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Discussion Starter #1
Hi all,

My 4053 Holley from the Z/28 has a leak when parked.:mad: It seems that after the motor was running and has been shut off the secondarys will sit there and just drip gas from the booster area causing the car to flood and be hard to restart. I have had the carb off for a year or so and have been running a 750 DP but would like to put the original back on before the spring.

The car ran good with the 4053 and I dont remember any stumbles etc.. just the leak that I mentioned. I hate to just order a 100.00 kit as I dont think it needs it. I thought about about sending it off to Jerry @ CHP and have it restored but dont really want to spend the money right now. I have rebuilt many Holleys over the years with good luck but couldn't seem to figure this one out.

Any ideas why this is happening? I guess I should mention the floats were adjusted properly.

Thank in adavance,
 

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Nick, you need to check needle seat for trash if not replace them. You can also use the large fuel entry window type on the stock carbs. I would also look at your float levels too, but bet your issue is needle and seats if not the little 0-ring around it. Out where you are at, everything dries up quick. You need to be running stock fuel pressure too, 5-7 #.

Been there done that.
 

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Discussion Starter #3 (Edited)
Don,

Thanks, I will put a new needle & seat in it and give it a try. I dont think fuel pressure is an issue because I am not having trouble with the 750 DP that is on there now.

Thanks agian,
 

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If lowering does not work, unscrew the needle assy and check the needle & seat for debris. When the engine is turned off, there is still residual pressure in the fuel line and the needle being open, bleeds off the extra pressure.

Before installing, lube with petroleum jelly to save the O-ring while installing. If it still doesn't work, remove the bowl and remove the float and throw it into a bowl of gas to see if it floats. If it sinks, replace the float and swap out the bowl from the 750DP just to get you back onto the street.
 

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Discussion Starter #7
Ok guys new problem. I swaped out both needle & seats and bolted it back on. unfortunatly I didnt get to mess with it untill this evening. I fired it back up and it sounds good but man does it ever smell rich idling.

Just a quick note with the way it is set up. I have 70 jets in the primarys with a 45 power valve & 72 in the secondarys with a 65 Power Valve. I did put a vacumn gauge on it and it only has 6" of vacumn at idle. The idle mixture screws are only out about 1/4 - 1/2 turn to get the 6" of vacumn.

I will go this week and buy a 2.5 or mabey a 3.0 power valve for the primary side but should I put the same in the rear or just leave what I have?

I feel like I should go ahead and lean the jets back down 3 or 4 steps but I keep reading every one else is running 72/74's. I live a 5500' of elevation so mabey that might have a little to do with it.

I didnt get to drive it tonight as it started to snow but I still had to hold the pedal to floor to get it to restart after turning it off and it setting for a few minutes. I didnt notice any gas dripping like before but I am not 100% sure I corected the original problem. I will say it is not as hard to start as I remember though. :D Plus another thought is, I am sure as rich as it smells the plugs are probably pretty fouled and that might also be the reason it is still harder to restart than I feel it should be.

It's funny I have been playing with Holley carbs for years and can usually tune them with ease but this darn 4053 has been kicking my butt for almost 10 years now.

Any more Ideas on what to do with this thing besides the smaller power valve?

Thanks again for your help
:beers:
 

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If the needle and seat are closing, float level is correct, floats aren't leaking then it could very well be a bad power valve. It is my understanding when the power valves go bad, it goes to a very rich condition.

Or, contact Eric at this site:

www.vintagemusclecarparts.com

Todd was having issues with his 4053 and Eric really did a great job for him.

http://www.camaros.net/forums/showthread.php?t=120880&page=4

10 years is long enough to have your backside chewed on, must not be much left at this point.

alan
 

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Discussion Starter #9
Alan,

Thanks for the suggestion but both power valves are good. I am sure since it only has 6" of vacumn the 4.5 in the primarys is letting it run richer than it should but if this thing runs for 2 minutes it the garage it kills every bug for 5 blocks & darn near peels the paint off the walls. :D

Do you know if both power valves should be the same? Or can you / should you stagger them?

Thanks again
 

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Hmmm, that I can't say, it has been a while..........Perhaps on the Holley site there might be some help. Or PM Eric. The guy really got Todd's carb sorted out in short order and his prices are eminently fair. The thing is, these carbs are 39 years old, lots of places they could be worn.

Todd and I talked about his carb before he sent it to Eric and wondered about altitude or worn throttle shaft bores etc. Todd wasn't happy with how it was performing. The issue was in the accelerator pump circuit. But according to Todd, the thing runs like is supposed to. I know when I had my Z, altitude was never an issue and I drove that thing from Santa Monica to Mammoth Mountain which is way up there.

Double check all of your vacuum connections including the power brake booster. Check to make sure the vac advance and booster diaphrams aren't cracked and leaking.

I also found this on another site:

Gather all the numbers off your carburetor as well as the pertinent information on your truck (make, year, Model, engine, trans, etc.) and then contact Holley Technical Services at: http://www.holley.com/TechService/TechRequest.asp . Ask for the power valve number for your carburetor and the main jet sizes. There are many different numbers for both power valves and main jets so you need to make sure your carburetor has the correct ones to get optimum performance.

