Something else to think about, Try stainless steel or copper core plug wires, I put stainless on my "56" and it made a noticeable difference !

Thanks Ted.  I will let you guys know what I find.

Be sure the throttle is blocked in the wide open position when performing the cranking compression test.

Lorena, Texas (South of Waco)

Ted,

Thats what I was thinking of doing prior to taking the heads.  Thanks for the values.  To run a compression test I know I would take out the plugs, disconnect the coil wire, anything else?

Running a cranking compression check on all the cylinders and insuring that they are all within 10% of each other from the lowest reading to the highest would be at the top of the list.  This insures that the engine is mechanically in good condition while also giving a rough idea what the dynamic compression ratio is.  155-160 lbs of cranking compression would be considered a good number for a good running 272.

 

From the descriptions you give on the performance of the engine, I suspect you do have cranking compression readings that will be on the low side which would simply indicate a compression ratio that’s also on the low side.  This would explain the lack of power going up those hills.  Even if you’re going forward with a head and/or head gasket swap, I’d still recommend that a compression check be performed prior to pulling the heads so that those values can be compared to the numbers obtained after boosting the compression ratio.

Lorena, Texas (South of Waco)

My vote is for g heads, 57 4bbl intake and either stock 312 carb or 500 cfm Holley. Dual exhausts with crossover pipe and good turbo mufflers. Headers optional. All this will work great with 292 or 312 if you decide to upgrade latter to more cubes.

Thanks again for the info.  I will keep you informed as to how it is going.

Start a new thread with your inquiry. Tell us the modifications you made and we should be able to come up with a ball park figure.







If you had your block and heads surfaced at the time of the rebuild and the pistons are at least .030 in the hole, then use the shim gaskets. If they are less than .030, or the block/heads were not surfaced, then use composition gaskets.

If your heads are the late small valve truck heads, then they should be posted. Milling is an option. Heavy milling usually costs more than a clean up cut, and the intake surface will have to be cut which adds to the cost. I'd find out how much it will cost to mill your current heads, see how it compares to having the G heads reworked. If it's not much difference, then I'd go ahead and do the Gs. I think you will find more compression by swapping the Gs than you will by milling the truck heads. Ted says its about .0064" per cc for the G heads. If it's close to the same, you will have to remove about .045 to get the same compression as the Gs. That's why I've suggested swapping before milling.


Lawrenceville, GA

As Charlie said I think with a lower comp height piston, comp gaskets, + small valve heads have added to the problem.  I will probably leave the engine in the truck and take the heads off.  If the piston in the hole distance is more than stock should I put the thinner steel stock gaskets on?  I didn't really want to plane the heads down in that there are unposted.  

Charlie, I actually was hoping for some info about what I did to my engines in regards to compression. I'm new here so perhaps you could start another... uh, what do you call these lines of communications, threads? in tech section?

Dan in Seattle