After 5 months, 2 bottom end rebuilds and a lot of blood, sweat and tears, the 350 is in my 88 IROC - but it's running like absolute sh*t. It stalls, has NO power, won't rev over 3500-4000.
I helped a very good "mechanical" mechanic assemble and install the motor, but he's old and has no experience with TPI setups.

Combo:
1984 355" short block - 9:1
882 heads 1.94/1.60 mild porting - 3-angle job
Comp XE262 cam - 218/224 @.050" .462/.469lift
Stock TPI manifolds
24# LTI injectors
2200 stall converter

I know that I need a new computer to run this setup perfectly, but even the stock MAF system should be accommodating enough to run MUCH better than it is (24# inj. vs 19#stock means it should be running rich, but the extra 50 cu. in. should compensate, no?)
I'm thinking that in 2 motor swaps I've (we've) probably inadvertantly severed/pulled wires, damaged sensors, created vacuum leaks, etc. I wouldn't know where to begin troubleshooting this mess.

I know this is probably frustration talking, but I'm seriously thinking of going to a carb - here's my thinking:

Keeping the TPI setup-
Custom chip/Memcal - $350
3-5 hours diagnostic time @ GM dealer - $250
Fix whatever is wrong - $??? Likely $300-500
Total - $1000


Carb, intake Distributor, fuel pump, misc hardware (ebay) $400
Sell TPI & 24#injectors - $250
Total for Carb - $150

The car is a daily driver but only in the summer - (But here in Winnipeg the temps still vary between 0 - 40 celsius (40 - 100 Farenhieght?) degrees from March to October.

All opinions welcome - especially those who have converted to carbs - is this smart or should I tough it out? Please help!

Sorry this was so long.

 

carbs are great when its warm when its cold they suck carbs are easy also and its only summer driven so your probally not worrying about gas milage id go with the carb nascarrs run carb if im not mistaken must not be that bad

 

carbs DONT suck in the cold. maybe an ratty one with a busted choke, but properly tuned theyre ok.mine(85 lg4)is a daily driver and had no probs in wintertime this year(got down to 27f a few time)didnt have any cold start or drivability probs.when its cold i do let it warm up for a few minutes tho, otherwise i expect shed be a little cranky till warm.

 

You have the wrong cam.
Pull the cam out and install a cam that will work with what you have.

Accelerated Motion Cams in B.C. has just the cam u need and will ship to your door for less than you'd think.

search the online listings and find this cam
305 HO computer controlled cars 19811-20844
350 Computer controlled trucks 19811-20844
350 TPI engines 19811-20844
it will work just fine with a carb too.

Don't expect too much in the way of power with the 882 heads and stock exhaust manifolds.
Whats the rear gear ratio?

 

IMO, Thats a bit much converter for the cam. (Or a bit much cam for the converter)

 

Stekman - 2200 stall is only like 600- 700 more RPM than stock - is was at the low end of what Comp recommended....

F-Bird 88 - You mean I have the wrong cam if I want to go carbed, or the wrong cam period? I did a ton of research before I chose it and I know it should be a great street performance cam on a TPI car...not too radical, should have tons of low end..articles in Car Craft, SuperChevy etc about that specific cam said it was great...but do carbs like a different profile?

There's so many guys trying to convert to TPI that I think maybe I'm being hasty in ripping it off...

 

Those heads suck. I'd be real surprised if that combo would make over 200 HP because of them. It wouldn't really matter if you put a carb on there, they'll still guarantee that the motor will never come anywhere close to reaching its potential.

The cam is an excellent carb cam but is inappropriate for TPI. If you run a cam with that much intake duration, you need to get one with higher lobe separation (earlier exhaust events). There are lots of cams around that are better suited to the application at hand. In fact, Comp makes that same one, except ground with 112° lobe separation, as a TPI cam; it works pretty well in TPI motors. But you'd have to replace the one you have, you can't change that property of a cam after it's ground.

24 lb/hr injectors are too big. 22s are stock for a 350.

With a more appropriate cam and the right injectors, a stock 350 chip should work OK. Look in the classifieds on this site for a one, or advertise there for one; somebody probably has one that they'd love to get a coupld of pennies for.

If it was me, I'd make every reasonable effort to get what's there working right, before I got out my Jeffrey Dahmer saw and started hacking.

 

If you are die hard TPI then keep it but it will run in to a lot of money later on if you want to upgrade the motor more. I went to carb and have never looked back. A lot of people will say that you will lose low end torque and maybe a little, but my motor still had good power down low with a 2000 stall and my HOT cam. Carbs when tuned are awesome! I am always driving around on two barrels thinking it's floored then I push the gas a little more and hear the back barrels open and it pulls like a *****!!.

