Something weird going on

[cudabob496]

ok, Andy, 734406pk has steered me to the probable solution.
I have on the carb a main body to throttle body gasket from Summit,
part 108-5. I should have used part 108-7, which is a slightly larger bore
and which does not cover up some idle circuits.  When I bought the gasket, it said
for 4150s, and was the only one I saw at the time, and it seemed to fit up real nice,
but, I missed some of the small details. A painful 3 month leasson!
will order new gasket and see what happens.

[cudabob496]

so, why does Holley have a part that is ever so different from what is needed,
and even has same alignment holes, and yet blocks some idle passages!

[Strawdawg]

As, I said a few posts up, I have seen it before. I learned the hard way to check the holes.

Hope that does the trick. Nice to be ready for spring

[cudabob496]

As, I said a few posts up, I have seen it before. I learned the hard way to check the holes.

Hope that does the trick. Nice to be ready for spring

I think what got me was that 1) it came up on summit as what I needed for a 4150, 2) it looked the same in hand,
3) there were lineup tabs on the main body of the carb that the gasket fit over, which to me said it was the right one.
But, live and learn. At least this documented nightmare may keep someone else from experiencing it.
So, in summary, car was acting weird due to bad ground on 6AL box, then Summit sent me a bad coil, then
I put the wrong gasket in.  And, my variable timing unit tested bad. Like I got hit with 4 diff things all at once! Out of service for 4 months, but at least it always ran the previous 25 years, with a few hiccups here and there. But, we will see when I get the right gasket in a couple of days, if all is well.

[Flatdad]

Just looked at your thread today, can't imagine how frustrated you must feel.

My knee-jerk reaction for the problems you described was a worn out timing set retarding the cam and idle ignition. You did say the build was pretty old, and it sure fits the symptoms nicely. A retarded cam would make lower vacuum, affecting the idle circuit and late spark would certainly make it difficult to run at lower rpm. When you get the rpm up the spark advance would take over, and enough air could flow across the boosters to activate the cruise circuit, letting it run above 1000rpm. On top of all that, a worn out timing set would show up gradually like you described.

I hope the gaskets and electrical stuff turn out to be the solution though, good luck!

[cudabob496]

Just looked at your thread today, can't imagine how frustrated you must feel.

My knee-jerk reaction for the problems you described was a worn out timing set retarding the cam and idle ignition. You did say the build was pretty old, and it sure fits the symptoms nicely. A retarded cam would make lower vacuum, affecting the idle circuit and late spark would certainly make it difficult to run at lower rpm. When you get the rpm up the spark advance would take over, and enough air could flow across the boosters to activate the cruise circuit, letting it run above 1000rpm. On top of all that, a worn out timing set would show up gradually like you described.

I hope the gaskets and electrical stuff turn out to be the solution though, good luck!

Thanks. Ya, as Chryco said initially, my problem at first could be pretty much anything.

[Strawdawg]

Looking them up, it's an easy mistake to make.  I see -5 is for carbs with 1 11/16" throttle bores whereas -7 is for carbs with 1 3/4" bores.  I bet a million other people have made this mistake before you came along.  Probably sold a lot of new carbs because people got fed up and just bought a new carb.

I would concentrate of being happy about all the little things you fixed in the past few months and all the things you learned.  Anyone that claims to never have gone thru something like this is probably awfully new to the game.

[cudabob496]

Looking them up, it's an easy mistake to make.  I see -5 is for carbs with 1 11/16" throttle bores whereas -7 is for carbs with 1 3/4" bores.  I bet a million other people have made this mistake before you came along.  Probably sold a lot of new carbs because people got fed up and just bought a new carb.

I would concentrate of being happy about all the little things you fixed in the past few months and all the things you learned.  Anyone that claims to never have gone thru something like this is probably awfully new to the game.

yes, a somewhat painful experience. Having your car sit in the garage, and not knowing why it will not run, can wear on a person.
I just sent Holley tech an email discussing this issue.
Told them to design carb so wrong gasket cannot be placed on the throttle plates.

And the initial issue of a slowly deteriorating ground on the 6AL box was another mysterious pain in the butt.

[734406pk]

Looking them up, it's an easy mistake to make.  I see -5 is for carbs with 1 11/16" throttle bores whereas -7 is for carbs with 1 3/4" bores.  I bet a million other people have made this mistake before you came along.  Probably sold a lot of new carbs because people got fed up and just bought a new carb.

I would concentrate of being happy about all the little things you fixed in the past few months and all the things you learned.  Anyone that claims to never have gone thru something like this is probably awfully new to the game.

This is an easy mistake to make, I have done this myself.  One would think Holley would have caught this and made some adjustments in the Mfg process but IDK. This post may help someone else in the future who is rebuilding a Holley carb::: Check all of the gaskets carefully!

[734406pk]

Just looked at your thread today, can't imagine how frustrated you must feel.

My knee-jerk reaction for the problems you described was a worn out timing set retarding the cam and idle ignition. You did say the build was pretty old, and it sure fits the symptoms nicely. A retarded cam would make lower vacuum, affecting the idle circuit and late spark would certainly make it difficult to run at lower rpm. When you get the rpm up the spark advance would take over, and enough air could flow across the boosters to activate the cruise circuit, letting it run above 1000rpm. On top of all that, a worn out timing set would show up gradually like you described.

I hope the gaskets and electrical stuff turn out to be the solution though, good luck!

I was thinking the same thing (and then some) but the AFR reading went lean. As it turns out the transition part of the idle circuit (1200 rpm+)would have fuel available but not the (adjustable) base idle passage. Crazy isn't it?

[cudabob496]

ya, last time it stalled AFR was 16

[734406pk]

Yes, the engine is able to get fuel from the transition circuit (unblocked) but not through the metered idle circuit (blocked by the gasket). 1200 rpm or  above, the engine would run from the transition circuit. That would be the hole in the gasket closest to the power valve, prior to the mixture screw.  Do you see it?

[cudabob496]

Yes, the engine is able to get fuel from the transition circuit (unblocked) but not through the metered idle circuit (blocked by the gasket). 1200 rpm or  above, the engine would run from the transition circuit. That would be the hole in the gasket closest to the power valve, prior to the mixture screw.  Do you see it?

Yes sir!

[cudabob496]

Wow, amazing, took the Cuda out today, and it ran like there was never a problem
in the first place. Thank you God and Jesus, and all that contributed to the solution to
this headache. And we had our first sunny and warm day of the year! I was in heaven.
AFR about 13 to 14, depending on throttle. What else have I learned:

1) if you have a problem, 50% chance its because of something you did.
2) Product techs are valuable to speak to, but they don't always have the answer.
3) The necessity to have all wires separate from each other may be a little overblown.
4) Keeping a record of all you do, as in this thread, allows you to go back and realize
what may be causing the problem.
5) Attention to detail is really important, especially when rebuilding a carb. being able
to see helps too!

Thanks again!
(wonder what the next problem will be on this 45 yr old car?) Gotta feeling
the control arm bushings need replacing!

[Cudakiller70]

Sooooo good to hear!     we all can learn from this, at least I did. Thanks for posting it all.

Bob I'm looking for an AFR, do you like the one your using?