Bee Jay

I recently constructed a 383 engine for my '79 Yellow Vette. More on that later. My biggest concern about going to increased displacement was heat management or overheating. I paid close attention when Paul Dana struggled with cooling his small block 427. And he has an aluminum Dewitt radiator. So when I installed my Performer RPM Air Gap intake manifold, I took advantage of the built in plumbing holes, and did the coolant bypass. Those of you wondering if this is worth the effort, it is. I've had my 383 autocross racing and some pretty hard summer fast driving on the highway, and a little stop and go in traffic on a hot day. The engine hasn't gone about 180 degrees yet. I've had the oil get up to 195 degrees though. I have a 180 degree thermostat, and it's fun to watch the water temp edge up to 180, then the thermostat opens, and the temp drops 10-15 degrees real quick. Then the thermostat closes and the temp edges up again. The old L-82 350 never ran this cool. This is a mod that works.
Bee Jay

Metalhead140

Cool! Specs on the 383? You still happy with your solid engine mounts? I have a set of solid mounts that I'm likely to use when I drop the 383 (388 strictly speaking) that I'm currently building into the car.

gungatim

for those that may not know, do not confuse what he did with a coolant bypass, it's not the same thing. What those hoses do is promote even cooling to cylinders 7 & 8 when not using stock heads. sbc's have coolant bypass built in. The cooling system for Big Blocks like the 427 mentioned are completely different. it's akin to cooling the end cylinders like in old VW air cooled motors did when cyl. 3 would get hot because of it's position.

jim2527

Small block..

Metalhead140

Bee Jay, have you got any links with more info on this mod? Did a bit of googling but didn't find much. Wondering if it's something I should do on mine while it's apart.

gkull

Glad to see that you went to a manifold filler also. Hey are you running the 420# pound mono rear spring this year at auto-X?

mikem350

This trick will help the back cylinders. Not much for overall temps.

What has biggest effect is ign timing, size of rad, and airflow THRU the rad. etc etc.

Also have to say if a thermostat "opens and closes" near operating temp it is sticking and not right.

Bee Jay

Same radiator, same waterpump, same cooling fans, everything is the same as before, except the displacement increased 33 cubic inches, and this manifold bypass. Coolant bypass was the only other change. The car used to cruise at 195 degrees, and up when racing or haulin ***. I can tell when the thermostat opens at 180, the temp drops.
BTW, Paul Dana's 427 was a small block.

Bee Jay

Handles nice, but I now have oversteer. I'm adding negative camber before next race. What do you recommend?

gkull

Buy a thermal laser heat gun and do skid pan testing . I've never been one to give a blanket camber setting. You did not say if the rear comes around on entry to a turn or leaving..... Lets also say that you have more TQ with the new 383.... so turn exit you have less grip. Are tires older now also?

Is your rear ride height exactly the same with the 420# as before?

With less body roll of a stiffer rear spring you have less camber gain. If you have smart strut rear place the inner link arm lower for less camber gain and set them to about .40 to .50 neg on the rear with minimal toe in like less than an 1/8th

gg521

Your mod is a fairly common in road race engines. As far as oversteer, try reducing your rear tire air pressure a couple lbs. before you try anything else.

gkull

http://www.johnnyoconnell.com/tips3.html

Jebbysan

I have done this quite a few times.......it does work.....but I have never seen drastic temperature changes as much as the temp evened out.......
One application where it is downright handy is where the radiator is lower than the block.....such as in an early *****'s.
You can burp the air out through the front fittings while filling the rad.
Did you go from a stock block to an aftermarket? The increased soak due to thermal transfer of thicker cast iron walls could be what helped you here as well.....
Anyway.....looks good and can't hurt......
I was reading one of your threads......did the engine make a difference in weight? Where are you at now?

Jebby

Bee Jay

Same L-82 block, bored .30 over.

Kubs

I would suggest using a probe when taking tire temps. The surface of the tread will start to cool down as soon as you stop driving hard. You want to know what the temp is inside the tread.

And, knowing when the car gets loose (entry mid exit, throttle on, etc.) will help with setup as well like gkull mentioned.

That cooling setup looks neat though. Glad its working out.

Bee Jay

The rear gets loose and try's to come around on corner entry. Brake hard, start your turn, and the rear wants to rotate. I can catch it in curves, but as you know, auto cross can be turns, followed immediately by another turn. The front sticks! (285 tires up front) And the Borgeson is fantastic.
I filled it up with gas at the lunch break, thinking it would give me more traction on launch and turning. I was wrong. 23 gallons out back made things worse. Felt like a 911 with all that weight back there. I lose it in corner exit too, because this new 383 is a monster. Punch it anywhere in second, and it lights up the tires.
I trimmed your 420 lb spring one inch on each side, so I don't know if that made the spring stiffer or softer, but I had to do it to get the 315, 180 tread wear tires on. I didn't mean for this cooling thread to turn into a handling thread, just answering your questions.

Robert Thomas

The shorter spring is stiffer than before being cut. Could be your front springs are too soft, allowing the weight to transfer forward off the rear tires, causing them to lose traction. You may have to learn to finish braking before turning, complete the turn, straighten the front wheels and then flatten the accelerator pedal.

My car has similar behavior, especially exiting. The experts here told me to slow down.

Bee Jay

Last night I tuned the camber rods out two turns each. My digital level showed me going from almost 90 degrees to now 88.5 degrees. I drove the car to work today. The car still tracks straight at illegal speeds, and it seemed to handle on Harris Grade pretty good. You can't really tell until you have a track to play on.

The13Bats

You might want to clarify that the reason number 3 gets hotter on ACVW's is because the oil cooler is partly blocking it's air flow, not because where it is, when we run external coolers number 3 cools the same as the other 3.

gkull

You need to 90% of your braking in a straight line and actually lift on the petal for turn in. real trail braking is an art. My first time in a 125 shifter kart. I did a bunch of 360's entering turns. You have to brake in a straight line.

You can have all the settings right for the most lateral traction and then you have to know how to drive it.

My manfold came pre tapped for external water. My return is above the thermostat so I always have some pump flow