[chuckies76ta]

Originally Posted by Gach

There’s a few Myths on figuring out convertor stall. The most common not using line lock, pump up breaks real hard, then bring up the rpms until the breaks won’t hold the car anymore ( car starts moving) keep your eyes on tach see when that occurs. That’s you stall at that rpms. In other words if rpms are at say 3500 and it’s still holding car, but starts moving at 3800 rpms your stall is closer to 3800.

I’m sure you already know this but sometimes it helps to refresh one’s memory

Isn't this exactly what they say not to do?


Q: Should I do a stall test?
A: No!! ATI strongly recommends that you do not conduct stall tests. Stall tests break parts, and not just converter and transmission parts. Remember, you are at Wide-Open Throttle (full power) and maximum load. The pistons, pins, rods, and crank will really take a beating.

Many racers ask why it is okay to leave the line at Wide-Open throttle, but not okay to do stall tests. The difference is this – when at the starting line at wide-open throttle, you release the brake and the RPMs accelerate from that point. In the converter, the stator is locked via the clutch assembly (sprag) and goes from maximum load in a controlled constant reduction in force to zero load (free wheel) as the car accelerates. The hydraulic forces in the converter are directed in a smooth and efficient manner for maximum torque multiplication and flow for adequate cooling. When performing a stall test at wide-open throttle (or even with a rev limiter such as the MSD Two-Step), you lift off the throttle and the RPMs, now at 5,000 or 6,000, get jerked down to idle. The stator and clutch assembly goes from maximum load and torque multiplication to zero load in an instant. The clutch is unloaded rapidly and the hydraulic forces are instantly disrupted into unknown flow paths due to the rapid reduction in torque.

We have seen many converters damaged by this rapid unloading when a ring and pinion, planetary gear set, or input shaft fail. The rampant hydraulic pressure actually breaks the pump blades (fins) completely off the converter pump.

It is for this reason that converter manufacturers have for years warned against “snagging the slicks” coming out of the water as RPMs can go from 5,000 or 6,000 to an idle as the tires catch. Once again, damage can be done to the sprag assembly. Also remember that the converter builds up a tremendous amount of heat in a short period of time. By not running an engine after a stall test, all that heated fluid lays in the converter without having a chance to go through the cooler. Excessive heat eventually “fatigues” the metals in the converter.

So, just say no to stall tests. They damage parts. Use the transbrake ON THE STARTING LINE ONLY – not in the pits, not in the driveway, not for your burnouts – AT THE STARTING LINE ONLY! Your cost per run will diminish significantly.

[Gach]

That’s why I said Myths.. he’ll know once he gets to the track. He’s just excited to finally get the car back together.

[Cliff R]

Determining converter stall is easy with a TH350 or TH400.

Disconnect the kick-down cable on your TH350 (if used) or the downshift solenoid on the TH400.

With the engine, trans etc fully warmed up find a open stretch of road and take off gently. When the trans reached 3rd gear slow down to about 25-30 mph and coast for a second or two. Then, as quickly and hard as you can stick the accelerator to the floor and observe where the engine RPM's flash to, and hold. You are basically simulating a full throttle start with good traction on the starting line (most vehicles woln't roast the tires in the above scenario).

The 10" Continental converter behind my 455 flashes to right at 3500rpms and pretty lock solid from there to the shift point. I've seen cheap/loose converters flash to a given RPM with this test then as the engine gets into better power you can feel it "pushing" thru the converter and it may or may not eventually catch up and couple well. In other words they are poorly coupled above the observed stall speed.

The holding the brakes deal till the tires start to spin is NOT testing converter stall. The observed RPM for that type of test can be 1000rpm or even further below the observed stall speed seen on the high gear test........

[ta man]

My initial tests were just for street feel and to see if the convertor/gear combo felt good. Overall it feels tight for the street. Fully hooked at the track will be the real test.

[77 TRASHCAN]

Ernie,
I'm sure you are still using the low gear set in your TH350???

[ta man]

Originally Posted by 77 TRASHCAN

Ernie,
I'm sure you are still using the low gear set in your TH350???

Yes it was one of the few parts that wasn't replaced!

