The No. 48 head was also used in the 400 engine. The WS-coded 400 engine was rated at 366 hp, and Pontiac listed the compression ratio at 10.75:1. This is a Ram Air III engine.
You should take the heads off the engine you've had for years and cc the combustion chambers; then you'll know what you have.
I put forth a hypothetical combus-tion chamber size in my response to Mr. Knautz's questions. Sixty-six cc's could be the factory volume of the chamber, or it could have been milled to arrive at that speci-fic number. A blueprint for compression ratio always includes combustion-chamber volume.
There were two versions of the '69 No. 48 head. After 40 years of buying, selling, and building No. 48s, we've seen two different chamber volumes-66 and 70cc versions.
It's the same thing that Pontiac did with the later 6X heads: one chamber size for 400 engines and a smaller size for 350 engines. (You don't even need to read the "4" or "8" stamped on the 6X head, as you can see the intake-side valve-cover rail is much thinner due to the milling of block and intake sides of the head to reduce chamber volume.) The 66 cc's I used was a guideline, not a statement of fact.
Hopefully your engine is untouched, and you can remove and cc the heads. Then you'll know for sure.
Brake Swap On The Cheap
I own a '69 Firebird with drum front brakes, and I have a '74 T/A parts car. Is it possible to interchange these or other brakes? Yes, I would love to have the money to buy new box kits, however I'm disabled, raising four kids alone, and bringing in $21,000 a year. I just can't spend $2,000 on brakes.
I know Hollander used to make a book of interchanges. Can you help a poor guy out? I don't have a computer, but my son does-he says my drum brakes are worse than dial-up Internet.
James Steppe
Suring, WI
Rocky Rotella Responds:
I can relate to being on a limited bud-get, but having converted a First-Gen Firebird from front drum to front disc, I believe you'd be better off delaying the swap until you can save enough money to purchase a complete conversion kit from a vendor such as Master Power Brakes (www.mpbrakes.com), Performance Suspension Technology (www.p-s-t.com), or another reputable company.
Our Firebird was converted several years ago. At the time, donor vehicles were scarce but not overly rare, as they seemingly are today. The list of potential donors that allow for a direct front-disc swap includes late-'60s and early-'70s A-, G-, and X-body cars. Some components from your '74 Firebird may be compatible, but I think you'd be much better off starting with a complete donor vehicle instead of mixing and matching components.
We were fortunate enough to locate a donor G-body from which to pirate all the associated power-disc conversion pieces for our swap. However, I was uneasy to trust brake components that were nearing 40 years old and in unknown condition, so we purchased new wheel bearings, rotors, brake pads, rubber brake hoses, and remanufactured calipers. After tallying up the receipts, I found we'd spent almost as much as we would have simply purchasing a complete conversion kit from an aftermarket company such as those mentioned.
While you may get lucky and find a donor that can provide all the necessary components in good reusable condition, a brake system is one area in which I'm uncomfortable suggesting anyone cut cor-ners in an attempt to save a few bucks. You might consider putting up with the front drum brakes until you can afford a quality kit that contains everything you'd possibly need to stop your Firebird in its tracks. And after completing the swap, I can tell you that your son is absolutely correct-you'll find a significant improvement in your Firebird's braking ability.
What's The Best Factory Intake That Will Fit Under The Shaker Scoop?I have a '78 Trans Am. What's the best-flowing factory intake for the 400? I want it to look factory and not alter my Shaker height.
Mike Dion
Kankakee, IL