Governor kicking in too early all of a sudden?

[jaredg]

Hey all,
I've been racking by brain on this one for a few weeks now:
The bus used to top out around 53 mph. I put a rebuilt (identical) carburetor (Holley 4152eg) on it about a year ago and the bus would top out at around 63 mph. All of a sudden I noticed about 3 months ago that it was topping out at exactly 49mph. Since then it hasnt let me go faster than this exact speed. I got some good advice to check the redundant throttle return spring. Turns out, it did need to be reset - I was also experiencing a much heavier accelerator pedal for the past half a year. I reset the spring and noticed the pedal to be much smoother and lighter. Unfortunately it didn't fix my 49mph problem. Is there maybe a chance that the secondaries on the carburetor aren't opening?

Do you guys have any insight on this problem?

Stats:
1987 366 V8 gas
Holley 4152eg 4 barrel
Allison AT545 Trans

Thanks for your time.

[bansil]

when the gas pedal is depressed does it open up the primary throttle plates all the way?
Since you had to reset the return springs maybe the throttle linkage got bent?

[jaredg]

Originally Posted by bansil

when the gas pedal is depressed does it open up the primary throttle plates all the way?
Since you had to reset the return springs maybe the throttle linkage got bent?

Thanks for your reply. It does appear that the primaries open all the way when depressing accelerator.

[caseythenose]

Did it get hot enough to redden the silencer?

There was one in the shop that drove them nuts one time similar...it ended up being a spark arrestor getting red hot and melting to create back pressure in the exhaust, making it top out a what seemed to be a predetermined top speed.

Might be a long shot...but it's worth a consideration.

[GreyEagle]

Well at least it's a starting point....... We're all just grabbing straws here.....
Best of luck.

[chev49]

What is the silencer?

Other than something ya make on the lathe for your gun...