All About Q-Jet Gaskets, Header Fitment And Pcv Parts
I've been a happy HPP subscriber for 5 or 6 years. You have a great magazine and I have a few questions.
What's the order of the gaskets (some are fiber and one is metal) between the intake and carburetor (Rochester Q-jet 750-cfm) of a stock '67 GTO with a 400ci motor? Does the metal one go on first?
Do you know which exact brand name and model header fits best on my Pontiac? I'm presently trying to reconnect a set to the heads on the motor. I've accepted the fact that the header bolts on any header in this engine compartment are going to be next to impossible to get to. The one toward the firewall on the passenger side on the middle set of tubes is unbelievable. I've tried putting the bolt in first and slipping the hole in the flange of the header over it, but the header will not clear the frame and/or the head. I've tried hex-head bolts, making a slot in the head of a regular header bolt, mangling several tools to try to make one specific to that purpose only-none of these things has worked. I can tighten it only by using the shortest 71/416-inch open-end wrench I've ever found, turning it about 11/410 of a turn, flipping over the wrench, and turning it another 11/410 of a turn until it's as tight as I can get it with a short wrench. I want to know if there's a header that fits so I can actually tighten all the header bolts.
Do you know where I can locate the grommet that goes on the PCV valve and in the valley pan? I've tried the one GM says fits all V-8s from the'50s through the '70s. It doesn't fit.
Thank you very much for your time.
Dave Prue
Canton, New York
Via Internet
Paul Spotts Responds:
Regarding the '67 Q-jet carb gaskets, the metal one went to the carb and the fiber went to the intake. That way, there wasn't an exhaust leak under the carb. If you look at the gasket, it makes sense; but it doesn't seem to make sense to have a metal-to-metal seal between the carb and shim. I usually sandwich the metal between two gaskets for assurance of seal. I tap and plug those holes in the intake on a rebuild since that was not a good design-Pontiac dropped it in '68.
On the headers, I'm assuming you have a '67 GTO; but, in any case, if it's a '64-'67 A-body, I've found the Doug's headers fit best. I'm sure there's another brand, but that's my experience. Remember, however, they're a tight fit either way-it's just one of those Pontiac nightmares for these models. You have to be inventive, as some of the bolts need to be tightened from underneath the car. Snap-On makes a nice locking (sockets won't come off until unlocked) quarter-inch ratchet extension and strong swivel sockets for the tight areas. Use grease in the socket to hold the bolt and keep it from falling out or use tape to help start the bolts.
The correct PCV valve grommet is available from GM under PN. 5646418. I carry them or you can get them from most Pontiac restoration houses. If you're installing the PCV valve first and then trying to insert the assembly in the valley pan, it won't fit. First install the grommet in the pan with a little WD-40, then insert the valve.
Which Gm Ring Gear Do I Have-8.125 Or 8.2 Inches?
I'm restoring my '69 Firebird 350 and want to get a new ring-and-pinion for better performance off the line. The technical information I've read states the ring gear in my Firebird is 8.125 inches and the closest thing I can find to that is a GM 8.2-inch gear.
Is my information wrong or was the number rounded up in the technical information I've seen?
Paul Devitt
Via Internet
Rocky Rotella Responds:
Like many GM models produced from the mid-'60s through the early '70s, the '67-'69 Firebirds also used an 8.2-inch-diameter ring gear. There were, however, three different carrier housings used with this gearset: one for 2.56 and 2.78 ratios, another for 2.93 to 3.23 ratios, and the last for 3.36 and numerically higher ratios. The ratio your Firebird currently has will dictate the possible gear-ratio choices.
If you learn that your desired gear ratio requires another carrier, I'd suggest a new Auburn or Eaton limited-slip replacement unit over a used original. The 8.2-inch limited-slip differential used a cone-type system that's virtually impossible to rebuild. Though the modern unit may be more expensive, it should limit the frustration of buying and installing a poorly functioning original.