Confused on which Alm Heads I need

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Thanatos340

Thanatos340

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I recently had a Lifter fail and wiped a lobe off my cam and decided that since the motor is now tore down, It is time to do some serious upgrades.

Engine:
1969 340
Stock Steel crank and rods
.030 over KB Sivolite Pistons

Rotating assemble appears to be solid and I do not plan on changing anything.

I am going back with Lunati Voodoo 10200704

  • Advertised Duration (Int/Exh): 276/284
  • Duration @ .050 (Int/Exh): 234/242
  • Gross Valve Lift (Int/Exh): .513/.533
Using a Holley Strip Dominator I had sitting on a shelf and was looking at upgrading to Edelbrock RPM Aluminum heads while I am at it. This is where my confusion is.

According to the Edelbrock site I need the 60179 Heads (Open Chamber) but after doing a search here, I read where someone with a similar set up was advised by several people to go with 60779 (Closed Chamber) Heads.

The edelbrock site makes it sound as if I need the Open Chamber because of piston clearance. What am I missing here? Why would the closed chamber be better and should I be concerned about clearance if I use them? Thanks..
 
I think the open chambered heads have more clearance for stock high compression 340 pistons or any piston modeled after them. So if your KBs are 68-71 replacements you would need the open chambered ones.
 
Do the pistons come up above the deck surface of the block?
 
I Just assembled an above deck 340 less than two weeks ago-you have two choices with LA heads...even if your pistons are above deck, you can get thicker head gaskets from cometic and run the closed chamber heads...if you want to run regular thickness gaskets, and your pistons are out of the deck, get the open chamber heads (60179).

Edit: we also the KB 243 pistons and they're out of the hole a good bit more than the assumed .018"...I'm pretty sure the machinist decked it below blueprint height, but that's why my brother went with the open chamber Eddys
 
All three posts,are correct. The missing elements: A picture of the piston,or (better yet) a actual deck height reading . If you are going to spend money on heads,I wouldn't guess. You might look for .038-.045 clearance between piston and the combustion chamber surface.(called quench). Let's start there.
 
Have the machinist check the installed height of the pistons. Unless there was some extra effort made, they should be below deck by a little bit. In that case, the best bet (and IMO the overall best choice) is the closed chamber set. You will want to help the static compression as much a you can.
 
Cometic will make gaskets up to I think .120" thick. Be prepared to pay around $200 for a set.
 
Also be prepared to have the block's deck, and head surfaces cut on the right equipment to get the surfaces right for Cometics.
 
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