Pablo

iTrader: (1)

Hello all,
Just wanted to drop a line about a swap I just completed. The engine is a stock LB9 w/ t5 (non peanut cam). Headers, full exhaust.
TPI unit was stock with the exception of 24 lb injectors. Injector constant was adjusted and factory rich WOT tune was corrected. The car ran strong but of course ran out of breath very quickly. Made good torque. Would be a good setup for towing.
Swapped to a 650dp (4777-5) and Performer RPM. Doing this swap correctly and cleanly is not cheap but worth it. 1 inch open spacer, dropped the front jets to 65s, put .015 wire in the IFRs, 9.5 power valve. 31 primary squirter, 28 secondary, blue pump cams, and choke delete. I am using the stock computer controlled distributor with 730 ecm controlling the spark timing. I had to rework the chip to compensate for a lack of TPS PE spark adder.

I weighed both setups and the SD TPI with everything including the over radiator camaro intake snorkel was 44 lbs. The carb setup including everything is 38 lbs. So a 6 lb loss up high. If you went with one of the newer aluminum holleys I believe you'd lose another 4 lbs. It all adds up.

As for performance, the car is an animal now for what it is (lightweight road race car with 3.73 gears). Pulls hard to just shy of 5500. Power doesn't drop off abruptly either so shift points are less critical than with the TPI. No et or dyno numbers just some friendly before and after races with a friend (big difference there). As someone with years of seat time drag racing and time attacking the qualitative improvement is definitive.
I've done a similar swap before, with a 454 TBI to Edelbrock 600 on the same manifold, both were wide band tuned at the track. Edelbrock won hands down even without enough pump shot available.
To get this kind of performance out of the TPI will cost you 2-3 times as much in time, money, and effort. Not sure you'd see the same gains with a peanut cam car.

Just wanted to add my experience in case anyone ever wondered about this particular combination of parts. I will probably experiment with pvcr size increases in combination with jet decreases to get the part throttle AFRs where they need to be. Runs really well though as is.

Pablo

iTrader: (1)

Thought I would add a pic. Forgive the nasty engine bay. This is not a show car by any stretch.

I forgot to add a couple of tips, first off, the TBI throttle cable works for this swap. Secondly, the allstar throttle cable bracket I used is excellent though I would advise against using the dual return springs (just use one) with this throttle cable. With dual springs the added force required ended up pulling the crimped end of the cable through the plastic retainer that snaps into the pedal arm. I will have to come up with a fix for that.
Lastly, the holley throttle stud 20-37 (7/32") works perfectly with the TBI cable. Another thing I discovered is that the thread and length is exactly the same as the bolt that attaches the return spring to the throttle arm on the carb with the allstar throttle bracket. After realizing this I moved the throttle cable there and re-adjusted the bracket for proper opening. This gives you almost exactly (if not better) pedal travel than the stock TPI and much much better travel and feel than the other throttle stud mount holes on the double pumper.

Johnny Blaze

iTrader: (15)

What about milage comparison between the two?

Pablo

iTrader: (1)

The pvcr to jet ratio of a 650 dp basically guarantees worse fuel economy out of the box. So having not changed that, I am sure it is worse.
I do plan on tinkering with that and I think I can match or beat the stock TPI tune. They like to stay close to stoichiometric for NOx reduction. Carbs don't care.

Johnny Blaze

iTrader: (15)

Itemiezed parts list and price would be interesting as well. How did you make the center bolts work with intake?

midias

Looks good, now get one of these for that hole in the wall.


http://www.ebay.com/itm/82-92-CAMARO-FIREBIRD-HEATER-A-C-DELETE-PANEL-/150818293882?pt=Motors_Car_Truck_Parts_Accessories&hash=item231d78887a&vxp=mtr

Pablo

iTrader: (1)

The center bolts of the intake just need to be slotted a good ways. I started with an air grinder and fluted bit but ended up just using a rat tail file. A little patience is necessary as you'll have to remove material and then test fit the manifold until bolts all fit. I was all set to make some angled shims to fit under the bolt heads but realized that this was really not necessary. The way the heads end up, the bolt (or more appropriately, cap screw) bearing surface is in fact not at the edge of the head because it ends up toward the outer edge of the manifold. A little hard to describe. I might snap a pic if you need it. So all things considered, it's fine to just tighten them down as is.

