What's up guys! I've been doing a whole lot of research and understand the actual swap procedure well but picking a carb/manifold combo is proving to be kinda hard because I'm so new to carb. I don't even know what's a good brand what a vac. Secondary is or why people say a double pumper is better.
I'm goin out on a limb and I'm gunna say a Holley 750 cfm vacuum secondary with a rpm air gap intake would be a good combo for my stock internals 350? Or is that to big for my setup? It's a bare bones motor, no emissions, heat or ac. Would a mild cam even it out? If so which one should I look for? I don't have money for cam and heads yet. Also since it was a tpi I do have a hydraulic roller set up. Also what kinda dist. Should I buy? Mech. Advance? Vac. Advance? Any help would be nice. I have a budget of 700.00

 

I'm under the gun the get this thing running this weekend so I just bought these few items. Hope it works!! Lol
EDL-2604
MAA-4309
PRO-66941
And this refurb. From eBay
http://www.ebay.com/itm/360657444015...84.m1439.l2649

 

Intake I prefer....other then that you look good.
http://www.summitracing.com/parts/pf...make/chevrolet

 

Oh yea that's nice too, I like the price tag as well. I heard rpm air gap was the way to go though... I'm sure it won't make to much difference on a mild 350.

 

That manifold is just a cheap knock off and in your application you probably couldn't tell the difference between the two on your motor. I've seen one manifold from Professional Products where the casting wasn't the greatest and I've seen some were they looked okay.

Plus that 750 is a lot of carb for a motor with stock heads and cam.

 

750 seems like a lot of carb for your motor.

I would go with something smaller

 

The RPM Air Gap gimmick is kind of pointless. It's a good intake, but the ports are the same as the regular RPM, which is cheaper. Take a running motor with an aiir gap on it that's been running longer than 10 minutes and I doubt you'll see much if any difference in temperature from the runners to the engine itself. Regardless a barely cooler air intake charge doesn't make as big of a difference as people would have you believe. 750 is too much carb, but since it's vacuum secondary it should be doable. It might be easier to tune a 650, DP or vacuum secondary.

I would stick with EFI if I were you. A holley stealth ram perhaps? Super ram?

 

Under the tech artical I read on picking a carb it said to go a little larger because an engines average flow rate might be 650 but engines don't take in air smoothly. In really they might be pulling 300cfm one second and 800cfm another second because the pistons go up and down in sequence. At least that's how I understand it. And people have told me to keep the tpi but I'm just so over it. It's constantly breaking on me and there is no arguing a carb is easier to work on. More reliable in my opinion too. Well see how it goes but Im excited to make the switch that's for sure. Tpi's are sweet looking and cool engines in general but I just feel like try take the oldschool out of these cars. I'm living the carb life now boys! Lol

 

I'm not expecting the air gap intake to blow me away but I did read somewhere on this forum that a company tested multiple intakes on the same engine and the rpm air gap did the best. And I'm hoping I can just jet the carb slightly smaller and it'll work out just fine and give me room to upgrade when I go heads and cam. The tuning a Holley sticky on here seemed very helpful and I'm excited to follow it and see how it turns out. I do like the stealth ram though! Maybe ill buy another thirdgen down the road and give EFI another shot when I don't need it to be my daily driver but for now carb it is! I could always switch back if I hate it..... Lol

 

What cam and heads are you going to be using. I know a lot of people then went from a 750 to a 650 and enjoyed the results on 300-350ish Hp motors. A stock l98 will not do well with a 750.

I run a 600 on my vortec build and have tried a 750. While I gained some top end near the 5000-6000 RPM range it suffered on low end driveability and had an off idle shudder I could not get rid of to save my life. I work with carbs a lot and generally don't have to many issues tuning them for driveability.

 

A Holley 650 will support over 400hp no problem.

 

So you think a 650 mechanical secondary would be better?

 

Well since I've got a world class t5 and stock rear behind it all I'm not looking for more than 350 hp max and that's pushing it. I'm not sure on heads and cam but those are my hp goals. Deffinatly not top of the line stuff. Probably a budget for cam and heads is around 850.00

 

I do, a lot better than a 750.

Go with a 600 or a 650 carb brand of your choice.

You can probably tune a 750 to work well with it but it will be far more of a headache.

 

The reason I say stay with EFI is it's really a lot harder to switch back than it is to switch to carb to begin with. Costs quite a bit of money too if you dont keep all your TPI stuff. I would suggest you keep it somewhere. You can always get a super ram setup and bolt it onto your TPI manifold and computers etc. But if its not a DD, that changes things. But I just feel like any car that makes streetable power should have EFI. Carbs should be for cars with big cams I think. Although the 083 heads are not fantastic, they will wake up nicely with something like an LT4 hotcam or even larger, and the carb will support the power increase much better than TPI will. There are very real advantages to carbs especially as you up the power level. But for a mostly stock car it's good to at least sit and think about it a minute.

