Kinda wierd issue..... car picking up the worse the air is

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B3422w5

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My 69 Dart street strip car made its second outing of the season this weekend. First really, initial outingwas rain shortened, three passes total
Anyhow car has been about a tenth and a half off from where it was last season. I am factoring in conditions when i say that. Little bit everywhere on the slip.
First outing three passes
Nine passes this weekend.
Every single pass the car has made it has continued to pick up. Yesterday we got only one time trial. About 10 in the morning. I add three on it as first round was 1 in the afternoon. I always drive the car around a good bit to warm it up, and the car always enters the water box at the sane temp.
So first round, much hotter, instead of falling off a little car picks up 3 out of nowhere. I got beat.....
Bought back in. Now its 4:30 in the afternoon. Its hot, we are seeking shade.
I put 2 extra on it from the earlier pass, figuring the car has to back up in the heat.
Nope picks up two this time. Got me stumped. So a 9 flat car beats me. Sucky day for the driver. Not gonna lift on a 150mph car coming at me.
Put new plugs in this morning. Hard to tell much but it definitely a little fat. I drive the car. Need to pop in one new plug and make a pass and check
Plan to pull a couple jets out of the front and back
So now, after a dozen passes on it, car is probably about half a tenth from normal.
Have no clue why its picking up in worse air, and why it is taking some passes to come around.
Last year on a typical summer day car wouldn't move around more than one, maybe two, racing it from morning to late night.
Any ideas?
 
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That's usually only two things. You are lean and as the weather goes away, you pick up power.

Or, as the weather goes away, you are losing power and the car hooks better and goes quicker. It's a lot easier if you are looking at time slips. I spend more time looking at MPH at first. Then ET second.
 
All twelve passes the car has went 1.57 60 foot exactly.
Minitubbed low 11 sec car with ladder bars and radials. Stock 360 shortblock with mild eddies and healthy Howards solid cam
It always hooks.
Incrementals are little soft everywhere. Mph started off nearly 3 off, its now gotten to about 1 mph from the norm. Slower to 330, 660, 1000 and 1320
Its almost( dumb thought i know) that ring seal has gotten better as i beat on it???
 
SpeedThrills said:
Change anything since last year? (Over the winter?)
Click to expand...

No.
Although between the first outing and second outing i did swap to a 4.30 gear from a 4.10.
Havent seen where that has played a factor. As i said, the 60 foot has been identical all 12 passes( same with both gears)
 
What about plug readings? Always good idea to do have a baseline leak down or even a basic compression test shortly after break in, but rings seal is always worse proportionate to wear. But, check your timing. If its off from where you set it you may be getting a little timing chain stretch, which would have the effect of retarding timing.
 
B3422w5 said:
No.
Although between the first outing and second outing i did swap to a 4.30 gear from a 4.10.
Havent seen where that has played a factor. As i said, the 60 foot has been identical all 12 passes( same with both gears)
Click to expand...
Well thinking about it more, I guess going progressively quicker wouldn't be affected by any changes. Comments about lean don't add up either. Would've been lean last year, too. I can understand something causing progressive slow down, but quicker? Thats a head scratcher.
 
SpeedThrills said:
Well thinking about it more, I guess going progressively quicker wouldn't be affected by any changes. Comments about lean don't add up either. Would've been lean last year, too. I can understand something causing progressive slow down, but quicker? Thats a head scratcher.
Click to expand...

Exactly

Got to thinking..... i had the car professionally rewired over the winter. Everything spins quicker, added new MSD box, starts now like its 16 volt
Guess i should check fuel pressure, etc. t
 
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