As far as itemized parts list, sure, lets start from the top
Edelbrock 14x3 drop base open element air cleaner ~$32 from Amazon
Holley 4777-5 - purchased used 10 years ago with accel pump tuning kit and jet assortment 65 to huge - $150
Holley Fast Kit 37-1544 to give the carb a quick freshen up - $38 from Summit
Allstar ALL54210 Silver Anodized Throttle Cable Mounting Bracket for 4150 Style Series Carburetor - $70 from amazon (pricey but worth it)
Edelbrock Low-Profile Vacuum Fitting Reducer 8096 (You can probably find the same thing at the hardware store for much cheaper) - $13
Trans-Dapt Carburetor Spacer 2103 - $26 from Summit (they include the absolute cheapest studs with this thing but I was able to make them work)
Edelbrock Performer RPM 7101 - $170 Amazon
Mr. Gasket 6080 Super Intake Manifold Bolt set - $17.50 amazon
Spectre Performance 29683 Dual Feed Fuel Line for Holley 3310/4150 - $37 amazon
Spectre Performance 4933 Aluminum Water Neck for Chevy $21 - amazon
Holley 12-803BP Fuel Pressure Regulator - $73 amazon (check the threads in this thing, I found chips from the machining process)
Goodyear 62160 SAE 20R4 Molded Radiator Hose (tbi car hose) - $17
Earl's Performance AN to NPT Adapter Fittings 981666ERL, qty 4, total price $16
Earl's 9894DBH 14 mm to -6 an fitting adapter (hard line to AN line) - $7 amazon
Earl's 9894DBJERL 16mm to -6 - $9 amazon
Earl's 991204ERL 3/8 to 1/2 npt reducer (to use CTS in manifold) - $6
Earl's 993205ERL 1/2" plug for manifold - $5
ATP Y755 throttle cable - $15 rockauto
Holley 20-37 throttle stud - $7 summit
pine tree air freshener 99 cents ( jk)
AN hose and fittings I had laying around, one 45 degree - 6, one 90 degree, and three straight fittings. A couple of feet of hose. You might want to spend the money on teflon hose (rubber braided hose breathes a bit)



So you are looking at the better part of a grand to do it the way I did it. A lot of the costs are the same as if you were to go to an aftermarket EFI manifold.
You could cheeseball it and do it for half as much but I've been there and done that, not my cup of tea anymore. I also needed something reliable and safe for road course use.
The nice thing is that this setup will support a lot of power (this will be transferred over to the next engine), and when a lot of power isn't enough, it's another $150 for a 750 main body.
I have an 11.2 second T type to get my fix in that dept. though.

Pablo

iTrader: (1)

Thanks for the tip Midias. I just might have to pick one of those up.

Alice89

iTrader: (6)

Thanks for sharing the weight comparison. I'm basically about to do the same switch you performed (I'm following a David Vizard 383 build). I'm building my car to handle so every little bit of weight off the front helps; especially when its that high in the engine bay.

Ignore the mess of a garage and dirty valve covers:

Pablo

iTrader: (1)

Looks good.
I really prefer the classic dichromate finish on your carb. Looks like it means business. I wish mine was that way.
For weight reduction it's hard to beat a pair of aluminum heads. 50 lbs is no joke. With all of the aluminum bits on an SBC it looks like you can get within 25 lbs of an all aluminum LS. Definitely lighter if you compare an SBC w/ aluminum parts + T5 vs an LS/t56 combo. Probably close to 50 lb advantage to the sbc combo.

dmccain

iTrader: (2)

Everybody keeps ******* on the "peanut cam" EVERY stock cam in 3rd gen V8 is a peanut cam! Every time an engine is pulled if your not going back stock it should be used for scrap iron.

dmccain

iTrader: (2)

The PEANUT CAM that is

jwfirebird

iTrader: (2)

curious as to why you didnt get rid of the pcm controlled ign? you lose alot of weight with the pcm/ all that wire on the passenger side harness,etc

Alice89

iTrader: (6)

Thanks! Yours is looking good too.

