It sounds like it is really suffering during the first part of the run.

I have been involved with two SBF ford combos. Both were stroker motors.

One of them has a C4 behind it and the runs are counted very carefully as we ran across the same thing. At that power level the C4 requires a lot of maintenance. When the magic number of runs got close, it was time to pull the transmission and service it.

The other car has a Turbo 400 with a adapter kit. It just plain flat requires a lot less transmission service time and parts.

I can fully understand why the transmission guy is pulling his hair out with this combo.

The driveshaft is 1 to 1 with the engine at 6600 rpm, hopefully the op realizes this is what's wrong with it. Probably killing high gear in the transmission too.

It would be ok if the driveshaft were 1 to 1 with the engine at 7800 rpm, but then again the car would be going 153 mph, and this thread wouldn't exist.

quote:

Originally posted by Joe Burkleo:
At that power level the C4 requires a lot of maintenance.

Talk about what you know, not what you think you know.

This 3100 lb. footbrake launched car with a 351C under the hood backed by a C4 has been run for 40+ years

Typical passes now....

1.39 60 foot
6.57 @ 103
10.50 @ 124

with an 8" ATI converter and 4.86 rear gear, this C4 goes 750-1000 passes before a rebuild.

The best this car has run with the same carb, same manifold, same trans, same converter and same gear is....

1.34
104
10.17 @ 132.5

with a 366 "stroker" sbf under the hood.




First and foremost the car in question needs a lot more gear and a trans builder that knows what he is doing!

No need to squabble, I'm sure the Op has contacted Chance converters, Chance has confirmed the tech in this thread.

It's obvious to the experienced, the converter in play, wasn't built originally for a sbf.

Good luck Op, keep us posted on improvements in et, when you get the converter back.

chance has no business building a converter for this combo

it was built for the combo and unfortunately the customer mentioned possibly using nitrous occasionally.
At that point it went from an 8” converter to a 9” converter so I’m told and obviously too tight.

quote:

Originally posted by B.C.Malibu:
it was built for the combo and unfortunately the customer mentioned possibly using nitrous occasionally.
At that point it went from an 8” converter to a 9” converter so I’m told and obviously too tight.

Look on the bright side, at least you've now identified the solution.

I'm sure the driveshaft is 1 to 1 with the engine at the top of 2nd gear as well, causing a flare at the 2-3 shift, taking out 3rd gear in the transmission. I wouldn't rush to judgement on its builder, just yet, if I were you.

Good luck

No flare into high just a firm shift

quote:

Originally posted by B.C.Malibu:
it was built for the combo and unfortunately the customer mentioned possibly using nitrous occasionally.
At that point it went from an 8” converter to a 9” converter so I’m told and obviously too tight.

quote:

Originally posted by Mike Rietow:

Look on the bright side, at least you've now identified the solution.

I'm sure the driveshaft is 1 to 1 with the engine at the top of 2nd gear as well, could be causing a flare at the 2-3 shift, taking out 3rd gear in the transmission. I wouldn't rush to judgement on its builder, just yet, if I were you.

Good luck

quote:

Originally posted by B.C.Malibu:
No flare into high just a firm shift

I'd imagine so.

I wouldn't rush to judgement just yet.

quote:

Originally posted by B.C.Malibu:
it was built for the combo and unfortunately the customer mentioned possibly using nitrous occasionally.
At that point it went from an 8” converter to a 9” converter so I’m told and obviously too tight.

Ding, ding, ding!!
Never bull**** your converter builder.
There is no such thing as a NA / NOS converter.

quote:

Originally posted by B.C.Malibu: unfortunately the customer mentioned possibly using nitrous occasionally.
At that point it went from an 8” converter to a 9” converter so I’m told and obviously too tight.

so besides needing more gear and a competent trans builder it needs the right converter too.

How much slip does it need to et properly?
Fix the converter and it’s trapping over 7000 with its 3.90s.
This is a 351W based engine not a 302 with tiny mains.

quote:

Originally posted by B.C.Malibu:
How much slip does it need to et properly?
Fix the converter and it’s trapping over 7000 with its 3.90s.
This is a 351W based engine not a 302 with tiny mains.

It's not gonna pickup much mph most likely.

The incrementals will improve to put the car in the high 6.50's, to low .60's.

This is a copy and paste from the previous page.

This is based on the same math converter companies use.

Converter needs a stator & adjustment, this converter wasn't built for a n/a sbf. With a 3.90 gear, it should cross around 7300 rpm, converter slipping 10%.

Then you could put a 4.30 gear in it if you wanted, it'll then cross around 7600 slipping 6 - 7 %.

This engine is making 600hp, possibly a hair more.

i think the obvious solution is turn on all of the nitrous and dont turn it off

Ya really need a Opel 8" converter. Call Transmission Specialties, tell em you have a 3200 lb car 600-625hp. They'll send ya a fast Opel 8" spragless. Tell em you wanna cross 7300, ask for Justin. It'll be 5800-6000.

Part # 802 CRCXLS

Trans Specialties is only an hour away.
I don’t know why he didn’t purchase it there.

This is a 802 B-CRCXLS Transmission Specialties Opel 8"

You'll be hard pressed to find a quicker 60 ft anywhere in the world, 10 x 28 bias 3200 lb 23 sbc n/a. 1.27

2400 da

This message has been edited. Last edited by: Mike Rietow,

quote:

Originally posted by B.C.Malibu:
Trans Specialties is only an hour away.
I don’t know why he didn’t purchase it there.

Aston Pa., that's why I suggested them. Talk to Justin or Kenny.

They can adjust the 9" too. Probably won't be as fast as a 8" Opel 802 CRCXLS, though.