Cam duration and shaking engine?
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 3,472
Likes: 18
From: Lake Ozark, MO
Cam duration and shaking engine?
Never had a performace engine before..will an engine with a high duration, higher lift cam idle rough (shaking) at "idle", or should it be smooth, but just sound rough? It shakes pretty bad at idle, but goes dead smooth at about 1200 rpm. I have to ask in order to try and figure out if I have a miss (see post about black plugs) I need to find.
East bound and down...
Joined: Dec 2004
Posts: 987
Likes: 3
From: Jonesboro Arkansas
Generally, yes. When I went to the XE 284 that is in my car right now, the difference was like night and day. The stock cam made my tame 454 idle like a sewing machine, now, the whole car shakes and shimmies. I kinda enjoy the feeling 
Team Owner
Joined: Feb 2005
Posts: 32,519
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From: central America
St. Jude Donor '08-'09
I find that the poly engine mounts also transmit quite a bit of the lumpiness of a cam. Are you running poly mounts as well?
Also, that 1200 rpm "dead spot" may be nothing more then a node in the vibrational wavelengths. How the engine responds I think is a better judge then how it feels. But wiser heads may prevail over this opinion.
trw
Also, that 1200 rpm "dead spot" may be nothing more then a node in the vibrational wavelengths. How the engine responds I think is a better judge then how it feels. But wiser heads may prevail over this opinion.
trw
Race Director
Joined: Dec 1999
Posts: 19,610
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From: Forked River NJ
What is the duration of your cam. I was running a solid cam with 248 @ .050 and it was not that bad. Your timing might not be enough at idle also. I plan on running a larger cam with the 383 I'm building
Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Bigger cams will give you a lumpy idle. In a street cam this should smooth out as you give it gas and usually be as smooth as it's gonna get by 1200 -1500 RPM
Safety Car
Joined: Jul 2002
Posts: 3,770
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From: St Louis MO
Originally Posted by Hvymtlc5
It's an Edelbrock 7162 with 240/246 duration and about .570 lift in a 454. Rough lumpy idle sound normal for this cam?
Brett
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Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Turn your idle up. That is allot of cam being h-flat. You probably don't have allot of idle vacuum.
My idle is @950 in "N" and drops to maybe 850 hot in gear.
My idle is @950 in "N" and drops to maybe 850 hot in gear.
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 3,472
Likes: 18
From: Lake Ozark, MO
Mine runs about 800 in Neutral..drops to 650 in gear. Never had performance cam so with this new engine wnated to make sure I didn't have a miss that was being masked by taking the engine to higher RPM. She's rock steady at 1200 and up..the air cleaner nut barely quivers..............
Burning Brakes
Joined: Aug 2005
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From: Hudson Falls, N.Y. 76 Vette Modified L-48
Originally Posted by MotorHead
Bigger cams will give you a lumpy idle. In a street cam this should smooth out as you give it gas and usually be as smooth as it's gonna get by 1200 -1500 RPM
Melting Slicks
Joined: Dec 2000
Posts: 2,130
Likes: 1
From: mesa,az
my motor shakes to about 850-900 RPM with my RPM cam but i don't see the problem? as long as it dosent stall and transitions well shaking , shimmering, loping, is what hot rod cams do. n'est pas? in fact. i like it.
