Shed tinkerer
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Posted 09 September 2016 - 07:12 AM
10.5:1 with the right cam & ignition timing is ok on 98 fuel.
10.5:1 static comp? Just clarifying... it would be a lot if dynamic comp 
Don't be shy about giving a 202 some CR - their burn is better than their breathing ability and they respond well to higher CRs.
What kinda squish clearance do you recommend when running comp on the high side? 40 thou?
_STRAIGHTLINEMICK_
Posted 09 September 2016 - 11:37 AM
Don't be shy about giving a 202 some CR - their burn is better than their breathing ability and they respond well to higher CRs.
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Posted 09 September 2016 - 11:32 PM
_oldjohnno_
Posted 10 September 2016 - 08:15 AM
I think 10.5 static would be the absolute minimum you'd want to run with a nice street cam - eg. Crow 626. I'd want to be closer to 11.5.
Squish clearance not too much more than 0.040"
Edited by oldjohnno, 10 September 2016 - 08:17 AM.
Shed tinkerer
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Posted 10 September 2016 - 12:24 PM
I think 10.5 static would be the absolute minimum you'd want to run with a nice street cam - eg. Crow 626. I'd want to be closer to 11.5.
Squish clearance not too much more than 0.040"
what is the tightest squish you would be comfortable running?
_oldjohnno_
Posted 10 September 2016 - 05:33 PM
With an engine like this one I'd be happy with 0.030"
_STRAIGHTLINEMICK_
Posted 10 September 2016 - 06:33 PM
With an engine like this one I'd be happy with 0.030"
Yep an easy way to get it done is have a 45 or 46 cc chamber and have the FT piston at about .005-010" above the deck and use the gasket to give the required clearances.
An even trickier trick is to stroke the engine .060" using std rods and under size bearings and machine the piston so that there is a small dome that protrudes into the chamber .
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Posted 10 September 2016 - 11:11 PM
So .007" above the deck & 43cc with flat tops is ok.(oops,did I say that aloud.)
_STRAIGHTLINEMICK_
Posted 11 September 2016 - 09:38 AM
So .007" above the deck & 43cc with flat tops is ok.(oops,did I say that aloud.)
Lotsa Posts!
Posted 12 September 2016 - 08:20 PM
A bit off topic but sort of related.
In this computerized world which can be a bit a bit of a thing if we don't have all the cam specs we can calculate DCR with a dial gauge and vernier.
Install cam and some sort of spring on intake.
We already know the stroke so set up some sort of arrangement so that the dial gauge can read valve lift @ the valve.
Turn over engine until the intake valve is fully closed after induction , zero the dial gauge and turn engine over again until intake
is 50 before zero , this should mean that with some sort of cam that the piston is now on the upstroke.
Stop at 50 and measure the stroke and use the usual way to calculate CR.
That should hopefully give us the DCR ?
Don't be surprised if the piston is up to an inch or more up the bore creating a short stroke ?
Shed tinkerer
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Posted 13 September 2016 - 05:51 PM
So .007" above the deck & 43cc with flat tops is ok.(oops,did I say that aloud.)
Im getting mid 11s with this ratio, although im not exactly sure what the compressed ratio is of MLS gasket. I run copper so I just used my size in my calcs
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Posted 13 September 2016 - 11:30 PM
Im getting mid 11s with this ratio, although im not exactly sure what the compressed ratio is of MLS gasket. I run copper so I just used my size in my calcs
12.6:1 & an Acl race series gasket.
Shed tinkerer
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Posted 14 September 2016 - 06:22 AM
12.6:1 & an Acl race series gasket.
I screwed up, my first calcs had the slugs .007 down the bore not past the deck. Just realised.
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