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I've only had 2 big block Chevys....both 496 13.5 :1 motors....well built. I'm using a BeeCool aluminum radiator with 1 large fan, and a CSR electric pump. If I make one quarter mile pass, I'm at or over 200. I'm running a 180 thermostat. Any solutions on how to keep the heat down? What temp. is the danger zone for these motors?...Gen VI block, Dart 335 CNC aluminum heads.
How many rows in your BeeCool I have 3 in mine with stock water pump and fan but I'm about 12:1 + or - is your fan pushing or pulling I believe pulling to work best. Do you have a schroud??
i know of the be cool s rads very well ..i had many bbc and built many using iron heads and alum up to 632 on the street most ran around 220.. it could be many things that are going on with your 468 .one thing is what head gaskets did you use ? i have dealed with many 355 dart heads so you need to watch what head gasket you used .track only car you do not need a stat just a shim or cut out the center of a stat and see what that will do
The radiator has 3 rows.....I don't have a shroud.....the fan pulls.
Is 220 fairly safe? I had a couple local guys who have had big blocks for a while tell me that 200 or over is risky with alum. heads. The only comparison I can think of is a couple C5 Corvettes that I modified. They were LS motors, with alum. heads, and routinely ran at 220.
Head gaskets are Cometic....not sure of the part #. They were recommended by a local and fairly well respected engine builder.
I will try cutting out a thermostat.......I don't know of anyone who has done that, but I've heard of it before. Honestly......I think I would be better off with no thermostat than the present situation.
I'm like you, anything over 200 scares me, but I am kind of learning that my thinking might be old fashioned. My daily driver has an all aluminum engine and it runs at 208-212 even at night. I took it back to the dealer and they told me if it gets up to 230 start worrying ! :eek:
They tell me the newer cars electric fans don't even come on until about 221 or so. But if you put a shroud on that fan it will help, I bet. We also just got some restrictor plates from Mondellos for the 455 Olds in my Sons car and they told us to toss the thermostat and put that in............we did and the temp came down 10 degrees.
Don
yep i posted on here last night ? less i sent it to don .?:D hell of a day .. well you can just take a old stat and cut center out thats a place to start there is kits that moroso sells for smaller and bigger holes for water speed.as for the bbc and heads they have a good bolt pattern and the heads are not going to fail @220 water temp to hold the head gasket guys telling you that BS are not in the know . less its BS the LS engine head bolt pattern are not the best same as the small ford..but hold .bbc is better... here is somethings to think about .what fire ring or with the MLS gastkets were is the edge of gasket to the head chamber .most 355 darts are set up for 4.600 bores.you do not need a stat for a race only race . were is your timing at. is this engine leaning out.is your water pump working . then there air flow getting in and out of the car ? or what you have this in?with the big 355 dart head s are you using Nos. blower. turbo s? it nice to be under 200 temp but most of the stuff i built or had is that or more the bigger engine plane make more heat
Thanks for all your input.....I will be making a few changes.....restrictor instead of thermostat......I have an aluminum shroud that came with another radiator, and I think I can do a little fabrication to make it fit this one. I guess I will just accept the fact that this motor is never going to run as cool as what I'm accustomed to with small block Chevys. To answer some of your questions, Pat.....I run 40 degrees of timing.....some will say is a bit much, but that is where it runs. The CSR water pump is pumping normally, but I have thought about switching to a mechanical pump to see the difference. The car has no blower, turbo, etc.
tell me abit more on your build if you do not mind ? why did you use the 355 head ? was the damper degree to the timming pointer@TDC .. sure its 40?Quote:
Originally Posted by lodilobo
Pat....you nust have mis read my original post. I'm using Dart 335 CNC.....not 355...heads. The build is a GenVI 454 4 bolt block, bored +.060 to 4.310 and stroked to 6.385 to 496 c.i. The rotating assembly is Eagle 4340 w/ H beam rods, J&E 13.5:1 forged pistons gas ported w/ total seal rings. The camshaft is a solid roller by Erson.....approx. .765 lift....310 duration....don't have the specs in front of me. The lifters are Lunati, Jessel shaft mounted rockers, the Dart heads, which I mentioned......with matched Dart intake, and Quick Fuel 1150 Dominator. Also using MSD distributor, locked for no advance, 6AL plus box. The timing is definitely 40 degrees. I have bumped it down to 38 at times, but lose a little 1/4 mile speed when that is done. Also....it tends to run even a little hotter....quicker...when retarding the timing. The cam was degreed by a professional builder, and the motor runs very strong, so I don't suspect any errors there. Keep in mind.....I don't consider myself to be an accomplished big block Chevy guru by any means, but I know my way around engines.....I've assembled several small blocks. I'm really not very famiiar with big block Chevys....that's why I'm here. Thanks for any additional input.
200 doesnt seem to bad for a big block mine doesnt have any where near the motor of yours but in town with a 160 stat runs 180-190 all day long, have you tried a 160 stat or restricting the water flow any?
Haven't tried a 160......thanks.
Try the restrictor instead of a thermostat. Need some restriction to water flow to have enough time in the radiator to remove heat. The shroud should help also. Have you tried Royal Purple Purple Ice or RedLine Water Wetter? May help additional degree or two.
yep the 335 is a better size had for a 496 still a good size head.i have some blower engines with some of the 335 heads on them .cams could be E129879 DUR @050 278-765 EX284- 731 lsa 108 or E129880 DUR @050.280-765 EX 288-731 lsa110 or E129886 DUR @050.288-765.EX298..731 LSA 110 .i am a dealer for Erson Cams .i buit many bbc over a 100 still picking up stuff . how big is the EX on the engine do you run any EX with mufflers or just headers what tube size ? on header . you try to richen this engine up ? what fuel are you using ? . i still would try a shim like i posted in the water neck and not use a stat play with the tune up abit . i ran my 548 14.8 cr on the street with cam close to the first cam the 278/284 on 108 car allways ran at 220 ,ran very good :) my 548 blower engine is never under 200 temp . one thing to think about is were you picking up water temp may be off abit .you could have a air lock in the rad if the water neck on the block is level or above the rad and still can get a air lock
I'm running headers w/ 2-1/8 primaries and 3" collectors, but have header pipes w/ flowmasters for street driving....also 3". Yesterday I switched from thermostat to restrictor, installed the mufflers, and drove the car around for 30 - 40 minutes. It gradually climbed to 220, and seemed to top out there. I'm running 110 octane. It was very hot out yesterday, so that was definitely a factor. The motor ran great, as usual....I never got on it, so this was simulating normal street driving....which the motor is not ideal for, anyway. I think this is about the best I can acheive. Maybe on a cool day it would stay around 200.
the hole may need to be smaller then what you had in the stat you may get abit less temp by using water wetter like red line makes .by moving the temp sender point up pickup could drop the temp to .see if you can get a heat gun and check true reading