Does anyone know what the factory stock jet sizes and power valves are for this carb?


alan
 

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Discussion Starter #11
alan,


I think you got it right when you said "these carbs are 39 years old". My carb has never been restored and does have worn throttle shafts etc... I most likely need to just send it off and get it restored and while I am at it yank the 302 and go through it as well. It is pretty tired and doesnt run like it should. I have been putting it off for years, mabey I need to just get going on it this spring. :yes:

Thanks again,
 

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Discussion Starter #12
Hi all,

I just got off the phone with Holley tech this morning and he is telling me stock jeting should be 68 in the primarys and because of my altitude |I should be somewhere around 65-66's in the primarys for a base line. He also comented about my low vacumn and thought the rich condition was causing the low vacumn.

He recomended lowering the jets and then rechecking the vacumn. If it doesnt come up to go with 2.5 power valves in the front and back.

What is your thought about this?

Thanks again for your help,
 

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I was about to say the same on jets, I run 68 for my 3500' altitude, you at 5500 may need less. I run a 65PV with my 288/290 cam , make sure your cam duration is not impacting this as well as timing.
Again, with motor running , check to see if fuel is dribbling on the back venturi clusters or even front. May have to back out those mixture screws to see it you have any impact here. Did you notice if you have the PV saver check valve in the base of the carb? One pop and the valve is gone if you dont have it.
Be sure to pull float site plugs and the fuel need to be at the lower threads of that hole.

Did you change any gaskets? Tear any? Any dried or shrivled? Even a 39 year old Holley will be as good as new when you tweak it correctly.
 

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alan,


I think you got it right when you said "these carbs are 39 years old". My carb has never been restored and does have worn throttle shafts etc... I most likely need to just send it off and get it restored and while I am at it yank the 302 and go through it as well. It is pretty tired and doesnt run like it should. I have been putting it off for years, mabey I need to just get going on it this spring. :yes:

Thanks again,
Well, a sloppy throttle shaft will amount to a vacuum leak. I am telling you, send the darn thing to Eric. 10 years is long enough to suffer.

alan
 

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Discussion Starter #15
I was about to say the same on jets, I run 68 for my 3500' altitude, you at 5500 may need less. I run a 65PV with my 288/290 cam , make sure your cam duration is not impacting this as well as timing.
Again, with motor running , check to see if fuel is dribbling on the back venturi clusters or even front. May have to back out those mixture screws to see it you have any impact here. Did you notice if you have the PV saver check valve in the base of the carb? One pop and the valve is gone if you dont have it.
Be sure to pull float site plugs and the fuel need to be at the lower threads of that hole.

Did you change any gaskets? Tear any? Any dried or shrivled? Even a 39 year old Holley will be as good as new when you tweak it correctly.
Don,

I didnt think to even look for the power valve saver. If I were going to guess I would say no it doesn't have it. I did end up changing 1 of the bowl gaskets as I tore it pulling the bowl off the rear. i replaced it with the Blue non stick kind so it should be fine from here on.

The car just has the stock 30 30 duntov but so far the best I got was 6". I will lean it out next and recheck the vacumn to see if ity comes back up. It sounds like 9 - 9.5 is what some of the others are getting with their 302's.

I have owned this car for almost 10 years and have never been able to get it to run clean with this carb so it has been off and on mostly off the car all these years. Unfortunatly it is dated way to early for my car is the main reason I never sent it off to be restored. It did come on the car when I bought it but it is oviously not original to my car.

I had planed to spend the weekend playing with the car but only got about 2 hours last night right before the darn snow started flying:mad:. I do still want to give it an honest effort to tune out the issues with it but I think if I still cant work it out I need to take Alan's advice and just bite the bullet an send it to Eric.

Thanks again to all that have helped,
 

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Snow flying? Better than sand, we are getting that almost daily around Lubbock.

If you ever want to install one of these PV savers, its easy, Holley sells the kit that you drill into the base plate( you have to seperate airhorn from base plate.

I would come down on the jet and look for a change. You are getting too much fuel from some place. Those old gaskets could have dried up and allow some fuel to come in somewhere, the thin paper gasket in the rear bowl , behind the meter block or plate could also cause this. Hope you fixit, it easy. Sometimes you have to take the carb all way down to find things but if you are not familuar with a Holley, it can be a problem.
 

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Discussion Starter #19
Eric,
Thanks. I may have to take you up on it. :D

Well I went out there and leaned the primarys out to 65's. the car smells much cleaner. The best vacumn I got fully warmed up was 6.5" :( I think I will try and sneak off to town later and try and find a pair of 3.0 power valves. It is drawing fuel from somewhere as it sounds the cleanest with both trim screws turned in all the way.:confused:

When you shut it off you can see a little gas smoke coming out of the primarys but I dont see it leeking anywhere. It is still hard to start when it sits for a few minutes. You have to hold the pedal to the floor like it is flooded. I have yet to drive it but it seems to now have a bog when you rev it and the secondarys come in. not to bad but it is definatly there.

The plugs were black as hell so I will try new set and see if it helps.

Thanks again for the help.
 

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Discussion Starter #20
Guess I could too , being across the state line. Let me know.

Thanks Don,

You have already been a great help so far. for some reason when it comes to this car i get stupid & forget everything I have ever learned about tuning cars.:D
 
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