Model T versus Model A Valve Springs

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ModelTWoods
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First Name: Terry
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* REQUIRED* Type and Year of Model Ts owned: 1927 Model T coupe, 1926 4 door sedan
Location: Cibolo (San Antonio), TX
MTFCI Number: 20180

Model T versus Model A Valve Springs

Post by ModelTWoods » Mon Jul 20, 2020 12:48 pm

What is the difference in diameter, length, and spring pressure of Model T, Model A, and flathead V8 valve springs? If a owner wanted slightly more spring pressure to run with a high lift cam, could A or V8 springs be used if they provided higher spring pressure and were compatible in size? Would using stock reproduction springs with shims be better?


Erik Barrett
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* REQUIRED* Type and Year of Model Ts owned: 1913 speedster 1924 touring 1925 dump truck
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Re: Model T versus Model A Valve Springs

Post by Erik Barrett » Mon Jul 20, 2020 1:17 pm

I have seen A springs in a model T. I think they put too much pressure on the cam bearings which are much larger in an A. I use new springs and you can shim them if you want more pressure but I have not found it necessary. The valves won’t float until you are way past the rpm limits of most T engines.


Joe Bell
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Re: Model T versus Model A Valve Springs

Post by Joe Bell » Mon Jul 20, 2020 1:38 pm

years ago I did a valve job on a T that had crap for compression, all the exhaust valves where mushroomed out from have a heavier spring they looked like A's but might have been some thing else?? All I know once the valves and springs where changed out it ran well after?? I have asked about extra spring pressure for my Rajo and have never got an answer on that one. Hope this helps?? Joe


Erik Barrett
Posts: 463
Joined: Mon Jan 07, 2019 12:32 am
First Name: Erik
Last Name: Barrett
* REQUIRED* Type and Year of Model Ts owned: 1913 speedster 1924 touring 1925 dump truck
Location: Auburn, Ca.

Re: Model T versus Model A Valve Springs

Post by Erik Barrett » Mon Jul 20, 2020 2:55 pm

Overheads want more spring pressure because the weight of the pushrods, heavier valves, and higher rpm range can all contribute to valve float.


Topic author
ModelTWoods
Posts: 1049
Joined: Tue Jan 08, 2019 10:53 am
First Name: Terry
Last Name: Woods
* REQUIRED* Type and Year of Model Ts owned: 1927 Model T coupe, 1926 4 door sedan
Location: Cibolo (San Antonio), TX
MTFCI Number: 20180

Re: Model T versus Model A Valve Springs

Post by ModelTWoods » Mon Jul 20, 2020 5:45 pm

Thanks Erik and Joe. You answered my concern.


Les Schubert
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Re: Model T versus Model A Valve Springs

Post by Les Schubert » Mon Jul 20, 2020 6:08 pm

I built a T engine with a really high performance A cam and the T springs float at about 4300 rpm!! So a useful built in rev limiter on a flathead T engine

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