starting the Holley carb "find the leak" project

[BarryK]

well, got the Holley back off the car, bolted on some 3" 1/4 bolts to use as legs and let it sit off the car in my office to see if I could better identify exactly where the leaks were coming from before just tearing this thing apart.

all I could determine was some drops of fuel sitting under both the front and rear bowls and by looking underneath it the bottom of the bowls were wet with fuel so no real way to determine if it seemed to be leaking from the fuelbowl/metering body gasket or the metering body/main body gasket or even if maybe from the fuel transfer tube that runs from the front fuel bowl fuel inlet back to the rear fuel bowl and just oozing it's way down along the body and dripping underneath.

Already just pulled off the rear fuel bowl and metering body. The rebuilder used a brown gasket on the fuel bowl and a black one on the metering body. The Holley brand rebuild kit I purchased has the blue gaskets and they are thicker so perhaps just those along will help the problem.

When pulling the transfer tube off carefully the o-rings stayed inside the fuel bowl so i'll need to pick them out but from what I can see under a light they look to be black o-rings. I was told Holley has a better o-ring for the transfer tube than what comes supplied in the rebuild kit so tomorrow i'll order up a set of those better o-rings. No point in taking chances and having to do this again so I might as well get the better o-rings and do it right the first time.

i used a metal t-square to check the straightness of the main body surfaces and so far on the rear side everything is perfectly straight and flat. I can see the machining marks so I guess the rebuilder did machine this thing true like he was suppose to, or else it had been done previously already. In either case, since it is flat and true that's one problem I shouldn't have to worry about.

Maybe i'll get lucky and the only problem was cheap gaskets and/or simple during reassembly. I will find out.

i'll report more as I go along.

 

[allcoupedup]

Barry,
How did you check for flatness? You and I are very much alike except I have had my car for a few years longer than you and am farther along the learning curve. The first time I pulled my 2818, I determined that the surfaces were square by taking a straightedge and checking it out with the naked eye. Yup - everything looks flat! Since then I have learned that a straightedge and feeler gauges are the only way to go. I recently pulled that same 2818 and checked for surface flatness the right way - vertical, horizontal, and diagnoal. Guess what - it was pretty warped.

If you did it using the method I described, please disregard the message!
Brian

 

[BarryK]

Hi Brian

I don't have a feeler guage but I used a straightedge to check to see how flat and true the main body surfaces were.
I actually but a light on one side of the straightedge and besides checking "by feel" that the straight edge didn't rock or moce against the surface of the main body at different positions or angles I checked to see if I would get a lightleak thru the area the straightedge butted up against the main body. If I would see any light leaking thru than I would figure there was warpage.
No light leaks thru the straightedge against the main body.

Also, the rebuilder did say he was going to machine the surfaces flat and I could see machining marks on the main body so I now have to assume that he did do that as he was suppose to.
I'm have a high confidence level now that everything is flat and true and no warpage to contend with.

I was suppose to get the new transfer tube and seals and the new fuel bowl screw washer/seals yesterday but there was a delay on the parts so it will be a couple more days yet until I have them.
Once they come in I'll put everything back together - using the blue gaskets for the metering bodies and fuel bowls, the nylon seals for the screws, and the new tranfer tube and seals.
Than I'll put some fuel in the fuel bowls with a plastic syringe thru the sight holes and let it sit for a day or two to check for any leaks while I have my fingers crossed.

 

[coves4me]

Barry, it sounds like you're on the right track, BUT don't forget to do the following while you've got the carb apart:

1. On the bottom of the carb there should be 6 or 8 phillips head screws. Tighten them up in a diagonal criss-cross fashion as they hold the throttle plate to the bottom of the main housing. With engine cycling (hot to cold) they will have a tendency to loosen over time.

2. Remember to diagonally tighten the float bowl screws with an inch-pound torque wrench to the proper spec. After a few hot and cold engine cycles, go back and re-torque them as they too will have a tendency to loosen over time.

3. Don't forget to use petroleum jelly on your new o-rings.

4. Drink a tall cold one when you're done.....you deserve it!!! Good luck!

 

[BarryK]

thanks for the tips coves.

I'll double check the bottom screws

yep, plan on cross tigtening all the screws, including the hold down nuts when I get the whole unit back on the car.

already planning to swipe the wifes vaseline for the transfer tube seals

A cold pepsi sounds good since I don't "drink'.



you know, even though I only did a very limited disassembly on the carb - the advice given to me before starting was "Don't take apart anymore than you have to!" - it was actually a breeze and very easy. I don't see reassemble being much more difficult.
Sure gives me more confidence for any type of future work I may have to do to the carb. Learning how to do new stuff is always nice.

 

[paul67]

Barry,
Vaseline corrodes rubber so I would avoid it. This is well-known in medical circles for certain...sensitive uses. A lithium-based lube would be better.

 

[BarryK]

ahhhhh, well, I wouldn't want to end up with a bunch of little Baby's 9 months after putting the carb back together........

 

[firstgear]

while I appreciate the improved looks, I have to say that the aggrevation that you got fom this is enough to make one think twice about going down the same path.....if it isn't broke....don't fix it......I think if I go down the same path you went down I would leave my carb alone.....clean up the other pieces and put it back together just as it was.........now that you have had this PIA, what are your thoughts?

