1bad51

Ok the problem is with a friend of mines XE it has a 351 clevo that has just had a good quality rebuild mostly stock with a resonable cam. It was going ok not fantastic but ran. Soon started playing upwhen you start to take of at the lights and while cruzing at sixty it would stumbel now and then so he got cran ignition for it did not quit fix it but better still stumbeled. Last week he degreased the engine bay and it died got it giong now run like crap miss a idel farts and splutters off the line once rpms come up it hauls ass. It has 780 holley that has had recon and been jeted on the dyno singel plain manifold. Mostly breaks down under load if you stall it up heavly it will backfire through the carb. PLEASE HELP RUNNIG OUT OF THINGS TO TRY NEARLY COMPLET NEW CAR

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351 WINDSOR XW GS BUILT NOT BOUGHT 1BAD51

TruBlu351

Sounds like possible accelerator pump issues.

The "hauling ass" in the upper rpms is a good sign.

Take air cleaner off and look down carb venturies as you open up the throttle fully (car turned off). Look for 2 big squirting streams of fuel coming the squirter. This sits inbetween the two front venturies near the top of the carb.

If no squirt or it dribbles out...........
1. Check accel pump linkage/cam (connected right / does it move when throttle opens?)
2. Check accel pump diaphragm and spring
3. Clean carb / possible blockage.

Whilst in neutral parked or on the road driving, accelerate the engine to 4-5 grand very slowly. If its only the accel circuit not working this should appear fine.

Also check for old rubber hose bits etc in the main jet area. Don't use old hoses etc.

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XE Falcon
393 Tremec TKO 9"

silicon

From your comments it was never running as you expected. Was the cam installed and timed correctly? This would explain "plutters off the line once rpms come up it hauls ass." if it was retarded. Backfire definitely point towards timing issues.
Since you have looked at electrics and fuel I would assume this is not the problem.

In relation to the cam: How much lift does it have and what valve springs were used. I just was wondering if you have had the springs binding/destroying cam.

1bad51

Acc pumps working ok. when it sputters lots of black fuel smoke poor out the pipe. waiting to hear actual size of cam and has standard valve springs

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351 WINDSOR XW GS BUILT NOT BOUGHT 1BAD51

pracy

same here mate :)

you using extractors?
running colder plugs, like BP6-FS i think, helped aswell as adding a plastic 1" spacer as the fuel is getting too hot in the carb bowls.
i also had a scoop installed at the same time though..
this completely took all break-downs and hesitations from my motor and its running great now.
XE ofcourse.

1bad51

Has the spacer has the plugs both new. The cam has intake lift536 and exh563. Has new cap leads rottor button only 6 month old new one tomorro this realy has me stumped even put fuel preasure reg on to try will try my 750 double tomorro see if that fixes it but keep the ideas coming

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351 WINDSOR XW GS BUILT NOT BOUGHT 1BAD51

george 351

Sounds like a fuel problem.Check needle and seats and also float bowl settings....lol...........

1bad51

I am a littel suss on the needel and seat will find out when we fit my carb tomorro i know it runs a ok will keep yous posted

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351 WINDSOR XW GS BUILT NOT BOUGHT 1BAD51

silicon

That is a lot of lift to have with standard springs; they would be very close to coil bind. The cam I assume is a generic one ie cam dynamics etc 224/234 degrees @ 50". It will need close to 120lb on the seat. You would be experiencing valve float as fairly low revs with the stock factory equivalent springs.

1bad51

With that cam it revs to 6000 on those springs ok but no higher but car is everyday driver. Changed the carb today and has fix the problem Funny though the carb is not very old 8 months since big dollar rebuild (bloody holleys)

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351 WINDSOR XW GS BUILT NOT BOUGHT 1BAD51