1962 300H.P. tuning
My 1962 300 H.P. runs rough and dies, if it is revved to about 3,000 rpm's and returned to idle. If I keep the engine at about 1,000 rpm's after running at the 3,000 RPM's it clears up after about 5 seconds of running rough. I was thinking about fuel pressure too high, so I installed a 0-15# pressure guage. The pressure was at 6#when the engine was cold. As the temperature came up, after about 15 minutes idling, the pressure slowly decreased to 0. I have the phenolic spacer and stainless plate under the AFB. The radiator is copper. I tried another AFB with the same results, and wiring the heat riser open did not help. The .040 over engine is low mileage. Performance is good at cruise speeds. Any comments would be appreciated.
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Re: 1962 300H.P. tuning
Kenneth,
When is the last time the engine was tuned up? Your problems could be many but you have to start with the simple things first. Fuel pressure cold or hot should not change so I am not sure what to make of the test on the pump. The max fuel pressure should be at idle and 6psi sounds OK for a mechanical fuel pump.
When is the last time someone took the carburetor apart and rechecked the float level and other adjustments to make sure all is set correct? How about the timing and dwell and making sure the distributor advance weights are clean and returning when the engine idles.
The 300hp engine should idle butter smooth at 600-650 rpm, when is the last time the emulsion screws were adjusted as they control idle fuel. You should be able to kill the engine at idle when the screws are turned in to seat which tells you they are controlling the idle fuel. If you can't kill the engine like this, the engine is getting fuel somewhere else, the stainless shield and spacer should not be a problem. -
Re: 1962 300H.P. tuning
Timothy and Michael, The float level was .245 and is now at 5/16" from the specs in the ST-12. The idle mixture screws are out 2 turns, and will kill the engine when seated. The advance weights spread and return when the shaft is rotated by hand. I have an Airtex 4V1005 vac unit. Timing without vac is 6degs at 600RPM, 15 degs at 1500RPM. With vac connected, timing is 20 deg, 18 in vac at 700RPM, and 37 degs with 20in vac. at 2500RPM. I am using a timing tape and a standard timing light w/o dial back. The fuel pump will fill a pint in 15 secs, with a cold engine. I have not done a fuel delivery check when the engine is hot. I have noticed that the fuel level in the glass bowl drops to about 1/4in when the engine is hot and an occasional bubble surfaces in the filter bowl. I put a mechanical temp guage bulb in the radiator fill tank. The reading was 190. The dash guage read 200degs. The ambient temps are about 70 degs on a warmer day in this area. Thank you both for your interest.Comment
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Re: 1962 300H.P. tuning
Timothy and Michael, I looked in the NCRS archives, thinking that excessive heat could be causing a fuel problem. I came up with two ideas, mostly from Duke William's information. The clutch fan on my car has the wound spring which was in the middle adjustment slot. Before, after shutting the engine down, I saw the fan continue to spin for several revolutions. I re- installed the spring tang in the position that gives the most fan performance, and now the fan stops immediately when the engine is turned off. The temp guage has dropped over 10*, and I could not get the engine to miss when revving to about 3500RPM and dropping to idle. The fuel pressure did eventually drop to 0, but it took about 1/2 hour of idling, more than twice the time as before, but the engine still would not miss with the rev test. I am ordering a new fan clutch, thinking mine might be weak. Another thread in the archives mentions that I probably have the wrong vacuum advance. The thread gives lots of information about vacuum advance units. My 300 H.P. should have a B22 can that advances 16* at 15". I presently have a B1 unit that has advance of 20* at 15." I do not know if this advance would affect cooling, but I will install the correct unit. Eventually, I will think about an aluminum radiator. DeWitts claims a 25* drop compared to copper. If you have any more suggestions, I am interested. Thanks, KenComment
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