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Old 10-12-2003, 12:39 PM
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Carb question

I've checked my carb trying to solve the idle- in gear dying problem
I found out the following.
The primary throttle shaft has some 0.03-0.05" radial slack/clearance, whatever it is called? (Holley 650DP)
Is this much allowed? To me it seems as an awfull lot.

idle screws are 1 turn out, going to some thing like 2 turns it will get too rich and die.

So far it seems to me as if the carb in in a "not too good" shape...

Tried to check the timing, distributor is a Mallory dual points, no vacuum.
There is NO timing marks at the cyl.1 firing lining up with the pointer.
Using my timing gun, I advanced it some 60 deg, and I saw a timing mark comming up at appr 12 o'clock but noting closer.

Seems that the distributor is put in in the wrong place...

Can I just take it out, turn it to the right position again and drop it in?
How does it catch the oil pump drive?

thx!

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Old 10-12-2003, 01:03 PM
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I assume you have a timing light with built in advance/retard adjustment and are turning knob till timing mark lines up with zero?
I cant see how it would run very good with timing 60 degrees off. Thats a lot!

I think you should confirm your timing marks by taking out #1 spark plug and turn engine over till piston is at TDC. Then check where rotor is pointing.
Could be that damper has slipped or distributor really is a mile off.

You can reorient the distributor dont worry about oil pump just install distributor keep the cam and distributor gears meshed together and turn engine over till distributor aligns with oil pump then tighten holddown.
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Old 10-12-2003, 01:37 PM
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The throttle shaft bushings being worn would affect idle fuel mixture by suppling the air that the idle needles normally supply forcing you to turn the needles all the way in to bottom with no affect. Idle speed is controlled by the idle speed screw, left/rear of main throttle shaft and should be set with engine warm and to 750rpm in gear. Your dual point distributor was at the time a race unit but loads of them found their way onto the street and work ok. Your biggest problem sounds like a badly worn timing chain. Quick check; remove distributor cap, turn harmonic balancer clockwise by hand (socket on retaining bolt if equipped) untill rotor moves, place a chalk mark on balancer at timing tab, turn balancer opposite direction while watching rotor for movement, stop when rotor just starts to move again. Look for the chalk mark. Anything more than 1/8 revolution indicates a worn timing chain. Replace it.
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Old 10-12-2003, 01:44 PM
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Something else to consider is that there are several combinations of timing indicators on the timing chain cover for a sbc.
It's entirely possible that sometime during it's life that an incorrect timing chain cover has been installed and that places the timing indicator in the wrong position relative to the dampner timing marks.
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Old 10-12-2003, 04:31 PM
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if you put timing errors aside, a couple carb problems i can suggest looking for are as follows:

1> the fuel is dripping out into the venturii. check this by simply looking down into the carb while it's running and observe and fuel dripping. if so, proceed to #2.

2> stuck needle and seat valve: if the float bowl is set right, or if you bottomed out the float bowl on the bottom and the fuel level still isn't down, this valve could be jammed open with something. check this by removing the needle and seat assembly (taking note of how far in it is screwed, in order to retain previous fuel float setting) and gently blowing through it a couple times and visually inspecting it for foreign objects. sometimes this is a common problem for people who use too much teflon tape when attatching a fuel fitting, and shreds get sucked into the carb. if the needle and seat assembly are okay, proceed to #3

3> incorrect float bowl adjustment: it could be set too high. check the fuel level with the engine off, and opening the sight plugs. if fuel drips out, this is the cause. lower the float adjustment 2-3 turns, close the sight plug, and run the engine. remove the sight plug, and check fuel level in the bowl. it should be just below the sight hole.



these are quick and easy things to check and can be done in a few minutes.

if the carb tips above did not help, you could try fixing your timing by manually finding your TDC on cylinder #1, and marking your balancer appropriately.

you can probably find the instructions on how to do this on the web.

stock, oem balancers can slip over the years, which could explain why the timing marks are so far off. mine used to be 10 degrees off.
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Old 10-12-2003, 04:56 PM
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Your problem is you have the timing light hooked up to the wrong spark plug wire. The number one cylinder is the one farthest in front. Look at both sides of your engine. One cylinder head sits farther forward than the other. Hook it up on one and reset your timing. Find out what your distributor advance is and set your total at 34o.


There is nothing wrong with your timing chain.
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Old 10-12-2003, 05:07 PM
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^ good point, lol!
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Old 10-12-2003, 05:50 PM
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this is confusing me too

The carb is probably junk and needs replaced. I only use Holley carbs for racing application and I don't race anymore, for everyday use I use Edelbrock or Q-jets. The duel point distributor is also for racing application and is not suitable for street use but will work. The number one spark plug is on the drivers side at the front of the engine. This COULD very well be a timing chain problem. What kind of car are you working on? How many miles does it have on it? Was it running when you got it? Are your spark plugs black and dry or black and wet? I think I answered this post in the dump thinking someone had posted it there by mistake.



Todd



Rat Rods Rule!
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Old 10-12-2003, 06:07 PM
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The only other thing it could be is if the one of the distributor springs broke or fell off. Or a worn bushing, or something that would screw up disributor curve, changing the advance at idle and off idle. Not very likely though.

It would be caughing and spitting back a whole lot more than that if it were timing chain problem or any other timing issues.
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