Joined: Nov 02, 2007 Posts: 437 Location: Seguin, Texas
Posted: Sat Feb 21, 2009 8:46 pm Post subject: Valve question
I'm a little confused........I see in the parts list for the M38A-1 that there are two seperate part numbers for exhaust valves depending on which side of a serial number your engine is on.......but when I look in suppliers parts list I only see one exhaust valve listed for the M38A-1. There is a second valve listed for the F-head engine but it doesn't indicate that it is M38A-1 compatible. Isn't my M38A-1 F-head engine just a standard F-head engine such that I could use the normal valve and not the one specifically listing the M38A-1? And naturally, the M38A-1 specific valve is about twice the cost of the regular F-head valve. I realize the entire assembly is different.....such as different locks, no spring retainer, and a rotator.......but could one use the standard F-head assembly in an M38A-1 engine successfully. Or are there other differences such as diameter of the valve that I'm missing? And before you ask.......I have no idea what my engine serial number is.......it was erased by decking.
On another topic........my machine shop is giving me grief about the hardened exhaust valve seats saying they are not worth the cost to install on this engine because of the low compression and low rpm. They are basically quoting $5.00 a seat material plus $25.00 installation.......so.....for $120.00.........are these seats gonna give the valve seat eternal life.......or just be a possible source of trouble if they become loose or break and get ingested by the engine? I need some really good pro and con dicussion so I can give them an answer on Monday. Thanks.
I believe in keeping things simple. The more potential failure points you add the greater the propensity for a failure to occur. I agree with your machinist. The seats are not necessary for these type engines. They should only be utilized when you have an original seat which has eroded or is damaged beyond limits.
The early vs late rotator exhaust valve set=up is interchangeable so long as all the valve, rotator, retainer and lock parts are from the same set-up.
Yes when you take away the accessories (IE water proof ignition, carb and 24 volt electrics) the M38A1 engine built in 1955 is the same F134 used in the CJ3B and CJ5 in 1955 except for the serial number. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Nov 13, 2007 Posts: 289 Location: Fort Smith Arkansas
Posted: Tue Feb 24, 2009 3:00 pm Post subject: early versus late
I have the early type engine with the odd valve set up. I converted to the late setup because my stems were worn beyond limits requiring new valves. I could not find the early rotator "cap" that was missing on one of my valves either so I went with the common valve rotator setup. My machinest and the parts guy at Walcks recommended changing my seats because the new valve was Stealite (?) and the seats would need to match.
I took it to mean if you change valves you change seats as a rule of thumb. My guides were shot also. I have it assembled now and it all fit well. _________________ 1955 M170
1980 JD 450C
1948 Ford 8N
2008 Rubicon Unlimited MyGig
Joined: Nov 02, 2007 Posts: 437 Location: Seguin, Texas
Posted: Tue Feb 24, 2009 3:19 pm Post subject:
Well......this might be a lesson in patience but......the whole question of hardened seats and what kind of valves has been answered. The block already has the inserts installed and the machinist says it looks to him like they were factory installed. Even better yet, all the seats appear to be in good shape......he'll grind them down a little and lap them and he said they should be good for a long, long time. And he agrees......hardened seats means he'll be using the Steelite valves.....so there ya go. If I had just waited to hear from the machinist and not been so nosy I'd of gotten my answer before I even had a question.....but thanks guys, for the info......never hurts to know a little more then the bare minimum.
Joined: Feb 18, 2009 Posts: 43 Location: Seattle, WA USA
Posted: Tue Feb 24, 2009 4:07 pm Post subject: Valve Keepers
I've also got an Exhaust Valve question to follow up on the replies. My engine had a stuck valve. After getting it out, my valve keepers apparently are a rather small flat washer type, not the tapered ones. Can I put the tapered ons in and not worry about things? Do I need a different spring retainer? I've not gotten into the other three valves to see what's on those.
Or, are those flat ones, someone else's mistake and that's the reason for the stuck valve in the first place?
You must go by the parts list and do no mix and matching. The flat key/locks are for straight cut wells in the retainer and the tapered key/locks are for tapered wells in the retainer. On the MC engine that means the exhaust with the rotators got the flat keys/locks and the intakes got the tapered keys/locks.
This discussion comes up often but as I recall the hardened exhaust seats are required with the stelite exhaust valves but the non-stelite exhaust valves can be use with either hardened seats or the original seats in the block. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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