If I want to stay with my 410 set up (390 block bored .30 and 428 crank), what are my options to yield a higher c/r? Right now it is 10:1 c/r with stock flat top pistons. What are my piston options? Deck the heads?

Also, my heads are off a 1968 Galaxy 2 barrel, without any casting numbers, most likely what cc are these heads?

 

You did not say what you will use this engine for? 9.5 CR is good for street driven trucks higher is okay with aluminium heads and higher octane. Some propane engines go 14 to 1 CR. We discussed using silvolite 1139's with Edelbrock heads and .040 felpro gaskets. But we do street driven truck engines and since these engines use lots of fuel we were shooting for the less expensive 87 octane. Tell us more!

 

The engine will be used for truck pulling and no street use whatsoever. Racing fuel will be the only fuel used. Last season I was running 110 octane, but higher is obviously available. I have quite a bit of porting done on the heads so I plan to stick with them and not use aluminum. The engine will be running in the 6500-7000 rpm range.

 

There were some early 406 heads, number C3AE-6090-C, that have 56.4-61cc combustion chambers and 2.022x1.645 valves. I'm sure those would raise your compression up. DSC Motorsports MAY be able to locate these heads for you.

For the pistons, ross pistons makes some good forged 410 pistons. Or you could order custom domed pistons to obtain whatever compression ratio you want.

Hope this helps!

 

why not mill the heads? have them cut for O-rings while your at it if you wanted since you'll be replacing the head gaskets anyways. seems like it's the cheapest way to bump compression

 

i had my heads milled .10 does that help anything or not, thanks

 

Fordman, you really meant that your heads were milled .010, didn't you ? Milling a full .100 is possible, but not wise. >100 would give bunches of compression, but would cause other problems. If your heads were milled .010 when they were in the shop, it was probably just to make sure they were flat. It will increase compression, just a little. Not enough to notice or worry about. Jamey, what pistons are in the engine now ? The 410 came from the factory with dished pistons, giving something like 10 1/2 to 1. Flattops would give you even more. and Steel shim gaskets more yet. How much do you want ? DF

 

I am not really that concerned with the way the engine is now. It runs really hard. It's just the off-season, and I was looking at some of my options to try and get her to run a little harder for next year. I figured if there were any tricks you guys would know what they were. Thanks again for all the posts.

 

Jamey, you might consider the TRW L2291F pistons. They are a forging with plenty beefy tops. The are intended for use in a 390, being 1.76 tall. I cut mine to 1.66 to use in a 421- 390 block, .060 over, and a 410 crank. This leaves a flattop, but I cut the valve notches a bit deeper, just in case. The 360, and the 390 4 bbl of the early 60s, also have flattop pistons. But they are castings and I don't think there is enough meat to be whittliing on them. If you DO swap pistons, you'll need to rebalance the rotating assembly. lots of effort for not a huge gain. How about milling the heads ? you could cut the decks .040, cut the intake side of the heads the same .040, ( DON'T cut the intake itself ! ) and run steel shim gaskets-.017 thick- instead of the felpros- .041 thick. That would give a noticeable increase in compression for not to much money. You will need the .060 shorter pushrods, however. DF

 

Do you have to run a different intake and head gasket or just different head gaskets. What brand of steel gaskets? Also, if I am running adjustable rocker arms is there enough adjustment to compensate for the pushrod length or are new pushrods mandatory with this modification. Reason asking is that I've already bought three sets of pushrods 1.) hydraulic cam non-adjustable 2.) hydraulic cam adjustable 3.) solid cam adjustable.