Need Help Diagnosing Popping - Chevelle Tech
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post #1 of 18 (permalink) Old Apr 15th, 19, 9:27 AM Thread Starter
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Mike
 
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Need Help Diagnosing Popping

Hey guys, I fired the chevelle up this weekend since it was so nice out. It's been asleep all winter and today was the day. But I noticed somewhat of a popping coming from the drivers side exhaust. All my specs are in my signature. I only drove the car once after the roller cam swap in the Fall and maybe didn't notice the popping. What I did so far was pull the plugs. In the pic, from right to left is 1-3-5-7 and you can see #1 is far darker. I cleaned up the plugs, started and no change. Thinking #1 is the culprit for the popping, I then replaced the plug with a spare, no change. I made a new ignition wire and no change. I also took a vid and put my hand in front of the exhaust so it amplifys the popping. Towards the end of the vid you can really see the popping moves my hand. Any thoughts or next steps in diagnosing? Could my valve adjustments be off? I used the EOIC method..


https://urldefense.proofpoint.com/v2...AL1bQ9qF3lM&e=




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post #2 of 18 (permalink) Old Apr 15th, 19, 10:31 AM
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Justin
 
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Did you notice if one of the headers is colder than the rest? Maybe you should recheck the valves since you only drove it once awhile ago.

1974 chevelle with 73 laguna nose sbc 357 Brodix IK180 heads Comp Cams XE274H Edelbrock RPM airgap 650 AED double pumper, M20 muncie, Truetrac with 3.73s
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post #3 of 18 (permalink) Old Apr 15th, 19, 10:45 AM
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Mr Bill
 
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Re: Need Help Diagnosing Popping

Mike,

Do you know anyone at a modern auto repair shop that could hook up a scope to it and take a look ? That would at least tell you if it is an ignition issue or something else. If it was running fine before you parked it then I doubt it has anything to do with valve adjustment. If it is a hydraulic roller you would have to be way off to make it pop.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md


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post #4 of 18 (permalink) Old Apr 15th, 19, 11:18 AM Thread Starter
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Mike
 
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Re: Need Help Diagnosing Popping

Quote:
Originally Posted by JF74chevelle View Post
Did you notice if one of the headers is colder than the rest? Maybe you should recheck the valves since you only drove it once awhile ago.
Unfortunately I broke my infrared temp gun. I just ordered a new one.



Quote:
Originally Posted by BillK View Post
Mike,

Do you know anyone at a modern auto repair shop that could hook up a scope to it and take a look ? That would at least tell you if it is an ignition issue or something else. If it was running fine before you parked it then I doubt it has anything to do with valve adjustment. If it is a hydraulic roller you would have to be way off to make it pop.

I don't know anyone at a shop and I think around here, if they can't hook a scan tool up to it, they probably wouldn't know.

It's a nice rainy dark day here in New England, maybe tonight i'll check for moisture in the cap or look for some arching?

67 Chevelle 454, M21
Gen IV 454 (out of C30 ), 390 heads 1.88/2.19 valves by Vortecpro, with ISKY Hyd Roller cam (at 050 218 int./228 exh, lift 530 int./552 exh.), RPM performer intake, Fitech 600HP, Dougs headers, and M21, Gear Vendors OD, 3.73's, UMI Suspension, Viking coilovers.
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post #5 of 18 (permalink) Old Apr 15th, 19, 3:08 PM
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Mr Bill
 
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Re: Need Help Diagnosing Popping

Quote:
Originally Posted by mdelgado View Post
It's a nice rainy dark day here in New England, maybe tonight i'll check for moisture in the cap or look for some arching?

Not a bad idea. Where are you at in Boston ?

Bill Koustenis
Advanced Automotive Machine
Waldorf Md


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post #6 of 18 (permalink) Old Apr 15th, 19, 3:31 PM Thread Starter
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Mike
 
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Re: Need Help Diagnosing Popping

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Originally Posted by BillK View Post
Not a bad idea. Where are you at in Boston ?

I'm north of Boston, in Hamilton

67 Chevelle 454, M21
Gen IV 454 (out of C30 ), 390 heads 1.88/2.19 valves by Vortecpro, with ISKY Hyd Roller cam (at 050 218 int./228 exh, lift 530 int./552 exh.), RPM performer intake, Fitech 600HP, Dougs headers, and M21, Gear Vendors OD, 3.73's, UMI Suspension, Viking coilovers.
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post #7 of 18 (permalink) Old Apr 15th, 19, 8:44 PM
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Mr Bill
 
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Re: Need Help Diagnosing Popping

Quote:
Originally Posted by mdelgado View Post
I'm north of Boston, in Hamilton

Thats a ways up there. I consider Medford my second home Spent summers there till I was 19 and still visit a lot. My Mothers family is up there.

