Advice on Compression Ratio needed

[wyrmrider]

deeper dish - tight quench glad you caught it
IDK but do those heads work better if you open the chamber around the intake valve flow maybe a few cc's there

 

[Garys1969RR]

Yep, that's why we say CHECK EVERYTHING BEFORE you put it together.

 

[Garys1969RR]

deeper dish - tight quench glad you caught it
IDK but do those heads work better if you open the chamber around the intake valve flow maybe a few cc's there

• Yes, there may be easier ways to get 5 cc. out of there other than replacing pistons. Did you take into account that the valve reliefs take out 5 to 7 c.c. from the calculation?

 

[wsutard]

• Yes, there may be easier ways to get 5 cc. out of there other than replacing pistons. Did you take into account that the valve reliefs take out 5 to 7 c.c. from the calculation?

Yes, factoring in the valve reliefs. I haven't ordered pistons yet. So we will see what needs to be done.

 

[66Satellite47]

I'd double check the valve reliefs, those may need to be deeper to accept a larger cam if ever desired. My flat tops with reliefs that will accommodate about 270* @.050 measure 6.6cc. Unshrouding the valves could also add a couple of cc's to the chamber. Going to the .051 head gasket is significant too.

 

[wsutard]

I'd double check the valve reliefs, those may need to be deeper to accept a larger cam if ever desired. My flat tops with reliefs that will accommodate about 270* @.050 measure 6.6cc. Unshrouding the valves could also add a couple of cc's. Going to the .051 head gasket is significant too.

With the heads at 84cc I was planning on using the .051 gaskets to get the DCR to 8.3. So now...

 

[lewtot184]

in the 9-10:1 compression range a cc will make about a 1/10 of a point difference in static compression ratio. when the static number goes over 10:1 a cc makes a little more than 1/10.

 

[wyrmrider]

do not go to 0.51 head gaskets
keep tight .034-.040 quench and use whatever dish it takes to get where you want to go

 

[wsutard]

do not go to 0.51 head gaskets
keep tight .034-.040 quench and use whatever dish it takes to get where you want to go

Roger

 

[BSB67]

Without looking I think there are12 and 13 cc dish pistons available. Pair that with a tight quench and you'll be close. Might need to mill the heads a bit.

 

[lewtot184]

836 pistons and mill the heads for desired compression. fairly easy to do.

 

[JimKueneman]

I have an almost identical build...
Same 3842 cam
KB237 pistons .010" in the hole
Stealth aluminum heads 80cc
.030" Cometic gasket
.040" quench, 10.4:1 CR, dynamic is around 8.4
I run 91 pump gas without issue with the cam drgreed straight up, 24 degree initial / 36 total.
Edit---I'm running stock rods with ARP rod bolts, floated wrist pin.

Yea but @threewood proved that this combination is quite a dog this weekend...
Gosh he could not even break 650 ft-lbs of torque. I decided not to run the 318 on the dyno cause I did not want to make your car look bad.....

 

[Glenwood]

Yea but @threewood proved that this combination is quite a dog this weekend...
Gosh he could not even break 650 ft-lbs of torque. I decided not to run the 318 on the dyno cause I did not want to make your car look bad.....

Now we know where the stones came from!

 

[threewood]

Yea but @threewood proved that this combination is quite a dog this weekend...
Gosh he could not even break 650 ft-lbs of torque. I decided not to run the 318 on the dyno cause I did not want to make your car look bad.....

Hey!!! You want some more rock chips?

 

[JimKueneman]

Hey!!! You want some more rock chips?

 

[threewood]

Hey @Billccm , Jim's talkin trash about your car!!!!!

 

[JimKueneman]

Hey @Billccm , Jim's talkin trash about your car!!!!!

No I am trying to get the price down to his threshold level

 

[threewood]

No I am trying to get the price down to his threshold level

Lmao!