Just discovered my new Cutlass has several very weak cylinders...25 and 65 psi...

so that motor is coming out and I need to decide whether to let my friends shop rebuild it OR buy a new crate motor...

I put a GMPP motor in my el camino 2 years ago and am happy with it....

I'd love to get some first hand feedback on Olds 350 crate motors and some suggestions for vendor....

Thanks, John

Just heard from shop again - the motor IS a numbers matching with the car... I guess that should be part of the 'rebuild or not' question???

 

I don't think you will find any Olds Crate motors....

 

What were your actual cylinder pressures 1-8 and did you do them dry and wet? Have you done a leak down test? See link below:

http://www.carcraft.com/techarticles...r/viewall.html

Slim pickins for Olds crate motors.

 

I guess I'm asking if there is a good olds rebuilder that sells a good rebuild... I don't expect to find a GM crate or factory motor

 

Why not have your 350 rebuilt? Buying an Old 350 from a rebuilder is gonna be a crap shoot.

 

I would rebuild what you have especially since it's #'s matching.

 

Not only that you might not even need a rebuild. I'd start with the heads and see where it goes from there as bad valve seats can kill your compression.

 

the plugs that came out of the car when I bought it looked very good, almost like new.....

I should be so lucky that it would just be head work....

these are the dry numbers

1 75
2 60
3 60
4 85
5 25
6 70
7 45
8 65

acknowledge that a wet test would bring these numbers up, but enough? with the wide variations?

no leak down test either, but we haven't started to tear it apart yet...

 

The wet test would show you rings (or cylinder walls) as being the issue if the numbers came up, but little to no increase would show the valve seats as being the most likely culprit.

 

You did do that compression test with the throttle completely open, right?

- Eric

 

A leak down test would also point you to the possible culprit.

 

Across the board those numbers look low to me.Highest 85 psi seems to me the numbers overall are low.I'd do a wet test to see if the numbers come up and a leak down test to see where its leaking.Number matching i'd have that engine repaired -rebuilt.

 

Bore it! stroke it! and enjoy the heck out of it!

 

Just go buy that 350 olds crate engine.

 

It seems to me possibly a head gasket.

 

I agree with Eric that the compression drop between 5 & 7 may indicate a blown gasket. Also agree with above that the numbers,across the board seem low. How did the engine run? Any smoking issues? Plug fowling? I would take others recommendation on the leak down and wet test before giving up on that engine.

 

Just know that if you put freshly rebuilt heads on a worn short block, you'll have an engine that'll have a lot of blow by.

 

no smoking that I ever noticed, plugs that I swapped out looked great, no oil in the coolant. So I'm gonna talk to my buddy whose shop has the cutlass now and talk to him about wet test and leak down test....before we pull the heads

either will do just head work and new gaskets, or take the whole thing apart and refurbish/rebuild it - probably....

OR - just sell as is and take my losses

 

FWIW I'd deal with the motor that is in the car unless block is not rebuildable. I agree with dc2x4drvr.

Numbers matching is no big deal to me but it is to many (particularly on specialty models) and so it is a point in favor of rebuilding your own motor to retain the match. Another advantage to using your own motor is you know everything is going to fit right, wire right etc. plus you can hold a specific shop and owner responsible. Not always the case if a truck drops off a 'rebuilt' engine on a pallet in your driveway.

 

Going to have my motor rebuilt unless the machine shop finds some reason not too....

I think this car sat for quite a while previous to my purchase so I am prepared for whatever we determine is needed to make this a nice, reliable and FUN car to drive. A little bit more performance than stock in all probability

 

Make sure you approve the pieces going in prior to their installation. I'd be happy to put you in touch with a few guys who regret not doing that from the start.

 

Thanks, we (good friend and I) will be choosing all the parts and supplying them to machine shop (parts they need) and then the final assembly will be done at my friends shop - with me watching over things pretty much at every step... I feel comfortable with it.

 

so your saying that this is not a good idea to do?

 

http://www.mondellotwister.com/

 

https://classicoldsmobile.com/forums...tml#post580059

 

I recently had low compression on my '74 Cutlass 350 on no 7. (75psi) It had 120 in all the other cylinders. Engine had 492,000 miles on it, and for the same reason mentioned by this poster, I had the entire engine rebuilt. All that was actually wrong was a sticking exhaust valve, but with the amount of mileage I figured It would become an oil burner after just a valve job. Valve springs were very weak, as was tension on the rings, but amazingly clean inside, no knocks or smoke when I pulled it. If I were you, I would freshen up your original engine.