Pop sound in 345 powered scout

This is in my 1974 Scout II. it's a 345 with 30K miles on it. it's got a new holley truck avenger 490 carb. i replaced the ENTIRE ignition system, and even swapped a carb. it had a bent pushrod, which i replaced including the lifter. this is under acceleration, wide open throttle. if i gave less than 1/4 throttle it DOES NOT do this. it also changes pitch with the more or less throttle i give. i've confirmed it is coming out the intake. any help greatly appreciated!

Category:

Autos & Vehicles

Tags:

• International
• scout
• 304
• 345
• 392
• international
• harvester
• II
• 1974
• pop
• popping
• popcorn
• annoying

[69dieselscout]

yea, that's what it was when i pulled the cam

[69dieselscout]

think it's a bad exhaust cam lobe. replaced heads, and it has a new flowmaster exhaust. gonna put a cam in it soon

[fpeletz]

You have a worn out lobe on one of the exhaust valves.

[hooksmason]

@69dieselscout wouldnt it have a miss to it if the cam lobe's were worn?

[0HippyHunter0]

Did you check the exhaust? If it's more of a popping sound that makes sense that it only opens under high pressure. Just a thought.