'85 460 snapping and popping

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May 10, 2004 | 12:30 PM

Darkraven

Thread Starter

New User

Joined: Feb 2004

Posts: 12

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'85 460 snapping and popping

Hello all,

I have an 85 F250 with a carb 460. My question is when I use the engine compression to slow down (downshifting) I get minor backfire or at least that is what it sounds like from the tailpipe. It can be mild or it can really pop, depending on how much of a load I am putting on the engine.

I know that my vacuum advance on my distributor isn't working, and I have the vacuum ports plugged right now until I can get it fixed. I checked the time and it is 10-12 BTDC. Is there anything I can do to fix or reduce this?

Thanks

May 10, 2004 | 09:29 PM

neverenough

Elder User

Joined: May 2003

Posts: 549

Likes: 1

Sounds like your valve seats are sinking, common problem on Ford motors. Do a cylinder leak down test, I bet you will find the exhaust valves leaking. Running rich on the carb could be causing the exhaust to fill with unburnt gas too. An exhaust leak could also be causing the problem.