1962 300H.P. intake manifold gaskets

[Duke W.]

Re: 1962 300H.P. intake manifold gaskets

I don't understand your test setups. The fuel pressure gage should be teed into the fuel line from the fuel pump outlet to the carburetor inlet downstream of any filter.

The '63 327/300 has a steel pipe from the pump outlet to a GF-90 filter mounted in a bracket that is held by an inlet manifold bolt. From the filter outlet there is a short steel pipe to the AFB fuel inlet. Is the OE '62 327/300 the same? Is your configuration OE or something else?

Duke

[Ken A.]

Re: 1962 300H.P. intake manifold gaskets

If the fuel supply hoses are over 2 years old, they could be collapsing due to the heat. Ethanol would be the culprit.

[Kenneth F.]

Re: 1962 300H.P. intake manifold gaskets

I have not blocked the heat passage, but this will be my next job. The pressure guage is T'd between the filter and the carburetor. I moved the guage into the end of the hose just to see if the electric pump was still building pressure after I read 0 psi when the guage was T'd, and the engine was hot. I had about 3 gallons in the tank. When I finished the testing, I let the electric pump run to empty the tank into a storage container. It emptied the tank in strong bursts through the new fuel hoses. I noticed where I had the clamps on the new hoses, that the rubber was already starting to break down. I really appreciate the input. I will let you know the outcome after I work on the heat slot. Ken

[Timothy B.]

Re: 1962 300H.P. intake manifold gaskets

Here is a picture of the hot slot on my car, I don't believe this has anything to do with the fuel pressure problem.

Be careful driving these freeze plugs so that they go in square and cover/tape the plenum so nothing gets dropped inside the engine.

[Kenneth F.]

Re: 1962 300H.P. intake manifold gaskets

Timothy, The great photos are helpful. Do you happen to remember the diameter of the plugs you used? I am think of using high temp Locktite. I am looking forward to doing this job when I return home. Thank you, Ken

[Timothy B.]

Re: 1962 300H.P. intake manifold gaskets

I think the size is 7/16 but not 100% on that. Get a bolt and use it for size then go to a machine shop and get the plugs.

You may need to get some plugs a few thousands larger so they don't fall into the holes, this is very important because if they fall into the holes you will probably need to remove the intake and maybe the heads to find them. BE CAREFUL

You can also tap the holes and use allen head plugs, there should be some info in the archives about that method.

[Kenneth F.]

Re: 1962 300H.P. intake manifold gaskets

I blocked the heat slot with 29/64" plugs. I went on a 2 hour road test and monitored the heat with an IFR about every 1/2 hour. The car ran well, with one slight hint of a miss. The heat progression was greatly slowed, but the temp. of the carburetor base and the float bowls eventually ended up where it read, before installing the plugs. The fuel pressure was 0 at the end of the 2 hours. I slowly unscrewed the fuel pressure guage, and a lot of vapor came out with liquid. I would think at this point, I should block the heat at the manifold side gaskets. It would be interesting to hear from those who have blocked the exhaust or restricted, one or both sides. I had been using the lowest octane fuel. Today I had about 5 gallons low octane, and 5 gallons of the middle octane fuel. I appreciate the feedback. This has been interesting. Ken

[Timothy B.]

Re: 1962 300H.P. intake manifold gaskets

Kenneth,

If you have a cast iron intake manifold the most I would do is wire the heat riser valve open. This will reduce the heat in the plenum but I don't think that has anything to do with your fuel problem.

Does the car have headers or is the fuel line close to the exhaust causing the fuel to vapor lock. Fuel vapor will not pump, could that be what you are experiencing.

[Kenneth F.]

