| |
Click on image for the lowdown. 
====
| | |
7 members (TUTS 59, Gray_Ghost, panic, tclederman, Peggy M, MRMEROTH11, Wickedbass),
122
guests, and
0
robots. | | Key: Admin,
Global Mod,
Mod | | | Forums66 Topics128,068 Posts1,055,880 Members48,428 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | | | Joined: Dec 2008 Posts: 1,922 'Bolter | | 'Bolter Joined: Dec 2008 Posts: 1,922 | I'm trying to compare the water flow capacity of the early vs. late engines and pumps.
ve made a rough guess (via Photoshop) of the late water inlet at about 5-7/16" diameter, and the 2 smaller early holes at about 1-9/16" each.
Is this pretty close?
Forgive me, I don't have the parts where I can measure them. | | | | | Joined: Mar 2010 Posts: 10,275 Renaissance Man | | Renaissance Man Joined: Mar 2010 Posts: 10,275 | That is a quite the challenge right there.
I am sure that you have considered:
Water pump pulley diameter difference.
Crankshaft pulley diameter difference (?).
Impeller design/size difference.
Your estimates of the block hole sizes seem very close to correct. Close enough, given that you are probably looking for a percent difference in total square inches of hole area between the two designs.
Last edited by 52Carl; 07/19/2019 2:20 AM.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
| | | | | Joined: Dec 2008 Posts: 1,922 'Bolter | | 'Bolter Joined: Dec 2008 Posts: 1,922 | Thanks.
The late pump flow in GPM (with the same drive pulley ratio) is about 72% higher accoding to GM data, but I think the driving factor of that huge hole is the pump impeller diameter, it's many times larger than +72%: 23" vs. 4" areas.
I would guess that locating the smaller holes way up is Chevy's way of getting the coldest water to the hottest area of the #1, and the bigger late hole is the price you pay for simplifying parts - too much water reaches the entire face of the #1 jacket. There is no obvious way to mask part of that opening, unless you want to insert and attach a plate inside the block to direct flow upward, but how and made of what?
This "#1 too cold" supposedly plagued many L6 truck engines in long service: the hot #6 made it knock, but the cold #1 wore out its rings due to distortion and started burning oil first. | | |
|
|
| |