Bill Koustenis
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post #8 of 18 (permalink) Old Apr 16th, 19, 5:20 AM
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Geoff
 
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Re: Need Help Diagnosing Popping

I doubt this is an ign issue. More likely a mis-adjusted valve or valve sticking in the guide in #1 cyl.
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post #9 of 18 (permalink) Old Apr 16th, 19, 8:19 AM Thread Starter
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Mike
 
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Re: Need Help Diagnosing Popping

No luck last night. I pulled the cap hoping to find some moisture or tracking and nothing, it was clean. I ran the car at dusk and couldn't find any arching either. My temp gun should arrive today and hopefully see what header is off. I did pull the plugs again after the engine warmed up. The color looked more consistent. There wasn't one wet plug like before. If the popping is due to a valve adjustment, think a comp test would tell? Thinking if one is stuck open a bit? Because popping would be fuel bleeding into the exhaust stroke, right? And my concern is how this is effecting my AFR. With the Fuel injection, my one o2 is in that header

67 Chevelle 454, M21
Gen IV 454 (out of C30 ), 390 heads 1.88/2.19 valves by Vortecpro, with ISKY Hyd Roller cam (at 050 218 int./228 exh, lift 530 int./552 exh.), RPM performer intake, Fitech 600HP, Dougs headers, and M21, Gear Vendors OD, 3.73's, UMI Suspension, Viking coilovers.
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post #10 of 18 (permalink) Old Apr 16th, 19, 10:28 AM
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Mr Bill
 
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Re: Need Help Diagnosing Popping

Any chance it is something in the injection ? I guess that is throttle body injection ? Does it clear up any if you raise the rpm ?

Bill Koustenis
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Waldorf Md


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post #11 of 18 (permalink) Old Apr 16th, 19, 10:55 AM
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Ed
 
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Re: Need Help Diagnosing Popping

a spray bottle with water on the exhaust after a cold start (or your bare fingers) will let you know if a cylinder isn't warming up as fast as the others.
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post #12 of 18 (permalink) Old Apr 17th, 19, 8:16 AM Thread Starter
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Mike
 
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Re: Need Help Diagnosing Popping

I didn't have enough time last night. All I was able to do was a cold compression test. And all the holes pumped up to 175-180. I pulled the valve cover too and the rockers were pretty loose. I can't imagine a valve being held open at all.

Bill, if I can find a helper I'll try running the rpm up and seeing if theres still popping

67 Chevelle 454, M21
Gen IV 454 (out of C30 ), 390 heads 1.88/2.19 valves by Vortecpro, with ISKY Hyd Roller cam (at 050 218 int./228 exh, lift 530 int./552 exh.), RPM performer intake, Fitech 600HP, Dougs headers, and M21, Gear Vendors OD, 3.73's, UMI Suspension, Viking coilovers.
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post #13 of 18 (permalink) Old Apr 23rd, 19, 11:56 PM
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Hey bud why not start by firing it up and then pull #1 plug wire. See what that does to the pop. At least you can verify the cylinder. I’m thinking ignition...go around your cap and make sure your firing order is correct. I’ve seen sillier things happen. I’ve also seen wires backwards and not backfire so worth a check.

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post #14 of 18 (permalink) Old Apr 30th, 19, 3:08 PM Thread Starter
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Re: Need Help Diagnosing Popping

Quote:
Originally Posted by blown70 View Post
Hey bud why not start by firing it up and then pull #1 plug wire. See what that does to the pop. At least you can verify the cylinder. Iím thinking ignition...go around your cap and make sure your firing order is correct. Iíve seen sillier things happen. Iíve also seen wires backwards and not backfire so worth a check.
I don't know how, but I put the timing light on it and it was at TDC at idle. I put it back to 16* where I thought it was before the winter and the popping seemed to go away. I wonder if the engine being 16 degrees off from what the Fitech thought it was at, was messing with the system?
I did do a drop test and I didn't hear any change. Weather still isn't too nice here, so I'll play with it more. The little that I did mess around I still don't think it sounds great.

67 Chevelle 454, M21
Gen IV 454 (out of C30 ), 390 heads 1.88/2.19 valves by Vortecpro, with ISKY Hyd Roller cam (at 050 218 int./228 exh, lift 530 int./552 exh.), RPM performer intake, Fitech 600HP, Dougs headers, and M21, Gear Vendors OD, 3.73's, UMI Suspension, Viking coilovers.
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post #15 of 18 (permalink) Old Apr 30th, 19, 5:54 PM
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Rame
 
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Re: Need Help Diagnosing Popping

Maybe just bad gas? My car sits a lot and the fuel quality around here is not great, I kind of had the same issue on a carbureted engine, lots of pops and back fires at random, put sea foam in the tank and cleaned the carb and the problem went away. Perhaps your problem may just be something simple like dirty injectors? Might be worth a try.

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