I am looking into a 1977S with a 78sc motor. Car has 124000mi mileage on the motor is unknown...The car has been sitting for two years. We had a compression test done today and here are the numbers: 130, 110, 115, 130, 140, 130. Shop says it is normal for a car that sat for two years to show low numbers...After driving it for 50-100 miles it should show "higher". I asked the owner to re-do a compression test and a leak-down test (at my expense) and here is my question: Is this normal? I know "healthy engines" are up to 140-150 psi...Is his motor pretty much gone? Thanks in advance for all your input!

 

More important than the 'high' number, is the differential between all cylinders. Normally, for a 'street' engine, + or - 15psi is acceptable. For 'extreme' or hard use, + or - 5psi is the limit. The engine you quote having a high of 140 and a low of 110 warrants some concern IMO.
Hope that helps. Mike

 

That doesn't sound good man, even for having 8.5:1 compression on the early engine, it should be better than that. The 944 turbo i used to have had 95000 miles on it and considering it's compression is 8:1, it had 150-160psi compression between all 4 cylinders. Plus the compression differences between the cylinders are substantial as stated by the previous post.

 

I would agree with the previous posters, the big concern is the difference in compression. Running it might get the rings to expand and up the overall compression number but the fact that two are noticeably worse than the others signals to me that something is amiss in those two cylinders. The bigger problem is that the only way to find out exactly was is wrong is to tear the motor apart. You could have bad rings, bad valve seats, a cracked head, . . . These are all VERY expensive problems.

That being said, this car could be a good candidate for a 3.6 swap if the price is low enough and the rest of the car is solid. Just a thought . . .

Good luck!

 

Thanks guys, he wants 16K...I am still waiting for the second readings...I will keep you posted!

 

$16k!!!!!!!! He's nuts. This would be a 10-12k car at best with an original engine, with a bad SC motor this car is worth around 8k. Check out Panorama, the 2.7 liter cars don't hold their value too well and a modified version may be worth even less.

 

I was going to say, if the car is offered cheap, then it might offset the risk that you are going to take. Hold out for a better example.

 

Run awaaayyyyy, Run awwaaayyyyyy!

 

I did...back to square one again...Thanks for all your help guys...