 

[BarryK]

Herb, the replating for the cosmetics appeal was secondary and a last minute decision of mine. It was still going in primary because I feel the carb wasn't operating 100% correctly.
since getting it back the car DOES idle better than it did prior to the rebuild so that was an improvement at least.

from what i've seem from the limited disassembly I just did though to try and fix the leaking issues (not to mention the work I had to do to make the choke work) I can safely say that in the future I'll do any additional carb rebuilding myself if it needs it.
The improved idle is not reason enough by itself to warrant the aggrevation of still having to make my own repairs on it after an expensive rebuild.

From what i've seem on the disassembly i've done this week, as limited as it may be, I don't see where any future rebuilding on the complete carb would be beyond my capabilities.

knowing what I know now, I should have just done it myself to begin with but to be honest, at the time I sent it out, I had never worked on an automotive carb and only had a small expereince with my motorcycle carbs so I was a bit intimidated by attempting it myself.
As I'm learning on many things on tis car, the best way to learn is to just jump in and do it though.

 

[vettepilot]

Barry,
Vaseline corrodes rubber so I would avoid it. This is well-known in medical circles for certain...sensitive uses. A lithium-based lube would be better.

For what it's worth, I agree on not using the petoleum jelly. If you have any silicon weatherstrip lube, that's what I have sucessfully used. A little goes a long way, just enough so the tube will easily slid through the o-ring without pinching, rolling, or otherwise damaging the o-ring. Also check for any old o-ring that may be stuck to the inside of the o-ring/transfer tube receptacle. I have used q-tips to clean that area using alcohol or paint thinner. Needless to say, make sure it's dry before reassembly. Also, having worked on these many times in the past, I discovered it's best to use the lowest torque needed to secure the bowl, fill with fuel as you have already planned. No leaks, then you can complete the installation. Leaks, increase torque by small increments until no leakage.
Somebody already mentioned the effects of heating/cooling in respect to expansion and contraction, this will happen, the key is to retorque after about 2 - 5 hours of engine run time. Again use the minimum torque required, those gaskets have a nasty habit of squashing and separating with too much torque applied. I wish the new Vettes were as easy to work on.... ahhhhh those were the days.

vettepilot

 

[BarryK]

vettepilot

actually, I believe the new transfer tube I ordered doesn't come with O-rings as much as they are somewhat larger "sleeves" on the ends.
This is suppose to be an improvement on the standard tube and O-rings and reduce the chances of leaking as this is a known "leaky" area on these carbs as I'm told.
The lube is really more just to help slide the transfer tube into the fuel bowls is how it was explained to me.

I looked in the fuel bowls and there is no old )-rings stuck in there but I'd be surprised if there were. This thing was only rebuilt a few weeks prior to to my taking it apart the other day! In fact, the fuel tube O-rings that were there still had the lube on them the rebuilder used when he put them in.

 

[allcoupedup]

My renew kit came with the new sleeves instead of o-rings for the transfer tube. There was no way in hell that tube was fitting in with the sleeves as they were delivered. I had to trim about 1/2 of the sleeve with a razor blade on each side to be able to slide the tube in enough to get the two fuel bols close enough to bolt on to the main body.

I hate cutting stuff up that was purpose designed but there was no way it was all going to fit.

Brian

 

[BarryK]

Brian
I was told the rebuild kits only came with the standard O-rings so I never even looked. Once I just read your message I checked and yep, they are the sleeves! Oh well, at least this way I'll have a spare set in case I need them and I still have to wait for the nylon washers/seals for the fuel bowl screws anyway rather than use the standard cardboard ones from the kit.

Using the sleeves that came in the kit I tried a "trial" fit of the transfer tube into the fuel bowl and I can see that getting the transfer tube to fit all the way in is going to be a VERY snug fit to say the least. I didn't try to push it in all the way and I wasn't using any lube, it was just a quick fit test to see how tight of a fit it was going to be and I can understand already the difficulty you encountered. I'll use a lube to help slide it in when I'm ready and hope for the best.

 

[coves4me]

Barry, I am not familiar with the sleeves on the transfer tube, but before I would try to assemble that new transfer tube and sleeves, I would do the following:

1. Just to make sure that the transfer is not too long and preventing the float bowls from properly seating against the float bowl gaskets, assemble one float bowl to the carb with gasket and tighten screws per spec.

2. Without sleeves or o-rings, loosely install the transfer tube and the second float bowl with gasket. As you tighten the float bowl screws, twist the transfer tube between your fingers. If you can twist the transfer tube between your fingers with the second float bowl tightened to specs, your transfer tube is OK for length.

However, if the tube resists twisting during the tightening sequence, remove it and file the ends until it fits. It could be the reason the float bowls are leaking!! I have seen one tube in my rebuilding days that was about 1/16-inch too long and it kept the rear float bowl from sealing properly. Drove me nuts trying to figure it out.

As far as the use of petroleum jelly on the o-rings, it's your call. I've used it for years with no failures. Good luck!!

 

[BarryK]

thanks for the tips again Coves

i'll be sure to check the new transfer tube as I'm installing it.
It should also be pretty easy to check against the one that was in there I removed before installing it to check it's length.