Agreed. I'm running a T-5 and the weight difference between it and the t-56 I planned on putting in this car is huge! I have not weighed it yet but it has got to be at least 100lbs heavier, No joke. I'm seriously re-considering my t-56 build; it's that heavy. I just don't know of another manual transmission to go with that can take some power.

While the vortec heads I have on this build flow well; they weigh a lot too. Aluminum heads are definitely in the near future for my build.

Also Pablo; I cant tell in the picture of your engine if you have one. But if your not running an aluminum water pump you may consider grabbing one. The weight sits far out in front of the wheels. The stewart pump I have is noticeably lighter than the old iron one.

Good luck with your build!

Alice89

iTrader: (6)

Just venting? lol

92g92

Every time someone swaps out EFI for a carburetor on anything other than an all out build, I cry a little.

Alice89

iTrader: (6)

Yea its such a tearjerker lol

sarcasm off.

InfernalVortex

iTrader: (4)

As someone who went TBI->Carb for a rather pedestrian build....

I agree with you. I'd do it differently if I were able to do it again knowing what I know now. But this is Pablo we're talking about, so I presume he'll make it work pretty well.

If it's any consolation to you... that 100 lbs is down very low and centralized in the car. If you're going to add 100 lbs, that's the best possible place to put it.

Pablo

iTrader: (1)

I hear you. They are all peanut cams, there's just one that is really a peanut more than the rest. This is coming from a guy that runs a 214/214 in a 3.8 V6 and considers it small too.


Couple of reasons, you wont lose "a lot" of weight by removing the ecm and harness. The ecm itself hardly weighs anything (1 lb?), and I can't see the harness weighting any more than 5 pounds. Probably closer to 3. I'd also still need some of the wires out of it for the thing to work and the mechanical dist itself will weigh slightly more than my dist.
The second reason is that I already have an eprom burner, software, and experience doing this on a a speed density setup before. A mech. dist. with all the bells and whistles is going to be somewhere around ~$150 or more. I have better than that (fully programmable timing setup) basically for free.

Yes, I have a weiand aluminum water pump. I swapped to the standard rotation pump along with getting rid of the old serpentine setup. Just doing this (smog pump and AC had already been deleted) dropped 17 lbs right off the front of the engine.
As far as your T5/ t56 goes. I hear you on the durability question. I've always been intrigued by the Gforce T5 as an option, or maybe a 4 speed swap for a track car.

I hear you, I used to cry a little too when I was smoked by carbed cars
EFI has had a lot of really overblown press. I have done both fairly extensively. I've run as much as 30 psi in my buick with dual M15 Methanol and a window switch nitrous system (controlled by the ecm) with closed loop open throttle. Forced induction, E.F.I. rules hands down. I've been doing my own chips and tuning since '98.
For naturally aspirated, you aren't missing much unless you are one of those guys that gets really into tuning chips on your dog slow car. I'm into performance, not nailing a particular IAC count on the money. I don't care if my car takes a minute to warm up. Fact is, there are very few fuel injection setups that can match an out of the box carbureted setup for WOT power (where WOT matters, not some stupid low rpm), and driving the car around, I actually enjoy it more because there is no throttle follower or weird IAC action changing my idle all the time. It is particularly annoying because I live on a mountain and basically coast downward to civilization for 20 minutes. Could I fix that on EFI? Sure, I could spend a lifetime messing with something that I nail in 15 minutes on my carb, and the TPI would still never in its wildest dreams make the kind of peak power the carb does. I have tuned both and datalogged using wide bands.
The carb is more reliable too if you are a car guy. What you see is what you get. I spent months tracking down and intermittent miss on my TPI that I traced down to a corroded injector junction in the wiring harness. That kind of aggravation is a lot less likely with carbs. If something is not functioning you just look at it and figure out why it isn't.
So anyway to sum up, the carb is much better where it counts (for me) and "good enough" everywhere else. If you are really into having your car crank in 1.2 seconds vs. 1.5, and having exact 128/128 in all of your blocks then play with programming for a few years on your 14 second car.

