Consistent issue with the fuel pumps i can use on my set up

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Old March 18th, 2021, 02:16 PM
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Consistent issue with the fuel pumps i can use on my set up

Over the past few years I have battled fuel leaks from these style pumps ( only ones that will fit my Aluminum head set up) . They leak where pointed to, where the top half meets the bottom half. Only when cold, only on initial daily start up, save 2-3 times over the years where it leaked more than just as noted. I've literally seen sprays of gas. I thought I had it licked when I changed from the chrome to the black one but low and behold after a year without a drip today it spewed, same seam. On one of the past chrome ones I took it apart and used some sealer, obviously pretty much a losing battle with the fuel right there, Seal All seemed to work for awhile. Ideas? Suggestions? Why only when cold/start up- high idle choked ( note it will slowly stop leaking as it warms up- caveat- most of the time). I have in hand pump number 5 but............



Last edited by boese1978; March 18th, 2021 at 02:19 PM.
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Old March 18th, 2021, 03:10 PM
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Does it have to be the same mechanical fuel pump that you are using? Can you use another mechanical pump or try an electric pump?
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Old March 18th, 2021, 03:37 PM
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Are there bolts or screws that hold the parts together? I would think they need to be tightened a bit more to maintain the gasket seal.
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Old March 18th, 2021, 03:57 PM
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I would prefer to stay with a mechanical pump. None others I’ve seen will fit. As noted the pump must be thus shape to fit machine work done to my head for pump clearance. There are screws that hold the halves together. I’ve tried.

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Old March 18th, 2021, 04:52 PM
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Since you have more than one, yes? try taking one apart to see if a gasoline tolerant sealer could be applied.

Good luck!!!
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Old March 18th, 2021, 05:23 PM
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Rock Auto just had the stock Olds fuel pump on closeout, with return line for $10.00, got two they where in Carquest boxes.
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Old March 18th, 2021, 05:35 PM
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Stock pumps will not fit. Sugar- tried seal all , worked ( or seemed to) for awhile.
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Old March 18th, 2021, 06:16 PM
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Those look like chinese reproductions of the older Mr. Gasket fuel pumps. I have an original Mr. Gasket and a slightly different casting Holley pump for sale. Both out of production, made in USA low miles and should clear the aluminum heads.

https://classicoldsmobile.com/forums...-pumps-148969/
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Old March 19th, 2021, 05:07 AM
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You can simply notch out the area where the head interferes. I did that on mine. It doesn't take much.

That way any fuel pump will work.
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Old March 19th, 2021, 07:41 AM
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My head is notched, a bit more than yours, done by Mondello. for said fuel pumps. I have only found 2 pumps that will fit. The chrome ones that Mondello USED to sell with the head package ( no longer made) and the black pump from some place online. I've tried fitting a few others, no go with out more head work which I do not want to do.

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Old March 19th, 2021, 07:51 AM
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Is there any contact of the fuel pump with the cylinder head when fastened securely? You can use the old trick of placing a sheet of paper between fuel pump and cylinder head prior to tightening and then see if it slides out easily after fuel pump is tightened securely. There should be about 1/16" clearance (minimum) at all close areas. Looking at AJR's post, it looks like he has a big block on the engine stand. The small block because of the shorter deck height has much more possible contact area between cylinder head and fuel pump.
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Old March 19th, 2021, 07:56 AM
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Originally Posted by 67OAI
Is there any contact of the fuel pump with the cylinder head when fastened securely? You can use the old trick of placing a sheet of paper between fuel pump and cylinder head prior to tightening and then see if it slides out easily after fuel pump is tightened securely. There should be about 1/16" clearance (minimum) at all close areas. Looking at AJR's post, it looks like he has a big block on the engine stand. The small block because of the shorter deck height has much more possible contact area between cylinder head and fuel pump.

No contact at all with the pumps I have. Pretty sure AJR's is small block, hence the head overhang.
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Old March 19th, 2021, 10:18 AM
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I'm pretty sure I'm the one that turned you on to one of those pumps from a California based supplier. I've had one on my big block with aluminum heads for ~5 years. I noticed a gas smell a couple of years ago and the joint between the upper and lower halves was wet. I tightened the screws holding it together (without removing the pump) and that fixed the problem. I check them periodically but haven't had to re-torque them. I'm not clear from your statements above whether you actually did this. If you did, is it possible you may have over-torqued one of them and put a small crack in one of the housings? I can only think of three possible reasons it will continue to leak; 1) loss of clamp-load from the screws, 2) the seal between the upper and lower halves is bad, or 3) the housing(s) are cracked.
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Old March 19th, 2021, 11:19 AM
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Originally Posted by boese1978
My head is notched, a bit more than yours, done by Mondello. for said fuel pumps. I have only found 2 pumps that will fit. The chrome ones that Mondello USED to sell with the head package ( no longer made) and the black pump from some place online. I've tried fitting a few others, no go with out more head work which I do not want to do.
That seems like a LOT of material on yours. This is all it takes to get a stock style pump to fit.




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Old March 19th, 2021, 11:23 AM
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Originally Posted by acavagnaro
I'm pretty sure I'm the one that turned you on to one of those pumps from a California based supplier. I've had one on my big block with aluminum heads for ~5 years. I noticed a gas smell a couple of years ago and the joint between the upper and lower halves was wet. I tightened the screws holding it together (without removing the pump) and that fixed the problem. I check them periodically but haven't had to re-torque them. I'm not clear from your statements above whether you actually did this. If you did, is it possible you may have over-torqued one of them and put a small crack in one of the housings? I can only think of three possible reasons it will continue to leak; 1) loss of clamp-load from the screws, 2) the seal between the upper and lower halves is bad, or 3) the housing(s) are cracked.
Yes,you did point me towards those pumps, So strange how the same issue is happening multiple times to so many diff pumps. I have tried tightening the screws that hold the halves together and I was very careful to not over tighten, i just snugged them a bit on past pumps to no avail. Will try again with the current pump. Thanks for the input!
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Old March 20th, 2021, 04:20 AM
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Maybe longer screws with self locking nuts and washers you may have to invert them. While pump is apart maybe flat surface with sandpaper on glass. Gasgacinch works well if you follow the directions. Even your factory screws should extend past the casting and should have lock washers or Loctite on them. Kirk out.
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Old March 20th, 2021, 08:45 AM
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AJR, that's the difference caused by the shorter deck height of the small block (330,350,403) as compared to your 455 big block. The fuel pump becomes effectively higher in relation to the cylinder head.
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Old March 21st, 2021, 06:23 AM
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Originally Posted by 67OAI
AJR, that's the difference caused by the shorter deck height of the small block (330,350,403) as compared to your 455 big block. The fuel pump becomes effectively higher in relation to the cylinder head.
Correct. I overlooked that. Makes sense.
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Old March 21st, 2021, 07:19 AM
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tweaked the screws that hold the halves together, again, but first time on this pump, they were all snug, so far so good. will see how long it lasts.
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