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avcat said:
Does anyone have any comments on using the Andrews 37G Cam with
SE 10:25.1 pistons in a 95 CI build?

Thanks,

Dave
Too much compression for 37g's. My understanding is that they should be run no higher than 9.8

Teu
 

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10.25 pistons with WHICH heads and head gaskets? Might find out your actual compression is more in the 9.8 range which is PERFECT for the tw37
 

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Discussion Starter · #4 · (Edited)
The Heads will be stock except for Stage 1 CNC porting done by Nallin Racing.
I haven't deceided on Cometic .030 or stock gaskets yet.

Thanks
 

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I'm running 9.9:1, runs fine.

Normally whoever does the heads will dictate which gasket to use.
 

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You may want to consider the TW31s , Same lift handles compression better. I'm running them and love them . (HD Wrench and Andrews suggested them)
 

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nidan said:
You may want to consider the TW31s , Same lift handles compression better. I'm running them and love them . (HD Wrench and Andrews suggested them)
I have yet to see dyno sheets, would love to see how it does.
 

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Discussion Starter · #8 · (Edited)
If you check the TC88/95 performance Gallery on the nightrider.com website
you'll find a couple setups that are similiar. The main componants on my setup
that are of interest to me are the Nallin Heads, SE 10:25.1 Pistons, 37G Cams,
and the 42mm Dakota Kid Carburetor.There some other minor changers else where. My main concern at this point is the Compression ratio.
When I get everything sorted out I will post the Dyno results.

Thanks
 

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I'll be posting a dyno as soon as I've got her broken in . I've only seen 1 on a 31/37 . The guy was running a similar build but on a bagger with fuely. His 37 was pinging and detonating running 10.2 , he switched to the 31 and was much happier, and it is more tolerant to gas grades. This was on the HD Tech forum
 

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nidan said:
I'll be posting a dyno as soon as I've got her broken in . I've only seen 1 on a 31/37 . The guy was running a similar build but on a bagger with fuely. His 37 was pinging and detonating running 10.2 , he switched to the 31 and was much happier, and it is more tolerant to gas grades. This was on the HD Tech forum
His pinging was an issue because he was running too much compression for the cam (9.7 - 9.8 for the 37):loser: nothing wrong with the cam just the dumbass who did not set the engine up correctly for it:gun:
 

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Discussion Starter · #11 · (Edited)
Thanks everyone for the comments.
It seems that 9.8 is the max Compression Ratio for the 37G Cam, for me anyway,
so it'll be Flat Top Pistons instead of 10:2.5 Pistons.
 

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Might want to check your head chamber size before deciding on a piston. Mine measured out at 89cc so i needed the hi-comp cast ones to get the proper cr.
 

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Go with flattops! If your chambers are to big then just mill the heads for the proper ratio....
 

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Discussion Starter · #14 · (Edited)
The 95CI build with 37G Cams, Flat Top Pistons, .030 Cometic gasket, and
Total Seal Rings is giving me a Static Compression Pressure of 185 psi.
I'm hoping that will drop off about 5 psi after I run it a few miles.
Dakota Kid Carburetor, Thunderheader Exhaust, 6200 RPM Performance
Ignition, NRHS Racing Stg 1 Heads.

Dyno indicated 92HP/104ft.lbsTQ

Nice Running FXDL :)
 

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Discussion Starter · #15 ·
The 95CI build with 37G Cams, Flat Top Pistons, .030 Cometic gasket, and
Total Seal Rings is giving me a Static Compression Pressure of 185 psi.
I'm hoping that will drop off about 5 psi after I run it a few miles.
 

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Do you leave home? I went with lower compression build because lots of places in this country have low octane. Out west 85 is common.

Was explained to me that higher compression produces power at higher RPMs??
 

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berserker said:
Do you leave home? I went with lower compression build because lots of places in this country have low octane. Out west 85 is common.

Was explained to me that higher compression produces power at higher RPMs??
Higher compression boosts the bottom end. For high end horsepower, you run larger cams with more duration and overlap...this lowers compression and weakens the bottom end. You use high compression in combination with cams like that to balance things out.
 

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Another question..........

avcat said:
The 95CI build with 37G Cams, Flat Top Pistons, .030 Cometic gasket, and Total Seal Rings is giving me a Static Compression Pressure of 185 psi. I'm hoping that will drop off about 5 psi after I run it a few miles.
avcat,

What year are the heads and what was the chamber volume?
I read that the 2006 chambers are larger..............
How is it running?

Thanks, John
 

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It takes a tight chamber and thin gaskets to get 10.25:1 with "10.25:1" pistons. The dome would have to be twice as big to actually be 10.25:1 with stock heads and gaskets. I've always thought it was ridiculous to call a domed piston a "xxx:1" piston.

I suggest most people go with flattops and mill the heads for proper compression. The dome impedes the flame front.
 

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Western 85 Octane

The reason Western states typically have lower octane (I presume) is elevation. I don't know the formula, but increasing elevation has the effect of lowering octane requirements. 85 out here is probaly roughly equivalent to running 87-89 at a few hundred feet above sea level. Here in NV, most of the valley floors are approx 4000' (higher between Elko and Wendover).
 
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