I am still trying to figure out if there is something wrong with my torque converter. I have a 350TH with a B&M Holeshot 2200 stall speed converter. My gear ratio in the rear is 3:70 and I am running 31" tall tires. While traveling down the road at 60 MPH the tach indicates I am turning 3400 RPM. This seems to be too high. Its almost like the car needs to shift. Anybody else experiencing this type of problem or any suggestions to remedy?

Here's a place you can fool around with your #'s and see what it should be. http://www.project33.com/tiresize.cfm
Here are the answers for your numbers plugged in for 2nd gear and 3rd gear. Do you feel it shift from 1st to 2nd to 3rd??

bob




Answer: It looks like you'll be doing about 3657 RPM in 2nd gear at 60 mph with this gear and tire combination.


Answer: It looks like you'll be doing about 3657 RPM in 2nd gear at 60 mph with this gear and tire combination.



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Bob the Builder-We can fix it !!

Calculates out to a about 30% converter slippage in 3rd gear at 60 MPH.
You should NOT have this much slippage.
Converters are a "you get what you pay for" type of part.

Buy Coan, Continental, dynamic or ATI.
ATI 10" Treemaster being my number one choice for that application, When you call ask for Charlie Plot, and tell him the application/specifics and fallow his recommendation.
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67' Camaro

One thing to consider is the use of a 7004R trans with your 3:70 rear gear....The first and second gears in the 700 are going to give you the equivilent of close to a 5:00 rear gear and the OD will help the cruising especially with a lock up converter, the slippige will be nil where the "holeshot" type converter will always be slipping running down the road and will really warm up your trans fluid..
Probably the best way to find out is to get a pit pass at the next race and ask questions about converters..drivers can answer your questions without having to worry about giving away any of their "secrets"...lol

Any kind of higher rated converter is really a trade off and depends on HP, weight, and a few other parameters..GL+
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Fred P.

In my previous street rod, with 3.36:1 gears, 350 TH, 31 inch tall rear tires, and a 2500 converter, I was turning 2850 rpm at 65 mph. Your calculations sound about right. That is why I am building my present car with a 700R4.
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Lynn
'32 3W

I have abs of steel--they're just covered with a layer of foam padding.

The latest Streetrodder had an article on torque convertors.
I figured your RMP's at 2400.
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Mike J
Unchartered DSRA Member
If it ain't broke, fix it anyway...

My "old school" math figures out to be 84.4 MPH at 3400 RPM, Dave
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Life's too short to drive an ughly car!
Massachusetts Safety Inspecter for KKOA
www.geocities.com/stupidbaker57/custom_green

Dave, don't know about your "old school math" but mine never included "slippage" either!! lol 'Course, my math and anything pertaining to numbers back then had built in slippage which may help to explain my "D's"...My luck at adding and subtracting the letters of the alphabet where even worse!!!

I have the idea that if one uses a higher RPM stall converter, most of them are the ones keeping the trans fluid cooling companies in business...

The new desk top dyno program has a function for stall converters I understand which is something else fueling my fire for one..
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Fred P.

I always thought that any converter worked the same at high rpm, and that they would "slip" up to the point of "grab" when you took off from a stop. Dave
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Life's too short to drive an ughly car!
Massachusetts Safety Inspecter for KKOA
www.geocities.com/stupidbaker57/custom_green

Only a lock up converter will not slip, Dave. It is not unusual for a 2200-2500 stall converter to slip 400-500 rpm going down the road. That is why you need a good tranny cooler with a stall converter. They make more heat.
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Lynn
'32 3W

I have abs of steel--they're just covered with a layer of foam padding.