Radiator

Dave Underhill · July 01, 2019, 07:51:01 AM

I have a 72 GT with a 2.8 5 speed out of a 83 Firebird.
Would a new MGB rad be enough to cool it properly? I have an older rad in there now and it doesn't seem to be enough.

ex-tyke · July 01, 2019, 09:23:31 AM

The older MG rads up to '76 were tube and fin construction - not very good from a heat transfer perspective.
Later RB rads from 1977 had a more modern serpentine construction. I would recommend a later rad with a suitable shrouded puller type fan. Don't be afraid to move the rad about 6" forward to the RB location.

Dave Underhill · July 02, 2019, 07:19:30 AM

Thanks Graham, I'm just an hour or so up the road from you. In the Aylmer area south east of London.

MGBV8 · July 02, 2019, 08:44:09 AM

A number of 3.4L V6 swaps have utilized the late stock radiator. I use a repop GT V8 radiator on my Buick 215.

Dave Underhill · July 02, 2019, 12:00:16 PM

Thanks Carl, I will give that a try.

jjohanski · July 16, 2019, 07:40:00 AM

I have a both an aluminum V8 rad of Chinese origin and a V8 brass repop and both work fine. I also have an expensive English made aluminum repop which is superior to both of these (superbly made and welded) which works even better but at twice the cost. Both of the first two are available from me. PM with any interest.

Dave Underhill · July 17, 2019, 07:32:56 AM

Thanks Johan, I ordered and received a Chinese 3 row aluminum rad. Put it in yesterday and took it for a drive last night.
It runs noticeably cooler at road speed but still gets pretty warm in town. It's a crossflow rad.

rficalora · July 17, 2019, 01:47:01 PM

If it's cooling sufficiently at road speeds but not in town or when idling, you probably have an air flow issue now. What fan are you running? Is the radiator shrouded?

Note, other issues can cause overheating too...
* Air in the cooling system
* Running lean
* Retarded timing

Dave Underhill · July 18, 2019, 06:10:18 AM

I have a 10 inch pusher fan on the front of the rad. No room on the back for a fan and a shroud. Could go to a bigger fan.
Timing is advanced form what the manual calls for. It's not pinging so I might try and advance it more. Don't know how I can richen it, it was running lean but not as much since I made a cold air intake for it.

rficalora · July 18, 2019, 09:40:24 AM

Can't say for sure, but the fan is probably a bit small.

Lean/rich - I'm guessing you have a carburetor. Should be able to change jets in the carb. Google/read up on how to tune your carb or have it done.

No room for puller fan/shrouding - you're effectively using the 10" diameter portion of the radiator for cooling when moving slow or stopped. Can you move the radiator forward? Or, post a picture of the engine bay so we can see what you're dealing with?

BlownMGB-V8 · July 19, 2019, 10:00:18 AM

Moving the radiator forward and using a puller fan would be a good first step. Volvo fans are quite good, readily available, have a very good relay, and are about the largest diameter you can fit. They also may come with a shroud that can be cut down to fit. Their dual temp sensor is available in the right ratings as well and does a good job. It's either a 16 or 18mm thread, taps that size are available for around $20 or so.

Jim

Dave Underhill · July 19, 2019, 05:42:05 PM

Here are a couple pics . I have room for a larger fan. The most I could move the rad forward would be 2".
Still not enough room for a fan and shroud on the back side.
I would have room for a 14" fan on the front.

ex-tyke · July 19, 2019, 09:14:38 PM

QuoteThe most I could move the rad forward would be 2"

The difference in factory rad position between your '72 and a '77 - '80 'RB is about 6" forward. Are you sure that 2" is all you can get?
Water pump mounted fan not an option?
Temps rising when idling,as Rob has pointed out, are typically due to low airflow and/or no recirc protection. Your front mounted pusher is contributing to a grossly underperforming rad - your rad is capable- just need to maximize its potential.
Feel free to stop by Chatham any time and we can go over a cooling diagnosis and strategy.

Dave Underhill · July 19, 2019, 09:22:01 PM

If I cut out anymore forward I will be cutting out a reincorcement piece. Might not matter though.

Dave Underhill · July 19, 2019, 10:38:17 PM

I might make a trip down Graham. Your about two hours from me.

BlownMGB-V8 · July 20, 2019, 01:43:03 PM

That piece you are referring to doesn't add much and is almost routinely removed. The stiffness of the front crossmember far outweighs it. On my car and the Roadmaster we not only removed that and the panel it is attached to, we cut off the frame stubs and welded in 2" x 1/16" wall square tubing that follows the taper to the outer edge of the grille opening, allowing us to install a 32" wide crossflow radiator, all with no ill effects. We modified the bumper brackets to match.

You don't have to worry about it. If you are concerned, a lower radiator guard can be built which adds back some at least of that stiffness plus protects the bottom of the radiator. I'm a big fan of those, but recommend you not build it heavier than it needs to be to protect the radiator. It can also be incorporated into the air dam (spoiler). With those changes the radiator can be moved all the way out to the grille and even tilted, giving you plenty of room for a puller type fan.

Jim

Dave Underhill · July 21, 2019, 08:36:49 AM

Thanks Jim, I will have to decide how much work I want to go to.