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Discussion Starter #1
I have found and fixed a couple of vacuum leaks , Cylinders 1 and 5 are running about 180 on the spark plug cermic . 2 and 6 are about 230 is this normal ? I am pulling 20 inches of vaccum at idle .
Engine seems to run better with oem air cleaner and PVC completely hooked up. In neutral and reved to 3000 I get a little break up but driving at 3000 in 4th the truck just falls flat on its face like you run out of gas . If I try to push through it starts to buck . When I back off below 3000 she cleans up and sounds good. I am running the stock .60 vapor fuel return valve with a new 600cfm holley street warrior. I also have my fuel line run around the carb and than to the carburetor so I could get a inline filter in there. I have the intank electric low pressure pump. Help much appreciated
 

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Discussion Starter #3
Have you put a timing light on it to see what its doing in that department ?
yes , Why do you think timming
 

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Discussion Starter #4
I found a vac leak this am in the carb between main body and base
 

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HI I don't think a vacuum leak would effect it at 3000 rpms. what is your timing set at?? your symtoms show to much timing.
good luck
tim
 

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HI I don't think a vacuum leak would effect it at 3000 rpms. what is your timing set at?? your symtoms show to much timing.
good luck
tim
Set at 15 intial and 34 total and pretty much in by 2300. I know my way around a motor but am no expert. These old motors definitely make you have to think sinse no on board computer.
I do know at 15 it is very hard to start back at 10 it is easy to start back I need to call Scott next week as he dialed the dizzy in for me . So if I have too much timming what does that do exactly
I am trying to understand what effects what. Thanks
 

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Set at 15 intial and 34 total and pretty much in by 2300. I know my way around a motor but am no expert. These old motors definitely make you have to think sinse no on board computer.
I do know at 15 it is very hard to start back at 10 it is easy to start back I need to call Scott next week as he dialed the dizzy in for me . So if I have too much timming what does that do exactly
I am trying to understand what effects what. Thanks

Did you try blocking the vapor return in the fuel system to get more fuel volume?

Float levels set properly?

The timing curve provided for this low static c/r application is not going to cause you to fall flat on your face at 3000 RPM. If this were true I'd be out of the dizzy business lol.

Too much vacuum advance can cause a miss like roughness at light throttle at 3000 rpm however I dial back vac advance to under 15* when EGR is not used.

Late model 460 starters prior to the gear reduction EFI type units are weaker than the older counterparts with the solenoid on top. Battery cables, grounds and the starter when in good condition should not drag trying to start a low static c/r at 14 or 15 btdc.


SJ
used 2b RHP
 

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Discussion Starter #8
Did you try blocking the vapor return in the fuel system to get more fuel volume?

Float levels set properly?

The timing curve provided for this low static c/r application is not going to cause you to fall flat on your face at 3000 RPM. If this were true I'd be out of the dizzy business lol.

Too much vacuum advance can cause a miss like roughness at light throttle at 3000 rpm however I dial back vac advance to under 15* when EGR is not used.

Late model 460 starters prior to the gear reduction EFI type units are weaker than the older counterparts with the solenoid on top. Battery cables, grounds and the starter when in good condition should not drag trying to start a low static c/r at 14 or 15 btdc.


SJ
used 2b RHP
[/QUOTE

Finally , Finally. Got it worked out except for a some minor tweaking . OK the aluminum spacer was warped so I sanded it down on a 12 inch disc sander than tried it , almost it still had a minor leak with the water bottle test ,sanded a little more than went and got some permatex spray copper and sprayed both Gaskets and the spacer , let dry . I can get motor to idle down to 510 rpm.
It still has a little more shake than I like but when I rev up to say 1200 or so it smothed out.
I think it has a low idle misfire but not sure how to correct. The spark does not seem that strong when I pull the plug wire off . With the stock Air Cleaner I dont hear any noise or the secondary’s
With the 14 inch chrome air cleaner I hear the moan of the secondary’s plus very slight flutter when I lay into it in high gear but this is on 87 Ethanol Free. I will install larger battery cables but finding the vac leak helped that problem. The vacuum gauge is down to 17to 18 and temps are down. It will be interesting to tow with , I will post results of that. I have oem single exhaust now with exception of a Delta FlowMaster 50 muffler . Would Duals hurt my low end and if no what do you suggest . I dont like super loud but I do like hearing the rumble. Thank you for all your input.
 

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Discussion Starter #9
Solved this . Was a vacuum leak between the carb base and the main body of the carb
 
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