Help with Backfire

[Todster]

Hi,
I have a problem with a backfire, it only seems to happen on the over-run in 4th and 3rd coming down the box. I'm running a weber progressive carb and a single quiet pack exhaust. Ive checked the dwell today and its 50 degrees (smack bang in the middle of Bentleys published 42 - 58 degrees. I also checked the timing, and it also seems to be bang on. I've not had chance to check the valve clearances yet. Seems like the PO has installed the distributor drive 180 degrees out as the plug leads are all 180 degrees further around than the manual, could this cause the problem?? Anybody got any ideas?

Cheers.

 

[slammedresto]

exhaust leak from your header???

 

[Todster]

Hi,
Thanks for that, is that between the exhaust and the manifold heater pipes?
Cheers

 

[slammedresto]

Hi,
Thanks for that, is that between the exhaust and the manifold heater pipes?
Cheers

yup, try fitting a new exhaust kit, with new clamps etc etc

 

[noddy]

Can also be caused by a lean tick over mixture, or is it a rich tick over mixture, I cant remember which.

 

[Todster]

Hi,
I took off the header pipes and they fell out of the manifold in my hands :x I temporarily gunked them back in with exhaust paste and am now looking for a manifold for a 32/36 Progressive Weber. Took the bus to Skeg Vegas yesterday and the backfire is no more. Thanks for all your help.