halfmoontrail

So I got my '70 W30 project from L69, and she's got a lot of potential (kinda like a "great personality" on an attractiveness-challenged person?).

Engine in the car appears to be a '73 455 with J heads. Engine is stuck, but my guess is a little rust on cylinder walls. Oil and coolant are clean, and it hasn't been registered since 1991.

I was going to go with some Marvel or PB Blaster in the intake, on the rockers, and in spark plug holes, and then try and break the engine loose, BUT...

I have 2 pairs of E heads ready to go, and Olds 442 FAQ says this:
...it appears that in '71 (when they needed to drop all of the compressions in GM cars - 10.5 to 8.5) that their first method of doing it was to dish the pistons more. In 1973 they increased the chamber sizes on the heads and went back to piston comparable to 1970 and prior..."

If this is the case for '73 455, meaning earlier piston style/combustion chamber volume, won't I get good results from bolting on my E heads?

If so, I'll pull the intake and heads, and clean up the cylinders with emery cloth, free it up, and install my E heads.

Thanks for looking, Steve

matt69olds

I'm pretty sure all the dished piston are the same. I'm pretty sure both the E and J heads both have a 80cc combustion chamber. Its also a well known fact the J heads are about the worst flowing BB head Olds made. As Bill Travoto says in his book "J is for Junk", nuff said!

Any increase in performance by swapping heads probably wont amount to much. You still have the stock cam corking the engine. If your willing to install a mild modern camshaft and mill the heads and reassemble with a thin head gasket that will make a noticeable difference.

455man

I had to bore mine .020 to get rid of the rust pitting. Just make sure the rust is not too bad. PB blast and trying break it free. I took off 3 or 4 other rods to make it easier to turn by hand. I eventually got to break free.

joe_padavano

With the exception of the D heads, all BBO heads have about the same 80cc combustion chambers (allowing for production tolerances). D heads have about a 72cc chamber.

halfmoontrail

Thank you everybody, and thanks Joe for putting the detail on the cc volume of the heads.

I think I'll try the easiest way first, trying to break it loose. If I can't, I'll go looking for a donor engine.

Of course (sacreligious, I know), I have a good 403 and 2 sets of #7 heads. BTW, a bit of internet (mis)information suggests that all 403 cranks are drilled deep enough for a 4-speed input shaft, when using the mondello bushing...true?

My W30 was a 4-speed car (now TH400), and I have all of the 4-speed bits to put it back.

Steve

halfmoontrail

Joe or anyone else, what's involved with putting a set of SBO #7 heads on my low-compression smog '73 455? Apparently these heads have a '69 cc combustion chamber.

I know the valves will be smaller, I'm just asking about mechanical interchange to increase the compression ratio. I'm also less concerned about port matching for intake, as long as sealing is not an issue.

Any pushrod/lifter/valvetrain geometry issues?

I'm cheap, and want to use my existing parts without machine work wherever possible.

Thanks, Steve

joe_padavano

This comes up a lot. Once again, CR is NOT the only thing (or even the first thing) you need to consider when building an engine. The small mismatched ports and tiny valves will hurt far more than any CR gain will help. You'll end up with a low-performing engine that requires expensive premium fuel. Just because you CAN do something doesn't mean you should.

Build an engine with parts matched to the intended application and to each other. This will be money well spent.

Warhead

We did this years ago, but the heads were fully ported to the BBO intake port size, and large valves installed.

So we have apples and oranges.

Did you know a bad set of guides can cost 30-40 hp even before oil cakes up on the backside of the valve? And it can still ping on premium fuel.
The machine shop can find big power.
I'd rather see you do a quality valve job with new guides, positive viton seals, back cut intake valves, and a .060 chop on the BBO heads.
JMO

442rocketdave

I agree with Warhead, the guides and seals and back cut the valves and have them done by a competent machine shop. I think its important to get the cylinders clean and make sure they are not pitted, if they are pitted then dont waste your time and money putting the heads on just rebuild it and do what is necessary so you dont have to come back and do it again. Check out the engine rebuild specials on Rockauto, clevlite bearings and moly rings dont forget to get your discount code from the moderator to save an extra 10%. Thats if you need to rebuild.