Re: 1962 300H.P. intake manifold gaskets

Hi Timothy, I have a new original type exhaust system with oval mufflers. When I had the mechanical fuel pump bypassed with an electric fuel pump, I used a long fuel hose to stay away from the exhaust, but the fuel pressure still dropped to zero, and when I ran the electric fuel pump into a container, I did not notice any vapor in the fuel stream, The heat riser is wired open. The distributor was checked by Don Baker, initial timing is 10 degs, the Direct Fit radiator is new, and the engine temperature is about 185 degs. The 327 is .040 over with about 1K miles. The heads were done about 20 years ago and had hardened seats installed before I knew better. I am probably going to block the exhaust with a new intake manifold gasket. I do not have another idea at this time. I do appreciate the feedback. Ken

[Joe C.]

Re: 1962 300H.P. intake manifold gaskets

Did you check the fuel sock in the tank as was suggested earlier? Either the sock is restricted, there is something floating around in the tank, or the tank to pump line is restricted. You should also check that your vented gas cap is working properly. It's acting like the problem is on the suction side of the pump.

The fuel pump has 2 check valves inside...............one on the suction side and the other on the pressure side. If either of them becomes dislodged, or defective, then the pump will still supply about 3-4 pounds at idle, but will drop off to almost zero under a load.

I don't think the problem is temp related. It might be coincidental. Check the entire suction side first, and if it's OK, then R & R the pump.

You should read my Restorer article in the Summer 2010 issue.

[Kenneth F.]

Re: 1962 300H.P. intake manifold gaskets

Hi Joe, One of my tests was to bypass the stock fuel pump with an electric pump and extra hose to route away from the exhaust. I used all of the stock suction fuel line, including the suction hose that threads into the pump. The pressure dropped to zero after the engine came up to operating temperature, just as it does like clockwork every time. After I was done with the electric pump, I let it run to empty the fuel tank. It pumped a quart in 30 seconds, and continued to pump the remaining 3 gallons in the same manner. I really do not think I am lacking for fuel to the pump. I then installed plugs in the intake manifold just under the carburetor, to block the heat slot. Now it takes much longer for the fuel pressure to drop. Two days ago after a 2 hour road test, I unscrewed the pressure guage that is mounted in a tee , before the sediment bowl. A fair amount of vapor leaked along with fuel. I screwed the guage back in. It read zero. Yesterday morning, the guage read 4 pounds with a cold engine. I will check your Summer 2010 article. I appreciate your help. Thanks, Ken

[Kenneth F.]

Re: 1962 300H.P. intake manifold gaskets

Joe, P.S. The 4 pounds I read yesterday was without starting the engine. Ken

[Kenneth F.]

Re: 1962 300H.P. intake manifold gaskets

Joe, P.S. The 4 pounds reading was with the engine not running. I had not started it after screwing the guage back in the previous day. Ken

[Kenneth F.]

Re: 1962 300H.P. intake manifold gaskets

I did not think that I could have been dealing with 2 separate problems. Installing plugs in the heat slot was an improvement on the performance of the engine. The carburetor flange does still get up to 170 degs after an hour or so and I might end up restricting or blocking exhaust at the manifold mounting gaskets. I removed the internal parts of the heat riser. The oil filled fuel pressure gauge was a separate problem. My last testing of the car involved a small container of fuel for supply, and the electric fuel pump outlet plumbed to the carburetor. As the temperature of the engine up, the pressure again dropped to zero. I have removed the gauge before and never noticed a spray of fuel indicating pressure, but this time I did see pressurized fuel. I plugged the pressure side of the hose from the electric pump with the gauge to see a read of 5 pounds. I applied heat to the gauge with a heat gun. By the time the gauge got to about 130 degs, the pressure reading was zero. I removed the plug in the gauge housing and bled off a few drops of the oil. I put the gauge back on the car, with the rubber plug at the top and had to release oil a few more times to maintain a solid read of 5-6 pounds. What an experience. Ken

[Will B.]

Re: 1962 300H.P. intake manifold gaskets

Did you ever resolve this fuel problem? Was it 'winter' fuel with a vapor pressure problem?