Re: 67 L71 Carburetor temparture
Assuming it has an OE equivalent cam, converting from ported to full time vacuum advance requires replacing the 15" OE 201 15 VAC with a 12" B26. The easiest way to implement is to buy a couple of feet of 1/8" vacuum tubing and a Tee. Remove the existing hose from the choke vacuum break and make a new harness with the tubing and tee to route vacuum to both the choke vacuum break and VAC.
The above can be easily "undone" for judging. Full time vacuum advance can also be implemented by plugging a hole in the carb base plate and drilling another hole to get manifold vacuum directly at the carb vacuum advance port. This mod is invisible other than the non-OE VAC.
Normal L-71 idle behavior with an OE equivalent cam is 900 @ 14". Once implemented you will also need to adjust idle speed/mixture and reset fast idle speed as the additional idle advance from full time vacuum advance will increase both. Low speed driving in hot weather will reduce engine temperatures and the tendency to diesel will go away because the additional idle advance cools down the combustion chamber surfaces and EGT and eliminates the pre-ignition that caused the dieseling.
Duke
Assuming it has an OE equivalent cam, converting from ported to full time vacuum advance requires replacing the 15" OE 201 15 VAC with a 12" B26. The easiest way to implement is to buy a couple of feet of 1/8" vacuum tubing and a Tee. Remove the existing hose from the choke vacuum break and make a new harness with the tubing and tee to route vacuum to both the choke vacuum break and VAC.
The above can be easily "undone" for judging. Full time vacuum advance can also be implemented by plugging a hole in the carb base plate and drilling another hole to get manifold vacuum directly at the carb vacuum advance port. This mod is invisible other than the non-OE VAC.
Normal L-71 idle behavior with an OE equivalent cam is 900 @ 14". Once implemented you will also need to adjust idle speed/mixture and reset fast idle speed as the additional idle advance from full time vacuum advance will increase both. Low speed driving in hot weather will reduce engine temperatures and the tendency to diesel will go away because the additional idle advance cools down the combustion chamber surfaces and EGT and eliminates the pre-ignition that caused the dieseling.
Duke
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