" it's rare to see a block that really is". Oh, so true.
409 piston manufacturers
- Thread starter Kevin Green
- Start date
It's the low end (valley side) Some one needs to make a fixture. I have one to set the angle of the deck. On the new blocks we can measure from the crank centerline while it's in the horizantal.
I think there were some older threads that may explain this better.
Sorry if appear to be dense here, but with a deck surface that is not 90 degrees to the crank centreline where do you measure the deck height
I realise there will be a simple or industry point but just wondering where it is? Steve
I've asked the same question Steve. Thanks for answering Bob!!
Just an observation but two of my truck block builds needed decking and this last build with a car block did not
I almost forgot you mentioned aluminum rods in the other thread!! They tend to grow up to .010" when they are at operating temperature. (Not stretched like when they need replacing....just normal expansion.) I think you'd be safe to deck it .010" to .015" but I think I'd just leave it be if I were you......OR swap to steel rods, rebalance, and then remeasure your piston to deck. I bet you'll be about .015" in the hole with just the switch to steel rods. Also don't forget to recheck piston to valve clearances if you change any of it.
Kevin Green
Well Known Member
3.50" stroke, 6.135" rods. 9.60 for the deck height and a piston that come out of the block. Still waiting to here back from them, at least my builder never filled me in on any news. I'm hoping they return money ( at least that's what I want, prolly never happen ) and I can Aubrey make a set for me.
Kevin Green
Well Known Member
Tough to measure indeed Bob !!! I have faith that they done it right and on top of that the suffix #'s was plain as day. If I told them 9.60" and I did and a longer rod and I wanted them .010" in the hole you would think they + in the hole a ton if the block had been cut.
What is the " perfect " quench # in your eyes Bob ?
Im not sure if im on the right track but is this diagram correct (ish) sorry for the old school non CAD drawings
Regards
Steve
Steve, That is correct. This will sound wrong but if you look at the drawing, increasing the bore will shorten the deck ht.. If I'm wrong, don't worry. It won't be the first time!!Im not sure if im on the right track but is this diagram correct (ish) sorry for the old school non CAD drawings
Regards
Steve
Bob
Kevin, Not sure what would make it "perfect" All motors react a bit differnt. As long as the piston never touches the head, you're cool. .035-.045 is a good range. If you change it by .005, I doubt anyone on the planet could notice. Larger clearance can promote detonation. Ask Ronnie. I believe he covered this before.
Bob
Wherever the piston ends up, you can try Cometic if you need a bastard size gasket. When I get them, the price goes up after around .070. Not sure exactly but there's a point where the price jumps. I've gotten them for several customers before.
Bob
Bob
CDNpontiac409guy
Banned
Except .027" is the thinnest gasket you can get from Cometic.
Kevin Green
Well Known Member
I have a pair of .040" too
Steel shims are what, .019 compressed?
CDNpontiac409guy
Banned
I measured this used set here... looks like about .022"
NHRA Stock blueprint spec has the piston .008" below for deck.
HHMM.... You'd have to have tight piston to wall ( power robbing ), and limit RPM, in order to actually run it at that ( .030" piston to head ) measurement
NHRA Stock blueprint spec has the piston .008" below for deck.
HHMM.... You'd have to have tight piston to wall ( power robbing ), and limit RPM, in order to actually run it at that ( .030" piston to head ) measurement