Low cost rad upgrade

[spycarrussell]

Please forgive me if this has been answered ad nauseum: What would you say is the least costly radiator upgrade when going from the original 1.8 engine to a mild 3.5 Rover unit? Please include fan configurations as well.

Thanks,
Russell

[Moderator]

MGB? Which year? What climate?


People have given widely divergent answers to this over the years... but surely the least costly option is to use the radiator you already have if you can. I cooled a fairly mildly tuned Buick 215 in my '71 GT for fifteen years with a stock chrome-bumper MGB radiator and dual 9" (Honda Civic) fans, pushing. To make it work, I soldered-in oversized ports and I cleaned up airflow into the radiator with some simple sheetmetal ductwork. I also removed the stock filler cap in favor of a high-mounted pressurized header tank, which let me mount the radiator higher than stock (because as I recall, on chrome bumper cars, part of the radiator core is below the radiator shelf and therefore ineffective.) Your electric fans will spin faster and be more effective if you rewire them with larger gauge cable, and it may help a lot to install a relay. An air dam will help by lowering air pressure in the engine compartment and under the car. Through-the-fender headers would help hugely,, but I haven't installed those yet.

In some cases, including I've been told on all "factory" MGB GT V8's, improper heater plumbing allows coolant to bypass the radiator and therefore greatly reduces overall cooling system efficiency.,

[pspeaks]

I have a bone stock 78 302 and no AC, though I live in Texas and know how the no AC is likely to work out.  I have a 65 mustang 6 cylinder radiator had hate the way it hangs down making it far to susceptible to road and critter attacks.  I've seriously considered re-coring and modifying the original, I mean what have I got to lose.  Well, there is that Texas thing again, but I can always put the mustang radiator back in.  I'm sure the first thing a radiator shop is going to say is "where do you expect me to find a 72 MG core?"  I'll have to give that one a little thought!

[roverman]

Russell, what is lc. to you ? Jeg's/etc. have all manner of alum . rad's., starting at $160. Good Luck, roverman.

[RMO 699F]

Russell, my personal experiece is that the mgb 1800 rad is more than up to the job, but wih  a couple caveats. I had a bop in a '78 mgb roadster, with block hugger headers, mgb rad, that was good in normal dring, but heated up quickly in slow moving congested trafffic. My 74 gt with a 3.9 rover has the standad mgb rad (inlet/outlet modiied of couse) but I have the rv8 headers that exit through the fender well. This car never overheats in any conditions. The point being that the rv8 style headers with a negative air pressure exit point gives the hot air a place to exit. Very important. If you ever want to know how much hot air is in the engine compartment, simply remove the two 3" X 4" rubber grommets in your firewall and drive the car. It will feel like a suana in the drivers seat. And of course having a quality high capacity cfm cooling fan is essentail also.