37 overbore

[Mark's 37]

What would be the advantage, if any, of over-boring a stock engine out to .100 vs just what is needed to clean up the cylinders? I have read that 37 blocks could go that far. Would the performance even be that noticeable?

 

[flatheadmurre]

I would do heads and cam before even thinking about boring for CI.
Have a good thought about what you want before boring out a good block to the limit...

 

[Walt Dupont--Me.]

I've bored those 37 blocks .125 and used 8BA pistons. In fact I have one in my shop right now. I remember back in the 50's a friend who is in the Me. stock car hall of fame, loved those 37 engine in his stock car, he'd bore .125 and fill the heads with 2 sticks brassing rod and a cam, you cain't believe how he screamed that engine around those dirt tracks. Walt

 

[JWL]

To answer the original questions---None, and no.

If better performance is your goal try matching the heads to pistons and valves with no more than .050 clearance.(and not less either) Install and tune dual carbs. And play with your ignition until it is optimized for your application.

And, unless you plan to operate at above 3000 RPM during the majority of your driving, do NOT allow any of the gurus to convince you to install a "good performance cam".

 

[Mark's 37]

The reason I asked is I was looking at an engine for sale which is a 37 and has been bored .100 over but with stock cam, etc. Could this have been done to use a more available later piston/rod combo? Another thought is the usable block located for the build could have been bored previously.

 

[scooder]

If you bore a 37 engine 0.100" over you can't fit the later pistons and crank, you need to go 0.125" over, then it would be 239" the 37 crank has smaller main bearings aswell, so the late crank won't "drop in" either.
That engine was more than likely bored to 0.100" over due to suffering a mechanical piston pin clip leaving stage left causing the pin to slide into the bore and dragged up and down. Or some such thing.
Martin.