Holley expert needed? - Team Camaro Tech
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post #1 of 9 (permalink) Old Apr 28th, 11, 10:46 PM Thread Starter
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SS
 
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Unhappy Holley expert needed?

I have a 4780-2 800 cfm carb; It always ran well and I have an AFR and have had it tuned for cruise of about 14.8-15.1:1 for at least the past year. I drove the car about a 6 six weeks ago and it ran very strong as usual and hadn't driven it until last last weekend: and started acting a little funny and lean at idle intermitently 15:1( usually 13.5:1) etc seemed off.
8 months ago started to notice a lean spike on the AFR 17:1 intermitently and thought it was the gauge and ended up replacing the o2 sensor. it still did it infrequently but couldn't really feel a surge. Last weekend I could feel it when the gauge was whacking out and noticed it was harder than normal to get to idle when warming up and was going lean.

I pulled the carb today and found some gasket debris in one of the IFRs and ended up replacing base gaskets and throttle body gasket. I noticed the inner TB screws between the throttle blades were deleted but I believe they have always been that way in effort to avoid falling into the intake. If I had lost them both in the intake I think it would been catastrophic ...

Anyway, put it back together and it wouldn't idle was going totally lean, checked and double checked vac lines etc etc.

Ended up throwing another metering block on thinking something was blocking something and it started fine, ran smooth and idled for about 30 secs and then same thing. I was thinking it maybe was an intake man gasket going bad but the Metering block switch changed my mind. It acts as if it has a huge vac leak or something (WON't IDLE)..actually just dies and quick, I was thinking needle and seat but usually it will dump fuel and bowls will overflow; but it is not rich but lean?

checked the site plugs both looked fine, I am not sure what to do but it is acting majorly weird and I was planning to race this weekend and now I am not sure WTH is wrong with it.

fuel pressure seems fine, only thing I did different was got gas before I put it away; it has basically a 7/8 of tank.

the carb has been modded years ago, no choke horn, smooth bored, typical tricks and has always ran well, it does seem like a progressive problem since it ran a little funny and surged with the gauge spike 17+:1 AFR LEAN! and has been getting harder to get to idle when cold, when it used to idle cold after a short time.

I am baffled, and could use some help badly, thanks SS.

406, TKO 600 and 12 bolt posi.

Last edited by railing68; Apr 28th, 11 at 11:03 PM.
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post #2 of 9 (permalink) Old Apr 28th, 11, 11:17 PM
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Michael Gekko
 
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Re: Holley expert needed?

Reads like you have some trash in it to me. You might want to take it apart and use carb cleaner and compressed air to blow any debris out of it.

And yes, the screws would likely cause a catastrophic event if they fell down in the engine. I built a 350 for my best friend while in high school for his '79 Z, he beat that engine through and through.....called me one night said it was locked up. Took it apart and the air cleaner stud had vibrated out and went into the motor, luckily it just left an impression on the top of the piston.

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post #3 of 9 (permalink) Old Apr 29th, 11, 06:04 AM
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Dan Ensign
 
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Re: Holley expert needed?

Do you have power brakes, did you try disconnected and plugging the vac. port to the brake booster?

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69 SS396 4spd. 4.10 posi. x66 coupe
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post #4 of 9 (permalink) Old Apr 29th, 11, 06:26 AM
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Steve
 
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Re: Holley expert needed?

Might want to try a little dry gas too...maybe water in gas?

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post #5 of 9 (permalink) Old Apr 29th, 11, 03:06 PM
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Wes
 
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Re: Holley expert needed?

I agree with you. Sounds a lot like a vacuum leak.

1) You sure your intake manifold is properly sealing? Any evidence of coolant in the oil? Any evidence oil is being pulled into the chambers past the intake?

2) To what are all your vacuum lines connected? In almost all cases, the lines are connected to a diaphragm of varying uses and sizes (from brake boosters to a transmission modulator valve). If any of these are bad, she can lean out a bit.

3) If you listen real closely, sometimes you can hear a vacuum leak.

3a) If you run your hands over the lines, sometimes you can feel or hear a leak.

4) Has an unused vacuum port (tube) rattled out of the carb? (they're only pressed in).

5) Is your PCV valve stuck open?,..(it should more or less closed at idle)
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post #6 of 9 (permalink) Old Apr 29th, 11, 03:18 PM
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Re: Holley expert needed?

Is fuel up to the sight plugs when running or does the level drop and the engine act up? The bronze inlet filters will varnish up after sitting for a long time. That equals very low fuel flow.
E85 alcohol is scary too.

One owner 69 Camaro,(yep, bought it new
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post #7 of 9 (permalink) Old Apr 30th, 11, 08:01 AM
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Re: Holley expert needed?

Quote:
Originally Posted by Eleanor's Nemesis View Post
Reads like you have some trash in it to me. You might want to take it apart and use carb cleaner and compressed air to blow any debris out of it.
X2 Take it completely apart and blow out every passage you can get to. Squirting carb cleaner through the passages will show if they are blocked or if you got them freed up.
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post #8 of 9 (permalink) Old May 7th, 11, 10:08 AM Thread Starter
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SS
 
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Re: Holley expert needed?

I ended up taking the carb completely apart again and blowing out every passage, needle and seats etc...

I also found that the cheap filter element summit supplies with their copy of the Fram HPG1 is glued together? It slowly comes apart and contaminates the system. I am pretty sure it has been deteorating for quite a while. I got it running and was able to make the event, it runs just like it did, strong. The lean spikes are also gone in cruise for the time being, Very Nice!

By the way anyone using the summit filter as a replacement for the HPG1 element should replace it with the WIX #33900R, which is better quality and doesn't appear to be bonded with any inferior adhesive...

Thanks for the help, SS.

406, TKO 600 and 12 bolt posi.
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post #9 of 9 (permalink) Old May 7th, 11, 10:44 AM
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Ron
 
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Re: Holley expert needed?

I stick to Inline Fuel Filters and never use Bowl Filters in my Holley's.

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