a guy i know down the road just pulled a 350 tpi outta an 87 trans am, i want to put it in my 87 z28 that has a 305 carb, i was just wantin to know what the horsepower of the 350 will be if i put my stock carb on it. i think the 350 tbi has 225 hp stock right? so i was just wondering what the horses would be if i did that. thanks.

 

I assume you meant 350 TPI both times.

There will probably be a slight gain in upper RPM HP, maybe 10 HP, but a larger loss in low RPM torque. If you don't do anything about the LG4 exhaust and air cleaner, though, it will be a big loser for both.

It would certainly be a simple matter to change over the carb stuff to the 350 long block. But, you've got to do something about the exhaust air cleaner in the process.

 

yeah your right i meant TPI but so what do you suggest I do about the exhaust air cleaner any suggestions would be sweet. putting the 350 in and Carbing it would still be a improvement over the 305 i got now though right? and the guy im getting the engine from said my T5 would bolt right up to it.

 

But how long will it last ?
There was a reason GM never put the T5 trans behind a 350 in the F-Bodies

 

will it hold up as a daily driver? I don't intend to drag race or anything.

 

imho hard to say about the T5. sometimes they break in stock applications, some hold up to mild 350 builds just fine. the worldclass T5 is stronger but i think they didn't put those in until '88 or something, not sure on this though. If you have a WC T5 you should prolly be fine.

You are still using the stock quadrajet carb setup on your 305? Dunno if it's gonna work real good with the 350..

 

well i have an 87 z28 so its prolly not a WC T5

 

Unless you just REALLY REALLY REALLY want TPI for some reason, that's not the best way to go.

The car will be AHELLUVALOT faster if you just take your existing intake, carb, and dist, and put it on the other motor. Sell the TPI stuff.

Yes the T-5 will bolt right up. Just don't forget to put a pilot bushing or bearing in the crank.

 

no my intention is to keep the carb and stuff for 2 reasons 1. the guy wants 650 for the 350 as is BUT if i dont want the TPI he will take it off and sell it to me for 400, 2. it would be easier to keep it carb so i dont gotta switch the lines and fuel pump and other things.

 

Good plan. IMO better than a TPI swap. Just use the long block and put all your external stuff on it.

 

i'm not sure how the '87 LG4 ECU is gonna like it though..

 

why

 

It won't care. Knows nothing about how many CID is under it.

The computer in my 83 was COMPLETELY happy with a 400 under it, except that I had too much cam (Comp 282S) for it at idle, so it didn't do that real well. Everything else, it was fine.

If it'll run a 400, it'll run some little bitty motor like a 350.

 

this may be a dumb question but what does the computer do on my car? is it just for operating the carb and stuff? could i do without it?

 

It controls the mixture, ignition timing, and TCC.

You could put some other carb on it, a distributor that has timing controls (centrifugal and vaccum advance), and if this is a T-5 car, not have to worry about TCC obviously.

No reason to do that though. What you've got will work fine. Try it before wasting money on anything else.

 

okay because before i do put in the 350 im probably gonna do a Cam swap and im gonna put headers and new exhaust on. How would this affect what i got?

 

good points again sofa i haven't quite found out how the CCC systems on those cars work exactly, but then again i don't care that much either ^^ haven't messed with my 84 too much in that regard.
good luck with the swap greenie, should be good! as mentioned, if you swap the distributor and carb for a old-style ones (mechanically operated), you should be good to go i guess.

 

Depends on the cam you use.

In a 350, if you stay down to no more than in the mid-220s of intake duration, it'll be fine. Much past that and the idle calibration of the CC carb will have trouble dealing with the lack of vacuum.

The CC carb setup works by having a solenoid that works 2 things: metering rods with a taper that go through the jets, and an idle air bleed valve. The solenoid is constantly operating and releasing, about 5-6 times a second (the clicking noise they make). When released, the tip of the rods (thinnest part) is in the jets, and the idle air bleed is closed, resulting in a rich condition; when operated, the opposite is true, resulting in a lean condition. The computer uses the O2 sensor reading to determine what proportion of the time to spend in each state. If it sees lots of oxygen in the exhaust stream, i.e. the motor is running on the lean side, it adjust the duty cycle lower (tries to spend more time in the rich state); and conversely if it sees no oxygen, i.e. motor is running rich, it adjusts toward a higher duty cycle (greater proportion of the time in the lean state). There's a certain amount of adjustability in it; it has a rich stop, a lean stop, and an independent adjustment for the IAB valve, and so can easily cover a fairly wide range of engine characterstics.

Its timing control is crude. Basically just a static multi-dimensional lookup table. For a given RPM, if the coolant temp is here, the throttle position is there, the MAP (vacuum) is wherever, and so on, it looks up a pre-programmed value for the timing. No real "feedback" on that except for models with a knock sensor, which lets it pull timing out if it adds enough to make it spark-knock. Very Stone Age and Neanderthal.

More nearly modern control systems, TPI or TBI for example (still unbelievably crude by modern standards but a MAJOR leap forward from the CC carb computers) have an actual "learning" function built in. They store long-tem values for how much they have to adjust things to get to where the mixture is right, and use those stored ("learned") values to modify what is pre-programmed in the tables. I could be wrong but I don't think the carb ones are that smart.

You used to be able to buy "chips" for those; mostly, all they did was replace the timing tables with something a little more performance-oriented, and a bit less emissions optimized.