I have a question about a 1990 corvette coupe, L98. I put a 421 in it, and am putting a summit racing elec water pump (hope it's good!) in it. The pump has a provision for the heater hose, but it is the 4 oclock position instead of the 10 oclock position ours is in.

I was going to by-pass the heater core, but notice if I do that there is only a 1/4" +/- alum fill tube going to the radiator. So how would you fill it. I have a DeWitts radiator, with no cap other than the black expansion tank.

Just wondering what others have done....

Thanks

 

125 people have read your post, but no answers. It's hard to visualize your problem. How about posting some pictures?

Could it be possible that your wp is mounted upside down?

 

DO NOT, I repeat, DO NOT bypass your heater core; its on a water circuit that takes hot water from under the thermostat and send it right back to the suction side of the pump; the only cooling that that water circuit receives is by passing through the heater core.

A 421 is gonna be one immense engine to cool and your gonna need every trick in the book to do it, and bypassing the heater core ain't one of them.

The small block chevy had a bunch of compromises built in it that compromises it's ability to cool the engine, and no, it's not bad engineering per se, just imagine some poor farmer in Minnesota trying to star his work truck at 4 a.m. and thirty below.

To cool that beast, your model will be the race engines, when NASCAR and other sanctioning bodies actually used "stock" engines and you're far, far, from being there.

 

I gave up on the idea of bypassing it. I even figured out how to redirect the plumbing. the real peoblem ended up being the a/c bracket. Would have had to chop it up too much and it would have broken under the a/c load. I ended up using a Hi Volume water pump instead.

I would have liked to use the electric pump, because of hot weather traffic. Plus in Florida it's freakin hot! And it's black! If I ever go full on Race Car, I'll take off the a/c and put the electric pump on it.

Thanks again for the reply.

 

I think you're on the right track. But first, does your "high Volume" water pump have a CNC machined impeller with curved blades? Beware so called high volume pumps with the stamped sheet metal straight (oem) blading and a circular disc rived to it...sure an improvement, but not what you really want for your 421 engine...allow me to quote:

" One of the latest developments is the Stewart Stage IV pumps (with this type impeller..other manufactures offer the same or similar) made possible by CNC machining...This impeller almost doubles coolant flow while consuming less horsepower than conventional impellers".

What you really need to consider is plugging the bypass hole ( the third hole on the passenger side water pump mounting area on the block)...again allow me to quote:

"...improved cooling efficiency results when this bypass hole is plugged ...(some high po water pumps come with the corresponding hole in the water pump body already plugged)...and four holes typically 1/8th inch in diameter ate drilled in the thermostat....(or a restrictor plate ala circle track racing is used in place of a thermostat)...Even if everything in the cooling system is operating properly, drilling holes in the thermostat and plugging the internal bypass usually results in a measurable drop in coolant temperature"

from HP Books "SMALL BLOCK CHEVY PERFORMANCE";

I can only add, put a valve in the discharge hose from under the thermostat housing to the heater core...note this is not the same as "bypassing the heater core"; it merely forces that hot water which otherwise does nothing but transfer heat into the dash/cockpit, into and through the radiator where beneficial cooling can occur...open the valve if it ever gets cold in Florida.

 

Wow! I never got so much valuable info about it. Thank you. I just got a Summit High Volume pump, and if it dosen't work well enough, I'll get the CNC Machined on you mentioned. I was upset because I had a FloKooler Water pump on it and it only has maybe a thousand miles on it and started leaking water out the weep hole.

I already drilled 4 holes in the thermoatat, I did this for "burping". I will plug the hole on the pump before the install.

Liked the idea of the electric pump because in traffic it would have better flow. Here in Florida, heat is crazy plus high humidity.

Thanks very much again