Need Valve job on my 1925 T
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DonH
Topic author - Posts: 47
- Joined: Wed Jan 23, 2019 10:33 pm
- First Name: Don
- Last Name: Hanson
- * REQUIRED* Type and Year of Model Ts owned: 1925
- Location: Rochester, MN
- MTFCA Number: 22351
Need Valve job on my 1925 T
Been reading the forum and I need some suggestions.Do I replace the cam or regrind? What valves to use and who would you suggest as a supplier? Never done a valve job. I also read that milling the head .125 will improve performance. Your thoughts very much appreciated. Don
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Dan McEachern
- Posts: 1190
- Joined: Sun Jan 06, 2019 11:08 am
- First Name: DAN
- Last Name: MCEACHERN
- * REQUIRED* Type and Year of Model Ts owned: too many. '14 touring, 2 depot hacks, 2 speedsters
- Location: ALAMEDA,CA,USA
Re: Need Valve job on my 1925 T
Milling a stock head 1/8" will not give you any noticeable performance increase. Others may not agree. What diameter valve stems are in your engine now? are the guides worn or have they been previously reamed to an oversize? You need to provide more info on the current condition of your engine to get any useful feedback.
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AZTerry
- Posts: 86
- Joined: Wed Jan 16, 2019 11:18 pm
- First Name: Terry
- Last Name: Loftus
- * REQUIRED* Type and Year of Model Ts owned: 26 Speedster
- Location: Phoenix, AZ
- MTFCA Number: 7379
- MTFCA Life Member: YES
Re: Need Valve job on my 1925 T
Hello Don,
Dan is dead on. I strongly suggest you do not do this. I tried it 15 years ago. No improved performance. Worse it made the head so thin in one spot in one cylinder, I broke the head at the edge of the combustion chamber on my next speedster run. I went onto the trouble truck on the first leg. An after market head has been very reliable for me and provided the added performance I wanted.
Terry
Dan is dead on. I strongly suggest you do not do this. I tried it 15 years ago. No improved performance. Worse it made the head so thin in one spot in one cylinder, I broke the head at the edge of the combustion chamber on my next speedster run. I went onto the trouble truck on the first leg. An after market head has been very reliable for me and provided the added performance I wanted.
Terry
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J and M Machine
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- First Name: John
- Last Name: Gulbankian
- Location: Massachusetts
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Re: Need Valve job on my 1925 T
If you are to proceed to do a valve job:
Once you remove cam,inpect the cam lobes for wear and pitting.
If the lobes aren't pitted it can be reground to touring or stock lift.
The valve guides will need to be checked for wear if valves have never been replaced then you'll need to ream the valve guides oversize for larger valve stems .015" over.
You'll also have to magnaflux "crack check" the block valve seat area as cylinders 2-3 exhaust seats often crack towards exhaust manifold side of block.
Once the guides are machined oversize then you can cut the valve seat area if it can be reground or a new seat has to be installed.
The parts you can get from all the dealers as they will be stainless steel valves and we would recommend you get the adjustable lifters. Along with new springs,keepers and retainers.
You'll have to have the valve stems shortened to use the adjustable lifters in the engine.
Rather than machining the head as others have said will make no improvement; is to get high compression pistons as that will make the power improvement you are looking for as it ups the compression ratio. If you are going to go that route the cylinders have to be in usable condition for the new piston rings to seal or you'll have to machine cylinders to accept pistons. The other alternative to more power is to find a good low cylinder head as it will accomplish what the high compression pistons will do with the high head.
Once you remove cam,inpect the cam lobes for wear and pitting.
If the lobes aren't pitted it can be reground to touring or stock lift.
The valve guides will need to be checked for wear if valves have never been replaced then you'll need to ream the valve guides oversize for larger valve stems .015" over.
You'll also have to magnaflux "crack check" the block valve seat area as cylinders 2-3 exhaust seats often crack towards exhaust manifold side of block.
Once the guides are machined oversize then you can cut the valve seat area if it can be reground or a new seat has to be installed.
The parts you can get from all the dealers as they will be stainless steel valves and we would recommend you get the adjustable lifters. Along with new springs,keepers and retainers.
You'll have to have the valve stems shortened to use the adjustable lifters in the engine.
Rather than machining the head as others have said will make no improvement; is to get high compression pistons as that will make the power improvement you are looking for as it ups the compression ratio. If you are going to go that route the cylinders have to be in usable condition for the new piston rings to seal or you'll have to machine cylinders to accept pistons. The other alternative to more power is to find a good low cylinder head as it will accomplish what the high compression pistons will do with the high head.
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DonH
Topic author - Posts: 47
- Joined: Wed Jan 23, 2019 10:33 pm
- First Name: Don
- Last Name: Hanson
- * REQUIRED* Type and Year of Model Ts owned: 1925
- Location: Rochester, MN
- MTFCA Number: 22351
Re: Need Valve job on my 1925 T
Thank you all far taking the time to respond. I will get back after I get started in disasembly and see what U have. At this point I have the head off and can see several valves are really pitted.