I've owned a 1966 Coupe with a 327/300 hp motor for about two years. I have always had a problem with difficult starting. One of the first things I noticed about the car after I bought it was that the choke/fast idle mechanism had been removed and the choke plate was literally wired in the open position. I attributed this to the fact that the car was in Arizona and didn't need a choke. Since I live in Omaha, however, one of my first projects was to have an electric choke installed in the belief that this was going to remedy the hard starting situation I was encountering. However, even with the new choke (which by all appearances seems to be functioning properly), the only way to get the car to start and keep running is to pump the gas pedal at least three times (the accelerator pump seems to shoot two nice stream of gas) and then continue to pump it gingerly for about 60 seconds until the car warms up a bit. This requires a bit a care because if one gets too heavy footed it is easy to cause a backfire. I've read from various posts that this causes damage to the "power valves" (what do these do?), so I try to avoid this. Once the car has warmed up, it runs great. Acceleration is good, idle is good. It's just so touchy getting it started.
A little additional information may be relevant. Somewhere along the line the stock exhaust manifolds were replaced with headers. The carburetor is a Holley 4160, but I have determined that it is not the original "3367"(?) unit. However, I believe it has roughly the same cfm rating (600 v. 585?). The previous owners of the car thought the original camshaft may have been replaced with a more aggressive one, but they were sure. But again, both these guys thought the car had an L-79 engine instead of the L-75 (which is a whole other story).
Anyway, my theory is that if the car does in fact have a non-stock cam that it doesn't produce enough vacuum during the starting process to draw enough gas through the idle circuit to get the car started and keep it running. Is that a symptom of these types of camshafts? Can I offset this by "richening" the idle mixture. Also, would a vacuum leak be a likely culprit? BTW, I think the choke is set plenty high since the idle often never comes off the last step of the fast idle cam.
Two related questions: Is there a way to determine which camshaft is installed in the moter without pulling it? How does one determine if the vacuum secondaries are functioning properly? Again the car seems to run great, so they probably are fine, I'm just curious.
Any thoughts would be appreciated. Thanks in advance. This is a great resource.
A little additional information may be relevant. Somewhere along the line the stock exhaust manifolds were replaced with headers. The carburetor is a Holley 4160, but I have determined that it is not the original "3367"(?) unit. However, I believe it has roughly the same cfm rating (600 v. 585?). The previous owners of the car thought the original camshaft may have been replaced with a more aggressive one, but they were sure. But again, both these guys thought the car had an L-79 engine instead of the L-75 (which is a whole other story).
Anyway, my theory is that if the car does in fact have a non-stock cam that it doesn't produce enough vacuum during the starting process to draw enough gas through the idle circuit to get the car started and keep it running. Is that a symptom of these types of camshafts? Can I offset this by "richening" the idle mixture. Also, would a vacuum leak be a likely culprit? BTW, I think the choke is set plenty high since the idle often never comes off the last step of the fast idle cam.
Two related questions: Is there a way to determine which camshaft is installed in the moter without pulling it? How does one determine if the vacuum secondaries are functioning properly? Again the car seems to run great, so they probably are fine, I'm just curious.
Any thoughts would be appreciated. Thanks in advance. This is a great resource.
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