73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: rich weyand on March 26, 2015, 06:38:03 pm
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I can't answer your question in a PM because your inbox is full!
Move the vacuum advance line to the "air cleaner vacuum" port on the Holley.
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Should have put it my last pm but when I was setting the timing I also moved the vacuum line where you told me to. I didn't realize I was only allowed 1 message. I guess because I haven't posted just lurked and tried to learn.
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Next question: You are setting the base timing with the vacuum advance disconnected, correct?
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Yes but there doesn't seem to be any difference whether it is connected or not. Will the engine speed change when I connect to vacuum advance line after timing?
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What should change is the timing value you see with the timing light. The mark should move way counterclockwise. About 15 degrees' worth.
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Should have put it my last pm but when I was setting the timing I also moved the vacuum line where you told me to. I didn't realize I was only allowed 1 message. I guess because I haven't posted just lurked and tried to learn.
after a couple post you get more than 1 pm. its just there to prevent people from joining then just sending pms
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Yes but there doesn't seem to be any difference whether it is connected or not. Will the engine speed change when I connect to vacuum advance line after timing?
are you unhooking the hose then plugging the end of the hose with a golf tee or a nail?
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FlatBlack77 - Yes, I am plugging the vacuum line while timing.
Rich - Will the timing mark move 15 degrees while at idle as soon as the vacuum is reconnected? If so that is not happening. When the vacuum is attached the timing mark moves under acceleration but it also moves the same amount with the vacuum line detached and plugged.
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OK, so the vacuum advance isn't working. You should be able to watch it move 15* counterclockwise when you hook up the hose, if you have it hooked to manifold vacuum. Check that the hose isn't split or something, but it may be time for a new distributor.
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I'm with Rich. i had trouble with my trucks timing and it turned out the vacuum advance wasnt working AND the mechanical advance was totally shot.
$30+ for a new vacuum advance from AdvanceAuto orrrrr $90 for a whole new distributor.
http://www.jegs.com/i/JEGS-Performance-Products/555/40002/10002/-1?parentProductId=
i got this one and its nice for the money and free shipping.
it will eliminate any questions about the distributor being bad ya kwow
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http://www.ebay.com/itm/SBC-BBC-Chevy-305-350-454-V8s-HEI-Distributor-with-Red-Cap-65k-65-000-Volt-/171698117754?hash=item27fa015c7a&vxp=mtr
$44.98 for a new distributor (RED)
http://www.ebay.com/itm/Chevy-SBC-350-BBC-454-65K-Coil-HEI-Electronic-Distributor-Clear-Cap-/181567616389?hash=item2a4645f585&vxp=mtr
$47.00 (CLEAR)
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maybe i should have checked ebay
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Well, the eBay ones are more in my price range. I was looking at the red one and it mentions a 4 pin ignition module is this some I need to be concerned with? Also, how do you set up an adjustable vacuum advance?
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Well, It's ordered. Not going to be here until next week so looks like I'll b e rebuilding the front hub, ball joints, and spindle until then.
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Went to install the distributor today and I've got problems. Apparently mine is a 5 pin ignition module which has its own set of wires leaving the distributor straight back to the firewall. The distributor that I bought is a 4 pin and has no use for these wires. Now what? Can the Electronic Spark Control be abandoned? It doesn't appear to connect to anything except the distributor and detonation sensor.
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Dump the ESC... It is garbage...
http://73-87.com/7387garage/drivetrain/escrepl.htm
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Went to install the distributor today and I've got problems. Apparently mine is a 5 pin ignition module which has its own set of wires leaving the distributor straight back to the firewall. The distributor that I bought is a 4 pin and has no use for these wires. Now what? Can the Electronic Spark Control be abandoned? It doesn't appear to connect to anything except the distributor and detonation sensor.
If you bought a new HEI distributor, all it needs to connect to is switched +12V at the BAT terminal. That's it. The other connector to the cap comes out of the distributor base itself. You just need to hook the BAT terminal to switched +12V, which is to say IGN on the fuse block.
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Got everything in the front hub put back together and decided to do the distributor. Everything went well. Got the timing set. Has knock at wot. That should come out with adjusting the vacuum advance. Only problem I have now is hesitate off line. My guess is carburetor adjustments. Any guesses? I appreciate and thank all of you that have helped so far.
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what did you set the timing at and what octane fuel are you using?
also is the advance connected to manifold or ported vaccume?
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The WOT knock will not come off with vacuum advance adjustment. You need to back the base timing off. What are you set at now? Back off a couple degrees at a time untill there is no WOT knock.
Don't bother adjusting the vacuum advance. Stock is 15* and that's fine. It's not that picky.
Vacuum advance should be connected to manifold vacuum. An off-idle hesitation sounds like you have it on ported vacuum. You sure it's on manifold vacuum?
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The other common cause of off-idle hesitation is an inadequate shot from the accelerator pump. When the throttle plates open, the air moves immediately, and it takes a while for fuel flow to catch up, so carbs shoot a jet of extra gas in there for a second or so when you open the throttle. If that isn't working, you will get that hesitation.
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Ok, I won't touch the vacuum advance. I didn't get a chance to work on it again this afternoon, so I haven't touched anything except timing. Timing is set at 14 degrees. So I should take that back to 12 degrees? I am guessing that vacuum is attached to a manifold port off the carb. It is the one Rich told me to connect to. As for the octane rating I use regular which I think in MD is 87.
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Yeah, knock it back to 12. Knocking on WOT is not good for the engine.
Post a pic of the carb showing the vac advance connection.
Check the operation of the accelerator pump. Remove the air cleaner. With the enging off, look down the bore of the carb, and with your hand advance the throttle to full open and hold it there. There should be a jet of gasoline that you can see into the bore that lasts a second or two.
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Here are the carb pics. In first pic the hose that looks like it is going to the orange emissions thing actually loops back to the vac on the distributor. I'll have to clean up the vac lines tomorrow. All the emissions is gone except for the pcv and egr. All the lines coming off the carb are plugged just long so I'll pull them all off and plug at the carb.
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Keep the PCV, it's important. It allows the carb to suck blow-by out of the crankcase and keep it from turning into sludge in your engine.
Vacuum advance is hooked up properly.
Check that accelerator pump operation.
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Ok I'll check that hopefully tomorrow. I think the PDF document you gave me early talks about that. Thanks again and I'll keep you posted.
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Reset the timing to 12 and that took the knock out. Started working on the accelerator pump today and found one of the accelerator pump arms stuck on the shaft. Finally out that unstuck and greased up. That helped some at least the pump arm wouldn't stick down. Still have to try some adjustments on the pump and possibly new larger squirters.
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So, I ordered a new squirter (discharge nozzle), accelerator pump arm, accelerator pump arm stud, and some new accelerator cams. Replaced all of that because the arm stud was rusty and making the pump arm(plastic replaced with a metal one) stick, the squirter was a #37 and should have been a #31, and the cam was an orange and should have been a green. Everything seems to be running great now, no hesitation. Thanks to everyone that helped with this I really appreciate it and hopefully someone else can use this information. ;D
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Excellent. Thanks for reporting back.