Moreover, the RPM (Air gap or non air gap) is probably the best performance street manifold available. The equivalents from Holley (Weiand) are probably close, maybe better, but they're not as well proven. The Professional PRoducts intakes are just cheaply made chinese interpretations. They may not be bad, but quality control and attention to detail is what gets hurt on those. Edelbrock does a lot of things badly, but the Performer RPM series is the gold standard for street performance. You cant really go wrong with either. Just stay away from single planes and torkers etc.

http://www.hotrod.com/techarticles/h...pm_vs_air_gap/

The Air gap made 3 more horsepower over the regular RPM in a 600 hp engine. That's a .5 percent increase in power. That may even be within measurement error. You'll never feel the difference between them, so if you want to cut a corner, cut the air gap down to a plain RPM. You can even see the picture in the article that shows the Performer RPM has the exact same runners as the air gap. So if you want to save $30-$50 that's a good place to do it. The air gap definitely looks cool and everyone will assume your car must be much faster with it, so if that counts for you, go for it.


Since you have a T5 I'd say go with the DP. They're finnicky to tune, but it's not too bad. I barely know what Im doing with mine, but the holleys are easy to understand when you take em apart, and I've got my car running nearly perfect by a combination of guesswork and reading the holley tuning thread. The hardest thing to get right is flooring it from cruise... The holley tuning thread will tell you how to get cruise and WOT and idle right. From there you'll have to experiment with power valves and squirters to get the secondaries to kick in just right. It's really the only tricky part and it just takes a little experimentation.

There's a lot of voodoo in the cfm ratings of these things. Do a little research into carburetor CFM myths if it interests you. NASCAR setups made 700+ hp through what I believe was a 390 cfm carb. Corvette C6R LS7.R engines breathed through two 30mm restrictors and made tons of power. Smaller carbs get better throttle response, and larger carbs get better air flow at wide open throttle. Get one thats appropriate for your power level. A 650 may be a little large for you, but very manageable and should work out fine and grow with your setup.

 

You know that's not a bad idea to just keep the tpi stuff around. Ill keep the computer, runners plenum, fuel rails, injectors and, tb, but I sold the nice ported setup I had already. I think if I ever do go back to efi ill do it right with totally aftermarket efi system and something much easier to work with then the tpi. And im just putting a regulator on my intank fuel pump so it really would be too hard to go back if i ever wanted too. There is pros and cons to each for sure.

 

And my air gap will be at my house tomorrow so ill just keep it I guess. It adds some style points too lol.

 

What about these heads?
http://m.summitracing.com/parts/tfs-30310005

 

Those are good heads. Avoid pro comp, if you go cheap I hear Blueprint Engines makes some decent (not great, but decent) aluminum heads. They're a great alternative to mediocre with bad QC procomp type heads. I think Trickflow is one of those brands that's not really the most popular right now, but they're still great heads. Brodix IK series are really good but currently are having a very bad problem with premature valve guide wear which is a big deal. They may have that fixed by now... but I wouldnt want to guinea pig it... Avoid edelbrock heads. You can do a lot better for less money than those.

The top of the heap according to the community seems to be AFR and Pro Filer. Make sure you look into Pro-filers. "Jegs" brand aluminum heads for an sbc, are actually Pro-filer heads. This may have changed, but that's been the case for a while. SO that's a GREAT way to get into a pair of those for $1000. And those are VERY good. Summit aluminum sbc heads I think are Brodix IKs? Im not sure, but with the valve guide wear issues they're having you may want to keep your distance from those.

Choosing between pro-filers, AFR's, and Trickflows etc is going to make it really hard to go wrong. They will all make great power especially if you stick with a roller cam.

Also. Keep your TPI harness and all your sensors. Preferably keep them sealed. The TPI computer and sensors etc will work with all of the aftermarket intakes. The actual aluminum of the intake with the TPI is probably the least useful part. The harness, sensors, manifold base, injeftors, fuel rails, and throttle body are the parts you'll want to keep

 

Yes the 750 can be made to work...I have used them with great success on mild to wild sbc's but your right....getting there, to where they actually work right can be a hassle. I spent the last weeks chasing a tune on mine that was flawed from the word go by a hairline crack in a metering block....soooo
My combo is as simple as it gets.
355, zero decked, flat tops
Pro-Filer 195's
Tiny comp 268H
Comp roller rockers
Performer RPM
Holley 650DP
Headmen Shorties
Its about as cheap as u can get without using pro comp or blueprint heads.
And it would shock you how well it works.
With a 700R4 and 327 gears it shows 12.65 on an obviously optimistic g-tech dashboard dyno.
We have some Fri night fun on an almost legal "track" and I have put down a fairly modded skyline, a silly 4.6 auto stang on a 100 pill, a 396whp speed 3.
Ive also been handed my *** by an M6, a newer Vette with almost no mods....but I digress
For the cash the pro-filers are pretty hard to beat.....
If you just can't swing the 1100 bucks then look at Promaxx heads. They are re-branded patriots and can be had as low as 850$. They are head and shoulders above pro-comp and i have, as well as several friends used them with amazing results.

