Hi all, I'm rebuilding a 364 Nailhead from my 58 Buick. When installing new guides in the heads, what height or depth should the new guides be driven in to ? Where on the head is that measurement taken from ? because the valve spring pocket area is in 2 steps. Thanks
Did you check the protrusion before removal? How about the distance from the top of a guide to a retainer? Do you have another head to look at? Can you stick a valve against the seat and measure off of OAL? Shops that don't have published specs note these things upon disassembly. Sorry if that's not helpful...
I did check before removal but they were all different heights. Someone had obviously played with the heads before. I do not have another head to look at. I don't under stand the other 2 suggestions.
I will measure a few sets later. I'm not a part of AERA, I don't have published specs. Someone might chime in with those. With the other two suggestions I guess what I meant was that If you have a valve, caps, locks, you could still figure it out. Obviously, make sure your cam lift doesn't put the retainer into the top of the guide, but you know that... As you've noticed, sometimes shops just pound them in wherever. Can be annoying.
Ah I see what you meant now ! Yes I can sort of figure out at what height the guide is too high and will get in the way of valve travel but I really do want to drive the guides in, to the factory specified depth. If someone has undisturbed factory heads and measure them, that would be ideal !
Hello, I caliper checked a few. Not sure what the heads really came off of, but... 64(?) 401, OD not cut for any seals, from top of guide to outer spring seat: .700" +- .005" all. 66 425, OD cut for seals on intake; .515" +- .010". On exh. side, .680" +- .010". The .020" deviation was from one head to another. It was .010" total on each head, +- .005". My other sets all have springs still installed.
I can supply some numbers along with a photo from a 401"/425" head. I would assume these numbers would apply to the 364" heads also?? From the outer spring seat to the top of the OEM guide it should measure .690". This is a "nominal" number, in other words give or take "a couple thou or so"! From the inner spring seat it should measure .880", also "nominal"! I give both numbers so you'll know if any machining has been done! Just a tip, if those heads came in here as a build I would recommend stepping the guides down to .343" stems, put in some bronze liners (make certain the 3/8" guide holes are perfect first), use some SBC valves, and do a real nice valve job. The lighter stems help in two areas, first, they flow more air, and second, they "work the springs" less. (Add) Wanted to add using the SBC valves also eliminates the OEM 3/8" "cast" valve locks, we've found many of these broken/cracked over the years! The head in the photo has aluminum retainers, this is "years-ago" technology. It was and still is a bad idea! Thanks, Gary in N.Y. P.S. Here's the photo with the numbers included! Again, these are for the 401"/425" platform. If the 364" is different I apologize. Easy enough to measure though!
A big thank you to members "8AD-F85" and "GOSFAST" for the effort taken to give me the measurements !! Much appreciated folks !!
Gary, if the inner spring pocket measures .690" how can the outer measure .880"??? Maybe reversed??? Tom T.
Hi Tom, I think I have it right up there???? How you doin? (Add) To "8ad", I like that explanation above, really. (Add-2 10/29/14) Tom, good catch, it was posted correct but written wrong in the photo, should all be OK now?? Thanks, Gary in N.Y. P.S. You have me questioning my own sanity, but that's OK! (Add:I may be "losing it", but only gradually)
