Acceptable Converter Slippage

jimmyray · Jan 2, 2009

My engine combo:
408 cast crank stroker from Hughes
9.6:1 compression
93 Octane gas
mild port/polish on Edelnbrock al perf heads, closed chamber, fresh valve job
M1 single plane airgap with gasket match (heads too)
Holley 750 DP with proform center section, jetted 74/84, 3.5 power valve
Comp roller .544/.541 236/242 110 centerline
FBO ignition, ditributor curved to 16 inital, 34 total @ 2900 rpm
Hooker comp 1 5/8" headers (dented bottoms on driver side, naturally) 3" collector
3" pipes into/out of welded Summit 3" mufflers into a-body tips
3000 stall TCI streetmaster
727 manual reverse
3.73 sure grip in a narrowed Dana
28 slicks, 27.8 inch street tires

My best time thus far with the combo on slicks is 12.26 @ 109.59

I noticed my last trip out that hitting the lights aroun 107-109 mph was tripping the shift light which is set for 5500 rpm, but my calculations are that it should be revving around 4900. What I've noticed thus far (see attachment below)

So, I think this is too much slippage. I plan on calling Dynamic convertor next week. The Converter I have was recently rebuilt by PTC, and they fixed several issues, but...

Thoughts?

jimmyray · Jan 11, 2009

advice bump

fishy68 · Jan 12, 2009

Jim that is a tremendous amount of slippage and I bet is costing you some e.t. and mph. I ran the numbers on my chart to see if yours correlate with mine and they are within 1% so your calculations are correct. I'm not a converter expert but when I was shopping around a couple yrs. back for a verter for mine everything I read lead me to believe a cheap piece of crap converter only slipped about 9-10% and a real good one as low as 3%.

I also have 3.73 gears but my tires are only 27" tall and at 60mph mines only turning 2900 rpm so yours with the taller tires should definetly be spinning less.

If your positive your readings are right (actual speed and rpm's) then there is definetly a problem.

jimmyray · Jan 13, 2009

Thanks, Fishy. I suspect the same thing. I have tried to catch Dynamic on the phone, but am always calling at the wrong time.

65 Dartman · Jan 13, 2009

jimmyray said:
Thanks, Fishy. I suspect the same thing. I have tried to catch Dynamic on the phone, but am always calling at the wrong time.

Try them mid to late afternoon. They is good people and will ask you a lot of questions about your build, chassis, exhaust, trans, etc. Then they will custom build you a convertor based on that info and what you're trying to accomplish.

SRT_DSTRHOLC · Jan 13, 2009

you sure you have 3.73s? just wondering. whats the website you used for those calculations?

SRT_DSTRHOLC · Jan 5, 2010

yes what website did you use for this? Im having converter problems as well

moper · Jan 6, 2010

That is extremely high. I dont want to see anything higher than 7-8%. I'm sure it's costing you ET and mph. I'm going to go out on a limb and say Dynamic will try to sell you a 9.5" tight convertor that feels normal but flashes to 3800. Because that's what everybody gets...lol. I would talk to them, but stress this is a street car that races, and you don't want it to flash higher than 2800 with a brake stall around 2500. I've had several Dynamics I've restalled because the customers say "drag race" and the product ends up way too loose for anything but. Or give Lenny at Ultimate Convertors a call. He just moved so I'd check for a post on Moparts that lists the new numbers.

Acceptable Converter Slippage

jimmyray

Well-Known Member

jimmyray

Well-Known Member

fishy68

Tyr Fryr's Inc.

jimmyray

Well-Known Member

65 Dartman

1 of None 65 Dart Sedan Delivery

SRT_DSTRHOLC

"There is never enough horsepower...."

SRT_DSTRHOLC

"There is never enough horsepower...."

moper

Well-Known Member

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