 

the 750 will be fine, you just have to tune it a little until you get the cam and heads. being a manual you have a advantage of being able to start higher and overcome the slight over carbing until your engine mods require it to be changed back


you are going to need to wire the pump to come on somehow and not sure if that hei comes with connectors, i think i went to the yard and got some off a old sbc car. the big pink has to go to keyed voltage and the little white is the tach signal

 

Not sure what CC size your old heads are but those are 56CC so just be sure they will give the compression you want.

 

I think you got the right idea. I've been into cars since the 80's and have worked on street rods to drag racing cars over the years and you are right there are pros and cons for both. My main issue with TPI systems is that the OEM system is not tuner friendly as compared to more modern EFI systems and they are RPM limited due to runner lengths. I'd rather have something more modern like a 5.3 liter Gen III

I installed an Air Gap because I got it for $25 used.

 

Just an FYI, RHS heads are good as well.

 

Well apparently I can't exchange my carb cause they guy wont return my emails and the 750 is on its way... I guess it'll have to do for now. You think ill even get it running out of the box? Once it starts I think I'll be able to tune it ok. And the issue with a bigger carb is to much gas right? So ill need smaller jets, Does anyone know te size of 650cfm jets? Will I be able to just swap them out and get it running that way? So many questions.. Lol

 

Its a VC secondary right? Leave the jetting alone and it will be fine. The challenge is more idle and tip in issues when your over carbed. Run as much initial timing as you can without going over 36 total, use vacuum advance with a 10-12 degree curve from a manifold source, you will be surprised. The 750 will work just fine and your going to be close enough on jetting that without a timeslip your not gonna know the difference.

 

It is usually not an issue with extra fuel but more with poor atomization. It will work out of the box and may work fine after you tune it. Most people with 750s get weird studders at low throttle or when they mash it.

 

That makes me feel better. And yea it's vac secondary. Now when you say 10-12 degree curve on the dizzy is that just what I should expect or is there a way to get a more aggressive curve out of a distributor? And 36 degrees total advanced timing; when I'm looking for total timing is there a certain rpm I should hold at or will it eventually level off and that's just where i should hold it

 

Yes it will eventually peak and level off. The RPM that this happens depends on the strength of the advance weight springs and the weight of the advance weights.

 

If its a stock HEI and a stock cam, you may get lucky with having to limit timing, most hei's have a 20* curve built in, so I would start at 16* initial, giving you 36* total timing. Your spring combo will dictate how fast it comes in. If i remember right I use 2 medium springs. You want it "all in" by 3000rpm.
Leave the stock weights alone and just play with the springs....
Actually, instead of me spouting info lol, read this....its excellent and very useful and give u the answers u need.
http://www.crankshaftcoalition.com/w...EI_distributor

 

Wow that's a sweet write up! My brain hurts now lol. So much information!!!!! And I just realized the 750 i got is a manual choke. Not dealing with that so i might just resell it and probably take a hit but whatever, lesson learned. My local pepboys just got this cool "speed shop" section where they actually don't sell garbage! It comes at a price of corse but whatever. I'm heading over there now to see what kinda carbs they have. Is it the end of the world if I go with an edelbrock carb? I know people on here don't really like them...

 

Carb? Your nuts...

Cam, HSR and injectors, then bring it to me for a little prom tuning...

 

Damn your right in old bridge too, I'm over there all day for work... Wish I woulda known that a week ago. I had a pretty sweet tpi setup too, slp runners, Bosch III's had the whole thing fully ported. Oh well, I'm still excited about goin carb. I just love the simplicity of it. It keeps the oldschool in these old school cars. And when I do get heads and cam I won't have to take it to get a chip reburned.

 

I never ever burn chips for anyone, but when hearing how someone local wants to switch from fuel injection to carb I will definitely try and help them out with it before they make the jump, as well as teach them what it is we're looking at on the screen while I do it...

Carbs are just as good though, tear up those streets when it's done...

