Help with possible valve issue
Thread Starter
Racer
Joined: Aug 2017
Posts: 352
Likes: 47
From: Bham, Alabama
Help with possible valve issue
I have an engine that was just rebuilt by a friend (awesome engine builder). When I fired it, it was running like I had plug wires wrong. As I was checking my wires, which were correct, I noticed the exhaust on the passenger side was not very hot. At the exhaust tips, the passenger side is putting out about 25% the amount as the drivers side and the temp is very cool. I pulled #2 plug with it running and no noticeable difference in how it ran. Also, it is backfiring out of the exhaust.
So, what could it be? Maybe the exhaust valve is to tight?
im a rookie with engines and my buddy just took a job that will have him traveling for the next 6 months. So our schedules aren’t aligning and I need to figure this out on my own without destroying a brand new motor. Any thought or suggestions?
thanks in advance.
So, what could it be? Maybe the exhaust valve is to tight?
im a rookie with engines and my buddy just took a job that will have him traveling for the next 6 months. So our schedules aren’t aligning and I need to figure this out on my own without destroying a brand new motor. Any thought or suggestions?
thanks in advance.
Last edited by Hig116; Mar 19, 2020 at 07:11 PM.
Race Director
Joined: Nov 2006
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
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Cruise-In VIII Veteran
I would start by removing spark plugs. The cylinder or cylinders that are not running will definitely show on the plugs. Then check if you have spark on those wires when you crank the engine with plug firmly gounded of course. If you do, then run a compression test on the cylinders not firing.
post your results and we can help you from there.
post your results and we can help you from there.
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Thread Starter
Racer
Joined: Aug 2017
Posts: 352
Likes: 47
From: Bham, Alabama
More info: My heat riser has been welded open at all times. I checked the spark on #2 wire/plug, which looked great. I haven't checked 4, 6 or 8 yet.
The distributor is a brand new HEI. The wires and plugs are brand new as well. I think the only suggestion on this thread I haven't tried so far is to check the compression.
Also, I don't know how to set the lash, but will have to figure it out. (any suggestions).
Thanks everyone. The weather is finally nice enough to drive and gas prices are low. It's killing me!!!!
The distributor is a brand new HEI. The wires and plugs are brand new as well. I think the only suggestion on this thread I haven't tried so far is to check the compression.
Also, I don't know how to set the lash, but will have to figure it out. (any suggestions).
Thanks everyone. The weather is finally nice enough to drive and gas prices are low. It's killing me!!!!
Le Mans Master
Joined: Aug 2005
Posts: 6,541
Likes: 1,973
From: Temple Terrace Florida
Put a vacuum gauge on the intake manifold. Check your readings with videos found on You Tube. The gauge is less than $15 and can diagnose timing, valve problems etc. Report back. Jerry
Race Director
Joined: Jul 2015
Posts: 13,082
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From: SW Florida.
all 8 180 off? won't run. just blow fire out the carb. cuz firing while intake
valve is open. now if firing order off, or plug wires put on ccw, some will fire and run while others are way off and making all kinds of funny noise. fourple check firing order.
valve is open. now if firing order off, or plug wires put on ccw, some will fire and run while others are way off and making all kinds of funny noise. fourple check firing order.
Last edited by derekderek; Mar 20, 2020 at 05:30 PM.
Melting Slicks
Joined: Jul 2006
Posts: 2,291
Likes: 492
From: Salmon Arm, BC
I'm pretty sure some of the earlier models with a point distributor didn't have a full 12 volts at the coil, or ran with a resistor in the wiring circuit bringing it down to 9.5v.....it's something for you to look at as you recently made the HEI swap.....make sure 12v is there all the time.
Last edited by OMF; Mar 22, 2020 at 02:04 AM.
Thread Starter
Racer
Joined: Aug 2017
Posts: 352
Likes: 47
From: Bham, Alabama
Pulled the plugs and the passenger bank all look fouled. They were brand new when I installed them. I failed to also mention that the carb was recently rebuilt by Lars. I’ll check compression and vacuum tomorrow. Keith
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Joined: Nov 2006
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
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Cruise-In VIII Veteran
All of them on the right side. Starting to look like that intake manifold gasket wasn't installed correctly. Compression test will likely confirm this.