Re: NORMAL COMPRESSION???
[Re: polyspheric]
#841591
10/30/10 12:36 PM
10/30/10 12:36 PM
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Joined: Feb 2005
Posts: 4,321 Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,321
Prospect, PA
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Quote:
...out the exhaust valve" ???????
Which cam is that where the exhaust valve is open during the compression stroke?
I think you failed to understand my post. Obvously none, that's why there are the question marks. I'm quoting the other poster.
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Re: NORMAL COMPRESSION???
[Re: BSB67]
#841592
10/30/10 05:09 PM
10/30/10 05:09 PM
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Joined: Oct 2007
Posts: 4,213 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,213
New York
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You're right, sorry, yes I understood your comment to mean "Whaaaa?". Was referring to prior comment.
Boffin Emeritus
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Re: NORMAL COMPRESSION???
[Re: polyspheric]
#841593
10/30/10 05:24 PM
10/30/10 05:24 PM
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Joined: Jan 2003
Posts: 4,616 Kissimmee Fl.
dusturbd340W5
master
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master
Joined: Jan 2003
Posts: 4,616
Kissimmee Fl.
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But, FWIW, the Calulater that Dodgem posted was Happy about by 20# PSI for my Combo. But with your engine specs, it was almost right on. mike ![](/ubbthreads/images/graemlins/iagree.gif) it's not even close for my motor and as stated my leak down is less than 3% so I know it is sealed up well I also know someone that there roundy round motor is well over 600hp and only 165 cranking compression.
70 duster full chassis super pro 416 CNC Indybrock heads 727 w/brake
best so far 1.212 60 6.219 in 1/8 at 110.88 9.768 at 137.81 1/4
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Re: NORMAL COMPRESSION???
[Re: dusturbd340W5]
#841594
10/30/10 05:34 PM
10/30/10 05:34 PM
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Joined: Jan 2003
Posts: 17,926 Akron, Ohio
ProSport
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 17,926
Akron, Ohio
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I run a big overlap pump gas cam, I get 150 cranking compression. ![](/ubbthreads/images/graemlins/grin.gif) I put one gallon of 110 race gas in the tank when I race but don't need to. I've used lawn mower gas to drive to a local car show before, and still goes 9.80's. If I go E85 this winter, it will get a better cam for performance. ![](/ubbthreads/images/graemlins/wink.gif)
1970 Challenger, all aluminum 528 Hemi, HDK suspension, Tremec 5 speed manual
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Re: NORMAL COMPRESSION???
[Re: Labratt]
#841595
10/30/10 05:44 PM
10/30/10 05:44 PM
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Joined: Apr 2006
Posts: 3,675 Akron, Ohio U.S.A.
roadhazard
master
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master
Joined: Apr 2006
Posts: 3,675
Akron, Ohio U.S.A.
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Quote:
BTW...how important is it to have the butterflies partially open,as Hardcore suggests?
LABRATT, I feel it's very important. With the throttle closed can cause a restriction and produce lower than normal cranking compression readings ![](/ubbthreads/images/graemlins/Twocents.gif)
My personal preferance is to set the carb @ WOT when testing. Usually I'll hold it open with a wire or use the return spring to hold it FWIW.
Don't forget to return the throttle closed before you start the motor again ![](/ubbthreads/images/graemlins/laugh2.gif)
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Re: NORMAL COMPRESSION???
[Re: Dodgem]
#841597
10/30/10 08:52 PM
10/30/10 08:52 PM
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Joined: Jan 2003
Posts: 4,616 Kissimmee Fl.
dusturbd340W5
master
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master
Joined: Jan 2003
Posts: 4,616
Kissimmee Fl.
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yep carb wide open or removed and all 8 plugs removed and a battery charger hokked up and running is how I do it.
70 duster full chassis super pro 416 CNC Indybrock heads 727 w/brake
best so far 1.212 60 6.219 in 1/8 at 110.88 9.768 at 137.81 1/4
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Re: NORMAL COMPRESSION???
[Re: polyspheric]
#841598
10/30/10 09:05 PM
10/30/10 09:05 PM
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Joined: Dec 2008
Posts: 1,200 UK
602heavy
pro stock
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pro stock
Joined: Dec 2008
Posts: 1,200
UK
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Quote:
large overlap cams bleeding compression
How exactly does this happen?
My thoughts exactly , overlap has no bearing on compression whatsoever. ![](/ubbthreads/images/graemlins/shruggy.gif)
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