454 popping through carb help
 

Friend stopped by with his 68 impala. He had it a shop for a while to have new motor mounts I talked and got it back with new noise. Mechanic told him it was a cam lobe but never pulled covers to confirm. I believe it's a solid roller. I didn't have time to ck out and pull covers but my guess would be possible lobe but just quick guess is possible rocker arm or vacuum leak or even something electrical??? Been a while since I've heard this. Any thoughts. Timing didn't change anything and float levels are good. All I had time to ck

seems almost mechanical,I'd be pulling the valve covers and looking around.

Is that a 2 stroke big block ? Sounds like a broken reed valve. :)

Seriously, That;s no vacuum leak nor lean 'pop.' Only motor I've worked on that did that had a burnt valve. ie: pie shaped 'hole' missing out of it. An exhaust valve that's not opening can cause the same thing.

I'd be pulling the VC's and also doing compression test while watching needle.

I told him I'd pull the valve covers to help him out tomorrow but videos didn't turn out well. Engine sounds fine at idle with slight miss but i just wanted to calm him down cause he was concerned about complete tear down. I will pull the covers for him tomorrow and rotate engine and of course look and see if there is a broken studs and also make sure all rockers are moving as should.

Hah. I recently rebuilt top end of a ford tractor for the golf course and the broken/burnt up exhaust valve didn't sound anything like this. The popping noise was much less at lower rpm. He just help it at prolly 3,000 cause he was pisszed.

Sounded like a normal SR at idle.

Tell him to repair that schitty wire connection going across the frt of the motor too. LOL.

stupid question but did you check the firing order? if it was at a shop you never know what went on.

I moved that as well quickly and didn't make a dif.
Tks.though jr

went through that right away and not it. Only thing that concerned me is the guy/mechanic that replaced motor mounts is a gear head and happens to have a son or daughter with same car and my friend is leaving for CO and leaving car behind with mechanic and just have wa weird feeling might be some parts swapping while in CO so he needs to leave behind. I will have Hume leave behind before leaving with mechanic.

LOL. Wasn't saying it was the issue.:) It just needs fixing, ;) And I was saying it chuckling. :)