at maximum torque

Let’s take for example, a 300 C.I.D.
V
-8 which has a maximum RPM limit
of 8000 RPM. It’s been determined that
this particular engine has a volumetric
efficiency of 85%. According to our
chart the engine’s airflow requirement
is 700 C.F.M. at 100% volumetric effi-
ciency. At 85%, however, the C.F.M.
requirement is 595 C.F.M. This engine
would, therefore, require a 600 C.F.M.
carburetor.