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Post by RIP OLDS on Feb 3, 2016 21:55:27 GMT -5
Having my 65 A heads redone. According to web info, the valve guides for these heads have a spiral inside surface to aide in oiling the valves.
The guy doing my heads (he's been building race engines, including Olds, since before I was born) said if the guides need to be replaced, he drills them out and inserts copper (or bronze) guides, I forget the specific material. But they will not have the spiral inside surface of the stock Olds guides. He said he's been doing it this way forever.
Is there any difference?
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Post by sascha on Feb 4, 2016 3:20:02 GMT -5
Assuming the rest of your oiling system works correctly, there is no problem using bronze valve guides.
I have been using them in B- and C-heads on 455 engines with best results on street and strip. So it will work on A-Heads as well. Always assuming the guy really nows what he is doing on an olds head. But if he has been in the racing business for a long time he will now.
Sascha
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Post by joepadavano on Feb 4, 2016 10:53:44 GMT -5
Bronze valve guides have been used forever. The bronze is somewhat porous, so they load up with oil, however they are sometimes knurled internally to provide the same effect as the spiral grooves.
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Post by RIP OLDS on Feb 4, 2016 19:33:55 GMT -5
Thanks for clarification guys, just wanted to make sure before I drop them off this weekend.
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Post by warhead on Feb 5, 2016 21:16:01 GMT -5
The spiral from the factory was just a little extra help to oil the guides. With the "umbrella" seals you would think they don't need the extra help, but most cast iron guides rarely last more than 100k miles, from what I have seen. Most bronze guides are somewhat self lubricating (they claim), and they do last much longer than the factory guides, especially when subjected to higher lift cams, and increased spring pressures. However, bronze guides should not be confused with GUIDE LINERS, which are as good as full bronze guides, only if they are installed correctly. Guide liners are .060 thick inserts that are originally intended for small block Chevy .342 guides (.341 stem), whereas the Olds needs to go out to .344 (the stem being .3427). The liner HAS to be broached (sized stem rammed through the guide to remove any possible air pockets), then cut with a reamer to .344", .002 over the intended Chevy installed size. If not installed this way, it has the possibility of falling out as soon as 10k miles. Full bronze guides are usually installed just like cast iron guides, and are much thicker than liners. The above not necessary, except for the sizing of the guide. I always used positive seals, however, I would take a small file and put a MINUTE notch in the seal to allow some oil into the guide area. Always worked well for me. No smokers, low wear.
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