Flathead block dimensions

F

Fox Valley Hot Rods

Junior Member
Can someone help me out? My computer crashed and I lost a bunch of information!!! I used to have a mechanical drawing of the front of a flathead engine that had all the internal dimensions on it and such, does any one have some good pictures like this?

Specifically I'm in need of the dimension from cam c/l to crank c/l???

Any help MUCH MUCH appreciated :)
 
Send a pm or an email to JWL. Maybe he can help you out. I believe I read a post on here some time ago where he was talking about FH dimensions on a blueprint that he has.
 
The front cross sections are from the backs of the dyno sheets in about '38-48 Service Bulletins.
Blown49 prints and sells posters based on these, very clear enhanced ones. I belive he can supply the pre and post 1945 versions showing the different valve angles.
 
Fox Valley Hot Rods said:
Can someone help me out? My computer crashed and I lost a bunch of information!!! I used to have a mechanical drawing of the front of a flathead engine that had all the internal dimensions on it and such, does any one have some good pictures like this?

Specifically I'm in need of the dimension from cam c/l to crank c/l???

Any help MUCH MUCH appreciated :)
Click to expand...

The "nominal" dimension is 4.689"/4.690", C/C on the cam and crank!

Thanks, Gary in N.Y.

P.S. I have 3 blocks here at the moment, 1 early and 2 late, and all are in that area!
 
Well, once again, "Gofast" has contributed bad information. Please do not machine your blocks to the dimensions submitted.
 
JWL said:
Well, once again, "Gofast" has contributed bad information. Please do not machine your blocks to the dimensions submitted.
Click to expand...

Hi JW, those are measured on the block I have here, be glad to have you correct the numbers if you know them??

It's not my goal to pass along "bad" info!

Thanks, Gary in N.Y.

P.S. That measurement was taken from one early block here!
 
The cam CL is offset from the crank CL. It is possible to measure the chordal distance, apparently as has been reported, but that does describe the actual location. The vertical dimension, perpendicular to the pan rail, from crank CL to the cam CL is 4.6875 +-.001 Then, the horizontal distance over to the cam CL is .0212 +-.002
 
Hi JW, like I stated, I try my best to keep the info "on the level" here.

The C/C that I gave him is correct, given the fact that the C/L's themselves may be different does not change the actual C/C distance! Those "different" C/L's are incorporated into the final C/C number! This is how I see it.

It may change the "locations" but if someone like Cloyes happens to be making the timing sets they need the "true" C/C.

The best comparison I can give you would be on a 4 or 6 cyl Chev (see the photo below). It more or less exaggerates what you are saying if I understand your point. The crank gear is a "few inches" over from the cam gear, but this doesn't change the C/C?? It does change the location of the timing marks with respect to both gears, but not the C/C.

I know I don't need to explain the following to you, but some here may see it better with some "fixed" numbers:

One of the blocks I took the dimensions from reads as follows:
main bore=2.672"
cam bore=1.929"
block distance=2.389" (The actual C/C using these numbers is 4.6895")

From these these dimensions come the C/C. All the dimensions on that specific block are really above the "high" limits (tolerances), but these are the numbers! (The other 2 blocks here have better main and cam hole sizes)

Thanks, Gary in N.Y.

P.S. I understand about the C/L's, but that wasn't asked and I wouldn't answer that question without actually "probing" the block in the "CNC". All "offsets"/"dimensions" would show up immediately.
 

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I used an online calculator with the numbers offered and come up with some differences. If I use 4.6875 for the vertical and .0212 for the offset, the angled C - C leg is only slightly longer at 4.68754 +.
If I use 4.6875 for the vertical and 4.6895 for the angled, the offset calculates at .1369.
Did I mess up somewhere, or is there an error in some of those numbers?
 

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Yes, Bill, the hypotenuse dimension(or the center to center of the bores) is about .0004 longer than the vertical dimension of the right angle.
 
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