caddyman

I recently did a valve job on my 71 coupe. One of the heads blew a gasket so I tore it down and took the heads in. The car has headers on it, but I'm not sure where from as I just recently purchased it. I think they are from jegs... After some research I purchased some Percy's XXX carbon gaskets and cleaned the port surfaces on the headers. I assembled them by tightening the middle bolts and working out twards each end. I only have a 1/2" drive toque wrech so this proved to be a problem when trying to torque the lower bolts. I got a few of them with a crowsfoot and then did the others by hand. Now at start up I can hear what I think is one or two cylinders leaking. You know the old phff.... phff ....phff . Any thoughts what I should do? Do I loosen all the bolts and pull the gasket and reinstall? I'm at a loss as I have no exp with headers. If I had $ I would invest in some good headers but that is not the case. I am broke!

On another note I am running an older holly 4bbl carb and the back float is leaking though the side where the fuel is delivered from the front. There is a round brass fitting on the back where the gas inlet is for the front and it looks like that is where the leak is. Is there a way to stop that leak at the brass circle?

Any help would be greatly appreciated. I take thinks apart with one problem, put them together and have 3 new problems... depressing.

Thanks!

Tom


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fast66

With regards to the headers leak, I have the same thing. I was told to use the gaskets with the perforated metal on one side, and use some hi temp exhaust gasket sealant on them. I did this and it still leaks slightly. I have also heard that using two gaskets per side helps to take up the warp that the header mount plate sometimes gets. I havent tried that yet though.

Soaring

A really good thing to do is use stock exhaust manifold gaskets, the thick steel encased type. Do not over tighten, drive for a week or so, then re-tighten them. Also headers with heavier flanges are less prone to developing leaks. Try taking off the header and using a file, try to get it flat. It sounds like the header is warped.

THUMPIN455

On the carb, if it is leaking right where the arrow is pointing, its the bowl that needs replaced. If its leaking from the transfer tube, then its an O-ring. If its leaking above the float where the 5/8" sized nut and a flat screwdriver type screw is, then that is the float adjuster.

To replace gaskets at the float adjuster, unscrew the top screw while holding the nut with a wrench. Dont turn the nut if you can help it. Once the screw is all the way out of the shaft the nut is on, pull the nut straight up and put another gasket under it.

To repair the transfer tube O-ring, remove the 4 screws that are at the corners of the float bowl. If you pull a bottom one first, you can catch the fuel that is in the bowl with a plastic cup. I like the lids from rattle cans. less mess that way, and it limits the fire potential. remove the bowl, it might take some effort and will probably need its own gasket replaced as well.

Put a new O-ring on the transfer tube end and slide it back into the bowl where it came from. Between dissassembly and reassembly, you should clean all the parts and remove old gaskets that ripped or have torn. When you are tightening the screws that hold the bowl on, do so in a radial pattern, and dont tighten one before the others are seated. In other words, dont crank one down before the others are all the way in. Leave them slightly lose untill all are finger tight. It doesnt take much to hold the bowl on, so dont overtighten them.

Where do you get new gaskets? Well the only place I can find the ones I need are in carb rebuild kits. It looks like your carb could use some attention anyway. The only tough part is not over tightening things and getting the float level right.

caddyman

Thanks for the help so far. I have a matching spare carb that came with the car. I could use it for parts or rebuild it. I'm a little nervous as it was already partially torn apart but came with a rebuild kit. I am assuming that the previous owner was going to rebuild it but had not finished yet.

As for the exhaust, I'm at a loss. When I cleaned the headers they looked pretty flat and I thought the Percy xxx gaskets would make up for any leaks. Do you think I could double up on them?

Thanks again!

Tom

Soaring

That usually doesn't result in a permanent fix. Either get you current headers flat (not warped) or get a new set of headers.

caddyman

Any thoughts how I can flatten the headers whithout taking them to a shop? Do I flatten each port individually or does the whole header nead to match? I should say that each port has an individual port seal so can I just check the flatness of each or do I need to worry more about the entire length of the header? With regular exhaust manifolds one would just have them planed but I'm not familiar with headers. Thanks again for the help.

Tom

fast66

To flatten the headers sealing faces, you will need to remove them from the car. Then using a straight edge (like a steel ruler) check for high or low spots. you will then need to carefully file the high spots down, so that the entire surface is nice and flat. You need to be carefull when filing that you dont 'round off' the surface in the up-down direction. the entire surface needs to be as flat as you can possibly make it. People have also been known to use 'engineers blue' to highlight the high/low spots. It is even a good idea to do this on brand new headers, as they can be warped from new. (I failed to do this on mine!)

69mach1377

Honestly, just recently I used a belt sander and straight edge to make mine seal. Make sure it doesn't move in the vice when sanding. I also used the steel core type gasket and made damn sure the head surface was perfectly clean with no old gasket material left over. My original welds cracked so they rewelded from the outside, no more leaks.

caddyman

Ok, so I got things torn down and here is what I found out. Part of it may be design error some of it is my error. The gaskets when aligned with the bolt holes only sealed over the exhaust port bottom by about 1/4". The port holes in the gasket were too long leaving only a small amount of sealing surface against the head. However they were longer than the port seal on the headders or only overlapped by 1/32". Therefore they blew out of the bottom almost immediately. I should have looked this over first... another duh moment for me. I shouldn't be so hasty, but damn if I don't wanna drive it!

Question 1

Several of you have mentioned just using stock manifold gaskets, the perforated metal kind. Is this my best option, or what about copper gaskets if I can find them? Are they worth it? Both of the auto stores I called that were open this late in the eavning would have to order the stock gaskets anyways.

Question 2

If the gaskets I bought were slightly a design error, should I bother calling Percy's or Jegs to get some $ back?

Thanks for all the help getting my 71 rolling agian everyone!

P.S. About the carb problem, I had a spare 1850 holley laying around with some gaskets and fixed the leak in a lunch break! I love it when things go like that.

Tom