292 Chevy .060" Over = Heat Concerns??

I'm curious if anyone is running a .060" over 292 Chevy 6 (301) and if they have any heat problems.

Leo's book talks about .060" as being the max without getting into sleeving and other issues but no mention of heat problems for the street.

This is in my roadster and the 292 has a 194 head that has been milled .040" and worked with valves, lumps etc. but it turns out the bottom end needs help so I'm thinking about boring it out to a nice little 301.

I'm running a new walker radiator, mechanical fan and no hood so I would think it would be fine but looking to see if others are running a .060 over 292 on the street.

 

i have run one in my '39 gmc for over twenty years, and almost 100k. i have a full hood and inner fenders,with an automatic tranny. i used a radiator out of a '70 dodge dart, which was able to fit between the grill shell, but not as tall as the original. the motor runs 205 degrees when running on the highway, but never any higher...even loaded and pulling hills. stays around 180+ any other time.

 

I knew a guy that had one .080 over in a three on truck and it was ok

 

The Mexican blocks are much thicker and preferred for any kind of HP use and racing purposes. The typical US blocks are hit and miss as to being too thin to bore up to even .060 over, so you need to have it sonic checked. But just because its not thick enough to make a .060 over bore doesn't mean it will run hot either, a poor cooling system and bad tuning are usually the cause of overheating and not thin cylinders.

 

Thanks guys and all good information. I was hoping I could get away just with a re-ring but this thing has as much as .012" taper in a couple of cylinders.

I would think a .030 -.040 would clean this up but then got to thinking why stop there.

Good point on the sonic checking as this is a 1970 block and if I remember right the mexican blocks were later.

 

i have one .060" over, clifford cam and edelbrock. no overheating at all pretty much stays at 190.

 

Countin, as a engine builder I'll make this suggestion. If the cylinders will clean up at .030" leave it at that. To go to .060" will only net you maybe 3 or so additional cubic inches. It's just not worth it, and you will be stuck with a block that needs to be sleeved or replaced if you have a issue with the cylinders down the road.

You will pick up way more torque/H.P. and reliability by doing a careful blueprint and meticulous assembly than by boring to .060", and you will have a better piece when you are all said and done.

If you go the .060", yes I recommend the sonic test.

No, it should not be a cause of runnning hot due to the increased bore size.

 

You must have very high compression with a 194 head on a 292. The head swap will increase compression a lot, the overbore will increase it, so will the .040 head mill.

CC the combustion chambers (at least 1) and figure out your compression ratio. If it's over 8.5:1 you may need hi test, if it is over 9.5:1 hi test may not be enough.

This is not an exact rule, there are other factors involved but something to consider.

 

Regarding compression ratio, I got it figured at just under 8.5:1 with the milled 194 head and stock pistons.

I was also leaning towards having this blocked decked .010" during this to not only clean up the deck but to take that compression up just a little more.

Good advice regarding the .030" instead of the .060"