Meep-Meep
дворянин
Well, the six pack was an abysmal failure. It started off strong then a few feet into the run it fell flat on its face. Back to the drawing board.
As a side note I did get a chance to weigh the car and it was heavier than I expected. 3735 without me and 3905 going down the track with the spare, the jack, lug wrench and Mrs. Frenzel’s broom and dust pan in the trunk. This at least makes me feel better when I take my best run so far (12.80 @ 107) and factor in the HP numbers. Previously I figured on 3700 as raced weight.
Yesterday I couldn’t get out of the 13’s (13.40’s) and trap speed was 105, lowest so far. I ran with 4.10’s, which were better suited for my combo, and RPM through the lights was about 6100. I think 3.91’s will be better yet and should drop the RPM by another 300 or so. The published top end for that cam (MoPar .455" / 272) is 5800. Best MPH (109) was with the M1 intake or the factory iron, 3.55’s and street tires. Oil pressure through the lights at 6000 RPM was a solid 70 PSI and I got a little lifter pump up at 6300 – acted like a miss – but it was very subtle. Otherwise smooth sailing all the way up to 6K.
My thoughts are the outboard carbs are coming in too quick even though I put the black springs in the vacuum pods. On the last run I even put an extra spring on the linkage and it still fell on its face. Since I can’t see the carbs work the issue is a guess at this point.
Another theory is the fuel is sloshing in the bowl during acceleration and spilling into the outboard carbs because the bowl vent is not very tall, however, no black smoke was reported.
Or, someone blocked the secondary vacuum bleed, assuming it has one. Vac secondary 4 BBL Holleys have a passage that bleeds off the vacuum signal to the secondary diaphragm to soften their actuation and if this is blocked they will respond like a double pumper. I got these carbs used and did find the vacuum pod springs were the lightest ones, and cut down at that, so tampering is a possibility. Also, the 6 BBL carbs have huge diaphragms so I’m sure the Holley spring guide is not accurate in this case.
The reduced trap speed indicates it's down on power, and I think it's too rich for the following reasons: With the 750 AFB it would ping on hard acceleration but not with the 6 BBL. With the AFB it wouldn't idle cold without a choke but it does with the 6 BBL. No question the AFB so far is king on this engine combo but I do have hope the 6 BBL will outperform it with tuning.
Need to do some research for sure, but I can say with some certainty that what feels pretty good on the street is about as good as a promise made by a politician.
As a side note I did get a chance to weigh the car and it was heavier than I expected. 3735 without me and 3905 going down the track with the spare, the jack, lug wrench and Mrs. Frenzel’s broom and dust pan in the trunk. This at least makes me feel better when I take my best run so far (12.80 @ 107) and factor in the HP numbers. Previously I figured on 3700 as raced weight.
Yesterday I couldn’t get out of the 13’s (13.40’s) and trap speed was 105, lowest so far. I ran with 4.10’s, which were better suited for my combo, and RPM through the lights was about 6100. I think 3.91’s will be better yet and should drop the RPM by another 300 or so. The published top end for that cam (MoPar .455" / 272) is 5800. Best MPH (109) was with the M1 intake or the factory iron, 3.55’s and street tires. Oil pressure through the lights at 6000 RPM was a solid 70 PSI and I got a little lifter pump up at 6300 – acted like a miss – but it was very subtle. Otherwise smooth sailing all the way up to 6K.
My thoughts are the outboard carbs are coming in too quick even though I put the black springs in the vacuum pods. On the last run I even put an extra spring on the linkage and it still fell on its face. Since I can’t see the carbs work the issue is a guess at this point.
Another theory is the fuel is sloshing in the bowl during acceleration and spilling into the outboard carbs because the bowl vent is not very tall, however, no black smoke was reported.
Or, someone blocked the secondary vacuum bleed, assuming it has one. Vac secondary 4 BBL Holleys have a passage that bleeds off the vacuum signal to the secondary diaphragm to soften their actuation and if this is blocked they will respond like a double pumper. I got these carbs used and did find the vacuum pod springs were the lightest ones, and cut down at that, so tampering is a possibility. Also, the 6 BBL carbs have huge diaphragms so I’m sure the Holley spring guide is not accurate in this case.
The reduced trap speed indicates it's down on power, and I think it's too rich for the following reasons: With the 750 AFB it would ping on hard acceleration but not with the 6 BBL. With the AFB it wouldn't idle cold without a choke but it does with the 6 BBL. No question the AFB so far is king on this engine combo but I do have hope the 6 BBL will outperform it with tuning.
Need to do some research for sure, but I can say with some certainty that what feels pretty good on the street is about as good as a promise made by a politician.
