2000 134 gas head on early 172 gas block

riveroadrat

Well-known Member
John Smith says they will fit but other poster says it would raise the compression ratio too much. My compression ain't that great. And the answer is?
 
I would take John's word over most anyone else.
I've never done it myself, but I do know a guy who pulled a 740
with a 172 engine in it that he told me had a 134 head on it.
He kicked butt. There was no doubt about that.
 
Figure out why your compression is low first. Adding a 134 head to increase compression without fixing the cause of the low compression could make something worse.
 
The combustion chamber is considerably smaller in a 134 head than that in a 172 head. As a result, installing a 134 head on a 172 engine will raise the CR considerably.

Commonly done as a performance enhancement but not effective in competitive pulling because the 134 valves are badly shrouded, limiting high RPM performance.

Dean
 
It will work. The 2000 134 head has the smallest combustion chamber. If you have a compression problem the head won't fix it. You need to have good ring seal. Then put the 134 head on it.
Ron
 
I have a no air cleaner 2000 4 cylinder gas motor (wore out) but I'm going to install a 800 short block in it. I just don't want more compression than it can deal with. The shortblock is an older block, the head is a 1963.
 
You see 172's mated to 134 rears all the time. Just b mindfull that the rear axles can't be loaded like a heavier rear. On the other hand, you will be great in the pto department. In fact you can run a full load on the pto and still have plenty of travel power.
 
Interesting thing is the 800, 2000, and 4000 gas 4 cylinders use the same part number for the cylinder head. I'm guessing they lowered the compression on the 4000 by putting a larger dish in the piston. As the head gasket goes the bore is bigger for the 4000 than the 800/2000. In order to get the same compression ratio of 7.5:1 out of the 134, and the 172 you only need to loose about 21cc's from the combustion chamber. The difference in the bore diameter of the head gasket between the 134, and 172 probably makes up the roughly 21cc needed to lower the compression in the 172.
 
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Thats quite a bit of difference. I still have some tetraethyl lead I could use. I sure miss those Sunoco dial your octane pumps. I'm going to put this in a loader that I only use when needed. It has a diesel in it now but with a loader on everything is harder to get to.
 
Thats quite a bit of difference. I still have some tetraethyl lead I could use. I sure miss those Sunoco dial your octane pumps. I'm going to put this in a loader that I only use when needed. It has a diesel in it now but with a loader on everything is harder to get to.
 

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