The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1947 - 1959 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 10-24-2012, 01:59 AM   #1
71_bowtie
Registered User
 
71_bowtie's Avatar
 
Join Date: Sep 2010
Location: nebraska
Posts: 11
56 chevy help???

hey, i'm working on a 56 chevy 1 ton, and i have a question on the radiator cap. first off the truck now has a baby 400/th400 combo and a stock 3/4 ton radiator in it. the radiator i just got used and had it boiled and cleaned and good to go. the radiator had an original gm ac cap that was marked for 5 or 8Lb. but the original radiator that was with the 400 was a 16Lb. which radiator cap should be used? there is no heater in it right now but i have one to put in from a 3/4 ton. thanks
71_bowtie is offline   Reply With Quote
Old 10-24-2012, 03:31 PM   #2
spinned
Registered User
 
spinned's Avatar
 
Join Date: Oct 2012
Location: Beaverton
Posts: 102
Re: 56 chevy help???

I just rebuilt my radiator and put a copper 4-core in the existing frame for a SBC 350. The old timer radiator quy said to stick with a 6-9lb cap so that it would not build up too much pressure and blow the welds. He said that I dont need any more than that. It runs fine and cool.
spinned is offline   Reply With Quote
Old 10-24-2012, 09:29 PM   #3
sabre67
Registered User
 
Join Date: Mar 2012
Location: British Columbia Canada eh
Posts: 43
Re: 56 chevy help???

I might be wrong but i think the higher poundage caps are used on a closed system radiator set up, with a overflow reservoir the lower poundage caps were used on older vehicles that just had the overflow tube mounted on the rad and vented to the ground Correct me if Im wrong
sabre67 is offline   Reply With Quote
Old 10-25-2012, 02:01 AM   #4
71_bowtie
Registered User
 
71_bowtie's Avatar
 
Join Date: Sep 2010
Location: nebraska
Posts: 11
Re: 56 chevy help???

ok, thanks for your help.
71_bowtie is offline   Reply With Quote
Old 10-25-2012, 10:49 AM   #5
1project2many
Registered User
 
Join Date: Mar 2012
Location: Lakes Region NH
Posts: 3,168
Re: 56 chevy help???

The higher the pressure, the higher the temp when the coolant boils. If you're going to run the lower pressure cap you might want to use a 180 T-stat to provide a wider temp range between operating temp and boiling temp. Radiator guy might have seen something he didn't like or just might be playing it safe. Can't tell without talking to him. But next higher cap pressure is 10-12 psi and that's what I'd use with 195 T-stat.

The difference for the recovery bottle (overflow) type system vs open system is a small gasket on the bottom of the cap. Look at the original cap upside down and it's probably just brass on the bottom with a gasket inside the cap. Look at a newer cap and there's a gasket where the brass is on the old one. You can use the recovery type cap on the non-recovery system but not vice versa. If you run non-recovery bottle don't fill the radiator to the top or it will push out coolant when it warms up.
1project2many is offline   Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 12:52 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com