Author Topic: racing my 66 Comet  (Read 12460 times)

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6667fan

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Re: racing my 66 Comet
« Reply #45 on: August 08, 2022, 09:44:23 PM »
Are those A/F numbers through the traps? What did the 1050 show for A/F at the same rpm you are noting for the 780?
Where is your A/F sensor located?

Is  the “pull” on the 780 so strong that it is causing the carb to dump more fuel than it can use?

At least you know the combo likes the 1050
JB


67 Fairlane 500
482 cid 636/619.
Tunnel Wedge, Survival EMC CNC heads, Lykins Custom Hydraulic Roller, Ram adjustable clutch, Jerico 4-spd, Strange third member with Detroit Locker, 35 spline axles, 4.86
10.68@125.71 1.56 60’

Jim Comet

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Re: racing my 66 Comet
« Reply #46 on: August 09, 2022, 06:38:05 AM »
The A/F numbers are from the high gear shift through the traps. The 1050 showed high 12's through the same range. I initially made 4 passes with the 1050, switched to the 780 for 2 passes before it started to sprinkle. When the rain stopped and they dried the track, Wanting to see if it was carb, weather or engine causing the slow down I switched back to the 1050 and made 2 more passes after trying the 780 and the car was right back running 10's. My A/F sensor is mounted in my RH header, just after the merge area. I do have an 18 inch extension behind it so hopefully there is no reversion messing with the sensor.

6667fan

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Re: racing my 66 Comet
« Reply #47 on: August 09, 2022, 08:02:21 AM »
Well, I guess you could experiment with the 780. Different, tunable metering blocks might net different results but it’s not like you need to with the performance the 1050 is giving.

The header extensions are a tuning device? Just curious if any passes were made without them. I realize the reversion factor could go up and skew your sensor numbers.
JB


67 Fairlane 500
482 cid 636/619.
Tunnel Wedge, Survival EMC CNC heads, Lykins Custom Hydraulic Roller, Ram adjustable clutch, Jerico 4-spd, Strange third member with Detroit Locker, 35 spline axles, 4.86
10.68@125.71 1.56 60’

Stangman

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Re: racing my 66 Comet
« Reply #48 on: August 09, 2022, 07:53:51 PM »
If the 1050 is in the high 12s then tune that one to low 13s and see where you are. Im a fan of 780s but that ones not right for some reason. leave it be for now
and play with the 1050.

Jim Comet

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Re: racing my 66 Comet
« Reply #49 on: August 09, 2022, 08:42:12 PM »
My main deal is that the exact same 780 ran 10.7's last year and this year with no changes other than the exhaust collectors it is has slowed to 11.6's. Almost like the secondary's aren't opening plus it is super rich. I will wait until the next test day, when there is no rain in the forecast to retry the 780. My next race is Labor day weekend to run both brackets and index class so we will see what happens running just the 1050 that weekend. Jim
« Last Edit: August 09, 2022, 08:45:34 PM by Jim Comet »

6667fan

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Re: racing my 66 Comet
« Reply #50 on: August 13, 2022, 10:58:23 AM »
Jim, whenever I doubt that the secondaries aren’t opening I put a paper clip under the pod onto the actuating rod. If the rod goes up,(indicating at least that there is movement of the diaphragm), the clip will be pushed down lower onto the rod by coming in contact with the underside of the pod body. The clip should end up close to the throttle shaft end of the rod.
This test has to be done under a load of course.
JB


67 Fairlane 500
482 cid 636/619.
Tunnel Wedge, Survival EMC CNC heads, Lykins Custom Hydraulic Roller, Ram adjustable clutch, Jerico 4-spd, Strange third member with Detroit Locker, 35 spline axles, 4.86
10.68@125.71 1.56 60’