HEI knocking sound - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Alexis · 05-03-2003, 08:09 PM

I just finished installing a HEI. it starts up and i get the timing sometime near pefect but there is this wierd knocking sound that happen when i lay on it, sometimes a pop. do you have any idea what this might be?

oh i also didn't use a 12 gauge wire I used a 14, can this effect it?

MOTHERTRUCKERS · 05-03-2003, 09:17 PM

Run a temperary 10 gauge wire from your battery to the hei and see if that fixes your poping problem.

**BAD4X4** · 05-03-2003, 09:23 PM

The rotor might be rubbing on the cap, I know my old 69 did the same thing, and it was the rotor rubbing.Hope this helps.

BLACK AND BLUE 67-72 · 05-03-2003, 10:37 PM

Yeah, check to make sure that the cap is locked down properly, mine had one of the locking tabs improperly seated, and when I started the truck it would make a knocking sound and when reved up it would misfire.

Alexis · 05-03-2003, 10:59 PM

what if the rotor is cracked where the screw holds it down?

Ok I messed with the timing and I was way off. But it seems i can't really drop the timing any lower cause the engine seems to kick a little. Any one know what this kick means?

thanks for your help guys.

O'l Buck · 05-04-2003, 01:00 AM

If the engine is fighting the starter, it is either retarded or advanced too far......I can't remember because it's been awhile since I messed with one. I do know if it's advanced too far, it will ping when you hammer on it. The cracks in the rotor aren't helping your situation any. They can cause the spark to go to ground in places it shouldn't and also slow the timing down and make it run like crap, same as cracks in the cap will.

jmanz69 · 05-04-2003, 09:47 AM

Go to the autoparts store and get a new cap without a crack in it. Why use a broken part when a replacement is cheap!!! Then run a bigger wire to the coil, and then set your timing. If your not going to do it right, then don't do it. And don't ask why it doesn't work with an improperly installed unit... If you are going to do it half-a$$ed, then don't wonder why it's not working like it should.

gmc67swb · 05-04-2003, 10:35 AM

Quote:

Originally posted by jmanz69
Go to the autoparts store and get a new cap without a crack in it. Why use a broken part when a replacement is cheap!!! Then run a bigger wire to the coil, and then set your timing. If your not going to do it right, then don't do it. And don't ask why it doesn't work with an improperly installed unit... If you are going to do it half-a$$ed, then don't wonder why it's not working like it should.

WHY DON'T YOU TELL HIM WHAT YOU REALLY THINK!

jmanz69 · 05-04-2003, 01:08 PM

Sorry, I was in kinda a crappy mood this morning. I guess I was a little hard on him. Also, he should check to make sure there isn't a advance weight hitting the cap as it speeds up. Could have a broken spring there, it would also make his timing different.

Alexis,

Sorry for being rude, but you have to install things right, then ask why it doesn't work. Take away all known weak areas such as the 14 ga wire, and the broken hold down tab on the cap.

I hope you get it going, good luck!

05-03-2003, 08:09 PM	#1
Alexis Member since 2000 Join Date: Dec 2000 Location: Mountain View Ca / Mexico Posts: 7,879	HEI knocking sound I just finished installing a HEI. it starts up and i get the timing sometime near pefect but there is this wierd knocking sound that happen when i lay on it, sometimes a pop. do you have any idea what this might be? oh i also didn't use a 12 gauge wire I used a 14, can this effect it?

05-03-2003, 09:17 PM	#2
MOTHERTRUCKERS Registered User Join Date: Dec 1999 Location: BRADENTON FLA Posts: 3,269	Run a temperary 10 gauge wire from your battery to the hei and see if that fixes your poping problem. __________________ Rest in Peace Ed. Thanks for all the good times.

05-03-2003, 10:37 PM	#4
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Yeah, check to make sure that the cap is locked down properly, mine had one of the locking tabs improperly seated, and when I started the truck it would make a knocking sound and when reved up it would misfire. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

05-04-2003, 01:00 AM	#6
O'l Buck Recovering Truck Driver Join Date: Mar 2002 Location: Orleans, NE USA Posts: 1,883	If the engine is fighting the starter, it is either retarded or advanced too far......I can't remember because it's been awhile since I messed with one. I do know if it's advanced too far, it will ping when you hammer on it. The cracks in the rotor aren't helping your situation any. They can cause the spark to go to ground in places it shouldn't and also slow the timing down and make it run like crap, same as cracks in the cap will. __________________ 67 K-20 350, SM465, Eaton rear, 4.56 no spin option 00 Dodge 2500 4x4, 24V cummins, 5 speed Chad South Central Nebraska

05-03-2003, 09:23 PM	#3
BAD4X4 Senior Member Join Date: Jan 2003 Location: La pine Oregon Posts: 1,668	The rotor might be rubbing on the cap, I know my old 69 did the same thing, and it was the rotor rubbing.Hope this helps.

05-03-2003, 10:59 PM	#5
Alexis Member since 2000 Join Date: Dec 2000 Location: Mountain View Ca / Mexico Posts: 7,879	what if the rotor is cracked where the screw holds it down? Ok I messed with the timing and I was way off. But it seems i can't really drop the timing any lower cause the engine seems to kick a little. Any one know what this kick means? thanks for your help guys.

05-04-2003, 09:47 AM	#7
jmanz69 Careful, they attack... Join Date: Aug 2001 Location: Waterford, MI, USA Posts: 1,107	Go to the autoparts store and get a new cap without a crack in it. Why use a broken part when a replacement is cheap!!! Then run a bigger wire to the coil, and then set your timing. If your not going to do it right, then don't do it. And don't ask why it doesn't work with an improperly installed unit... If you are going to do it half-a$$ed, then don't wonder why it's not working like it should.

05-04-2003, 01:08 PM	#9
jmanz69 Careful, they attack... Join Date: Aug 2001 Location: Waterford, MI, USA Posts: 1,107	Sorry, I was in kinda a crappy mood this morning. I guess I was a little hard on him. Also, he should check to make sure there isn't a advance weight hitting the cap as it speeds up. Could have a broken spring there, it would also make his timing different. Alexis, Sorry for being rude, but you have to install things right, then ask why it doesn't work. Take away all known weak areas such as the 14 ga wire, and the broken hold down tab on the cap. I hope you get it going, good luck!



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