idling issues

[j_oetjens]

carb 7045183 on  a 1970 olds 455 camshaft xe284h lca 110 duration 0.050 intake 240 lift 0.541 exhaust 246 lift 0544 heads are factory ported E heads 403686 77cc 2.000'' intake valve 1.625" exhaust valve 5 angle valve job flat top pistons are flat top did not have compression checked machine shop said probaly around 10.5 - 11.0 compression 2500 tight stall converter on a th400 i have d.u.i distributor msd 8.5 wires ac delco plugs intake manifold Single plane with divider  Professional Products CrossWind

i have a holley 800 spreadbore that i have rebuilt and adjusted to work with my engine with zero problems with air fuel ratio of 13.3 equal on each side. i have never been able to run a quadrajet on my engine which i would perfer until now. i purchased your book and i have since, at least got my car to start and stay running after drilling idle bypass to 0.203 here is a list of everything else:

down channel: 0.0625
upper idle air:  0.787
lower idle air:  0.787
idle bypass:    0.203
idle mixture screws: 0.0197
butterflies:      0.0937
hanger F
secondary rods 0.0394 smaller and 0.0472 larger tubes
secondary spring tension 1/8 turn
 
i was unable to remove idle tubes to be able to drill them out as well i have removed primary rods and have no choke it will run with idle set at 1000 rpm (seems way to high) with nozzle drip if i lower the idle to 850 (where it is set on my holley with no problems) engine slowly drops to 500rpm and then will die after about 5 minutes. idle bypass was at 0.1875 and would not stay on unless pumping gas so i removed the primary rods and it stayed running but with idle set at 1000 rpm but with tons of nozzle drip and when i put it in gear it would die.

do you have any suggestions??

http://www.youtube.com/watch?v=QWSxxq2ol0s

link to car running with holley carb

[429bbf]

welcome aboard . from my personal ex.i think you can do all the other mods you have done . but without increasing the size of the idle tube the rest is not going to do any good until you get the right combination.i have very good luck pulling them and reinstalling.theres always junk under them that i cant get out .im sure cliff will chime in and know exactly whats wrong.hope this helps. dean

[j_oetjens]

thank you for your reply 

[j_oetjens]

finally got idle tubes out increased size to 0.0396 still was dripping from boosters so increased to 0.0472 only dripping very little from passenger side increased timing from 6 to 10 degrees idle set at 950 drops to 750 in gear passenger booster still wet and very slow drip idle mixture screws 2 1/2 turns secondary spring tension dropped to 1/16 short road test in neighborhood car launches harder then with the holley.  now only 2 things the slight drip from passenger booster and  new problem after I range car had to wait 15 - 20 minutes before I was able to start the car back up it wouldn't even turn over I am thinking it needs more ground

[429bbf]

good news at least your on the right track .you may try screwing the passenger idle screw out another round. they do not have to be the equal the engine will tell you where they need to be. i believe most peple think they have to be set the same .but when you finally get one tune i found they are very seldom the same .dean hope this helps

[Cliff Ruggles]

Too large for idle tubes, .039-.040" should have been enough.

Idle airbleeds should have been around .070" for that carb number, not closer to .080".

What in the idle system is drilled to .203"?  Idle bypass air?

What are the idle down channel restrictions drilled to?

Holes in the throttle plates?  Why?......Cliff

[j_oetjens]

thanks for the reply

I have your book and followed example #3 on every thing except the idle tubes as I was unable to remove them. Then I followed what it said in the book about starting small and then working in small sizes and going up. While testing and trying things everytime I put the carb back on and it would not run properly I increased all the holes up a size until finally I got it to at least idle and stay on at least in park.

Too large for idle tubes, .039-.040" should have been enough.
When I was able to remove them I did them to 0.039 and still no changes. Then to 0.0394 and still no change. Then the next size I had was 0.0472 and drips from boosters almost completely stopped. But did not increase anything else just idle tubes.
Idle airbleeds should have been around .070" for that carb number, not closer to .080".
As mentioned above increased sizes together everytime I removed carb.

What in the idle system is drilled to .203"? Idle bypass air?
yes idle bypass air in baseplate is 0.203 this is the only hole I did by its self to increase air flow. I increased from 0.1875 to 0197 and still would not idle properly so I drilled out primary butterflies and it got better then I increased from 0.197 to 0.203 it finally stayed running better

What are the idle down channel restrictions drilled to?
down channel: 0.0625

Holes in the throttle plates? Why?......Cliff
as in your examples it says optional so when I got to a certain point with the idle bypass air I drilled them out to see if it would help. I understand that holley and quadrajet are 2 different systems but I drilled out all 4 butterflies in my holley and it made a day and night difference when I was tuning my holley. So that played a part in me drilling out butterflies when it still would not idle properly as your book says as an option. I do have a spare carb that I can change them if you think it would help.

[Cliff Ruggles]

Increasing idle airbleed size KILLS pull to the idle screws even with larger settings.  If anything, make them smaller, not larger.

.203" idle bypass air is nothing but a HUGE vacuum leak.  If you don't have enough fuel to the mixture screws, idle bypass air will NOT help to control nozzle drip.

If the carburetor is a later model, and has idle bypass air, there is no need to drill the throttle plates, as idle bypass air is much more effective.

If you can't get on the idle system with .110" bypass air and that engine/cam combo, something else is wrong someplace.

That's not really that big of a cam in a 455 engine, only 284 degrees seat to seat timing.

We've ran 308-320 degree cams in 455's with zero issues for idle fuel delivery using smaller settings that what you are using.

I'd go back to the idle airbleeds and make them smaller, and things will start to work better everywhere else......Cliff

[j_oetjens]

I will try that thanks for your response it is greatly appreciated  I will work on it this weekend and get back with you

[j_oetjens]

 idle great news everything is running perfect I think I decreased idle air bleeds to 0.070 and got a rebuild kit and with  timing at 10 degrees. its idling great at 800 no nozzle drip, idle mixture screws respond great starts great hot or cold, and just a tap of the gas pedal will give you whip lash. I didn't decrease idle bypass air in base plate due to gasket has hole 0.125 so I did not drill out new gasket.

 thanks everyone that posted especially you cliff  ;

[Cliff Ruggles]

Good news!.....Cliff

[j_oetjens]

thanks for all your help