I just got a 91 formula with a locked up 305. I found a guy that has a L98 longblock with 100k on it that I'm gona swap in. I will be using the stock 305 intake & TB, but with the stock injectors from my 88 IROC L98 motor. I am swapping in the chip from a 91 L98 Z for the computer along with a 350 knock sensor. Since the miles are somewhat high i figured id do a freshen-up on the motor. Summit has the Sealed Power packages with pistons, rings, bearings gaskets, etc for a pretty good price. Now since I plan on tearing the engine down and punching it .030 over, I figured it might not be a bad idea to tweek it a little. The kit I'm looking at has 9.72:1 compression (with 64cc heads which I think the L98 heads are) forged pistons. I can also get a kit with 10.72:1 compresson. Anyway,my questions are these:

1. I think the stock c/r ration in a L98 is 9.5:1, correct?

2. If I want to end up at around 10:1 compression, is the 9.7 kit or the 10.7 kit the way to go, assuming I have the heads and block decked. (I know, obvious quesion but I want to make sure I'm not missing anything).

3. Any opinions or experaince with the Sealed Power kit from Summit?

4. If I wanted to do a mild cam where I wouldnt have to mess with the valves & springs at all, what would you recommend? I am going to replace the springs, seals, etc but I dont want to spend a lot on machine work.

5. If I bump the compression to 10:1, add a mild cam, headers and a full 3" exhaust and leave everything else stock, what do I have to do to the computer? I know that burning a custom chip for it would be the right thing to do but I'd like to avoid that at this time if possible. I have heard that the MAP cars a very sensitive to mods (all my experaince is with my 88 IROC with a MAF). Will the car run ok (i.e. not run too lean or rich) until I have the cash to get a custom chip burnt for it?

Any other input that you have would be fantastic. This car is going to be my stand in for my IROC until I have the cash to completely restore that vehicle an go ***** to the wall on it. This is not going to be a daily driver but it need to be reliable as I plan on taking it to shows and what not. Thanks a ton for the help.

 

Anyone?

 

please?

 

I also have a question about how a larger cam will affect the Map sensor or how the map will react. I have a 91 305 map motor in my car and want to swap in a ZZ4 cam. I think this is along the same lines as the prevoius question. What will I have to do to it to run properly.

 

I don't have any experience with the maf but i would asume that the chip would be your only option.

 

So nobody here has ever run a cam in a MAP car?

 

Do a and all will be revealed.

MAF cars tend to tolerate mods a little better as they indirectly measure the actual airflow coming into the engine.

SD cars on the other hand are more or less setup for how the car came. Any cam with additional duration over the factory will start causing some issues. The more mild the cam, the less the issues. The crazier the cam the worse it is.

The ideal situation in either case to get it 100% right is to tune the car for the application whether it be MAF or SD.

Do some more research on this board or go read the stickies on the PROM board.

Also we have an entire NW IN/Chicago Board here as well under the regional forums.

later
Jeremy

 

I've done some searches already and read through the PROM board. Unless you already know what you are doing or have a real desire to learn how to burn a chip, a lot of info on that board is greek to me. I dont really have any desire to burn my own chip. I know its the least expensive best way to do it, but i dont really have any desire to. I guess the better question here would be, if I dont want to do my own tuning, where should I get a PROM made at? And what cam would you guys recommened.

 

1. 87-89 compression ratio is 9.3:1 and in 1990-92 they put flat top pistons, raising the compression to about 9.75:1.

2. If you need to deck the block and the heads, do some measurements and math and figure out which you'll need. Sounds to me the 9.7 kit will get bumped up a bit to 10:1 and the 10.7 kit will get bumped up to 11:1.

3. I am not familiar with the sealed power kit, but I do run Total Seal rings in my engine. Its my belief the sealed ring is too thin to effectively do the job, as my engine and another friend's engine both use oil. When I redo mine, I'm going to use 5/64" Total Seal rings instead.

4. I dont have much experience with stock heads, but I have heard you want to stay at or under .460" lift. I've also heard you can go up to .480" lift with different springs. The Compucam 2032 is the largest I have seen that meets these requirements, but I'm sure there are other cams out there. Make sure you get one with 112 or larger LSA.

5. Any cam with 212 degrees of intake duration at .050" should run ok in a MAP car, but again, the only cam I have info on like that is a ZZ4 and a ZZ9. I used a stock chip with my ZZ4 cam, and my dad used a ZZ9 but we do our own custom chips now. When I put in the LT4 HOT cam, it required a custom chip.

Andyiroc88, a ZZ4 cam has too much lift with stock heads. It meets the duration requirement, but you need to stay under .460" or .480" lift. You will want to replace the valve springs and seals if you havent already, as they do wear out quickly with more than 100k miles on them.

 

Thanks for the info, thats what I was looking for. I ended up finding a complete L98 (intake to pan with accessories & harness) from a 92 TA with 50,000 miles on it for a really good deal so I'm just going to drop it in as is. Thanks for the info though, It will be useful in the future when I decide to wake it up a bit.