Deck Whack and Lobe lift ?'s

C

Chevalade™

New Member
Joined
Sep 7, 2007
Messages
758
Reaction score
1
Points
0
Location
Alberta, Canada
Couple of questions....

1. What is the max anyone has decked the 500? (did a search...and it seems like the most has been around .040)

2. With 76cc heads.....what is the max lobe lift with flattops and 0 deck? (nothing came up on the search)
 
I would check any lift with a 76cc head and flat top.  Especially if the deck has been cut.  My bet would be about .520 lift with 2.19 intakes.

TED
 
I recall folks using Olds 403 pistons having a ch of 1.61 which would mean a deck cut of 0.304" on a 500 with stock rods ..

This was back in the early day .  Al @ MTS mentioned the use of that combo .
 
Pretty sure they were used with 7" olds rods. Iirc, one of Sean's turbo'd engines were as such.

1.910" - 1.615" = .295" - .250" for the longer rod = .045" would bring it back to same as stock [assuming 1.910" for stock].

Dave




MOCRUZN said:
I recall folks using Olds 403 pistons having a ch of 1.61 which would mean a deck cut of 0.304" on a 500 with stock rods ..

This was back in the early day .   Al @ MTS mentioned the use of that combo .
Click to expand...
 
IIrc, Shawn [yellow CDV] ran flat KBs and 76s and the valves kissed the pistons with a .600" at the valve cam, but not with a slightly smaller cam. Many factors could effect it though, such as LSA, advance, etc etc.

Dave
 
The original inquiry was regarding a decked block (zero) .. using the 425 Olds rod at 6.998" the cut to get to zero would need to be 0.051"
 
Thanks Mo....but it was as 2 seperate questions....as in how much is the most anyone has seen the cad block whacked.....and the other question...was.... if a guy had flattops and ran a 0 deck....what would be the most lift he could get out of a cam before piston to valve contact.
 
Chevalade said:
Thanks Mo....but it was as 2 seperate questions....as in how much is the most anyone has seen the cad block whacked.....and the other question...was.... if a guy had flattops and ran a 0 deck....what would be the most lift he could get out of a cam before piston to valve contact.
Click to expand...

It's not as easy as asking just how much lift. The ramp design, lsa, amount of advance might effect how close the valves are to the pistons at various spots of crank rotation. It depends. Sometimes, piston to valve is closest at max lift. Sometimes not. It depends on if the pistons are out-running the valves or vice-versa.

Dave
 
And don't forget the evil valve float, that'll ruin your day. All you need is a split second of wheelspin and your done
 
  I have a block that was decked .324 for a engine that has not yet been finished and it is still plenty thick.

  I cannot remember what the thickest and thinnest readings i got when checking that block were but I might be doing something similar really soon and ill post my findings.

  As far as the flattop pistons and actual valve lift....this is something that you will have to check if you are gonna go over .500 lift and you should.

  Good luck

  JW
 
You must log in or register to reply here.
Back
Top