One more thing...polish the combustion chamber?

Should I polish the dome of the heads? I know it would decrease my compression ratio a fraction. Would it be worth it to polish the rough casting off with a 9.5-ish:1 CR motor?

 

Scott; yes, polish the chamber. It keeps the carbon from building up on the head as much, and makes for a smooth flame travel across the head.

 

That is what I was thinking. But I wanted to make sure the loss in compression ratio was worth it on my fairly low CR engine...

 

Don't get crazy! Just sorta polishing, smoothing it, not digging for gold

 

I found "liquid" gold by digging too far on one of those ports...I will take it REAL easy from here on out...

I was not going for a mirror finish but more to just knock the tops off the cast roughness.

 

That is what you are looking for.

 

Thanks guys. Now if I can just get caught up and finished with LAST WEEKS work, I will get out there and mess with those heads some more...

 

Some suggest install in a couple of OLD valves into the chambers while you are polishing them.

 

Good suggestion. And after I polish them, I will lap the original valves to make sure they are all sealing 100%.

This is a fun project, I just seem to have lost some of the free time I have had recently, and it is taking longer (in days, not hours) than I expected. I was hoping to have at least one head done this last weekend, but we had a birthday party out of town, then visited family, then yesterday a 1-hour jet skiing session at the beach ended up being all day long because the weather and water temps were so nice.

So, what I estimated at 8-16 hours work and 2 days, is now still 8-16 hours, but now has lasted over a week....and will take at least through next weekend to finish, weather and family schedules permitting.

 

On the good news side, I got my roller-length pushrods in today. Also installed my brass dizzy gear on my old distributor. So things ARE still coming along...

 

Polish the chambers, remove any sharp edges in the chamber and on your pistons. When you are running compression that is close to the detonation point you don't want any sharp edges or points in the chamber that can cause preignition. Sharp points and edges get hotter than the surrounding metal and if they get hot enough to ignite your fuel/air mixture then you will get preignition. The pistons can be polished with 100 grit sand paper and just a bit of kerosine. be sure to blow any dust or filings out from the cylinder if you are doing this with pistons installed. Flust the bore with light weight oil and blow any debris out with compressed air.

 

Shoulda went with a steel gear. it'll last longer than the motor.

 

I was under the impression that the bronze gear was what was supposed to be used with the roller cam. I have the stock gear in the toolbox, but was told it would eat the cam gear up. The stock one is steel...

 

Steel gear goes with a roller cam. Cast iron gear goes with a flat tappet cam. Brass or Bronze goes with either, but they don't last long and were meant for race motors that get torn down frequently.

 

Roller cams are through hardened so they need a harder gear. Flat tappets are just fun of the mill grey cast iron, so they get a softer gear.

Bronze gears are softer then either through hardened cast iron or grey cast iron, so they'll wear out before the cam gear does, which is the point. You don't put a steel gear on a flat tappet cam, because you'll wear out the cam gear and never know it until it's too late. Bronze gears do wear VERY fast. I saw one on a small block chevy that didn't last one summer. Not so good...