950hp problems .

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jimjimjimmy

jimjimjimmy

lobsterman
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ok its a 418 sb with a air gap intake cam is around 250@50 . I squared my transfer slots up and now it wants to idle at 3000, i always had problems with this carb wanting to idle fast . my timing is set up 26 and 35 as tuned on the dyno . it will idle down with the t slots shut off .
 
If it can't get air it cannot run. So either there is an air leak outside of the carb, or the carb base gasket, or the bores are open further than you think.
 
I understand that , there are no vacuum ports on this carb and I can't find a leak anywhere . I will go over it again . and it would be a noticeable leak to want to idol so high .
 
I have found huge idle speed differences with minor adjustments on my Quick Fuel Q 950. I believe T slots shouldn't be any more than .030 exposed. Try that and idle circuit screws 1/2 to 3/4 turn out for a start
 
Look real close at the butterflies and make DAMN sure they are centered in the bores. There is some wiggle room there. They can be correct over the transfer slot but not be cantered in the bore.

It really doesn't take much air to get past the butterflies to make a high idle. Other than that, look for an air leak somewhere. Ive seen cheap base gaskets leak and drive people nuts.

Also, can you post the idle air bleed and idle feed restricter numbers. I've seen those be incorrectly marked. That will make you say bad words. I pin gauge every single jet and bleed I own, with the exception of the BLP stuff. Those things are dead nuts. Other brands....not so much.
 
I think I found a leak between the spacer and carb gasket.the gasket is not big enough to seal the spacer . I will make a new one and report back .
 
Fixed the vacuum leak got it idling with the mixture screws but now it seems lean . if I give it more on the screws the idle goes up. rev it and it takes a second to come back down .
 
jimjimjimmy said:
Fixed the vacuum leak got it idling with the mixture screws but now it seems lean . if I give it more on the screws the idle goes up. rev it and it takes a second to come back down .
Click to expand...

That sorta sounds like the idle circuits are not active, as in, not enough slot exposed "I think."
 
67Dart273 said:
That sorta sounds like the idle circuits are not active, as in, not enough slot exposed "I think."
Click to expand...


the idle circuits are active there only out half a turn , any more and the idle goes way up and any less it stalls . but I will not give up till its fixed .
 
yellow rose said:
Look real close at the butterflies and make DAMN sure they are centered in the bores. There is some wiggle room there. They can be correct over the transfer slot but not be cantered in the bore.

It really doesn't take much air to get past the butterflies to make a high idle. Other than that, look for an air leak somewhere. Ive seen cheap base gaskets leak and drive people nuts.

Also, can you post the idle air bleed and idle feed restricter numbers. I've seen those be incorrectly marked. That will make you say bad words. I pin gauge every single jet and bleed I own, with the exception of the BLP stuff. Those things are dead nuts. Other brands....not so much.
Click to expand...

I will give a careful look at the butterflies there is a hole in all four . I will try to center them up if need be .
I will get the air bleed #'s later .
 
jimjimjimmy said:
I will give a careful look at the butterflies there is a hole in all four . I will try to center them up if need be .
I will get the air bleed #'s later .
Click to expand...
A SBM stroker 250@.050 does not need holes in the butterflies IMO. Replace butterflies, move the IFR to the bottom of the metering block, and get the idle screws working in the 1-1.5 turns range.
 
mderoy340 said:
A SBM stroker 250@.050 does not need holes in the butterflies IMO. Replace butterflies, move the IFR to the bottom of the metering block, and get the idle screws working in the 1-1.5 turns range.
Click to expand...


I know when we dynode with this carb it would not idle at all without the holes . I thinking I have a small vacuum leak . its time to get serious, and get the straight edge out and also look for any small cracks .
 
Just throwing this out there Aaron. Have you checked around your intake ports? I know you were having oil transfer problems with the heads and I was thinking that maybe there is a casting problem around a port. You never know. Time to get the propane touch out and see if it is sucking in propane anywhere.

Jack
 
Coyote Jack said:
Just throwing this out there Aaron. Have you checked around your intake ports? I know you were having oil transfer problems with the heads and I was thinking that maybe there is a casting problem around a port. You never know. Time to get the propane touch out and see if it is sucking in propane anywhere.

Jack
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I found a small crack in the carb spacer i'm thinking this maybe the problem . I may have some time to look at it and report back later today .
 
Have you checked for vacuum leaks around the throttle shafts? You might have a throttle shaft bushing or two that need to be replaced.
 
ok update guys got it working where i'm totally happy, upon closer inspection I found a few problems ,the base plate screws were not tight enough and the butterflies were a little cockeyed and not closing all the way were talking pussy hairs here like fine blonde ones ,it don't take much . i'm very happy with the results . thanks all who helped and to yellow rose for mentioning to check and adjust the bf's .
 
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jimjimjimmy said:
ok update guys got it working where i'm totally happy, upon closer inspection I found a few problems ,the base plate screws were not tight enough and the butterflies were a little cockeyed and not closing all the way were talking pussy hairs here like fine blonde ones ,it don't take much . i'm very happy with the results . thanks all who helped and to yellow rose for mentioning to check and adjust the bf's .
Click to expand...


Glad you got that sorted out.
 
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