Holley spluttering

[ceejayjay]

Guys

Just bought a new ride - has a 562bhp 460ci Ford Bb built by ICE engines. Its superb so thats what concerns me. Engine has only 2900 miles and the build finisah alone and all the docs tells me its quality. Howver, it was standing pretty much idle for 12 months. It runs off a 950 holley double pumper and the fuel pressure is metered.

It coughs a splutters when staring from cold but thats fine I reckon, but it tugs quite a bit in any gear below 1500 ( though ticks over ok at 900 rpm ) but its backfiring through the carb ( black soot shows the problem round the venturis ). It does so at odd times too, someting when I'm trying hard and in between gears when it coughs and gagas before clearing. But once I hit the throttle it runs sweet as a nut right up to 6600 ( ist ok for almost 7000 according to the build spec ) and the power warps the landscape!!. When I shut off the ignition it sometimes overuns a couple of seconds before dying.

So my instincts say the timing may be a bit out , but the builders are a top outfit and this seems unlikely after just 2900 miles. The exhaust look black as though too rich, but that wouldn't expalin the blowbakc or would it. I tried a Summit air filter cover instead of the metal one but if naything this has made it worse.

Thoughts ?? - could do with a concensus before I start fiddling

Cheers
Chris

[Dutch Paul]

Originally Posted by ceejayjay

Guys

Just bought a new ride - has a 562bhp 460ci Ford Bb built by ICE engines. Its superb so thats what concerns me. Engine has only 2900 miles and the build finisah alone and all the docs tells me its quality. Howver, it was standing pretty much idle for 12 months. It runs off a 950 holley double pumper and the fuel pressure is metered.

It coughs a splutters when staring from cold but thats fine I reckon, but it tugs quite a bit in any gear below 1500 ( though ticks over ok at 900 rpm ) but its backfiring through the carb ( black soot shows the problem round the venturis ). It does so at odd times too, someting when I'm trying hard and in between gears when it coughs and gagas before clearing. But once I hit the throttle it runs sweet as a nut right up to 6600 ( ist ok for almost 7000 according to the build spec ) and the power warps the landscape!!. When I shut off the ignition it sometimes overuns a couple of seconds before dying.

So my instincts say the timing may be a bit out , but the builders are a top outfit and this seems unlikely after just 2900 miles. The exhaust look black as though too rich, but that wouldn't expalin the blowbakc or would it. I tried a Summit air filter cover instead of the metal one but if naything this has made it worse.

Thoughts ?? - could do with a concensus before I start fiddling

Cheers
Chris

Timing and possibly mixture at a guess.
Is the air filter flowing enough for the engine? If it`s too restrictive it will run rich.

[ceejayjay]

yep

I reckon its fien - at 14inch by 2.5 deep its a big filter plus I added a Summit Filter cored lid too, so don't think that would be it. Timing may be more likely.

Cheers

[wilf]

Stilll worth checking the ignition settings - the distributor advance/retard could have seized (if it is an MSD, they do that).

Has the carb ever been set up properly?

And lastly, does the engine have vac advance?

Engine sounds like fun!

[colinb]

I think your heading in the right direction, and more likely timeing advance problem.

Colinb

[keane]

Hi Chris, give the carb a good check, make sure the power valve is ok, has it backfired a lot? if its stood idle for so long there could be gumming up in the carb/jets, just a few more things to check, if its possible loan a known working carb off someone, size not too important 650/750 will do, try it again, it may point you in the right direction, and as already stated, timing, leads, plugs etc. Dave

[Clarkson]

Got a nice Barry grant carb for sale in the classifieds.

[malcy.t]

[Try taking off the float bowls and making sure all jets are clean, my chevy had the same sort of symptoms and all it was was a bit of float bowl screw fibre washer in one of the primary main jets. Its not flooding a bit is it? Tiny bit of dirt in float valve can cause that , dirt in carbs is reasonably common after a lay up or recent dismantling of fuel system upstream of carb.
A holley isn't a carb anyway, more like a bucket with a hole in it.quote=ceejayjay;312245]Guys

Just bought a new ride - has a 562bhp 460ci Ford Bb built by ICE engines. Its superb so thats what concerns me. Engine has only 2900 miles and the build finisah alone and all the docs tells me its quality. Howver, it was standing pretty much idle for 12 months. It runs off a 950 holley double pumper and the fuel pressure is metered.

It coughs a splutters when staring from cold but thats fine I reckon, but it tugs quite a bit in any gear below 1500 ( though ticks over ok at 900 rpm ) but its backfiring through the carb ( black soot shows the problem round the venturis ). It does so at odd times too, someting when I'm trying hard and in between gears when it coughs and gagas before clearing. But once I hit the throttle it runs sweet as a nut right up to 6600 ( ist ok for almost 7000 according to the build spec ) and the power warps the landscape!!. When I shut off the ignition it sometimes overuns a couple of seconds before dying.

So my instincts say the timing may be a bit out , but the builders are a top outfit and this seems unlikely after just 2900 miles. The exhaust look black as though too rich, but that wouldn't expalin the blowbakc or would it. I tried a Summit air filter cover instead of the metal one but if naything this has made it worse.

Thoughts ?? - could do with a concensus before I start fiddling

Cheers
Chris[/quote]

[G4NLZ]

I've got exactly the same problem with a small block 406 I built around 18 months ago, the engine has been dynoed at EDA around 12 months ago and ran sweetly. Installed the motor recently and I get the same spluttering at fire up, rough tickover, terrible transistion from cruise to power and it runs on, goes like a rocket when opened up though.

I'm using a dual-point....which I'm quite happy with.....all set up during the dyno. I've tried changing every component in the ignition change to no avail.

Now! had an interesting chat with the guys at Real Steel and they reckon that the problem may lay with plugs not firing properly and fouling up due to having a fairly high compression ratio (10.8 : 1) and the fix is to go to MSD or similar.

I've managed to lay my hands on an MSD and I'll let you know if it improves things

Has anyone else any thoughts on compression ratio and ignition

Keith

PS something else I tried was to set up a fairly high tickover, 2500 RPM and check the colour of the headers in subdued lighting. They should start to glow Red, when I tried this No's 1, 2,4 and 6 were much duller than the others suggesting the cylinders were not firing properly

[ceejayjay]

Thanks all.

Ignition is confusing to me!!. MSD dizzy which looks old type (Contacts etc ) but MSD box on the bulkhead. But nwver lifted dizzy cap to check as was home from Dubai and couldn't be arsed fiddling - just wanted to scare the wildlife. Just bought the car and ran it from London to Edinburgh without an issue. Its two wee problems. blow back when one floors I like its hitching its skirts! ) - a big cough back and then it bends the scenery. Other than that its a small overrun whe ignition shuts down but this isn't a consistent isseu either. It was laid up so the dirty jets. floats chambers makes logical sense. Bugger!