pros and cons

L

lameyer

Member
I am getting ready to rebuild the 239 in my 47 coupe. I was wondering about the pros and cons between solid and spilt valve guides. Also I saw a story in a Flathead rebuild book where they drilled 1/8 inch holes in the lifter bores to hold the lifters during adjustment, is this a good idea or will it cause problems later (cracking)?
 
There is no advantage to split guides unless you have mushroom valve stems, then they are a necessity.

People have been drilling the lifter bores for a long time, I've never heard of it causing a problem. It is only helpful if you use adjustable lifters.
 
lameyer said:
I am getting ready to rebuild the 239 in my 47 coupe. I was wondering about the pros and cons between solid and spilt valve guides. Also I saw a story in a Flathead rebuild book where they drilled 1/8 inch holes in the lifter bores to hold the lifters during adjustment, is this a good idea or will it cause problems later (cracking)?
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Now's the time to change it all around, bronze-lined guides (1-pc), stainless valves, Johnson adjustable lifters, etc.

Forged pistons/metric rings are also a good choice if they fit the budget! Am building 5 Flatheads here as of today, one is the same as yours.

(Add info) Something a little extra we offer here, pin the heads/gaskets to the block (photo below)

Thanks, Gary in N.Y.

P.S. Most definitely drill (3/16" bit) the lower section of the lifter bores, it MAY make your assembly period much easier!
 

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Some folks drill the edge of the tappet bore and others make tools to hold them. The Johnson tool wasn't strong enough so a person has to fabricate a pin spanner to hold them or drill a hole and insert a pin punch into the tappet body to hold. The tappet adjusters are very tight as they should be so the damn things don't back off adjustment in service. If a person uses stock OEM non adjustable tappets then the valve stems have to be ground to get the clearance. This is a time consuming job if a person doesn't have some the the old special tools to aid in adjustment.
 
A lot of the split guides are foreign made and have caused problems. If you have NOS guides then they should be fine. If you ever have to do a valve job, you will be glad you used the later guides!
 
I would definitely drill the lifter bores if you are going to use adjustable lifters. Also depending on the cam lift you may want to remove some material to clear a wrench.
 

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I have a set of Gary's bronze lined guides in my motor and there's no more sticky valves!
I also drilled the lifter bores. I used the Stainless valves & Johnson adjustable lifters that Gary recommended. Thanks Gary!!
 
jrvariel48 said:
I have a set of Gary's bronze lined guides in my motor and there's no more sticky valves!
I also drilled the lifter bores. I used the Stainless valves & Johnson adjustable lifters that Gary recommended. Thanks Gary!!
Click to expand...

Hi Joe, how's things going??

I must have done thousands (literally) of the bronzed-lined guides in the years of machining/building these Flatheads and cannot recall one single customer EVER having a "hung" valve, not one? We know it works, and it works well in conjunction with the stainless valves!

Thanks, Gary in N.Y.

P.S. I've lost count this year alone of all the bronze guides we've shipped overseas, including many to members up here! The "Johnson" tappets also, we recently had to put in 2 more trays (92/tray), that is over 180 lifters and we're already beginning to run low again!!
 
It might be time to buy a few books on thes engines. This might save you allot of time and money in the future. Max VP has allot of them.
 
We use solid guides and straight stem valves, together with adjustable lifters. All valve seats are replaced, as well, to match the valves to the block. Some customers plan to do much of the work, so they bring the block to our machine shop, but tackle the rest themselves, depending upon their experience. Adjustable lifters should not be a problem if they are good quality. The best part is that if you have a valve noise, adjustment is possible, unlike the old "grind to fit" method.
 
I have a few motors with both styles of guides. I think the split guide gets a bad wrap because there are more specialty tools needed to service them, and on an old gunked up motor they can be stubborn to remove. On a fresh motor I would use whichever I already had.
 
When using the split or solid guide, Put a small amount of silicone around to seal it. The late guides have a seal, but I never use them.
 
I've used both types of guides (in the past) - but only use the one-piece guides on anything that I build today. Due to the amount of "slop" in the guide bores on most engines, the alignment of the split guides is not perfect. So what does this mean -- well, it causes them to not have perfectly aligned stem bores between the two sides. What does this cause . . . more valve stem wear.

Also, I tend to put a slight knurl on my solid guides to give them a tighter fit into the guide bores - this helps to lock them into place and helps valve seat longevity as the valve isn't moving around and "finding" the center of the seat along the way. It is kind of hard to knurl 2-piece guides (though I could make a fixture . . . but why waste my time).

I think Gary's technique of bronze lined guides makes sense - no reason to not use them. With that said, I've never hung a valve using the stock guides yet . . . maybe because of the quality of the valves that I use (Manley Pro-Flo and Severe Duty - with hard chromed stems) as well as the increased spring pressure of the types of engines I build (more race than street oriented).
 
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