Board index Flathead Power-Technical Questions, Answers, and Suggestions 45 Flatties 45 Head replacement

45 Head replacement

Post Mon Sep 12, 2011 5:27 pm

Posts: 53
Planning on doing some work on my WLC this winter. and the front head has a few broken fins. Is there a difference in performance if one was to switch to WLD heads to increase compression ratio. ??? Will they fit??? or not worth it.

Post Mon Sep 12, 2011 5:49 pm

Posts: 391
WLDs just used standard #6 heads. Same as post war WLs. Yes they fit. Yes you will notice a little increase in power. And WLC heads can be made into WL/WLD heads easily! Have a friend with a mill?

Post Mon Sep 12, 2011 6:57 pm

Posts: 53
So what are you trying to say just mill a few thou off the head to increase compression ??? If yes how many thou

Post Mon Sep 12, 2011 8:41 pm
Pa Site Admin

Posts: 5843
Location: Ohio USA

I don't know off hand how much you can take off but it can be calculated by the cc / volume using a calibrated baby bottle or other measuring devise and liquid. Plug the sparkplug holes and fill heads to leveled gasket surface. Dump each head into the measuring vessel. Now you know the volume of each. Skin cut head gasket surfaces to volume required. Doing the skin cutting in this manner eliminates differences in front and rear head combustion chambers. Just don't get carried away and remove to much material. Check volume often.

Post Tue Sep 13, 2011 6:58 am

Posts: 304
Location: Jonesville, Louisiana, USA
In the 45 Power booklet, it says to mill off 0.12".

Post Wed Sep 21, 2011 8:59 pm

Posts: 36
I milled 7/64" off the stock heads on my WLA. (About .109")
That was the figure the old timers all quoted.
Works just fine.
A little relieving of the ports and the the barrels between valve and bore helps take full advantage of the compression bump.
If I was doing it again I would try the .120" and check valve clearance to heads with clay etc just in case.

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