valve guides

visionary

visionary

Senior Member
I'm in the proccess of rebuilding my 1950 8ba. this will be my first flatty and i'm looking for some advise on the valve guides, the old guides came out pretty easy just some lite tapping on an old socket and they dropped right out.

Now that everything is all cleaned up you can simply push the guides in by hand, i even purchased new guides hoping they would fit tighter but they fit the same. so my question is how tight should they be?

Thanks
Scott
 
John, the old valves where a little loose in the guides so that's another reason for the new guides and valves, but having never worked on a flathead i'm not sure if the guides themselves should should be a lite press fit into the block or if simply pushing them in by hand is acceptable?
 
I recommend knurling the guides for a tighter fit between the stem and guide look for .0005/,001 clearance. Install the guides into the block with some RTV. A word of caution most new guides are too loose.
 
The RTV is used in many engine applications today and wasn't available in the 50's. The 49 8ba did not use the "O" rings and were a stop gap FIX for a problem that plaged the flathead since it's inception. I have nothing against the "O" rings ans especially some of the new designed round one some people are using. My comment is their not necessary and the RTV does it;s job very well considering the clearance between the guide and the block is very close in the first place.
 
Scott, On a slightly different note, consider yourself very lucky the guides came out so easily. Many of us on here have spent many, many hours battling to remove valve assemblies from the block.
 
I would strongly recommend bronze-lined guides in the Flatheads, all we ever use for over 40 years now!

Eliminates valves "hanging" in guides during long rest periods. Have never had a single "stuck" valve since this procedure!

Also allows for much "tighter" valve-to-guide clearances and more accurate valve/seat machining.

Thanks, Gary in N.Y.

P.S. We use/sell a fair amount of these "bronze guides" during the course of the year! We install the liners in-house! Most original guides are re-usable for this operation!
 
GOSFAST said:
I would strongly recommend bronze-lined guides in the Flatheads, all we ever use for over 40 years now!

Eliminates valves "hanging" in guides during long rest periods. Have never had a single "stuck" valve since this procedure!

Also allows for much "tighter" valve-to-guide clearances and more accurate valve/seat machining.

Thanks, Gary in N.Y.

P.S. We use/sell a fair amount of these "bronze guides" during the course of the year! We install the liners in-house! Most original guides are re-usable for this operation!
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X2 Have done many the same way easy and reliable,bronze is a good choice.The seals are a personal preference rtv works very well as well as loctite can be used to hold guides in.I usually install guides in engine with loctite and do valve job and they are left in and valve train can be installed afterwards during final build.All the bronze work is done to the guides when they are not in the engine as well as cutting for a positive seal on intake if requested..
I have done both with good results.As Gary says it all helps to get a more precise valve job which is a very critical job if you want perfection and a job that your customer will get reliability from.And yes 1000's of valve jobs were done by old mechanic's and the engine survived but that was 50+ years ago.

My2¢

R
 
Gentlemen, thanks for all the help, overall i've been very lucky on this motor. it looks like it has been rebuilt at some point in time. the pistons are marked .060 and the clevite bearings are dated 63 it even has adjustable lifters and apears to have inserts in the exhaust and intake seats, i was told it was a 1950 vintage, but now Ron has me thinking about that because when i pulled the guides out there weren't any seals pressent, so maybe 49? when i pulled it down everything was extremely clean inside.

I like the idea of using RTV or Locktite. the guides are tight enough that there not rocking or wobbling just that they move freely. i feel better now knowing this is a common problem and that i now have a cost effective solution.

Thanks
Scott
 
The guides were designed and sized to allow the complete valve assembly to be easily installed with the pry bar by pulling the guide down, inserting the horse shoe clip, then letting the spring tension pull it back to seat it. It made for easy assembly at the factory and the fit is usually a stiff hand push fit. After they get crusty & rusty, they don't slip fit so good. An engine that has set out in the weather for many years is more likey welded together with rust than a slip fit or even a drive fit. An engine that gets regular use will be easier to disassemble than one that has been out of service for many years. God forbid you find one where the previous assembler has put the flat rubber seals on the exhaust guides. They will be vulcanized in place like an old motor mount. The seals were designed for the intake valves so that oil film wouldn't be drawn into the intake circuit during low pressure cycle of the intake stroke, causing the engine to burn more oil. As was mentioned earlier, this was always a minor problem with the flathead V8s in general.
 
Taking the valve assemblies out is tough task but there are special pullers that work well for this now. But at the same time the new valve guides going back in are sometimes loose and will cause early valve failure if left loose and assemble as this. Ron is right about knurling the outer part of the guide that seats into the guide hole. But must use a straight cut knurling tool not a herringbone pattern as it will damage guide hole further. I found a nice hand knurling tool for this job. A man in Michigan that is making one that I had purchased from him through Ebay auction sight. It is a hand operated one that works well and is great quality for a very reasonable price. They are listed on ebay now. The sellers ID on Ebay for this tool is: nbucsenean236i Hope this helps some..
 
I knurl the inner bore of the guide to provide a tighter fit and better lubrication for the valve stem. Nothing wrong with Bronze liners, I just try to keep costs down.
 
On a related question, a recent gasket kit I purchased there were enough seals provided for both intake and exhaust guides. My understanding is to use them only on intake guides. Why do they provide seals for both?
 
billfish said:
On a related question, a recent gasket kit I purchased there were enough seals provided for both intake and exhaust guides. My understanding is to use them only on intake guides. Why do they provide seals for both?
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16 seals are provided because so many of the engines produced had 16 valve seals in them. Just a matter of convenience for those folks who want to use them as they are cheap. At least those are my thoughts.
 
I agree with GOSFAST. I also have bronze liners installed in the old guides.
 

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Were the new guides NOS ? or reproduction ? It could make a difference. I got my split guides from Jim Gordon at Specialty Ford in Rosemead CA. He has about 7,000 NOS Ford ones they bought years ago
 
I don't use any seals on the intake guides just a thin film of RTV, and never seize on the exhaust.
 
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