Do Lower End or Leave It Be?

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Mar 23, 2009 | 10:19 PM

#21

Roarinbear

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Joined: Oct 2008

Posts: 121

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From: Hooksett NH

The lower end is orignal, and stock. I purchased this from the previous owner of 25yrs. And he was very meticulous. This Vett is in show condition, with all matching numbers. I am going to keep all take of parts together, and safe.

Mar 23, 2009 | 10:41 PM

#22

63mako

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Joined: May 2005

Posts: 10,674

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From: Millington Illinois

St. Jude Donor '08-'09

Quote:

Originally Posted by Roarinbear

If I don't find a ridge in the cylinders, can I install rod bearings, and rings? Would this be advantageous?

Your compression is fine now. Put it this way. It is a corvette. Very few run over 100,000 without either rear main leak, worn rings, worn bearings or some other issue requiring dropping the pan for some work. Most have been thrashed somewhat during their life. If you take it down enough to put rings in it, rod and main bolts, wrist pin bushings, oil pump, making sure you have proper clearances at the cylinder wall to piston and the other items I mentioned are a few more $ but the weak link always breaks. You might get 30,000 more out of it with no issues as is, but you might get 10,000. Spend a little more now, while it is coming apart anyway and, if you do it right your good for another 100,000. How would you feel if you go through all the work you plan on and a wrist pin starts knocking in 5000 miles? Just a thought. It is your call. You could go either way. Is it original since 1975 or a rebuild with 80,000 on it? If it's original it is 35 years old and 80,000 miles. That is different than 5 years old and 80,000 miles. And if it's a rebuild was everything addressed? Good luck on whatever you decide.

Mar 24, 2009 | 09:42 AM

#23

ED69ray

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Joined: Dec 2008

Posts: 531

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From: Frisco TX

Quote:

Originally Posted by 63mako

If you don't feel comfortable handling this remove the engine, disassemble it down to the short block, drop it at a reputable machine shop and have it done. You will have to farm out the machine work anyway.

Thats exactly what I did.

My dilema was the same - I wanted to power up my NOM L-65 (8.5-1 CR) and initially looked at doing a few bolt on upgrades. After giving it much thought I decided to pull the motor and refresh the bottom end as well. I figured it was cheap insurance and the proper time to do it as well.

I paid around $1K for all the machine work incl:

-vat block
-install cam bearings and plugs
-align hone
-balance rotating assembly
-deck block
-polish crank
-remove 1 broken head bolt
-complete short block assembly

Aftermarket rods were cheap insurance at around $250 and ARP bolts were used to assemble. New oil pan with windage tray and oil pump also.

I would either pull the motor and do everything described above or leave the motor in the frame and bolt on your new top end and go.

If you are gonna get into changing rings and bearings you might as well do a complete rebuild - with your compression numbers I don't see a need to change rings without doing a complete rebuild anyway. You might get another 5 yrs and 30,000 miles out of it by just doing the bolt ons - and then again you might not.

One thing to consider if you go the full rebuild route is to refit a roller cam.

Good Luck, Ed

Last edited by ED69ray; Mar 24, 2009 at 09:49 AM.

Mar 24, 2009 | 06:52 PM

#24

Roarinbear

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Joined: Oct 2008

Posts: 121

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From: Hooksett NH

Thanks everyone! Lots of good info. My plans were to do the top now and the lower or new short block in the future. Where is a good place to purchase a short block to use with my new parts. Nothing BIG, just around 290-330 hp. Dependable. If I can by a new short block for about the same money as a $1000.00 rebuild, I will.

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