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Old 11-23-2010, 01:28 PM
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Rpms too high

I have a 350 with 3.73 and th350 lock up and after the head swap at crusing on the freeway my rpms are 3000 at 45
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Old 11-23-2010, 03:28 PM
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Quote:
Originally Posted by prettyboyced
I have a 350 with 3.73 and th350 lock up and after the head swap at crusing on the freeway my rpms are 3000 at 45
3000 at 45 mph you have to be in 2nd gear, I have calculated out the ratios and base on your numbers in 3rd gear you would have to be running 19" diameter tires. with a 32" tire in 3rd gear you would be at 76.6 mph and in 2nd gear you would be 50 mph. I run a ZZ502/502 with a 700R4 and at 71 mph and 32" tall tires I'm at 1950 rpm. It sound like your not shifting into 3rd gear. Try dropping down to 2nd and see if your rpm's change. These numbers are straight calculations and are very accurate. Seeing the only thing you changed were the heads maybe your tranny kickdown is preventing you to go into 3rd gear. The lock up converter and heads would not make a difference.

Last edited by Hotrod-Bikerman; 11-23-2010 at 03:38 PM.
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Old 11-23-2010, 05:11 PM
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Maybe the vacuum line for the modulator valve isn't connected, or the cable is too tight. This would keep it from shifting into 3rd gear.
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Old 11-23-2010, 05:11 PM
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no im in 3rd gear and at 75 its at 5000 i have 28 inch tires
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Old 11-23-2010, 05:16 PM
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Head change should not have caused this, Sounds to me like to have some trans/converter problems like getting ready to go, If you are sure it's in 3rd doing this and the modulator is working correct then has to be in the trans IMHO.


Cole
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Old 11-23-2010, 05:16 PM
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If you were actually in 3rd gear at 75 MPH with 3.73 gears and 28 inch tires you would be turning 3447 RPMs. In 2nd gear you would be turning 5175 RPMs.
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Old 11-23-2010, 05:18 PM
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Quote:
Originally Posted by big gear head
If you were actually in 3rd gear at 75 MPH with 3.73 gears and 28 inch tires you would be turning 3447 RPMs.
What calculator are you using for this gearhead?



Cole
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Old 11-23-2010, 05:19 PM
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http://www.ringpinion.com/Calc_RPM.aspx I guess this one has some converter slip added in.
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Old 11-23-2010, 05:24 PM
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could it be my stall is going out because i go to uti and one of my teachers think its the stall
also 2nd-3rd shift is real quick
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Old 11-23-2010, 05:59 PM
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The math, and common sense, says that something has to be slipping, or your not in third gear.

sounds like trans/converter is going/gone...
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Old 11-23-2010, 06:03 PM
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so how can i find out which is going out
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Old 11-23-2010, 06:25 PM
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pull the trans, and take it apart.
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Old 11-23-2010, 09:12 PM
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Quote:
Originally Posted by big gear head
If you were actually in 3rd gear at 75 MPH with 3.73 gears and 28 inch tires you would be turning 3447 RPMs. In 2nd gear you would be turning 5175 RPMs.
Like I mentioned above, your defiantly in 2nd gear, 45 mph, 1.52 second gear, 28" tire, 3.73 gears = 3062 RPM, At 75 mph, 1.52 second gear, 28" tire, 3.73 gears = 5103 RPM

I all calculations it shows second gear rpm's. Sorry but numbers don't lie. BTW if the converter was slipping it would vary in rpms.

Another thing you can check is what rpm changes you see from you 2nd and 3rd gear. It may sound and/or feel like it shifted but it might not be getting out of 2nd.

Last edited by Hotrod-Bikerman; 11-23-2010 at 09:21 PM.
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Old 11-23-2010, 09:34 PM
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Quote:
Originally Posted by prettyboyced
could it be my stall is going out because i go to uti and one of my teachers think its the stall
also 2nd-3rd shift is real quick

I'm thinking the far bigger issue is the instructor at UTI ....

Anyone else see my point?
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Old 11-23-2010, 10:18 PM
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Quote:
Originally Posted by Dave57210
I'm thinking the far bigger issue is the instructor at UTI ....

Anyone else see my point?
GOOD POINT!!!


I agree with it not being in third.......but if you insist you are, you have big problems.
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