Cough and spluttering ???

[Anonymous]

Hey Guy's
Engine : XC 250 X-flow, mild cam, extractors, 2 inch exhaust, electronic dizzy, 3 spd auto Borg Warner.

I have Just recently pulled my 350 2blr Holley apart and given it a good clean etc. When i put it back on i could'nt get the idle mix right so i took it to a carburetor bloke to have it tuned up. When i got it back from him it was idling well but out on the road it ran really bad, worse then it ever has. it is hesitant on take off it will cough and splutter if accelerated too hard, and if you accelerate slowly it would have a slight bog. i took it back and he then put 63# jets in it (from 60#) the jet change only really helped the bog durring acceleration. I still have the coughing and spluttering, and the hesitant take off, not as bad as when it had the 60# jets in, but still happens!
Anyway the carburettor block was not very helpful, he just said i don't know..... we'll leave the 63# jets in,(even though he said it was running way too rich with them) i don't know what eles is wrong he said, maybe your electric's, oh yeah and it had a low vacume reading too, your cam is causing that most likely!
Could this be electrical?, i am thinking maybe ignition coil!, As the for the low vacum, i have had this engine running really well with the same cam in it in the past, so is it really possible that the cam is causing low vacume now? The carburettor bloke said the holley is set-up properly, but i don't think he spent much time on it though!! :x

Any idea's on what could be the problem??

It is idling good though, so i'm kinda thinking the vaccum is not so bad, as i thought low vac effects idle too, right?

 

[Anonymous]

Is the coil getting 12 volts? What ignition leads are on it? What power valve does it have in the Holley? It really sounds like a vacuum leak.
Doesn't sound like the module on the dizzy. When they go, they work when they are cold, but intermittently work when hot. Any ideas?

 

[Anonymous]

The holley has a 6.5 power valve.
I am not sure what volts the coil is putting out, i don't have any test equipment. I am going to see a guy who can test it for me in the next few days, so i will let you know how i go.
The leads are '8.0mm Eagle ultra series high temp silicone'.

 

[Anonymous]

Just a quick question, howmuch did it cost for him to change the jets?

 

[Anonymous]

He charged me $95.00!!!!, and basically did nothing except adjust the idle mix, changed the jets and changed the air cleaner.
I am pretty annoyed really, he said he spent over2 hours on it, you'd think he would know what he was is doing, like if the Holley was ok, then it should not have taken him two hours to figure that out...... for a bloke who does it for a living anyway!
And when I took it back to him cause it ran like sh#t, he's like i don't know the Holley seems fine to me ......what do you think, i just said all i wanted was the idle mix to be set, it idles good, but out on the road it's running worse then before i gave it to you! So he said we'll try larger jets, put the 63#'s in. The analyser said it was too rich, but it did run slightly better. So he said that is all i can do, I said is'nt it running a bit rich though, he said it'll be ok... maybe get your electrics looked at!,
When i paid him the next day he also said then that vacum was a bit low, but he was in a hurry and did'nt really explain to me what he had done (if anything) about where a possible leak is, he just said it could be cam!

So yeah...... i have put the 60# jets back in as the plugs were really sooty, but i still have the problem as stated above.

P.S: Sorry for rambling on, just kinda annoyed... ya know!

 

[DYNOED250]

Sometimes cams can have a low vacume at idle.... This doesnt draw enuf fuel through the idle circut at idle, what ive seen done is the air correctorin plug things on top of the metering block are pluged and drilled up, this draws more fuel through the idle circuit and this stops the lean spot of idle, anouther fix is drilling a small hole in the buter fly this way you can have hem slighly more shut and this creates greater air velocity near the idle jet ,.... Carby guys ar nothing more than carby cleaners mate, take it to a proper speed shop or decent mechacnial work shop, if they dont have a dyno dont bother with em.. there are that many people who claim to be able to set up carbys but the dont have a clue, there is so much more to do than just changing jets