how to determine block / head deck height

[slowpoke]

I just bought an engine that i want to rebuild for a mostly track day car.  first question (of many more coming) as i tear into is how to know if the block or head have been skimmed at some point in the past?  i don't want to get too far down the road and then find out there are issues w/ one or the other.

 

thanks

 

[uai]

Head is 129mm when new

Block is obvious when head is removed and you know the height between small end and piston top.

You'll skim the block anyway when you'll build something with a little power.

 

 

 

 

[slowpoke]

129mm from centerline of the cam?

 what would the gap be between piston top and block top?

 

Here in CA it appears if you want to run on pump gas you're stuck w/ 9.5:1.  though i'm thinking it'll be 70% track car i still want to be able to drive it a bit on the street...  

 

[jireland2002]

129mm is the full thickness of the head.  For the block measure the height from the top of main bearing bore to the top deck.  Then add 1/2 of the main bearing diameter.

9.5 to 1 is safe.  10 to 1 is usually ok with a 292 cam which has more overlap.

[Hans]

Out of curiosity, if you deck the block, what do you do with the front cover?

[uai]

49 minutes ago, Hans said:

Out of curiosity, if you deck the block, what do you do with the front cover?

You machine them together in one pass, just like you do with the head

Edited May 30, 2019 by uai

[slowpoke]

thanks, i'll keep that in mind:  10:1 if i use a 292 .  if i go for a 304, same?

[Hans]

On 5/30/2019 at 8:21 PM, uai said:

You machine them together in one pass, just like you do with the head

How do you deal with the tensioner tube?

[Schnellvintage]

I have built many engines with 10:1 and 284 cam w/o issues.  Just use super unleaded. 

[TobyB]

5 hours ago, Hans said:

How do you deal with the tensioner tube?

For the cam tensioner piston?

 

It gets the top edge of the end of it lopped off if the machinist isn't careful!

 

t

seen that...

[uai]

On 6/9/2019 at 5:42 PM, Hans said:

How do you deal with the tensioner tube?

If you do it on a machine like that it's no porblem

 

 

it's only a problem if you're using one like that