[ta man]

Finally! Track day tomorrow! Just need to double check both carbs are ready to go. If things go well I'm testing my Holley 950hp vs my ProSystems carb.
Heading to TMP in Cayuga, trying to get this monkey off my back. I've never ran a 10 second pass there yet in the last 3 years..almost did it into a massive headwind but the bad transmission has really held it back. Weather looks good and as long as the UCC convertor works like it feels on the street at the track I should have a good day.
Best et so far is a 10.76//125.64 with a 1.5471 60ft with 308 gears
Best mph has been a 10.88 /127.13 with a 1.6293 60 ft ProSystems Carb and bad trans with 308 gears

Goal is a 10.6 but ideally I would like to see a 10.5

[PAUL K]

Originally Posted by ta man

Finally! Track day tomorrow! Just need to double check both carbs are ready to go. If things go well I'm testing my Holley 950hp vs my ProSystems carb.
Heading to TMP in Cayuga, trying to get this monkey off my back. I've never ran a 10 second pass there yet in the last 3 years..almost did it into a massive headwind but the bad transmission has really held it back. Weather looks good and as long as the UCC convertor works like it feels on the street at the track I should have a good day.
Best et so far is a 10.76//125.64 with a 1.5471 60ft with 308 gears
Best mph has been a 10.88 /127.13 with a 1.6293 60 ft ProSystems Carb and bad trans with 308 gears

Goal is a 10.6 but ideally I would like to see a 10.5

Exciting! Good luck

[Gach]

Nice to finally get to make some shake down runs, good luck

[77 TRASHCAN]

A 10.5 it is!!!

[ta man]

Originally Posted by 77 TRASHCAN

A 10.5 it is!!!

I really think 10.5 is realistic...so the first real test is 373 gears and 3800? UCC convertor vs 308 gears 3200 Continental convertor. Last year running the 373's proved nothing because of the trans issues. But I did realize the gearing is well suited for the dragstrip and felt great and actually still leaving some rpm left at the stripe.
I used this same convertor a few years ago with the 308's and it didn't work out well..and may have actually started the issues with the transmission.
I'm hoping the convertor works well it will save R/R and swapping convertors and I can just tune and play this year.

[Gach]

Originally Posted by 77 TRASHCAN

A 10.5 it is!!!

Can’t wait for results !

[slowbird]

Good luck!

[ta man]

Originally Posted by Gach

Are you serious he went 10.50 ! Damn !

LOL its not Saturday yet!

[Gach]

LOL, I jump the gun, good luck can’t wait for results!

[ta man]

Originally Posted by Gach

LOL, I jump the gun, good luck can’t wait for results!

Bad redlight!

[Gach]

Originally Posted by 77 TRASHCAN

A 10.5 it is!!!

It’s his fault! LOL

[ta man]

Well good news and bad news.
I ran 10's finally at this track. Other than the first pass, 60 foot times were all quicker than the previous best. I also ran my quickest 1/8th mile ever.
1. 11.136/123.38 1.668 60ft (first pass soft launch) 7.161/101.12 1/8th (high mph??)
2. 10.904/123.45 1.544 60ft 6.930/99.29
3. 10.858/123.47 1.500 60ft 6.889/99.26
Swapped to ProSystems carb
4. 10.860/124.51 1.531 60 ft 6.912/99.60
5. 10.921/123.77 1.523 60 ft 6.951/99.14

Although the 60 foots are quicker..I feel the UCC is slipping too much at the top end..the car doesn't seem to pull and pegs the tach..by my calculations its over 10 percent slip I only have one log recorded from yesterday to look at. I feel I'm losing 2 to 3 mph and at least 2 tenths.

Plan is to swap the Continental again in place of the UCC to see if the back half of the track tightens up and the mph goes up and et drops.
I'm positive the Continental can 60 foot low 1.5's easily.

Overall it was a great day at the track..good track prep, not busy and good people.

[slowbird]

Making progress! I was wondering how the UCC converter would run, personal think the continental will be the one to stick with

[Gach]

Definitely a good day the numbers definitely look real good and promising. That sounds like allot of slippage. Interesting see what she does with the Continental. Bet it feels real good getting back out there