[jeepers creepers]

hi guys, silly question...
i'm rebuilding a acouple of old heads of a 350, (386 are the final number of the casting) should be of the '69, anyway, i've bought a kit with everything to rebuild valvetrain and there are included the "new" positive valve steam seals, i know old engine like mine has just the upper o-ring in the stear the keeper and lock but if possible i prefer to install also the postive one to avoid further oil burning.
i was at the machine shop and we tried to put the positive seal in the valve guide, that seems to be to big for that, surely valve guides are in different size like .50, .53, .562 etc...
i didn't measured valve guides diameter yet , so, question is: once i know the valve seals diameter how much should be the guides one?
this to avoid the seal popping out or damaging due an not appropriate coupling.
any help will be apprecciated

[richard stewart 3rd]

Hi,
I hope this is what your talking about or looking for.
Good luck,
Rich
(seals)
http://store.summitracing.com/egnsea...DS=1&N=700+115
(cutting tool)
http://store.summitracing.com/egnsea...DS=1&N=700+115

[BBCMudbogger]

The guide will probably need to be spot faced to accept that type of seal.

[jeepers creepers]

thank you for the quick replies guys, valves guide diameter is .562 and the new positive seals are probably for the .52 or .50 models, they need to be machined or replaced by new appropiate guides so i'll go with the o-rings as the stock configuration, unless change them later on, are spare heads so i have time to do it.
i apprecciate your advices,
thanx

[oldbogie]

Originally Posted by jeepers creepers

hi guys, silly question...
i'm rebuilding a acouple of old heads of a 350, (386 are the final number of the casting) should be of the '69, anyway, i've bought a kit with everything to rebuild valvetrain and there are included the "new" positive valve steam seals, i know old engine like mine has just the upper o-ring in the stear the keeper and lock but if possible i prefer to install also the postive one to avoid further oil burning.
i was at the machine shop and we tried to put the positive seal in the valve guide, that seems to be to big for that, surely valve guides are in different size like .50, .53, .562 etc...
i didn't measured valve guides diameter yet , so, question is: once i know the valve seals diameter how much should be the guides one?
this to avoid the seal popping out or damaging due an not appropriate coupling.
any help will be apprecciated

The top of the guide has to be machined to accept the seal, your machinist should know that. There's a tool that fits a drill motor or drill press for that purpose. It pilots in the guide.

Speaking of guide's, they need to be renewed and finish honed to establish the correct clearance with the valve stem. Then the seats are cut piloting off the position of the guide to insure that a line drawn across the center of the seat diameter is at 90 degrees to a line drawn thru the center of the length of the guide. This insures the valve will settle completely against the seat at every point of its circumference.

The guide can be refurbished by:

1) Boring it oversize and using new valves with oversize stems.

2) Boring it oversize, pressing in a bronze alloy or cast iron sleeve which is then finish honed to the proper diameter to provide clearance for standard valve stems. The bronze alloy inserts work best with positive seal, guide seals as this material doesn't require much lube. When working against a hard chromed valve stem, both will hold tolerance a very long time, while the small amount of lube present in the guide/stem interface helps keep the backside of the valve from forming carbon coke in it.

3) The least desirable refurbishment method, short of doing nothing, is knurling the guide. This is a process that looks similar to thread cutting, but it uses a blunt edge spiral tool to bulge the sides of the guide inward. The bulged guide is then finished with a reamer. This of course leaves what is essentially a screw thread pattern in the guide which is a path for oil to simply run through so this kind of guide refurb should also include positive stem seals. Also, the working surface of the guide has been reduced by the "threading" action of the knurling tool, so the guide doesn't wear well in service.

Bogie