Over scavenging?
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Le Mans Master
Joined: Feb 1999
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From: Hoosier
Cruise-In III Veteran
Over scavenging?
What are the signs of overscavening? Can excessive porting or too much exhaust lift overscavenge the cylinders and pull intake charge out the exhaust?
I had my heads ported and gasket matched on the intake and exhaust side, and added comp cams roller tip rockers. 1.52 on the intakes and 1.6 on the exhaust to sort of simulate a dual pattern cam. It runs a whole lot better but gas mileage dropped.
[Modified by AlwaysWave, 5:22 AM 2/16/2002]
I had my heads ported and gasket matched on the intake and exhaust side, and added comp cams roller tip rockers. 1.52 on the intakes and 1.6 on the exhaust to sort of simulate a dual pattern cam. It runs a whole lot better but gas mileage dropped.
[Modified by AlwaysWave, 5:22 AM 2/16/2002]
Drifting
Joined: Jul 2001
Posts: 1,418
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Re: Over scavenging? (AlwaysWave)
What motor,heads,induction and exhaust you running.Near impossible it is over scavenging.Something else is wrong.Hopefully the heads are not ruined.Many small block heads are ruined when ported on the intake due to directing the flow to the center of the valve.
But lets see what you are using first.Interested in the cam you have.
Usually though with good heads added to existing cam and all else leaning of the carb is required.
Many stick 1.6 rockers on without thought to rocker geometry.Have you checked?
[Modified by mountainmotor, 5:58 AM 2/16/2002]
But lets see what you are using first.Interested in the cam you have.
Usually though with good heads added to existing cam and all else leaning of the carb is required.
Many stick 1.6 rockers on without thought to rocker geometry.Have you checked?
[Modified by mountainmotor, 5:58 AM 2/16/2002]
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 6,807
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From: Hoosier
Cruise-In III Veteran
Re: Over scavenging? (mountainmotor)
It's a pretty much stock 350 in my 72. It has 487 heads, Edelbrock Performer manifold and Edelbrock 1406, 600 cfm carb, MSD Ignition, and Flowtech Jet Hot coated headers with 2 1/2 exhaust pipes. I'd bet the cam is stock too. The rocker geometry appears ok. The rocker roller is centered on the vlave with the rod/lifter on the base cam circle.