 

RB - Lets not get too crazy- those heads flow more than enough to support well over 300hp (look at the flow chats) and the cam is specific for TPI motors (114degrees lobe sep) - But I agree the heads do suck


I am soooo torn on what to do

 

Here are the charts:

 

and the l98's (sorry I don't know how to make thes just a part of the post)

 

Sometimes flow isn't the only thing to think about; you gotta look at things like compression. You're not getting close to, much less more than, 300 HP out of some 8¼:1 motor like a typical dished 350 with those heads. I've built (against my better judgement, but that's what the customer brought me) and otherwise been around enough motors with those heads all through the 70s and 80s that other people tried to build - "Just look at the flow numbers!" - and got nothing but a disappointment. I don't need magazine article scans to know that I'll continue to take them off of anything I'm trying to make power with and throw them in the trash, just like I've been doing for about 25 years now.

The regular XE262 has 110° lobe sep. The XE262H-14 has 114°. If that's what you have, then you're right, it's the FI version, and it will work fine with TPI. Next time, post the real part # of what you actually have, and we won't have that confusion.

 

I wasn't trying to pick a fight - just felt obligated to defend the POS heads I have b/c it's way to much work to change em!

And sorry about the cam spec confusion - I'll give you credit, you know your grinds!

Still dont know what do do though....

 

I would keep the TPI why spend all that money to change it.

First I would go over your wires to make sure that you dont have any bad ones and then check for vaccum leaks.
You may want to check the fuel pressur maybe it needs to come down some since you have bigger injectors.

If I was going to spend some money I would get me a old 486 labtop and a OBD1 ECM Diagnosic Cable I think they are about $20 on ebay so I could check if I had any code's and to see what the ECM is doing you can get a free Datalog program online.

After you know what the computer is doing you can maybe find somebody to reprogram your chip that would not cost you $350 maybe $100.

I hope it is not the cam because Im putting a bigger cam in a engine that Im building 224/230@050 and .503/.510 lift but my engine is SD and not MAF.

Dont give up yet.
JD

 

No fights here either.... I just have altogether too much BTDT to entertain any hallucinations that it's going to be any different in yoru case from any other motor I've ever worked with that had those on it. "The definition of insanity is doing the same thing, but expecting a different outcome".

Sometimes there simply is no cure for a lazy motor that doesn't involve some serious work. In this case, it's kind of too late for an easy fix, as the damage is already done. I think that no matter what you do, as long as those POSs sit on top of your motor, you're going to be disappointed. I know of no magic bullet you can shoot at it that will fix that.

Good heads, the right injectors, and the right chip are the place to start, as far as changing your combo. Mentally compare what you have to a stock L98 and base your efforts on at worst duplicating, and hopefully improving on, that. Keep in mind that the L98 heads are the best to appear, in stock form, since the old double-humps; and a bunch of 882s come nowhere close to double-humps, in any form or fashion. Again, I've taken 882s and 624s off and thrown them in the trash, and replaced them with 186s, enough times to know how inferior they are, even just on my own cars over they years. Meanwhile, obviously if there's anything that isn't hooked up right, you should find & repair it, at least to make sure there's no gremlins of that sort running around. One of those small Chilton's for 82-92 Camaro/Firebird should have enough wiring info to get you pointed in the right direction. A working "Check Engine" light should be alerting you to major malfunctions.

 

Hey RB, it's good to finally see a real world opinion of the old 882 castings. I've pondered picking up a set of them from one of the junkyards for years going on all the books I've read that say they're a "pretty decent" performance head. Now I'm glad I never got a set. I'm running 462 camelbacks with 2.02/1.60 and some porting with really good results though. Of course nowadays, if I had the money to spend over again, you can't beat a set of aftermarket heads that outperform all the stock castings straight out of the box.

 

There is nothing wrong with 882 heads. They just have huge chambers. Stock they flow better than any 300 horse heads. You can buy a set, rebuild them, have a good valve job done, and some porting and have less in them than buying virgin fuelie heads, but you have to mill them so they make compression. If you don't think they are worth a crap go to a circle track, every bomber car is running them. and not just because they are cheap.

 

RB won't argue or fight with you. He'll just reason you into submission if you pay attention.

And you left out another option - Get a PPII, a few spare EPROMS, and burn your own custom PROMs for whatever parts you have.

Cost - About $150 US
Value - Priceless

The 24#ers and stock fuel pressure will be fine with the correct injector constant and enrichment tables. You can alter the timing tables to compensate (a little, anyway) for the lack of cylinder charging due to the head/cam combo, and at least make it respectable with the TPI hardware. You can tune in fine increments to get the best fuel efficiency and power. Check out some of the veterans on the PROM board for some direction.

