500 overheat

[suburban4x4]

i put a 500 from a 73 eldo into my 79 suburban and on a trip towing my race car it ran very warm 230 degrees and only had power when lite on the throttle . i tried to adjust the timing but with little change and still over heated . i am running an hei distributor and edelbrock 750 and 1 3/4 headers into a single 3 inch exhaust
could it be the mechanicel advance in the distributor or the vacuum advance or is it something else? im running a summit racing dual 1 inch core aluminum radiator with the factory direct drive fan and a 14 inch electric pusher fan in front

[Caddycarlo]

first without some work to the cooling caddys run hot
second has the carb ben jetted or is iit as is out of the box?
third what port is the vac advance hooked to ?
forth does the mec fan have a shroud ?

[k10caddy]

which 750 is it? 1407 or the 1411? stock calibration?

if it is still at the stock calibration I'd say most likely, with the headers/exhaust, it's probably running a bit too lean. also, any vacuum leaks?
btw, what temp thermostat are you running?

[suburban4x4]

the carb is as is out of the box
fan has a 3/4 shroud
the vacuum advance is hooked up to the specified port on the carb should i hookit up to a full vacuum port
im running a 160 thermostat to try to keep it cooler
i havnt found any vacuum leaks but i am running a hydro boost setup for the brakes so no vacuum needed there
i thought i had this cooling thing covered with the aluminum radiator and added the 14 inch electric fan too
i did have alot more power when i had my predator carb on it though so is the 750 enough carb?

[Caddycarlo]

the problem with the edebrock carb and the caddy is that the caddy motor has so much vac that it pulls the rod into the jet and shuts down the fuel . I would bet that if you pulled a plug it would be ghost white . I would start by getting a spring kit for the metering rods and go up a few sizes .

as for the fan shroud 3/4 is not a lot of help ...

on the t-stat is it a caddy one or have you blocked the bypass ?

[suburban4x4]

blocked the bypass

[suburban4x4]

the carb is a 1411 and which rods and jets have worked best for a caddy 500

[gilby246]

I have had the same problem with my 500 running at everyday temps of 215 and 230 on hot days (hot is 85-90 here) (in a 79 GMC). I tried everything under the sun to get it down to as leat 200 -210 but nothiing worked. Timing, carb different coolant/water ratios.I put the largest radiator in it that would fit with a caddy 180 thermo, tied 3 different fans and two different fan shrouds. I put a hood scoop on it to get some air moving over the engine...still didnt drop a degree

I finally just drilled a couple small holes in the thermostat.... runs at 190 now ...will hit 205 on a hot day if sitting in traffic

[suburban4x4]

i was getting 230 ish degrees at the radiator as i dont use an engine mounted sensor for the temp guage it would run 185 to 195 as long as i didnt get into it on the highway but when i hit one of the many hills on my trip the heat would just climb
my speeds were 60 to 75 mph towing the truck has like 308 gears or 323s not sure but this dogged the old 350 chevy
i understand i could get the springs and jets and stuff seperatly so what should i get?

[Morella]

If it has good power when cold, but loses power as it warms up, then you most likely have a carb problem.

Vacuum advance units are almost always bad on a used engine. It should be hooked up to straight manifold vacuum, and you should see a dramatic increase in advance when you plug the hose in. Also, check your centrifugal advance mechanism to make sure that it's moving freely. If either is the problem, an adjustable advance kit is the best way to go. Check the timing chain for backlash as well.

If the air condtioning works well, then you probably don't have an airflow problem.

-denise

[suburban4x4]

power is about the same cold or hot good at lite trottle and it just falls off if i give it more gas it just doesnt accelerate very well
i know there is more there without overheating

[Necromancer]

I ran the Edelbrock 750 on my new 500 & it was kinda sluggish, almost "lazy". I changed it out to a Holley 870 Street Avenger (out of the box) w/minor tweeking on a few screws. Now the thing is like a 4700 lb. rocket! Plants you in the seat & keeps you there till you let off. Not everyones choice to be sure, but it works for me.
On the overheating. I run the stock 73 Eldo radiator & shroud w/the stock fan. The car runs very cool, between 200-205. It got to 210 when it was almost 100 outside & I was running hard on the freeway.
I have been looking at the Summit radiator trying to find something to fit between the fenders instead of in front of them, but I am concerned about the cooling ability.
Not sure this helped much. I am surely no expert.
Good Luck, Al

[suburban4x4]

well if changing the jets and rods on the edelbrock dont help i might just live with the predator carb then
the other thing is would a recurve kit help this over heating and what am i lookin for for total timing

my truck wheighs in at like 7000 pounds plus i was towing about 4500 pounds

[suburban4x4]

well the rods and springs individually from summit arent priced too bad so ill get those

[cadipacer]

I took the advise of " gilby 246" drilled 8 small holes in the thermostat ,,
drove Pacer tonight and HARD!!,, never got above 205 at a major intersection,, and 1/4 mile later back down to 193* w/ fans OFF while above 20 mph.. hope this solves the problem. Still need more test in different circumstances, but it looks good on the guage.

[Terrible One]

Why not just bump it down to a 160 or so degree thermostat instead of drilling it?

[Nashalac]

If the engine is going to run at 190 it is going to run there with a 160, a 180, or no thermosat. All the lower temp does is delay the enevitible. The drilling acts as a bypass as well as allowing all the air to escape the system during filling. I'm sure it does more but escapes me at the present. It's hell getting old and CRS set in a long time ago.

[Terrible One]

Shows what I know. Would this be a good thing to do for anyone? (i.e. myself?)

[cadipacer]

At this time 160 or 195 dont play too much into the problem I think its a VOLUME thing,, thats why after all else failed judging from the previous post of others I decided to go for volume so the 8 holes equaled almost the same diameter of the brass center in thermo.thus giving more movement of water, I assume the aluminum radiator is cooling what goes up front enough to come back to the block,, as the guage reads 190 most of the driving time. It appears a step in the right direction for my application with all virables considered.

[Terrible One]

I have to hand it to you, 190 is pretty low. Can someone post a pic of how I am supposed to drill?

[cadipacer]

PM sent to Terribleone....
I have now more running time on the 500 engine with the drilled out
theromstat,, and it DOES work much better stays around 190* until
sitting at long intersections hangs at 205* then when I start moving drops down within a 1/8 mile.

[Terrible One]

Sounds good. I'll definitly have to do this when I get the 500 built.

[rockhog]

If you could send me some picks as well that would be great!

[email protected]

[cadipacer]

PM sent to above