1850-1 holley vacuum secondary issue

[rayfinseats]

I have a 383 (388) 4.060 x 3.75 Vortec HEADS 1 piece rear main motor. All new. HEI, performer, ramhorn exhaust, 2.5 duels 350hp/327 cam. 222@.050, th350 Q-jet 2.73 gears stock converter. With the Qjet it idles fair at about 800 in gear with about 13-15 ported vacuum. 10.3 compression. Good milage but kinda slow acceleration. Engine builder told me to take it easy on the timing because of compression. I'm about 8 degrees at idle, and still have to shut it off in gear or I get run-on.

ANYWAY I tried a used holley 600 VS.I rebuilt to facory specs except I have a (blue squirter cam Front side and a metering block conversion on the sec side. 66 and 68 jets. I had a white cam but didn't look like it moved the arm much. PROBLEM: It revs great but I can't get it to run under half throttle. Checked adjustable float levels, brass floats, mix screws at 1.5 turns. Acc pump to .015. Elec pump set to 3-4 psi. I don't see any leaks but appears to be flooding into engine. Dies below half throttle. Any ideas?

[rayfinseats]

Or maybe 1850's or just used holleys are junk ? I tried an edelbrock 600 once but it was a gas hog.

[bdiamond]

It might have something to do with those rearend gears.


I reread.... If its dying thats something else. I'd try a new carb.

[rayfinseats]

Yes those rear end gears suck and I wish I would have put in a 2200 stall when I put the engine in. Mabe I'll try for a land sped record.

[geezer#99]

Could be your power valve is ruptured.

To cure your run on, high idle in park, and low vacuum, you need more initial timing.
Double or more than what you have now.
More timing will let you close the primary throttle and get you idling on the idle circuit.
That top end 151 cam and long gears needs as much initial timing as you can put in it.

[rayfinseats]

6.5 power valve was new when I put the carb on. I'll check it. The initial timing I will try.

[RootBeerFXS]

Originally Posted by rayfinseats

6.5 power valve was new when I put the carb on. I'll check it. The initial timing I will try.

If I remember correctly, the power valve is rated at half of your vacuum reading at idle. I think you said 13 inches so you should be there providing it is a good valve. Also I have had to drill holes in the lower throttle plates to cure your issue but as a last resort. I would try more timing myself as well first. just my .02