 

or if you decide to go carbd ive got one for sale for 190 (goes for 270) its a holley 750 vac 2ndary ...this one: http://store.summitracing.com/partd...LY%2D0%2D80508S

and im just trying to help the guy as he may not be able to find my ad in the classifieds but if im breaking any rules about posting for sale stuff, go ahead and edit the post for me

 

If you haven't made a decision yet, here are some things to consider.
You said your engine is powerless.
Better heads were recommended, and another cam as well.
I'm going to put in a vote for swapping to a carb. Here's why.
Every so often someone will post asking for info on how to get their EFI working right. It will be a guy who has no experience with EFI and it's at a point where things have gotten so screwed up that he has NO IDEA which way to turn.
Learning to work on and troubleshoot EFI is a good thing. But a guy who has little or no experience, trying to tackle a system that is working poorly or not working at all to begin with, would be biting of way more than he can chew.
Troubleshooting and repairing an EFI system that's not running is a job that a lot of good electrical shops won't even estimate.
On the other hand, a carbed system is so simple that you can have a motor sitting on a stand on the ground with 3 wires running to it, and fire it up and watch it run.
If there's an advantage to carb, it's simplicity. And there's not any lack of performance there either.
It seems to me like simplifying things would be a good way to turn for you at this point.
Troubleshooting a bad EFI is something that pros have a hard time with. If you want to learn about EFI start on one that has all "known working" parts and go from there.
The heads and cam that you have aren't the best combo, true. But with a VS carb and a 2 plane intake there will be some power there. It won't be completely gutless. There were a lot of earlier F bodys produced that had less than 9:1CR.
Swap a carb on there, follow the instructions in the carb swap article, and do some searches for other details too. And your car will be up and running in a week. You can be sure of that.
Trying to blindly troubleshoot an EFI system could take all summer.
You can get some better heads later and work on your EFI too if you want.
Just my opinion... Hope it's helpful.

 

I did the swap in a car that came equipped with TPI. I have not regretted it for a second. I'm still trying to find a reason to but can't. The choke works fine, have had to do hardly any tuning, and have no concerns about wether or not I'm starving it above 5500 rpm. Now I can't compare the mileage directly to the TPI because the TPI was on a 305 and now it's a carbed 350, but I can barely tell the difference. But that could be the old 305 wasn't running as effeciently as it once would.

 

Guys thank you so much for all of your input - varied as it is - I guess there is no right or wrong answer - I agree with what StreetIron said about being on the road in a week vs. trying all summer to troubleshoot the TPI...I could take it to a dealership but I know that means HUGE money...BUT...even if i'm leaning to a carb, that cam was made for a TPI steup...will it work well with a carb?

once again the CORRECT specs for the cam

218/224 @050 .464/.470 lift 114 lobe sep.

 

I had another thought on this...
Since you're a bit over cammed for your CR, it may be worth your while to look into some variable duration lifters, like Rhodes or Crane.
I haven't tried Crane, but I've tried Rhodes and they were good.
I'm not sure how they'd work on a Comp XE262 cam tho. Maybe someone else will have more to add to this.
On the cam... My guess would be that a EFI cam would be more likely to work with a carb than the other way around.

 

Mine is the EFI version of the 270HR cam. And it works find with the carb. I am probably just sacrificing a couple of HP due to the lobe seperation. Doubt I'd be able to tell the diff though. No proof of that though. But as far as driveability and mileage and all that stuff you'd never know the difference using it with a carb. In fact I think a lot of GM grinds made for EFI have similiar lobe seperations to their earlier Q-jet grinds. The EFI cams from the aftermarket just aren't as aggressive on the lobe seperation do to vacuum issues I beleive.

 

Thanks Jimmy-Mac that's good to know...I've given myself a deadline of Friday to make a decision.

CbraKlr88- Do you have an intake for that carb? After reading tons of archived posts from the carb board, I had kinda decided on a 650 VS - but there are strng arguments for the 750 too...

 

Something that's important with the carb is the linkage. The 700R4 is sensitive to TV cable adjustment and with the wrong linkage on there it might be hard to set up correctly.
... Something to look into b4 buying

 

That's your experience. And while it may be extensive, it isn't the rule. I wouldn't normally argue where I don't have any experience in the matter, but my uncle happened to be reading over my shoulder and INSISTED on replying.

Car Craft 9/00 put a "worst case" 350 together. 8.14:1 compression. Rebuilt 882s with no work done other than a mill to 71cc, XE274 cam, Performer RPM intake and 750 carb the engine put out 325HP@5200rpm. When I showed this to my uncle, who's been around a while and probably has as much experience as you, said that is better than average, but not out of the realm of reality. He said he's seen plenty of cars run well with those heads, but he still insisted they were "junk heads". He went on and on about quality problems and cracking and all sorts of things.

 

So what should I be looking for...I assume that no one make a TPI to carb throttle cable conversion kit! (although that'd be nice!)

Mark85Z28 - Thanks for posting that - I've been feeling pretty crappy about these heads - I still do - but at least there's some hope!

 

http://www.700r4.com/sitemap.shtml
http://www.tvmadeez.com/index2.html
http://purplesagetradingpost.com/sum...mnerindex.html


Here are some links that have some useful stuff.
Basically, if a carb has a linkage that's right for the 700 R4 then the setup isn't that hard. But if you get a carb that has the wrong linkage dimensions then you'll have to fabricate something, which isn't that tough to do either. But if you set it up wrong, it can wreck your trans. So you just have to make sure.
There's some good reading here.