jwfirebird

iTrader: (2)

i agree its not alot of weight but like you said every little bit helps, pretty sure copper weighs a significant amount. i never weighed mine but it had a efi-2.8 and a big wad of wires, all gone. the idea more was an aftermarket aluminum self contained dist because of the weight savings. as far as cost man have things gone up in the last few years looking at the one i bought from summit a few years ago is more than 50% more now. but still worth it to me because for the same reason you compared efi to carb, i would rather just make a little twist on the dist or change a spring than have to mess with computers and tunes.

skinny z

Why a mechanical secondary?

jwfirebird

iTrader: (2)

ill will say why i got a mechanical secondary, its easier to see at the track and tune. you can watch it and move the linkage and you know for sure when and how far it opens

Pablo

iTrader: (1)

Light weight, Low gear (3.73), Manual transmission, road race usage, and it helped that I had the carb already though I would have selected a double pumper regardless since it is well suited to my application.

Alice89

iTrader: (6)

You mean you cried too? Lol just messin with you.

Yes this is true. I've considered it that way but still. Its just a lot of added weight.

Awesome job on the weight savings! Like you said all that weight adds up. and that 17lbs you lost; was all in front of the wheels.

lol damn

skinny z

That's why I asked. So many enthusiasts make the mistake of going to a mechanical secondary carb because the "racers" do it. Same for forgoing the vacuum advance on the distributor. For most, both are foolish moves predicated not on fact but on misinformation.
Sounds like you're not one of them.

InfernalVortex

iTrader: (4)

And a lot make the mistake of going to vacuum secondary because "racers" tell them to. Tune em right and I dont think there's much of a difference, really.

I do run full manifold vacuum to my distributor, though.


When Im dealing with the fuel boiling in my feed lines and the constant ignition module failures (went to a stock type Borg Warner module and it's been fine ever since...) and a coil failure and so on... yeah... sometimes I wish I just had a bunch of factory junk on it. But I do stay away from Accel stuff. I try to keep my ignition full of stock replacement type stuff at this point.

skinny z

Here's my understanding of vacuum vs mechanical.
If torque output below peak torque is of any consequence then the vacuum secondary is the way to go. If the converter stall is higher than peak torque then there's no advantage to a having vacuum secondaries. This isn't to say the mechanical carb will be faster though.
A well set up vacuum secondary carb can provide better performance and faster times. The primary side functioning only at low WOT engine speeds will provide a better and more thoroughly atomized mixture and as a result produce greater torque as compared to the slower speed of the charge if it passes through four barrels. If the tune is on, the second barrels will provide the air/fuel charge as the engine demands it.
If you pick the right vacuum carb for the job, then there's no downside. If you choose a mechanical carb for an engine that doesn't really need it (see the prerequisite mentioned above) then you could be losing torque through the entire rev range.
Just like cylinder head port volume, it's important to keep the velocity up. Put big a port on an engine that doesn't need it and torque production is down across the board. We all know that. Same applies to a carb not only in cfm (something else we're all aware of) but in function.
Just something to think about when selecting a carb, especially a multi-purpose vehicle that sees more than just WOT.

But I'm not here to argue. I'm sure Pablo is quite comfortable with his setup. He knows the carb as has it tuned so there's not much more to say.

skinny z

Interesting that you should bring that up. I've just finished the installation of a new Crane fully adjustable vacuum cam and limiter (again). Connected to full manifold vacuum, the engine has never run better. Smooth 700 rpm idle, cooler idle temps, better throttle response and with the total vacuum amount dialed in, better fuel economy both city and highway.