I know this is like beating a dead horse.
I have a 500" low deck with a CSR 37GPM water pump with a Champion 4 row radiator. It has an HHR fan on it. It is sealed to the radiator. I have gotten to the point where the radiator will hold temp if the kick the fan on and leave the pump running. I have a restrictor in the water pump housing. I don't have a thermostat in it. However, this setup won't drop the temp during idle. Do I need to up the pump to a 55GPM unit for the street?

I bought a Mezeire 55gpm pump, I have yet to install it though... Perhaps this weekend.
Bigger, is usually better.

Pull the restrictor and see how it does... if you have a
restriction on a 37 gpm its acting like a 30gpm(depending
on the size of restriction)

If you call some "other" radiator people you may be surprised to find that that 4 core you have is terribly over rated in cooling capacity and the 2 core that Champion sells is very underrated in cooling capacity.

FWIW flow is WAY more important than "dwell" time. You should only need a t-stat to get the engine UP to temp. If you can't control the temp on the hot side a t-stat usually won't help.

IMVHO, you need a 2 core radiator with 1.5 inch tubes. The one you have is 4 tubes of .625 inches. so, 1.5 x 2 is 3 inches of tube diamter. .625 x 4 is 2.5 inches of tube diameter. Plus, the thickness of the 4 core impedes air flow so you get less cooling than with a properly sized 2 core.

It's all about flow. So even if you correct the radiator you may still need more GPM.

Thanks for all the help with the issue. I'll take the restrictor out and see what it does. I had a Summit racing 2 row in there. It was made by Northern. That radiator wouldn't keep the car cool at all. I just want to be able to drive this thing!! I'll try removing the restrictor, if that doesn't work, I'll look to the 55GPM pump. Thanks again!

That may be entirely possible you had a 2 core that didn't cool your engine. If you still have it, can you measure a tube and post it for our edification? I think that Northern only had 5/8 tubes in it. They may be 3/4 but IIRC they were the 5/8.

Would be intersting to know.

Something else you could try is a wider radiator, which gives you more frontal surface area in addition to more capacity. I put in a 19" x 28" wide Howe rad in my Duster, and it was able to cool a blown 528" Hemi on the hot streets of central Florida.

First thing is to get rid of the restrictor. You want the water to flow thru the radiator as fast as possible if you need more cooling. Having a restrictor in the system reduces the ability to cool the water. If you are having cooling problems then the one answer is always more water flow. The other answer is more airflow across the radiator and/or more radiator area. But more water flow is usually the first solution to try.

This is correct, you just said it better than I did. Dwell time (length of time the coolant is in the radiator) is a myth. The longer the coolant stays in the block, the hotter it gets and the harder it is for an already overtaxed system to get rid of the heat.

When it is all done, I suspect the OP will need the 55 GPM pump.

Ironically, all of this is covered in the MoPar SB engine book. I would ASSume the same or similar stuff is covered in the B-RB book.

I`m starting to think I need to remove my gutted t-stat cos last sat. in 112+ heat my temp was 210 bet 3000-3400 rpm`s on the freeway heading to a car show and that`s hotter than it ever has been and is unacceptable to me.......

The Meziere pump I have on my hemi flows 45 gpm. It works good, but I sure wouldn't want to use one w/ less flow than that. The big 55 gpm Meziere pump they have now is nice, but man that thing is pricy!

Been running the drop in Moroso for years and they don`t give flow numbers but "claim" 33% more flow than the competitors.....

Yup, if you new what the starting number was, the "33% more" would be much more relevent for sure.

It does make good advertising tho...........

I ran the 45 gph Meziere for ever. One thing I did that helped is I tapped the hole in the housing under the thermostat. put a plug in it and drilled a 1/8th inch hole in the plug. that was good for about 10*

And did the water just pour out or what? I think you stopped short in your explanation.

The 45 gpm pump he's referring to is the drop-in pump that fits the stock housing (same one I have). There is a bypass hole underneath the thermostat in a stock housing. You tap it for 3/8" npt (no need to drill), put a pipe plug in it, then drill a 1/8" hole through the plug. This is def. worth doing...dropped mine about 10° also. It reduces the amount of hot water that's recirculated through the motor.

Good to know Chip!

Is ur fan a pusher or puller. If it's a pusher, that is ur problem. U can't push air through a 4 core rad. I use a wizard 2 row core, 4 small pullers with a shroud, morose pump. Temp never goes over 190, fans pull temp down to 170 all day long no matter how hot it is. Wizard said to run a 180* stat.

Got any pictures of this?

I pulled the restrict-or out for giggles and only gained about a 1/4" going from the 1" gutted t-stat to the 1 1/4" t-stat housing. Think it will make a difference? Sorry to hi-jack.................