changing port timing on 760 Barrel

Knoxie

www.kp-parts.com
Location
New Zealand
I have heard about decking off the bottom off the 760 cylinder to lower the exhaust ports, then machining domes to allow for the pistons ....

questions are....
if the sleeves are removed to deck the cylinder bottom are they still ok to be re-installed or are new sleeves required?

and also ...should the transfers be raised back up to their original height (since they will be sitting lower after bottom of cylinder is machined)
 

jetski9010

Team RTYD
Location
Lancaster PA
I was planning on doing this but have not yet. Someone on here the other day said to cut .055 off the bottom of the cylinder. Yes you can install the sleeve back in after you push it out. You might want to clean up the transfer tunnels while you got the sleeve out. I forgot the port heights of the 760 cylinders but I belive the transfers are higher also so do not rise the transfers back up.
So cut .055 off the bottom of the cylinders or you could cut it off the top of the cases so you didnt have to push the sleeves out then widen you exhaust port to 66-67%. If you still running the stock head with head gasket just check you squish. You might have to get you head dome cut back but if after you cut your cylinders the squish is no closer then .045-.050 you should be good to run on premimum fuel.
 

Knoxie

www.kp-parts.com
Location
New Zealand
I forgot the port heights of the 760 cylinders but I belive the transfers are higher also so do not rise the transfers back up.

I thought the transfers on a 61x 701 cylinder were the same (or very close) to a 62t/64x 760 cylinder.....i will check again tho

or you could cut it off the top of the cases so you didnt have to push the sleeves out

only got one set of cases so dont really want to do that ...have a complete spare 760 top end that im thinking of playing around with.
 

SUPERTUNE

Race Gas Rules
Location
Clearwater Fl.
I just mill around them in the mill, Or if you have access to a CNC mill, write a program to mill around them.
Don't forget to trim the bottoms of the sleeves the same amount so they don't botton out and hold the cylinder up.
Some transfer work can be done to make it the best, but not a have to.
The exhaust port will need to be widened and a custom set of domes made to have the correct squish and compression ratio...
If you do this right, it will run exceptionally well.
 

Knoxie

www.kp-parts.com
Location
New Zealand
I just mill around them in the mill, Or if you have access to a CNC mill, write a program to mill around them.

Yeah do have access to CNC .....i contemplated milling around but thought it maybe dodgey....but hey ..if the pros do it :biggrin:

If you do this right, it will run exceptionally well.

sweet! thats what i like to hear!


So cut .055 off the bottom of the cylinders

So is this the magic number is it ?? =) :fingersx:
 
I just mill around them in the mill, Or if you have access to a CNC mill, write a program to mill around them.
Don't forget to trim the bottoms of the sleeves the same amount so they don't botton out and hold the cylinder up.
Some transfer work can be done to make it the best, but not a have to.
The exhaust port will need to be widened and a custom set of domes made to have the correct squish and compression ratio...
If you do this right, it will run exceptionally well.

Supertune just did above for a guy in Tampa and his 760 hits very impressive !
 

OCD Solutions

Original, Clean and Dependable Solutions
Location
Rentz, GA
I got a set of 64x for $200 last year with pistons in perfect shape. I had a buddy port them up as a backup set to match the porting on my TLR cylinder. If they are done right the 62T 760 cylinders will make very impressive bottom end and provide strong linear power all the way thru the power band.
 
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