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Which way to move the cam to reduce cylinder pressure? #971244
04/11/11 04:29 PM
04/11/11 04:29 PM
Joined: Feb 2003
Posts: 265
Garland, Texas
1badmopar Offline OP
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1badmopar  Offline OP
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Posts: 265
Garland, Texas
I would like to pull some clyinder pressure out of my motor at idle. I am not sure if I need to advance the cam or retard it.

I think retarding the cam will reduce the pressure at idle and move the powerband up in the rpm range. Can someone please confirm?

I am thinking about a 2 degree change. Thoughts? Too much, too little?

Thanks,


1966 Plymouth Belvedere
520" RB w/ Indy 440-1 Heads
FiTech Fuel Injection
TKO 600 conversion

[img]https://flic.kr/p/2j1ejsK[/img]
Re: Which way to move the cam to reduce cylinder pressure? [Re: 1badmopar] #971245
04/11/11 04:47 PM
04/11/11 04:47 PM
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert Offline
Circle Track
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Posts: 36,040
Lincoln Nebraska
Quote:

I think retarding the cam will reduce the pressure at idle and move the powerband up in the rpm range. correct

I am thinking about a 2 degree change. Thoughts? Too much, too little?
Thanks,


4 deg and recheck the P/V clearance or post what it was b 4 May I ask what is the prob/symptoms your having and more info on the build/what eng etc


live every 24 hour block of time like it's your last day on earth
Re: Which way to move the cam to reduce cylinder pressure? [Re: 1badmopar] #971246
04/11/11 04:55 PM
04/11/11 04:55 PM
Joined: Nov 2007
Posts: 21,808
Kirkland, Washington
Pacnorthcuda Offline
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Kirkland, Washington
Yep---retarding the cam will reduce Low Rpm pressure.
2 degrees is a small change, but it also depends on where you're at now compared to ICL. If you degree it and you are truely 'straight up' then you could retard it 4 degrees.
Your gonna loose some bottom end though.

Re: Which way to move the cam to reduce cylinder pressure? [Re: Pacnorthcuda] #971247
04/11/11 05:06 PM
04/11/11 05:06 PM
Joined: Feb 2003
Posts: 265
Garland, Texas
1badmopar Offline OP
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1badmopar  Offline OP
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Posts: 265
Garland, Texas
Thanks for the replies! It is on my 520" RB. I am having severe dieseling issues at shut down. I have tried two different carbs and the same symptom exists. It seems to have a tremendous amount of cylinder pressure at low rpm, so I am going to back it off a little and see what happens.

The motor made peak power at 5400 rpm, so I can stand to move the power band up a little. It made 708 ft lbs at 4500, so I am not worried about loosing a little bottom end. Especially with the low 1st gear in the TKO.

Thanks!


1966 Plymouth Belvedere
520" RB w/ Indy 440-1 Heads
FiTech Fuel Injection
TKO 600 conversion

[img]https://flic.kr/p/2j1ejsK[/img]
Re: Which way to move the cam to reduce cylinder pressure? [Re: 1badmopar] #971248
04/11/11 05:12 PM
04/11/11 05:12 PM
Joined: Jan 2003
Posts: 74,909
U.S.S.A.
JohnRR Online rolleyes
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JohnRR  Online Rolleyes
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Posts: 74,909
U.S.S.A.
Quote:

Thanks for the replies! It is on my 520" RB. I am having severe dieseling issues at shut down. I have tried two different carbs and the same symptom exists. It seems to have a tremendous amount of cylinder pressure at low rpm, so I am going to back it off a little and see what happens.

The motor made peak power at 5400 rpm, so I can stand to move the power band up a little. It made 708 ft lbs at 4500, so I am not worried about loosing a little bottom end. Especially with the low 1st gear in the TKO.

Thanks!




Dieseling is usually caused by the throttle butterflies being open to much at idle .

Re: Which way to move the cam to reduce cylinder pressure? [Re: JohnRR] #971249
04/11/11 06:32 PM
04/11/11 06:32 PM
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
Dodgem Offline
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Ontario, Canada

Dieseling is usually caused by the throttle butterflies being open to much at idle .






probably needs more idle advance! that usually allows the butterflies to be closed up some!
Shut it off in gear.

Re: Which way to move the cam to reduce cylinder pressure? [Re: Dodgem] #971250
04/11/11 07:14 PM
04/11/11 07:14 PM
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert Offline
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Lincoln Nebraska
What Dodgem and double R said


live every 24 hour block of time like it's your last day on earth
Re: Which way to move the cam to reduce cylinder pressure? [Re: RapidRobert] #971251
04/11/11 08:22 PM
04/11/11 08:22 PM
Joined: Sep 2005
Posts: 12,481
Chino Valley
RodStRace Offline
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RodStRace  Offline
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Chino Valley
Yep, you could even adapt an idle solenoid on it if you can't tune it out...

Re: Which way to move the cam to reduce cylinder pressure? [Re: RodStRace] #971252
04/11/11 11:34 PM
04/11/11 11:34 PM
Joined: Jan 2003
Posts: 27,421
Balt. Md
3
383man Offline
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383man  Offline
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Posts: 27,421
Balt. Md
Or drill 1/8 holes in the primary throttle blades. Ron







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