John93CTD

Hey guys just wondering why my top end speed is only 75 wot with the wind pushing. my signature has everything that is done to the truck. Any help is appreciated.

jimbo486

What is your rear-end gear ratio and tire size?

torquefan

If this is a condition that's just come up, I'll say that on a lot of the 12 valve trucks I've looked at for low power complaints, they haven't been capable of achieving wide open throttle due to linkage wear or misadjustment. Good place to start looking.

NJTman

Mine was 75 until I put in my 3200 spring and removed the throttle stop for high rpm. I'm well over 90mph now.

John93CTD

The tag on rear end say 354

Jim Lane

Was going to say don't see a governor spring listed, this spring determines at what RPM the engines defuels at.

jimbo486

Given a tire size of 32.83" and a rear-end gear ratio of 3.54. The Getrag's OD (5th) gear ratio is 0.77. Final drive is 2.72:1. Calculations say that at 71.8mph, the engine is turning 2,000RPM. The stock governor spring limits fueling to 2,500RPM and usually begins to defuel shortly before then.

92betsy

My truck topped out around 85 with the high idle screw removed. After the 3200 gov spring I can hit over 100.

John93CTD

No I haven't done the gov. Spring yet, just gotta get myself worked up to pulling the pump top off don't wanna booger Anything up. But I figured that with the added rpms it would give me a little more top end.

ofcmarc

3200 GSK and tighten/adjust the throttle linkage. She'll move well past 75mph........

MARF75

Way off topic but,
I love the Reagan quote Marc
Man was a genius!

ofcmarc

Couldn't agree more.

NE frmhnd

My speedometer is about 5% slow, so when my needle says I am doing just a hair under 75, 75X1.05=about 79.

I can bring my speedometer up to just about 80, so I'm guessing a previous owner swapped gears, and /or you're not getting full throttle travel at the pump.

John93CTD

Ill have to look and see if I'm getting full linkage travel, how do u eliminate the throttle stop?

92betsy

Just unscrew the bolt in the head that the throttle hits. Let the throttle hit the head.