Christmas Build, 3.2 Short Stroke, 10.1 CR

[trond]

well done and thanks for posting. How do you like the cams ?

[Tom_in_NH]

I'm also curious regarding the cams, mostly because I can't find ANY data whatsoever (lift, duration, lobe centers) on KR75 camshafts. Makes it tough to associate potential emulsion tubes candidates.

[snbush67]

Originally Posted by trond

well done and thanks for posting. How do you like the cams ?

I’m digging the cams. Strong immediate punch of power with a steep run up to peak and continues strong till it tapers off a little quicker than expected near max. William suggests that 42 chokes are likely to improve upper end with minimal impact to low end torque.

Originally Posted by Tom_in_NH

I'm also curious regarding the cams, mostly because I can't find ANY data whatsoever (lift, duration, lobe centers) on KR75 camshafts. Makes it tough to associate potential emulsion tubes candidates.

I mapped every lobe of this cam but it’s proprietary to Knightrace so, not at liberty to share it.

I just talked to William about this cam, call him, if he doesn't answer leave a message. He is very helpful and responsive. And you might be able to find out about some other grinds.

William Marshall can be reached at 615.969.4917 or knightrace@mac.com

[snbush67]

Smoothly Tuned with 42 Venturies. No bumps, stumbles, gasps, or hesitation.

Top end has opened up nicely. 14.2 AFR at Idle, 12.8 Cruise, 12.9 finish at 7500 RPM.

46 PMO’s with 42 Venturies
60 Idles, 135 Idle Airs
F11 Emulsion Tubes, 185 fuel, 205 Air

[snbush67]

To get everything smoothed out I ramped timing in a little sooner and bumped it up where the lean spot was.

Im going to try a different emulsion tube set up to try to bring more main in a little sooner.

[snbush67]

Tried a few different combinations today, none of which are worth mentioning, some which fell flat, specifically the F7 it went way lean on acceleration with a huge gasp and stumble.

On a whim I tried F3 tubes with great improvement across the entire RPM range. I was able to get optimum performance using 190 main jets with 210 Air Correctors. Idle is at 13.2 it’s a little rich still, I’m going to lean it out a bit. Light cruise is at 13.2, no stumble or lean spots, finishes nicely at 12.6 around 7200 rpm.

So far the F3 is superior for performance, power and economy.

[Glenfield]

Enjoying your progress and appreciate the updates. As you know, I’m going through this and your posts and a few others have tremendous value in posterity.

Case in point … emulsion tubes. I’m running the F7s and am pig rich and then scary lean. Your experience corroborates.

[snbush67]

Originally Posted by Glenfield

Enjoying your progress and appreciate the updates. As you know, I’m going through this and your posts and a few others have tremendous value in posterity.

Case in point … emulsion tubes. I’m running the F7s and am pig rich and then scary lean. Your experience corroborates.

I must have missed that you were tuning with the F7. The F7 supposed to be contributing more fuel earlier, but my AFR readings show it as lean earlier, it may be a false AFR reading and may actually be going super rich and bogging.

The F11's worked and the plugs looked great, but the F3 is another level, working incredible and can feel the results.

[Old H2S]

Well that did not work..
I just used your numbers above^ and way to lean at WOT. The F7 worked better. The F3 has 4, 1mm holes at the very bottom that add too much air at WOT.
Tomorrow I am going to try the F66

[snbush67]

Originally Posted by Old H2S

Well that did not work..
I just used your numbers above^ and way to lean at WOT. The F7 worked better. The F3 has 4, 1mm holes at the very bottom that add too much air at WOT.
Tomorrow I am going to try the F66

Tom,

My experience is that the main air corrector is what determines the top end.

How was the transition from the idle to main circuit? Any bumps or hesitations? if the transition was all good then, try the same set up but with a smaller air corrector, try 190 main jets with 190 Air Correctors.

[Old H2S]

The idle circuit was ok-ish.
Transition was lean..
Lead in to the main was ok if at light throttle tip in, 14.0. At 4k going way lean.

[Old H2S]

Well 190/190 did not work..
Dropped down to a 170, nope.
I am at 140 now and the F66 tubes and am getting somewhere now, time to work on the idea jet some.

[Old H2S]

Main is up to 205
idle is at 60
It is getting better..
More later, it is hot as ...

[Old H2S]

Main is up to 205
idle is at 60
It is getting better..
More later, it is hot as ...

[snbush67]

Originally Posted by Old H2S

Main is up to 205
idle is at 60
It is getting better..
More later, it is hot as ...

F66 tubes?

[Old H2S]

I should have posted a picture of the F66 tubes.. No holes at the bottom for the top end.

[snbush67]

And…. You guessed it, it just keeps getting better. Today’s tuning was all about timing, I brought the advance on sooner, added a small venture into 26 degrees at the peak (2400-3300rpm) and added a MAP curve of 13 degrees at choice locations. Results, smoother, stronger, faster. Idle purrs, light throttle hums, acceleration howls and WOT screams.

[snbush67]