[ta man]

Here it is

Sent from my BBF100-2 using Tapatalk

[slowbird]

Originally Posted by ta man

Here it is

Sent from my BBF100-2 using Tapatalk

That's a hard one to read lol

[ta man]

Let me find it..

[Skip Fix]

10.96 @ 123.64?

About the same mph with that time my 78 ran in good air and light wheels.

[ta man]

Here are 2 slips the best with 308's Holley Carb and one with the Prosytems carb

[Cliff R]

Same diameter tires with the 3.08's and the 3.73's?

I don't log all the details into memory but weren't you running a tighter converter with the 3.08's?

From what I can see in the time slips whatever converter you are using now is flashing higher with improved 60' times but not locking up as well on the run as both ET and MPH are down a tad.

Typically a tenth improvement in 60' will net close to .25 on the runs with no other changes, but you've made multiple changes so that really doesn't apply.

What diameter tires are you currently using? What is the engine RPM's at the stripe?......

[ta man]

Originally Posted by Cliff R

Same diameter tires with the 3.08's and the 3.73's?

I don't log all the details into memory but weren't you running a tighter converter with the 3.08's?

From what I can see in the time slips whatever converter you are using now is flashing higher with improved 60' times but not locking up as well on the run as both ET and MPH are down a tad.

Typically a tenth improvement in 60' will net close to .25 on the runs with no other changes, but you've made multiple changes so that really doesn't apply.

What diameter tires are you currently using? What is the engine RPM's at the stripe?......

All new runs using the same 10 inch Continental as before with the 308's. Exactly the same et Pro's 28 inch. Crossing the stripe around 5800/5900 rpm..tach is off a little.
I agree normally a reduction in 60 foot should yield a reduction in the overall et.
But is this an effect of the engine using the torque with the 308's better then trying to spin the 373's? Or is something holding back the engine? It feels good at the stripe still pulling hard..but is something off?
Yesterday I retarded the cam 2 degrees to see if the engine will respond to the power curve shifted slightly up. I'm also going to be testing a 2 inch spacer instead of my 1 inch.
I also checked my compression again it is now 190 after the cam retard.

[Cliff R]

What changes if any were made to the engine?

Something isn't adding up if the tires are the same, same converter, and only a gear swap.

You've lost some MPH and top end charge so not benefitting from the improved 60' times.

From what I can see nearly 2mph.........a mystery at this point.......

[TCSGTO]

Could be all in the air/wind speed & direction/weather conditions? In this part of the country and in this ET range .2s or 2 mph change from week to week isn’t all that unusual.
Go back in the cool/dry fall air with a little tail wind and you may find that top end charge you’re looking for.

[ta man]

Originally Posted by Cliff R

What changes if any were made to the engine?

Something isn't adding up if the tires are the same, same converter, and only a gear swap.

You've lost some MPH and top end charge so not benefitting from the improved 60' times.

From what I can see nearly 2mph.........a mystery at this point.......

No real changes to the engine, other than swapped my Hooker Super Comps for Doug's.
I've thought the same thing seems like its missing 2 mph and 2 tenths..but is that just the result of the 373 gearing and it needs more topend.?
I'm double checking the fuel system this week for flow..but it always holds good on the gauge all the way thru the pass.

[ta man]

Originally Posted by TCSGTO

Could be all in the air/wind speed & direction/weather conditions? In this part of the country and in this ET range .2s or 2 mph change from week to week isn’t all that unusual.
Go back in the cool/dry fall air with a little tail wind and you may find that top end charge you’re looking for.

I agree..but just puzzling with the quicker 60 ft times why it hasn't ran quicker than the 308 gears in similar weather.

[Cliff R]

Are you calculated DA into the equation in addition to headwind, crosswind, etc?

Difficult to beleive that you lost 2mph and nearly 2 tenths with a different set of headers and a gear change.

The gear change did what it was supposed to, improved short times (quicker to roll-out). At the top end of the track you are still not past where the engine makes peak power so no reason MPH fell off that far.

It's almost like the converter lost some efficiency someplace. I only say that because I saw the same thing when testing a couple of prototype converters from Continental. I tested versions to 4500 stall speed, and although I picked up a LOT is 60' times, dragging things out against my 3.42 gears and 28" tall tires resulted in a couple of tenths worse ET and nearly 2mph slower on top end..........

[ta man]

This will make it easier to compare
10/13/2018 09/24/2022
308's 373's
60ft 1.5471 1.4829
330ft 4.4488 4.4360
1/8th 6.8910 6.9080
mph 101.06 99.36
1/4 10.761 10.8230
mph 125.64 124.60

Da's should be close

[AG]

Do you know your rpm across the stripe in each case? This is when a GoPro inside the car helps.

[Stan Weiss]

Originally Posted by ta man

This will make it easier to compare
10/13/2018 09/24/2022
308's 373's
60ft 1.5471 1.4829
330ft 4.4488 4.4360
1/8th 6.8910 6.9080
mph 101.06 99.36
1/4 10.761 10.8230
mph 125.64 124.60

Da's should be close

Looking at that. It looks to me like for some reason you are just down on HP. Other than 60' the 373's are slower everywhere going down the track. Even thought the 330' time is faster you were slower from 330 to 60 with the 373's

► 4.4488-1.5471
2.9017
► 4.4360-1.4829
2.9531

Stan

[slowbird]

Just curious, when were your valve springs last checked? How many miles on them?

[ta man]

Originally Posted by slowbird

Just curious, when were your valve springs last checked? How many miles on them?

Never checked..about 5 years old not a lot of miles on them.

[ta man]

Originally Posted by Stan Weiss

Looking at that. It looks to me like for some reason you are just down on HP. Other than 60' the 373's are slower everywhere going down the track. Even thought the 330' time is faster you were slower from 330 to 60 with the 373's

► 4.4488-1.5471
2.9017
► 4.4360-1.4829
2.9531

Stan

Seems that way..

[ta man]

Originally Posted by AG

Do you know your rpm across the stripe in each case? This is when a GoPro inside the car helps.

308's I was 5300 and with the 373's 5800/5900

[slowbird]

Originally Posted by ta man

Never checked..about 5 years old not a lot of miles on them.

I would check them