TPI to Carb
 

Hey guys, geez it's been a while. I posted this on thirdgen thinking I might get more responses, 93 views and nothing. I'll copy over what I have written there:

I'm getting fed up with TPI tuning and having issues. The car is hardly used, strictly a nice weather car that sits in the garage most of the time and is not the worth the hassle. I'm going carb.

A little background: It's an 89 350 TPI, new GM heads probably about 2500 miles ago, Hooker super comp LT's, mufflex ORY, Magnaflow, 3.42 rear, and I converted it to a T56. I had the tail housing converted to use my stock speedometer, nothing is computer dependent.

I'm unsure of which intake, carb, and distributor to use. I've read a little bit but I'm still not sure which direction to head, this is all new to me.

Victor Jr intake, Holley 650, HEI Distributor?

Ted,

IMO a Performer RPM Air-Gap is way better suited for most street combinations than a Victor Jr. In a lot of dyno tests it outperforms the Jr by a few hp/ft-lbs under 6500 RPM. If your heads run out of steam before then it's a no-brainer.

How balls-out do you want to go? Do you want to sacrifice some drivability to get every last hp out of it?

what is wrong with your TPI?

This isn’t a hassle? carb, air filter, throttle cable & linkage, distributor, intake, gaskets, bolts, fuel pump/fuel system plumbing, some wiring changes, etc. Who’s tuning the carb?

cam matters too. a victor jr is not the right answer. What heads?

Bill, I guess I'b be willing to sacrifice driveability, I feell like I do that now lol. My ultimate plan is to build that 400 I have with a carb so I was hoping to be able to utilize the same intake and maybe carb, not sure on that one though as the 400 willl be cammed with good heads etc.

Scott, It's more so the whole fuel injection system. I've had electrical woes forever. Josh was able to get a tune in but it was by piggy backing the chip on a desktop, not through connecting with the port. One example is i'll have it running, go around the corner to get gas. Start it up again and it will crank and crank but nothing. Wait a few minutes and it'll will fire. While drivng, coming to a stop I push in the clutch and apply the brakes and rpms drop like it wants to die then they shoot back up. It's a lot of small issues like this and I'm tyring to elimate the BS.

I don't see it as that big of a hassle, intake, gasket, bolts, buy an air cleaner. I already have a walbro in tank pump so I'll need a regulator to drop the psi down. My dad will tune the carb for me, that's his game. Stock cam and theyre stock spec heads that had a valve job. When I have the means the 400 will be carbed regardless so this all has to happen at some point. I'm just thinking I'll be able to enjoy the car more right now.

Finding a good TPI harness is harder and more expensive than all that...?

Why bother searching for a "good" TPI harness when my engine chokes at 4500 right now and won't be needed once I change engines? I'd only trust buying a new one which is about $500.

ted i know what your going threw i started to hate fuel injection when i had a eletrical fire and changed the complete wireing harness and the car wouldnt run because of the vats i tried to by pass the car wouldnt run so i bought parts and swapped everything over to carb ihave a team g intake and a holly carb set up on my car with a msd hei dist on my 92 rs im going to use thoes parts on my 406 sbc

To do the swap you'll need a new water neck, new upper rad hose, Mallory FPR (pn 4309), and everything Bonzo said. My tach is also off after the PO carb swapped my IROC, but that could just be because he's an idiot.

My opinion:
Comp XE cam, Vortec heads, RPM Performer intake, Holley 650-750.

VERY proven combo with drivability dependent on cam size. All should swap over to a 400.


http://www.thirdgen.org/techboard/af...ad-xe-cam.html

My Nova runs great with this type of setup. Heads will need steam holes drilled for use on a 400.

Thanks for the advice everyone

cant you get a painless wiring harness for the tpi? if you still have issues after that its either ECU, or sensors. or why not just get a FAST XFI like i have, you can buy a tpi harness I believe and that system will be there for when you grow the car later.

That's an interesting idea. The ECU was replaced along with most major sensors so it would make sense it's the harness but who knows. My concern is #1 tuning, I'd like to be able to mess around with it myself rather then having to worry about sending it out to someone or briging the car. #2 I hate dealing with electrical problems and would love a simple engine where if there's a problem it's ether spark or fuel.

i went TBI to TPI to Carb... wish i stayed with the TBI lol. but it wasnt hard to do the carb swap, i have an edelbrock manifold, edelbrock carb, and an accell dizzy, i used a TBI harness and cut out what i didnt need, i used a TBI ECU to control the fans and fuel pump (removed the check engine light bulb) Im still using the TPI fuel pump with a regulator and return line, running off the stock fuel lines.

You can hook up a laptop to your computer and get diagnostics, and then for tuning you could try to burn chips. Never tried it, but some say it's a hassle. Maybe give that a try before yanking everything out?

Did you notice any big gain or improvement in your power range? Why do you wish you stayed TBI?


I do have tuning software but could never get a connection to diagnose. I burned a couple chips to piggy back the ECU but without seeing diagnostics I never knew how good they really were or where else to improve.

honestly ted, your combo doesnt sound too crazy, the fast xfi is a KILLER setup and will control anything from a simple motor up to 6 second cars.

if you go on FAST's website theres a step by step buying guide and let me tell you their support is KILLER I have had to call them on a few occasions and for the extra money you spend its totally worth it. I had TBI originally in my car then went to carb and had a bastard time, after having an edelbrock efi (which worked great, just didnt support my boosted application since i had the older proflo efi), then getting my FAST setup, id NEVER go back.

honeslty its your car/money/decision but if it were me the season is coming near an end, why dont you stash cash over winter and buy the fast setup or a whole new harness (for the price of a new GM harness i am sure the fast unit wouldnt be much more, and its totally not hard to hook up.

if you have any questions about the FASt setup etc jsut shoot me an email camaroracer1992@yahoo.com and ill help you as much as i can and/or i can refer you to my tuner.

improvement was huge as it ran correctly lol i never had luck with the TPI setup. wish i stayed TBI cause at that point it was unmolested and ran perfect, with all the TBI upgrades it was quick off the line for an otherwise stock 305... i had a performer manifold, ported throttle body and spacer, open element air cleaner with a cowl hood, and a chip.