The Stovebolt Site Forums The Shop Area The HiPo Shop reverse flow cooling vs standard flow

Hey everyone, I just built myself a little gen 1 small block chevy now built to 353ci. the block is from a 1974 monte carlo. and the heads are GM aluminum heads from an 1986 corvette. I have after market pulleys that use a trick gilmer belt drive, they are designed for standard rotation- standard flow cooling. in 1986 the corvette had reverse flow cooling by changing the design of the water pump and spinning the pulley in reverse direction of the crank. I had to fix some cracks in both of these heads because I believe someone used these heads with stand flow cooling.... is anyone familiar with a standard rotation reverse flow water pump either short or long style...? thanks ~Mykk

Well, I'm pretty sure it wasn't until the LT-1 350 appeared in the Corvettes that they became reverse flow. In 1986, the 350 in the Corvette was still the L98 tuned port engine, and that wasn't reverse flow yet. I'm pretty certain about that, but I can probably find out.

My son has an LT-1 powered Trans Am parked at my house while he's in the Navy. So I have a visual reference at my disposal. What is it that you need to know about it?

Yeah, it wasn't until 1992 that the LT-1 replaced the L98. Here is the website I found that information at:

http://www.idavette.net/hib/c4hib.htm

The dates are fuzzy, but the L98 started out with a hydraulic flat tappet cam and iron heads, and made 230 hp, but a BUNCH of torque. The mild cam and tuned port runners didn't allow much power above 4400 rpm, which is what limited the hp number.
Then the L98 got aluminum heads and higher compression, and went up to 240 hp, I think that was 1987.
Then the L98 got a hydraulic roller cam and was good for 250 hp. That stayed until 1992 when the new generation small block 350 with the LT-1 intake and reverse cooling configuration made its debut with 300 hp. It made less torque than the L98, but had much better top end power thanks to its new 6000 rpm redline.

It's a little trivia but it's interesting. If you can get ahold of that torquey L98 tuned port injection, it would be fantastic in a truck!!!

All L98s are standard SB1s. That said, those heads aren't the greatest things out there. Nice, if cheap, but the flow is pretty constricted. I'm converting a set of cast-iron LT1 heads to standard flow for my Vette, but that's a different kettle of fish.

Thanks for all the input, I was under the impression that all reverse rotation water pumps had to flow reverse... but I've heard from a number of sources that my aluminum L98 heads are standard coolant flow, wich makes my aftermarket application a whole lot easier.. thanks for all the input.

reverse rotation pumps are used for serpentine belt setups

You CAN get your L98 heads to flow well. Have a machinist blend the bowls and do a good 3 angle valve job at least, or even better, have him radius the valves.

OK, I was under the impression that the "reverse flow" meant the water went thru the Heads first and then thru the Block, there's the little piping on the back of those LT1 heads, I believe they're bleeders for air pockets because of this flow direction...

well there is reverse flow cooling that ls1 and i guess lt1 motors use. that is like what you just wrote as in the coolant flow direction is reversed, heads block then radiator.

then there are reverse rotation pumps for serpentine belt systems on non-rever FLOW motors. with a serpentine system, the water pump pulley rotates in the opposite direction than that of a v-belt setup