T400 help please - The 1947 - Present Chevrolet & GMC Truck Message Board Network

SunSoaked · 06-16-2021, 10:39 AM

I had same issue bit I had my vacuum advance cannister off the HEI T-d into it. The diaphragm in the cannister went bad and raised my shift points like you.

lux · 06-16-2021, 11:25 AM

Quote:

Originally Posted by SunSoaked

I had same issue bit I had my vacuum advance cannister off the HEI T-d into it. The diaphragm in the cannister went bad and raised my shift points like you.

i have my vacuum line straight to the intake on a Edelbrock pro flow 4. I made sure and use hard line for most of the route with rubber fittings on the ends.
I'll get a chance to look at it this weekend. Hopefully its just a line that came unattached.

lux · 06-20-2021, 08:51 PM

Well, I tested vacuum at the transmission it was 20-22 at 3000rpm. Does that sound about right?
Then I checked the kick down switch and it was stuck on. I took the Lokar switch apart and sprayed it with silicone lube. That seems to have done the trick. All is well now, thanks for the help.

06-16-2021, 10:39 AM	#1
SunSoaked Registered User Join Date: Dec 2011 Location: Yuma Arizona Posts: 1,525	Re: T400 help please I had same issue bit I had my vacuum advance cannister off the HEI T-d into it. The diaphragm in the cannister went bad and raised my shift points like you.

06-20-2021, 08:51 PM	#3
lux Registered User Join Date: Oct 2016 Location: Austin, Texas Posts: 306	Re: T400 help please Well, I tested vacuum at the transmission it was 20-22 at 3000rpm. Does that sound about right? Then I checked the kick down switch and it was stuck on. I took the Lokar switch apart and sprayed it with silicone lube. That seems to have done the trick. All is well now, thanks for the help.



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