I’ve found considerable variation in the impeller position relative to the housing flange from pump to pump. In other words the how far the impeller penetrates the housing. Clearance between the impeller vanes and the pump housing is an important factor in the efficiency of the pump. On industrial centrifugal pumps this clearance is adjusted by down to a few thousandths of an inch to minimize recirculation. Give me 5 different pumps and I'll take the one that runs closest to the pump housing regardless of impeller design.

I made sure of that before I tested the waterpumps.
I had three 440source waterpumps and 2 housings to choose from. I chose the pump and housing where the waterpump impeller scraped the housing when mounted without a gasket.

Got the new Summit pump like in one business day.. wow, got the car apart, here is the difference between the aftermarket pump put on 20+ years ago and the new Summit.
Both 8 fins,
The summit has the anti cav plate, the fins are a bit taller and they sit about .125 closer to the engine.
I think it will be good.

do you have part # and price thanks

I bet it's this one. The only Summit one I saw.

https://www.summitracing.com/parts/sum-312317/overview/year/1969/make/plymouth/model/roadrunner

Did your new Summit pump out perform your aftermarket? You see your temps go down at all? I'm thinking of buying one of these. I've had my stock radiator on my Formula S soaked and rodded out. Played around with 160 and 180 thermostats and made sure my hoses, 16 lb radiator cap and such are all good. I still on a hot day will run down the highway at 195 or so. Pop the cap with the car running and it just doesn't seem to be allot of water movement. I even threw some money away on some water wetter. As in the past years with that stuff on anything, no gain.

Any gain with the Summit water pump???

Me three, it makes no difference at all. Pick one and don't expect it to fix a over heating problem with a water pump because that is not the problem if your running hot.

I went with the edelbrock the last time only because I just din't know what to get. Only dyno time so far.

That's my concern here of just throwing more money at it to reduce the temps about 15 degrees or so. Car has the stock 22" radiator in it but it just doesn't seem to get the temps down while running down the highway all that much. Not like my other cars do. I would think air flowing thru the radiator at higher speeds would cool things down to closer to the thermostat temp. The warmer outside the warmer the car runs. I ran 200 degrees yesterday down the highway with it about 89 and humid outside. Temps go up to 215-220 or so sitting still for a while and idling. Doesn't pee out the overflow or anything. That's just what the car runs.

I took my Charger for a 3 hour drive Saturday, temps in low/ mid 80s. Several stops, some 50Mph drive, but mostly 30MPH or stopped at a light.
Results were about 5-10 degree improvement over old aftermarket.

Settled in at about 185-190. took a long time to get over 170.

Anyway, stock 440 30 over. 50K miles since rebuilt about 25 years ago.. so well seasoned. 160 deg stat.
Running a clutch fan, no shroud, 26 inch rad, and a C body aluminum fan.