71 LT-1 Holley Carb Leak

[Mick D.]

I've read around and see that these carbs can have all kinds of leak problems, but I figured I'd put down my own experience here.

I had to drop out of flight judging due to the leak, which just seemed to start out of nowhere. The car had been sitting for 3 months which is my bad, I was busy and couldn't take it out. This is after no issues prior.

It started leaking from the drivers side, as shown below,

leaked-holley1.jpg

I stopped, cleaned it all up and made sure any hoses weren't off or loose, and gave any metal levers a good back and forth in case anything was stuck.

I then restarted the engine, and it had stopped leaking from that side and was now only leaking from the fuel inlet, which you can see below.

leaked-holley3.png

It looked like it was coming right out from behind the gasket. I tightened the two bolts, and it stopped it for the most part as far as I can tell. It's not leaking now.

leaked-holley.jpg

I'm a carb novice, so will need to take it to Race Street Rally and have it properly seen to, but it is a real pain to not be able to drive it there without worry of a leak (I don't have a trailer right now).

If folks have experience with this, would appreciate any advice.

- Mick

[Bill B.]

Re: 71 LT-1 Holley Carb Leak

Hi Michael,

I have rebuilt many a Holley 4150 carb over the years, and I have found today's gasket materials superior to the older cork and rubber parts used for fuel bowl assembly of years ago. I recommend Holley 108-91 and 108-92 blue non-stick gaskets for metering body and fuel bowl, and Moroso 65225 nylon fuel bowl washers for the screws. (Holley makes them too, but most hi-perf parts shops I deal with only carry the Moroso brand washers). I also re-torque the primary and secondary fuel bowl screws after several engine heat soak cycles.

This procedure and these materials have seemed to hold up well for me. Also, as to the fuel inlets, make sure that the fuel supply tubing does not impart pressure on the fuel bowls. They want to interface to the inlet with as much good alignment as possible. You may have to slightly bend the tubing in order to achieve this. Just be careful not to distort the tubing flare if doing so.

Good luck and have fun enjoying your ride!

PS - Please weigh this recommendation with an eye on Top-Flight points. I'm sure astute judges will deduct originality points when they see the blue gasket and white nylon washers behind the screw heads. I'm just sharing my experience for the best leak-free outcome that has longevity.

[Chris H.]

https://www.grainger.com/product/PARKER-Flare-Gasket-For-3-8-in-Tube-5WRW3

[Mick D.]

Re: 71 LT-1 Holley Carb Leak

Thank you for the advice and part numbers Bill!

Hi Michael,

I have rebuilt many a Holley 4150 carb over the years, and I have found today's gasket materials superior to the older cork and rubber parts used for fuel bowl assembly of years ago. I recommend Holley 108-91 and 108-92 blue non-stick gaskets for metering body and fuel bowl, and Moroso 65225 nylon fuel bowl washers for the screws. (Holley makes them too, but most hi-perf parts shops I deal with only carry the Moroso brand washers). I also re-torque the primary and secondary fuel bowl screws after several engine heat soak cycles.

This procedure and these materials have seemed to hold up well for me. Also, as to the fuel inlets, make sure that the fuel supply tubing does not impart pressure on the fuel bowls. They want to interface to the inlet with as much good alignment as possible. You may have to slightly bend the tubing in order to achieve this. Just be careful not to distort the tubing flare if doing so.

Good luck and have fun enjoying your ride!

PS - Please weigh this recommendation with an eye on Top-Flight points. I'm sure astute judges will deduct originality points when they see the blue gasket and white nylon washers behind the screw heads. I'm just sharing my experience for the best leak-free outcome that has longevity.

[Joe L.]

Re: 71 LT-1 Holley Carb Leak

Hi Michael,

I have rebuilt many a Holley 4150 carb over the years, and I have found today's gasket materials superior to the older cork and rubber parts used for fuel bowl assembly of years ago. I recommend Holley 108-91 and 108-92 blue non-stick gaskets for metering body and fuel bowl, and Moroso 65225 nylon fuel bowl washers for the screws. (Holley makes them too, but most hi-perf parts shops I deal with only carry the Moroso brand washers). I also re-torque the primary and secondary fuel bowl screws after several engine heat soak cycles.

This procedure and these materials have seemed to hold up well for me. Also, as to the fuel inlets, make sure that the fuel supply tubing does not impart pressure on the fuel bowls. They want to interface to the inlet with as much good alignment as possible. You may have to slightly bend the tubing in order to achieve this. Just be careful not to distort the tubing flare if doing so.

Good luck and have fun enjoying your ride!

PS - Please weigh this recommendation with an eye on Top-Flight points. I'm sure astute judges will deduct originality points when they see the blue gasket and white nylon washers behind the screw heads. I'm just sharing my experience for the best leak-free outcome that has longevity.

Bill------


I TOTALLY agree.

Also, what you mention as far as inlet tubing is VERY important.

No need for concern regarding deviation from originality when using current gaskets and washers. For me, IT'S ALWAYS FUNCTION OVER FORM, not the other way around. And, this is especially true when we're talking about preventing a safety related problem like fuel leakage!