I searched this site for three hours and my gosh there is a lot of information about pistons here. It seems that no one has asked this question specifically though:

I have a '71 W-30 with 70K miles on it. I am mildly porting the H heads, using the stock intake/exhaust manifolds and carburetor. It has an M22 with a 373 gear.

I have the engine out of the car and I would like to get the power up to more like the '70 W-30s were.

According to Oldsmobilewiki the '70 W-30 had this cam:

402569 108 328/328 .475/.475 455 4400 ST OAI (W-30)

The '71 W-30 had this cam

409759 68 294/296 .472/.472 455 4400 ST OAI (W-30)

I'd like to pull those low compression pistons out, install some that will be more like the 10.5 to one pieces that came in the '70 W-30, and change to a '70 W-30 cam. I do not care about pump gas.

The block does not look like it needs much more than a hone.

MVC-453F.jpg


I am going to run the Cometic head gaskets and install adjustable rocker arms.

Can you guys please help me out with some guidance?




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I would not cut on H heads but that is just me. If you are not building the engine as an original set up just upgrade all of it and not just to 70 W-30 specs. There are much better pistons and cams available today. If it is not going to be original why use olds technology parts.

 

Funny you have my car. And exactly what I have been contemplating (going to '70 specs, maybe plus that). Wanted to get the engine out before rotor cuff surgery but didn't make it, now will probably wait 'til it warms up a bit.
My engine builder says to let it tell us what it wants then go from there. I am bouncing back and forth, as the car was my moms DD since new.

Dual disc clutch too, you?
Blue/blue w/black stripes.

Jon

 

H heads are too rare to modify IMHO. Just a good valve job, 9.5 comp, and the right cam will give you 400hp..
Cutlassefi has your cam)

 

Hello Jon,
Nice car. I wish I had a dual clutch.

What does "let it tell us what it wants" mean?

 

Jensen, what would they be?


The heads needed it. I do not claim to have seen thousands of Olds heads but this is the most material shrouding a valve bowl that I have seen.

MVC-523F.jpg
MVC-521F.jpg

 

Unless you are restoring to stock (which changing to 70 specs isn't stock for a 71) there is no reason to use ancient technology. There are much better options that will make more power and have better driveabilty at the same time.

 

Thanks chadman,

What are they?

 

Well for one I would use a modern piston such as the Icon pistons that use a 1/16-1/16-3/16 ring pack. These create less heat and seal better than pistons that use the stock size ring pack such as Speed Pros and OEM's. The old W-30 grinds were low lift and had slow ramps so the seat to seat time had to be very long in duration to make power. Newer cam designs use more lift with more aggressive ramps that allow you to make even more power while having less seat to seat duration. This is where you will gain driveability. It's a win/win situation.

 

once it is dismantled let it tell its story of what it needs
hone vs. bore, crank (polish/turn) so on...

Then there is the - "I want this" and all goes out the window.

My dad and I rebuilt it in '85 just before he passed away. It is now .030 over, so somewhat out of sorts anyway.

I still have my reservations on pumping it up a bit from stock specs.

 

I have a 71 W30,M22,3:73's,and my engine will look stock on the outside,but that's it.I will likely stroke it to 4.500",and bore it .030",to make a 493".Keep the compression down to run 87 peepee gas. 7.100" rods with CP pistons,or similar.
If I keep the stock stroke,I will still put a longer rod in it,with a shorter,lighter piston.
Something that makes 500HP/550FT-LBS would be fine.I installed a customers engine that was made to look like a 70 W30 engine,and it was built very similar,and made those numbers.I'll keep the big power for the other cars.

 

Hey Brian,

Impressive numbers

I have decided to use CP pistons and go thirty over. My block is being dipped right now and the crank is being ground.

 

I just can't see doing a full restoration on one of these cars,and not increase the performance & drivability,so it can maintain respect with the modern performance cars.

 

ABSOLUTELY.

I just had this conversation about converting over to quick ratio steering with a guy. He said, “I have offered a guarantee for seventeen years that if anyone wanted to switch back to their standard ratio steering box after receiving the quick ratio I’d convert it back for free and pay for shipping both ways. No one has ever asked for it”.

We have forty years of technology to take advantage of. Why wouldn't we?