GASGZLR

I have two 627 305 engines complete in my garage and I want to get one of them going to replace the tired one in my 89 RS TBI. I want everything to remain stock but I wanted to put ported TPI 081 heads on the motor since I have them, And I want to put an L98 cam in it. I am looking for a nice running car with just a little more than stock without having to put headers on. i am trying to get it to run like a 305 HO or L98 while still keeping it quiet and TBI so that I dont' have to butcher the car(wiring harness.)

Will the motor run ok since the L98 cam is a stock one? Will the heads make a huge difference in power?

Also I would like to raise the compression while I am in there.

I want some opinions on this setup, thanks.

dimented24x7

iTrader: (2)

The stock exaust on a TBI car is as bad as they get. Might want to look into getting a full stock single cat exaust off of a TPI car. Would flow alot better then the soda straw sized exaust on the TBI car. IIRC, the manifolds they used on the TPI cars where larger as well. Also consider a good intake manifold but the stock one will probably work ok.

The heads and cam should make for a strong motor. Might want to look into getting larger 65 pph injectors and the cop car chip. The stock calibration might work ok but given the fact that the lobes on the stock tbi cam are nothing more then little bumps just about any motor will run way different then the stock motor will and the tune will be off. Just like a carb needs to be tuned so does tbi.

There are two options to tune it: you can fudge it and rig up a adj. fuel pressure regulator to get it sort of close or spend ~$200 dollars on some stuff to tune the computer and buy an el-cheapo used laptop. Tuner CATS makes a great 'point and click' tuning package thats very easy to use. Also has the ability to be customized so you can use it on other ECMs or just about any custom computer. One thing you dont want to do is get a 'chip'. They seldom work and most of the time, you end up spending lots of money for a chip thats essentially stock. All of those aftermarket chips are just snake oil.

ShiftyCapone

iTrader: (7)

Dimented hit it right on the head. As for raising your compression I wouldn't worry about it. Since you are going for a little bit more than stock it wouldn't be worth it to mill the heads. That would be an added cost. If anything go with a thinner .015" head gasket. L98 exhaust manifodls should be pretty cheap. You could also get a set of flowtech or dynomax hedders and mate them to a stock TPI cat-back. You really don't want to re-use anything from the stock exhaust if you can avoid it.

GASGZLR

Did I mention i am doing this on a huge budget. I have all these parts laying around and I will be doing all the work myself except for the machine work and i want to try ro do it without buying a single new part for the car. The car already has a Flowmaster cat-back that was donated off of my 1990. I like how quiet it is in the engine bay when it is running, I have another car that is for noise. Will it run OK with just the better heads and the stock peanut cam?

dimented24x7

iTrader: (2)

I was looking at some of the specs for the L98 cams and the 90+ SD cams would probably work ok without having to do major tuning. It would help but you could probably get away without it. The cams used on the MAF cars where a tad more aggressive and they wouldnt sit as well with the stock tune.

If you wanted to play it safe you could just re-use the stock cam. The heads alone would help make more power over teh cams operating range without shifting the torque curve. The L98 cam will shift the torque curve and the result is the motors volumetric efficiencies will change. Overall, it may be rich at idle, sort of ok in the middle, and lean out top. If I can find my stock bin ill post the before and after VE curves for the stock L03 vs my 350 with the slightly better flat tappet cam. IIRC, there where some pretty significant differences when I got done.

If your going to keep the stock sized exaust then keeping the L03's stock cam wouldnt be a bad idea. The small y-pipe and manifolds wont support much flow. In addition, keeping the stock cam will mean that you wont have to mess around with the computer.

dimented24x7

iTrader: (2)

Here are the tables. The top smaller table is the overall volumetric effiency of the stock motor and the larger table on the bottom is the present one im using, which is the overall VE of the 350. You can see that at low rpms the percentages are lower for my 350 then the 305. Both engines have similar sized fuel injectors. What does it mean?

Well, as you probably know, the volumetric efficiency is a measure of how efficient the engine is at moving air through itself. The higher the number, the relatively more efficient the motor is at pumping air, and the more fuel that will be needed. While the numbers dont look like much, in the car theyll mean alot and theyre a good illustration of the pitfalls of modding an engine without touching the computer. Basically the 350 with the stock tune will have WAY too much gas at idle and itll stink up my garage. Theres also a bunch of other stuff that will want to be changed but the fueling is one of those big ones that will make or break the performance of a motor.

dimented24x7

iTrader: (2)

opps... ataching the picture would help.