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RSA350 · 03-09-2008, 07:17 PM

Gday All,

Ive just registered but been a visitor for ages! Ive got a problem with my 253 backfiring out of the carby.

Basically its a second hand engine, from what i can tell and have been told it was a mild build. Its running flat top pistons and redline torquer manifold with a 600 holley. It feels like its cammed, not sure how radical but it feels best between 3500 and 7000 rpm.

The engine was in a vk commodore that i brought but i have since swapped it into my '84 CJ-10 jeep. In the commo it was mint, sat all day on revs, plenty of power etc etc. In the jeep it back fires thru the carb before it picks up revs.

This is what i have checked so far in regards to the backfiring.
- Carby, definitely not running lean, fuelly smell when running. Accel pump works fine.
- Dizzy, was mallory twin point but have since changed it out for standard HZ v8 points dizzy, vac advance works, weights not siezed, new cap, points, condenser, rotor button, leads and NGK BP5FS plugs.
- Removed the rocker covers and ran the engine, all valves seem to have about the same 'lift' compared to each other. I was told that holden v8s sometimes wear cam lobes away to nothing. No excessive clacking by any of the lifters either.

Has anyone got any suggestions about other avenues i can try before i start tearing my hair out!?

-Cheers, Adam.

03-09-2008, 07:17 PM	#1 (permalink)
RSA350 Newbie Trade Rating: (0) Join Date: Sep 2008 Location: West Oz Ride: '69 HT Monaro, '74 CJ5 Jeep, '85 CJ10 Jeep Posts: 20	Backfiring thru carb Gday All, Ive just registered but been a visitor for ages! Ive got a problem with my 253 backfiring out of the carby. Basically its a second hand engine, from what i can tell and have been told it was a mild build. Its running flat top pistons and redline torquer manifold with a 600 holley. It feels like its cammed, not sure how radical but it feels best between 3500 and 7000 rpm. The engine was in a vk commodore that i brought but i have since swapped it into my '84 CJ-10 jeep. In the commo it was mint, sat all day on revs, plenty of power etc etc. In the jeep it back fires thru the carb before it picks up revs. This is what i have checked so far in regards to the backfiring. - Carby, definitely not running lean, fuelly smell when running. Accel pump works fine. - Dizzy, was mallory twin point but have since changed it out for standard HZ v8 points dizzy, vac advance works, weights not siezed, new cap, points, condenser, rotor button, leads and NGK BP5FS plugs. - Removed the rocker covers and ran the engine, all valves seem to have about the same 'lift' compared to each other. I was told that holden v8s sometimes wear cam lobes away to nothing. No excessive clacking by any of the lifters either. Has anyone got any suggestions about other avenues i can try before i start tearing my hair out!? -Cheers, Adam.