 

i would keep the 750 4160, its simple and easy to learn, just hook up a manual choke to it. i got a 4150 for simplicity manual choke and manual secondary because you know that if the lever is in in the flap is open and you can adjust it if it only needs to be open a second like on those half warmish days. electric choke you dont know what its doing same with vacuum secondaries, but if you already got the carb i wouldnt sell it especially for a loss

 

It's coming along nicely I think.... Lol. And I am keeping the 750. YOLO!!! Hahaha, running the choke was annoying but it's done and looks good too. I'm pretty much done with the wiring I just have to finish te fuel lines and tighten everything down. I'm done for tonight but ill get back on it tomorrow after work. I'm excited!!!

 

Yea I still have lots of respect for the efi guys, maybe even more so now because I made the jump over a problem I just couldn't figure out. (I did try though, there is a thread in the tpi section of my issue I couldn't figure out) both induction systems have proven themselves time and time again. And if it wasnt my daily driver I would've kept toying with the tpi untill I got it going but I don't have teh luxury of time. One day ill pick up and old 350 tpi camaro as a project car and stick with the efi. HSR would be awesome. Ill come back to it when I'm ready lol.

 

YOLO?

im pretty good with electronics(its my profession) and i tore everything electronic out a long time ago and have not regretted it one single bit. i dont want it in my hobby for one and for two modifying car computers is a pain especially obd-1. people ran no electronics in their cars for a century and those cars were daily driven in all conditions imaginable

 

I am in the process of wrapping up my turbo build, but I am going to run the engine naturally aspirated first to get a feel for the cam I went with, along with the cylinder head and intake work that I did. Let me know if you want to run me over at e-town one night, as I need to get a few runs in before I slap on the turbo charger. It's over in the power adder section if you wanna take a peek at my build...

 

That would be sweet! Wouldn't be much of a race lol but I'm down regardless once I get her up and running. I haven't been to etown since I got my camaro but I've always wanted to give it a shot. What do you think I would run? High 12s would be sweet but I doubt it given my set up now.

 

Ok so I'm in the procces of settin the timing and a need a sanity check; when your at TDC and you set the timing to face the number one cylinder and set the plugs correctly my distributor can't be 180 wrong right? That's only if you don't if your at TDC or not right? I'm getting flames through the carb but I can't get it to start up.....

 

Rotate the engine until the rotor points at cylinder 1.Then take the distributor out and rotate the engine until the timing mark is at TDC AND cylinder 1 is at compression else you will be 180 off. Then replace the distributer

 

With the engine assembled, the only way to know for sure is to pull the number one plug out, rotate the engine by hand (ratchet with 5/8" socket), and listen for pressure build up, then you'll know where you are. The only other way is what you just did, set to one, see if it backfires then you know your 180 degrees off and on the wrong stroke...

 

Yep, its 180 off.....
Roll the motor until it pushes your finger off the hole from compression, then when you get to this point, assuming your balancer and pointer are correct, when you see TDC drop the dist in pointing at #1
Your going to need to give the dist a slight turn counter clockwise to advance timing so it will start easier.
As you didn't replace a cam (IIRC) then your not conceremd with break in, so get your timing light on it, get it running, set your initial at 14* with vacuum advance plugged, then go drive it and see what you think.

 

I like to put my finger over the #1 spark plug hole, you'll feel when it's on its compression stroke. Once you get there, you just turn til the damper lines up with the timing mark and you're at 1 TDC (assuming the damper is correct, obviously.)

 

Thanks guys!! I had it wrong in my head. It started right up after I spun it 180. With no choke too! I didn't have any coolant and it was getting late but just the few seconds I had it running it sounded and felt great! Can't wait to get the timing like on it and get it running perfect. Ill keep you all posted. Thanks again for the help!

 

Cool you got it running!

I did the same thing on my first car back in 1984. Had to replace the timing chain set because the plastic coating on the cam gear had broken off. My Dad told me to line up the dots, he didn't show me because I wanted to do it by myself and I wound up having the cam at #6 instead of #1. He got a good chuckle out of it when I had a good size fireball come out of the carb which scared the hell out of me.

It was a 72rs, 350/TH350, 2bbl, 8.5:1 compression. Later I installed a Performer manifold, Holley 600 and Cyclone headers.

 

So it's cruising around but once I has it past like 2200 the power drops off the table... And if I'm cruising at like 40mph it's very jumpy feeling. Since I'm so new to carb I don't really know how to diagnose it. Any ideas?

 

Where, and how, did you set the timing?

 

With a timing light but the stock timing tab only goes up to ten so I just guesstimated on where 12-14 would be. I really need to order some timing tape. And it's just a thought but could to much fuel pressure cause me to starve the fuel bowls when it has it up? I bought a cheapo fuel pressure guage that mounts to the carb fuel rails but its reading like 16psi with my Mallory PFR totally loose.... Would it even run with that much PSI? The gas did flow out through the blow breathers a lot when I first started it up. And I had to cut the gas way down. I used my stock fuel return line. Is it big enough?