they are not heat treared and wear quickly
good weights are hard to a file test.
good weights are hard to a file test.
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they are not heat treared and wear quickly
good weights are hard to a file test.Comment
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Re: Duke - advance curve plot
Duke, my car is a 67 300HP car, with full manifold to the vac. can. From looking at the data, it looks like my dist vac can is full on at about 12"Hg. In reading the many informative posts in this and "the other" forum, it seems that most discuss making sure your can is full on at about 2" Hg below the idle manifold vacuum so that you can be sure it is ON and steady. Since my idle vacuum is about 18", and the can is full on at 12", then is that too far apart? Should I switch to a can that doesn't go full on till 16"??Comment
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Re: Duke - advance curve plot
Duke, my car is a 67 300HP car, with full manifold to the vac. can. From looking at the data, it looks like my dist vac can is full on at about 12"Hg. In reading the many informative posts in this and "the other" forum, it seems that most discuss making sure your can is full on at about 2" Hg below the idle manifold vacuum so that you can be sure it is ON and steady. Since my idle vacuum is about 18", and the can is full on at 12", then is that too far apart? Should I switch to a can that doesn't go full on till 16"??Comment
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Re: Duke - advance curve plot
No. The vacuum can should provide full advance at NO LESS than 2" LESS than typical manifold vacuum. So if it's over 2", that's okay as long as the vacuum can is not so aggressive so as to cause part throttle detonation.
The early 250 and 300 HP engines have a 15.5" can. Later 300 HP engines have a 12" can, and if you check your AMA Specs or CSM you will find that your '67 300 HP has a 12" can.
I consider a 16" can to be optional if the engine exhibits light throttle detonation. Likewise the L-79 OE can is 8", and they generate 14-15" idle vacuum, so the 12" can can be considered optional if the engine exhibits part throttle detonation. The 12" can is also suitable for all big blocks including SHP since they idle at 14".
DukeComment
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Re: Duke - advance curve plot
No. The vacuum can should provide full advance at NO LESS than 2" LESS than typical manifold vacuum. So if it's over 2", that's okay as long as the vacuum can is not so aggressive so as to cause part throttle detonation.
The early 250 and 300 HP engines have a 15.5" can. Later 300 HP engines have a 12" can, and if you check your AMA Specs or CSM you will find that your '67 300 HP has a 12" can.
I consider a 16" can to be optional if the engine exhibits light throttle detonation. Likewise the L-79 OE can is 8", and they generate 14-15" idle vacuum, so the 12" can can be considered optional if the engine exhibits part throttle detonation. The 12" can is also suitable for all big blocks including SHP since they idle at 14".
DukeComment
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Re: Duke - advance curve plot
I noticed yesterday on my vac can that it is marked "B20".Comment
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Re: Duke - advance curve plot
0@6", 16@12" This is OE spec for later 300 HP engines. Early versions use a 16" can. (See your AMA specs or CSM for detailed ignition map info for your particular engine.)
The 12" can will also work okay for L-79s, which originally had a 8" can. The 12" can can be a "fix" to part throttle detonation problems, and the 16" can is a "fix" to later 300 HP engines with part throttle detonation. If these engines get into part throttle detonation with and aggressive centrifugal curve, backing off on the vacuum can is a possible solution, as long as the can provides full vacuum advance at not less that 2" less than typical idle vacuum.
The 12" can is also a good choice for all BBs including SHP. All mechanical lifter SBs should use the 8" can.
DukeComment
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