Rapidly moving vacuum gauge at idle - smooth above 1k

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Firedome8
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Re: Rapidly moving vacuum gauge at idle - smooth above 1k

Post by Firedome8 »

A leak down test is a good next step. You can inrich the mixture at idle with propane to see if the engine wants more fuel. Just thinking.
A good test is worth a thousand opinions.
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Re: Rapidly moving vacuum gauge at idle - smooth above 1k

Post by BigBlockMopar »

Just did a compressiontest with a screw in type gauge.
All cylinders were between 208 - 210 psi, except cyl. 6, which had ‘only’ 195-198 psi.
Engine temp was around 135F, carb at WOT.

I did 2 tests in a row, one bank at a time from front to back: 1357-2468-1357-2468.
First round I got numbers just above 200-205 psi, second round I got the numbers mentioned above.

So my focus is on cyl. 6.
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Re: Rapidly moving vacuum gauge at idle - smooth above 1k

Post by Diego3188 »

Hello Big block mopar... did you mange to find out the problem. Thankyou, Inhave the same problem as jou have
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Re: Rapidly moving vacuum gauge at idle - smooth above 1k

Post by Firedome8 »

Does it have any valve train noises?
A good test is worth a thousand opinions.
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Re: Rapidly moving vacuum gauge at idle - smooth above 1k

Post by BigBlockMopar »

Older topic, but,
no obvious valvetrain noise present, but I can tell during driving when valve-lash is getting upto around .010".

I currently have the engine opened-up and will replace the iron heads for a pair of aluminium heads and will do a cam change as well. Going to a hydr. roller.
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