Well RU-QWIK came over today with his compression checker and confirmed my worst fears on the 5.7 L98 I picked up in Santa Rosa last month. It was supposed to have 70k and run. Well it turned over fine, but I'll let the compression test reslts speak for themselves.
Cylinder 1-105 psi
Cylinder 2-112 psi
Cylinder 3-115 psi
Cylinder 4- 52 psi
Cylinder 5- 35 psi
Cylinder 6-120 psi
Cylinder 7- 45 psi
Cylinder 8- 70 psi
I was hoping to see them all in the 135-140 range, or at least consistant #'s within no more than 10 psi of each other. I'm not bitter, I just wasn't looking to overhaul or rebuild a motor right now. I thought I could drop this thing in my IROC with some new TPI sensors, injectors and plugs with little work. Looks like I'll be rebuilding or "Freshening up" this one before it goes into my car. Maybe I can talk the wife into letting me splurge on the AFR heads and Edlebrock intake while I'm at it. Yeah right, she's gunna kill me as it is.

Mark, if you read this, let me know how the hunt goes for the plenum and if it comes with a TB. It would really make me feel better about driving 4 hours to pick this up. The "complete TPI" was the real incentive for me as the next project I do will use TPI. Like I said before, I'm not bitter, just dissapointed.
Daniel U

 

How long has that motor been sitting? Is the motor on the stand? Before you condemn it, find out why compression is low. If you have more questions, feel free to call the Master Tech....that's me.....LOL: Don't raise your eyebrow!!! hahaha

916-715-4516 will be up til midnight.

 

Not sure how long it sat at Mark's place, but it's been in my garage for 1 month on the stand. Wouldn't low compression assume leakage somewhere?
It shold be noted that this was a "dry" test on a cold motor(as it was on the stand).

 

Squirt some transmission oil about 2 oz. in those low comp. cylinders. And yes, trans fluid. The rings could possibly be stuck and not sealing as it should. Cranking compression should go up. It compression stay up where it should then great. If not then it's worn, possibly really stuck compression rings, blown head gasket, cracked block/head. You can also use leak down tester to pinpoint where it leaks compression.

 

We did squirt WD-40 down the ports to assure there wasn't anything stuck. Should I do the trans fluid still? I'd call, but my cell is dead/charging.

 

I have 2 of those Snap-On compression testors... You want to borrow one for a while?

Jason

 

I still have my plenum and TB, I don't think I will need them any time soon; shipping should be under $20 no cost on the parts, not worried you will return the favor eventually. Let me know. The plenum is even polished, was bored one day. It is for a 91-92 so you will need camaro to disable the cold start injector. I mostly just want to play with the base plate.

 

Thanks, but I think I've resolved to tearing it down. Not sure if I'll get my upgraded Edelbrock base and AFR heads, or have these heads recoditioned? Thanks for your help though. Did you get your shades?

 

If I haven't got one by the next GTG, I may buy it from you then. In the meantime I'll patiently wait for Mark. I don't have another project yet, but like I said before, that was the other reason I drove 4 hours to buy a used 5.7 L98. I figured even if the core was shot, the complete TPI would help me in the future for a "Father/Son" project. When I was 1 hour from his place, Mark notified me that the motor was missing the plenum and TB. At this point it was a little to late to turn back. Thanks again for the offer. If you still have it at the next GTG, PM me. Daniel U

 

no worries.

 

Danial,

I bought the motor in May of 2006 has been on the motor stand you picked it up from ever since. I know that motor ran good when I bought it. In order to do a accurate compression test you need to put some oil in the cylenders. With the motor sitting for so long I'm sure things need to run to get a good reading. I am stricking out on the plenum, so if you can get one that might be the way to go till I can find one. Mark

 

Mark,
I'll try the oil and test it again. As stated before, I'm not bitter, just dissapointed about the "complete TPI". I should've asked for pictures before traveling up there to pick up the motor. That was my fault. I just wanted something I could drop into the IROC to hold me over until I have the ca$h to build a stronger one for it. The TPI was what sealed the deal.