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Update: measured the volume of these 1972 7a heads. Expected 64ish based on reading but they were close to spec. 68ccs checked twice. Just FYI for anyone searching.
Finally making the move to pull my 350 and have machine work done. From all my reading here and other places everyone recommends finding someone who knows olds engines specifically but they are very hard to find.
That being said for the heads is there something specifically I need to look for when speaking to a shop or is the work typical for all GM heads? Port, Polish, bowl work?
Same questions if I have them cut in bigger valves. Standard work or anything olds specific I should be looking for?
thanks!
Last edited by glamaina; July 30th, 2018 at 07:58 PM.
Reason: New info
Depends what your goals are. If you're just doing a street motor, 2"/1.62" will do fine and not break the bank. Any machine shop can do a valve job and surface the heads. I think those 7A heads have the raised exhaust spring pads so you'll have to keep that in mind as far as costs and valve spring choices go.
Depends what your goals are. If you're just doing a street motor, 2"/1.62" will do fine and not break the bank. Any machine shop can do a valve job and surface the heads. I think those 7A heads have the raised exhaust spring pads so you'll have to keep that in mind as far as costs and valve spring choices go.
Yes just a street motor. Some say don't bother with the bigger valves. My goal is to just get the heads flowing better, get the compression up to just under 10 and up the cam, ideally without having to change the rockers springs push rods etc. I just pulled the head 10 minutes ago and I do have stock giant dish Pistons so looks like in going to have to put Pistons in this thing.
Have read that the center valve guides should be on the loose side of the clearance spec to prevent the valve from seizing/sticking. Hopefully someone with experience on this chimes in. Although I've never seen one seize/stick that doesn't mean it won't.
Have read that the center valve guides should be on the loose side of the clearance spec to prevent the valve from seizing/sticking. Hopefully someone with experience on this chimes in. Although I've never seen one seize/stick that doesn't mean it won't.
Good luck!!!
Uhhh isn’t the center valve arrangement the same as a SBC? People make too much of that.
"Uhhh"...yes it is similar to the SBC; however, that wasn't the question. Should the center valve guide clearances on an Olds favor the loose side of the spec?
There have been a few builds where the center exhaust guides have stuck. It could be shops just slapping them all in too tight and those are the first to stick. If you want the heads to flow better, put in 2"/1.625" just like the factory did with the W31. Get them to open the bowls with a bowl hog cutter, any guides replaced to the right specs, new springs to match the cam, surfaced and done. Get Cutlassefi's Mahle 10cc dish pistons, they will give low to mid 9's compression, along with a cam from him. 10 to 1 is pretty high for a street cruiser with our old school heads. You will need 93 octane, aggressive cam, stall and gearing to match 10 to 1.
Going to have make sure your re-builder is aware of Olds non adjustable rockers. Have changed out a few sets of valves that had been cut down because of the valve seat being cut after a few rebuilds.
Going to have make sure your re-builder is aware of Olds non adjustable rockers. Have changed out a few sets of valves that had been cut down because of the valve seat being cut after a few rebuilds.
Yes, they need to all be within spec which is also another reason many will mill the heads .020" due to the thicker aftermarket head gaskets.
July 26th, 2018, 09:58 AM
