flat cam lobe= erratic vacuum?
Thread Starter
Melting Slicks
Joined: Dec 2000
Posts: 2,635
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From: Union Ontario
flat cam lobe= erratic vacuum?
I have a very erractic vacuum right now... I have tried to tune it out a bit....
Today I pulled the valve covers and found #1 exhaust rocker to be significantly loose. I'm not sure if its loose or the lobe is flattened... I'll check later tonight and update. as well as seeing if any other loose rockers.
BTW its a Comp XE274H
Today I pulled the valve covers and found #1 exhaust rocker to be significantly loose. I'm not sure if its loose or the lobe is flattened... I'll check later tonight and update. as well as seeing if any other loose rockers.
BTW its a Comp XE274H
Race Director
Joined: Oct 2002
Posts: 12,065
Likes: 2
From: Smalltownville Michigan
Cruise-In 5, 6 & 10 Veteran
St. Jude Donor '09
start it up with the valve cover off and watch the valve train movement.. if the rocker is not moving, the lobe is wiped
Note: thats AFTER you think you have that valve in adjustment
Note: thats AFTER you think you have that valve in adjustment
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Some rockers will always have some play while others will be tight depending on where they are on the cam lobe, don't sweat it.
How does it run ? Start from the beginning and check everything, spark plug wires on the correct plug, vacuum leaks in base of carb or hoses, idle mixture set right, timing OK etc.
How does it run ? Start from the beginning and check everything, spark plug wires on the correct plug, vacuum leaks in base of carb or hoses, idle mixture set right, timing OK etc.
Thread Starter
Melting Slicks
Joined: Dec 2000
Posts: 2,635
Likes: 0
From: Union Ontario
Originally Posted by MotorHead
Some rockers will always have some play while others will be tight depending on where they are on the cam lobe, don't sweat it.
How does it run ? Start from the beginning and check everything, spark plug wires on the correct plug, vacuum leaks in base of carb or hoses, idle mixture set right, timing OK etc.
How does it run ? Start from the beginning and check everything, spark plug wires on the correct plug, vacuum leaks in base of carb or hoses, idle mixture set right, timing OK etc.
I'm going to check over the complete valve train for loose rockers (and proper lift). I'm pretty sure that will improve my vacuum and idle quality a bit then the adjustments I make will work better.
Thread Starter
Melting Slicks
Joined: Dec 2000
Posts: 2,635
Likes: 0
From: Union Ontario
Originally Posted by David Ey
does the stud look like it has pulled out some.....longer than the others?
I fired it up the vacuum has stabilized but is extremely low-- 5 inches.
I'll take her out and get her to oeprating temp tomorrow and see what happens and tune it from there.
Advanced
Joined: May 2005
Posts: 99
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From: Lincolnton NC
I'd go ahead and adjust all the valves. If you don't know how, read up on it, its simple.
Been awhile, but Its something like tighten until it quits clacking and the back off a quarter or half turn....for hydraulic lifters.good luck, jim
Been awhile, but Its something like tighten until it quits clacking and the back off a quarter or half turn....for hydraulic lifters.good luck, jim
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Thread Starter
Melting Slicks
Joined: Dec 2000
Posts: 2,635
Likes: 0
From: Union Ontario
Originally Posted by MotorHead
Do you have the Comp Cams pushrods with the little ***** on the end ?
There was only one valve out so I adjusted it, engine ran nicer Vacuum staabilized... but low and stil running rich. I think Its mainly a carb problem now. I'lll get her up to temp tomorrow and tune the carb.... If I can't get it running right, I'll yank the carb and tear it down.
