Another Holley Idle Thread - I'm at wit's end!
Platinum Member
06-18-2010, 09:00 AM
#13
Registered
That dosent sound like verry much vacuum at idle. I would look in the valve train for some problems. Is the cam a solid roller? Are you sure the timming is at 34*? Sometimes stock balancers can slip.
06-18-2010, 09:24 AM
#14
Registered
Thread Starter
I wonder if having the throttle plates open too far is causing the poor vacuum???
Yes, could this be why I have to advance the throttle plates past the transfer slots?
I have done a compression test, 150 in all cyls, and everything seems fine.
The cam is a Hyd. Roller, speed pro CS1075R
110* Lobe Center
Specs at .050:
Intake .330" 236*
Exhaust .340" 246*
Adv Duration is 316/324, valve lift is .581 / .598
I will tripple check the timing again today.
Thanks all!
Yes, could this be why I have to advance the throttle plates past the transfer slots?
The cam is a Hyd. Roller, speed pro CS1075R
110* Lobe Center
Specs at .050:
Intake .330" 236*
Exhaust .340" 246*
Adv Duration is 316/324, valve lift is .581 / .598
I will tripple check the timing again today.
Thanks all!
06-18-2010, 10:58 AM
#15
Charter Member # 55
Charter Member
I agree, 5* of vacuum is very low. The 750 is on the smaller side, but it should work and have good throttle response. I also prefer mech secondaries on boats. You could try it and then pull a vacuum reading and see if it improves. Be careful testing with 750 since it is probably not jetted right. Depending on the carb, it may have the secondary plate instead of a metering block with adjustable jets. You certainly don't want it to lean out at higher rpms.
VIP Member
06-18-2010, 12:46 PM
#17
Registered
Thread Starter
I'll check what size squirter is in it this afternoon, I don't remember. All of the transfer slot is not showing, but more than I would consider normal. I usually turn the idle screw in3/4 to 1 turn once the butterflies start to move. This one I have to turn 2-3 turns to get it to idle at 750 or so. seems like way too much.
06-18-2010, 01:33 PM
#19
Registered
Thread Starter
Whe I tried this, it would instantly go lean and stall. I could force it to run by opening the idle mixture screws about 4 turns. It would only barely idle at that point, and the transition was terrible.
