Observed Deck Heights

[CTX-SLPR]

Howdy,

I've found one thread that documents how Dave Roland measured the deck height on a 109 to be 9.506 after getting the decks flat and parallel and a bunch of others jumped onboard saying that it was their experience too. I've not found anything for the earlier Hot Air type block that are "0.038in taller" for the shim gaskets.

Can ya'll share your experience with what the deck height has been both before and after surfacing on either type block? Trying to find the rough (will measure with real parts obviously) piston to head clearances on both block types as I have found a few of both types for basically the same money in the STD bore I need.

Thanks,

 

[earlbrown]

I've found .025" between the two blocks. 9.510" for a 109 and 9.535" for the others.


As far as deck heights after machining, that's up to how good the machinist is, if he has a square deck fixture, how much he cares, and if the machine is being a dick that day.

 

[turbodave231]

I have an early block (1983) that will be going on our CNC mill in the near future. I'll be able to report on the deck height (before and after machining) when I run the probing program and deck the block.

 

[CTX-SLPR]

That would be awesome Dave! Next couple of weeks?

 

[turbodave231]

The casting number on the block is 25514290 and the measured deck heights before resurfacing were:
Tallest height measured=9.5560
Shortest height measured= 9.5477

I milled off .009 to arrive at a finished deck height of 9.5470

Hope this is helpful!

Dave

 

[ek02]

Interesting. The Buick V6 Power manual and How to Hot Rod The Buick V6 both show blueprints with 9.560 as the deck height. I have 4, 4.1's with casting numbers 484 and 291. They are averaging 9.534-9.537 on the deck height. I once ordered a set of pistons for a 9.560 deck, only to find my deck was 9.535. Apparently there are at least 3 different deck heights. Got to watch the head stud lengths for sure.

 

[earlbrown]

It would appear the power source book make an error with the print. They show a .023" head gasket on top of the 9.560 diminution. If you swap those lines on the print and make 9.560" total with the gasket you end up with 9.537". That's not dead nuts to what I published but it is within 2 thou. Odd.

 

[turbodave231]

I forgot to mention that the block was line honed before it went on the CNC machine center. The caps were cut .004, so that operation moved the main bore up in the block approximately .002". So When you add another .002" to the figures I posted above, the measurements become:

Tallest height measured=9.5580
Shortest height measured= 9.5497
Dave

 

[Ttype6]

My stock 109 is 9.523" and my stock 291 is 9.533"