surfertom

i recently bought a 86 Z28 , very abused, i,ve pulled the motor and tore it down and found i have the 305 heads on top of a 1989 350 truck block, the car was running. is this going to be a major problem? what will it do to compression ratio? can't afford new heads right now. any imput will be helpful. tom

ljnowell

If they are the original 305's heads, they are probably better than most "350" heads. whats the casting number? IF they are the good ones, some porting will really wake them up.

stitchop

This is not a problem, it is a cheap way to raise comp. In return you get small valves and ports. The comp is high enough you will have to run 93 octane and adj timing and you may still get detonation. Smooth out the chambers to eliminate any sharp edges will help with hot spots and detonation.

I did this at 30,000 miles in my car (GM sent a 350 tpi short block instead of 305 tbi), I now have over 200,000 without ever having any issues. I used 350 injectors and adjustable regulator to solve lean idle problem.

I get some pinging if the water temp is 200 in stop and go traffic, and always read and heard how this is ruining my engine, burning the pistons, scortching the valves, but It has lasted longer tham GM intended it to last from the factory.

ljnowell

The compression ratio shouldnt be that high. The valves really arent a problem, as they should be enlarged to the standard 350 size before putting them on.

If you are having problems with pinging, you may want to checkyour timing.

surfertom

casting # on the heads is 14014416 # stamped on block k1031fbm i already have comp cam #12-34-4 and stage 2 chip for a 305, what do you think of this combo? also what # or size injectors should i run with a stock fuel pump which i have installed new? this is my first tpi car so any and all info will help. thanks, tom

ljnowell

Those are good heads, with some porting and bigger valves, the potential is there. Not sure of the part number on the cam, and i am too lazy too look it up. Off the shelf chips suck, to say the least. TPI is a real drag, IMO. You really need to clearly state your goal, before you start buying parts. Daily driver, with some racing, all racing, etc.

Sonix

iTrader: (1)

not enough #s on that cam, missing the last digit?

EDIT: 12-344-5 ? I hope that's a wrong guess, 'cuz boy oh boy, that's the wrong cam.

assuming you've got a stock 350 block, with stock dished pistons, those heads will put you in the *perfect* compression ratio. If you put in flat tops, like i'm doing right now, then you'll be a tad high.

bust out a die grinder, and go to town!

surfertom

all the info will help alot , why is tpi a drag? very strict smog laws in utah can't get away with too many mod's. i have a built 383 in my 67 but it's excempt from testing, oh ya the # on my cam is 12-34-4 ,thanks again, tom

Sonix

iTrader: (1)

tpi's stock runners in the intake manifold are such that it's GREAT for low end power, feels torquey, and powerful, but above 5000RPM it just can't flow enough air to make much more power. So a low RPM cam is great for it, but if you use a high rpm type of cam, the intake holds it back.

you can port the intake, or get a stealth ram, mini ram, etc...
and you'll be programming your own chips for it...
It's a fair bit of hassle, I prefer carbs, I can use 2 screwdrivers to tune up my carbed car, rather then a laptop and a bunch of cables and sensors etc...

I can't find any info on that cam, you have 5 digits, and I think you need 6....


if you need it to pass a visual inspection, a stock intake is probably a must, probably port the snot out of it... Injection isn't my strong point, so take my advice with a grain of salt. Perhaps post in the TPI board? Fairly common questions for over there...