new cam, chronic backfire

[Anonymous]

fDart 318.Fitted new cam (XE262H). Road testing produced a chronic backfire at anything over 1/4 throttle. Close to undrivable. Mechanic sez cam is fitted straight up with 14 dg advance. Tells me prob is carb related (Holley 600). stumlbe home in car and advance distibutor a bit, backfire goes but pinking starts.
i'm over my head now, all help appreciated as my formerely reliable car is now a dog!

[Guy]

Recheck your firing order I would sujest 5-7 are the wrong way round also check for an air leak

best of luck

guy

[Alex]

Who put the cam in? do they know Mopars? if not, betcha it is out!

[Anonymous]

OK chaps, Guy,firing order is correct, Alex, I dont know how much about small block Mopars they know. they fitted the cam 'straight up' but did note that the standard cam was fitted in the advance position.
Steve, I adjusted the mixture on the carb which removed the backfire (thru the carb) . I've now got it running VERY lumpy on idle but clearing and accelerating hard after 1,500 rpm.
Further suggestions happily accepted as I want to take it to Shakey this weekend. Is that too risky? The engine doesnt pink noticably and i'm going to Bananarama! up and down the local 'drag' and check the plug colours.
back later!

[Anonymous]

spec is XE262H comp cams - 262/270 gross duration, 218/224 degrees open at .50 462/470 lift.

[Guy]

What carb are you using ?

Check the amount of manifold vacuum you have at idle, you may need to change the power valve to a smaller one also check what the total advance is on the motor at 3000rpm you may have to much advance does not want to be more than 35/36deg all in

[Alex]

I agree with Guy... 8)

[Guy]

Cheers chap

[Anonymous]

Guy and alex, i'm working in the 'dark' kit wise. I can't check vacuum at this time (dont have the tools). I asked for a max advance of 34/35 degrees. In the workshop the carb was strobed at 14 deg advance but i,m not sure what total advance that comes too.
Carb is Holley 600 vac sec, edelbrock performer inlet. i'm just off to road test now!
Car is considerably better than last night but, i'm sure it could be a lot better with the right adjustments. A little knowledge (mine!) is an expensive thing!

[Alex]

14 sounds too much, better at 10-12 at idle but really you need to check it all in, i.e. at max advance with the vac pipe plugged

[Guy]

Miles do your self a favor and check your engine oil make sure it has not gone a grey paisty colour.If you havent changed it since the cam was fitted do it now.

[Anonymous]

OK Road test complete. Guy, the engine oil is dead clean and was changed after cam break in. Road test sees car feeling 'too rich' at up to a third throttle. Thereafter, goes like a bat out of hell! Doesnt pink, plugs show clean electrode and mildly sooty after that (not wet). I retarded the ignition a touch and car ran cleaner on lower throttle. Given the general turbulance of a flying brick at speed its dificult to feel how 'clean' the car is pulling at high speeds. Further complicated by new 3.23 gears which have thrown the speedo out. I intend to have it tuned properly, should I take on a long jpurney yet? Shakey is about 360 mile round trip!

[Guy]

As long as it not runnin too lean or rich you should be ok best bet is just to cruise up some one will have a timin light ( mine went bang yeasterday) and we shall get it set up for you.

[Anonymous]

Thanks Guy, appeciate all your input. Be nice to meet up with some of the faces of this board and see their cars in action.