[beargfr]

Just for your reference, the radiator opening in the core support on my 69 measures 34" wide by 17-18" tall. The factory radiator had the tanks on the sides, so the actual radiator core area is about 29" wide.

Bear

[HWYSTR455]

Can you take a pic of the top of the engine with the air cleaner off? I suspect you have the vacuum advance connected to ported, and suggest maniflod vacuum.

[Goin' Topless]

Here's what I did to solve my overheating problems:

I have a Desert Cooler radiator, stock pump with cast impeller, regular duty Hayden fan clutch, stock shroud, 185 t-stat on my fresh 462 and it wanted to run 210-220 all the time.

I did one thing: installed a severe duty fan clutch. That knocked it down to 200-210F.

After that, I took a look at the state of tune on my car. I messed around with my timing, making sure the weights weren't stuck on the distributor and were moving freely. I had the vacuum advance pulling directly off of the manifold, which is best. After I had a good handle on the timing and where it behaved the best (16 degrees mechanical w/20 degree stock vacuum advance) then I had to play with the idle mixtures. Now I run around 190-195.

I plan on putting a Mr. G's high flow thermostat ($5). Based on seeing what it did to my dad's cars (502 67 Chevelle & 454 70 Chevelle) this is good for another 5-10 degrees.

Hope that helps.

[mtnbktrek]

i have an edelbrock carb and the adv is hooked up to manifold i have the ported capped.....

my rad support opening is 27'' side to side im pretty sure my core w/out tanks is 18'' side to side

[Goin' Topless]

from US Radiator:

Year(s) Engine Core Size Rows
1968-71 V8 350/400/428 17 x 28-3/8 3,4
NOTE: 28-3/8" Wide, Factory 2" Thick Core, 2-3/4" Wide Driver Mount, 3-1/2" Wide Pass. Mount

1968-71 V8 All 17 x 28-3/8 4
NOTE: Factory 2-5/8" Thick Core, 3-1/2" Wide Mounts

[Squidward]

Like hwystr said, a pic would help, and might give some better direction.

There are a number of things that could be going on. There are 3 main coolant flow paths: from pump, through divider plate(s), into block, and up into the heads. From there, it goes 3 different ways back to the pump suction.

1. From the back head to the heater core and back to the pump suction, bypassing the radiator.
2. From the heads to the intake water crossover and back to the pump suction via the small bypass orifice between the crossover and timing cover. This also bypasses the radiator.
3. From the heads to the water crossover, through the open T-stat, and to the upper rad hose/radiator. Then it goes to the lower hose and back to the pump suction.

It's important to know that increasing/decreasing any of the above will change the others inversely to balance a given amount of volumetric flow capability.

#2 above is pretty much set from the factory based on the orifice size on your intake/timing cover. Ya can't change it much unless you drill or plug, and you shouldn't really do either.

#3 is the one we want the most of. Make sure your t-stat opens properly and you don't have any munge or blockage. You already said your pump/divider clearances were checked to maximize flow efficiency through the pump and to the block. I'm assuming your rubber grommets on your timing cover sleeves are also in place.

Do you have your heater core bypassed? This could cause an increase in #1, resulting in a decrease in #3.

Also, there have been a number of posts and tips about using a water neck/upper hose that doesn't allow air to remain trapped in the system. Trapped air also causes a flow decrease.

After that, you'd have to start troubleshooting possible airflow issues (shroud? fan?) and tuning, as has already been discussed.

I apologize for repeating any tech info you already know.

I ran a stock 4 core radiator in my 73 bird with a 180 tstat, nothing fancy, and it kept it under 210 in Arizona with 115F outside on the highway. This was after replacing the previous owner's water pump only to find the plate was never put in.

[goatwgn]

A shroud is very important. All GM V8 powered cars from 68 on had them. The ac cars had them standard several years before that. Once you have the basics sorted out (as others have stated on here) water pump to plate clearance,thermostat, all air out of system,fan shroud, decent fan,timing, water flow,air flow,adequate sized radiator (a 3 core is pushing it on a 400) you should be ok. Wouldnt worry about racing the half pint ricer toys until you get the cooling issues sorted out, then you can save up money and step up to a different cam, (a set of gears would make a big difference), head work, even a bigger hammer (such as a 428/455). I personally dont think it is even worth bothering racing these things, but none of my "peers" at my age ever had that stuff (it wasnt in existence yet) I can understand you be surrounded by all of them, but look on the bright side- you will still have a nice older Pontiac years from now-if you dont drive it in the winter a lot in PA. These other things will be recycled and wind up in the local vending machine.

[mtnbktrek]

yea thanks a lot i app. the input! all the ricers that beat me are like "there is a replacement for displacement its called a bi-turbo w/forged pistons " i just tellm yeah ur gunna smoke me but its a fact that i look better losing than you do winning! .... i think perf yrs sells shrouds im def going to pick one up... i have a posi rear that id like to build, im tring to keep it as stock looking as possible and i will take some pics tom morning

[goatwgn]

When you put turbos on V8s (with the appropriate built short blocks) you end up with some very hairy stuff (like 2500 hp or more)

[mtnbktrek]

the thought had x'ed my mind....too much $$$ in supporting mods

[mtnbktrek]

Ok I found a shroud on perform yrs part num Item: RPE65P does this part fit over the tanks and bolt to the rad support ? It cannt because there are no clearances made for the hoses... Right? I assume i have to fab mounting brackets? So the only area covered by the shroud is the core .... Correct ?

[mtnbktrek]

if anyone wants to answer my last question i am still checking this thread!!!thanks

[AG]

My '72 vert was running hot with a 455 and stock 350 2 bbl radiator. Had a Hayden severe duty clutch fanwith 7 blades, water pump mod, good shroud, high flow 160ºF brass t-stat. I threw on the flex fan from my other car and now it won't get over 180ºF on a 95ºF day on the highway, it's a cheaper route to try before an aluminum radiator. You can find a used one cheap because a lot of people don't like them.

[GT182]

Mtnbktrek, I can set you up to talk to a guy here in New Castle that can recore your radiator with a SLK core. It'll be like having a 4 core but still only 3. Extra tubes and fins but you'll still have the same tanks . Unless you look very close you can't tell the difference. And it works great. Far cheaper than the expense for an aluminum radiator. Just my .

And these SLK cores are made in Philly.

[am.mscl]

Originally Posted by mtnbktrek

Ok I found a shroud on perform yrs part num Item: RPE65P does this part fit over the tanks and bolt to the rad support ? It cannt because there are no clearances made for the hoses... Right? I assume i have to fab mounting brackets? So the only area covered by the shroud is the core .... Correct ?

I would say you need to get a shroud and put the clutch fan back on the car.
Most shrouds will cover the core area only, a few will extend out to the tank area but will not block the hose inlet and outlet. I can not answer your specific part number question about being the correct one for you car but if you call Performance years they should be able to. They should also be able to answer mounting question you have about it also.
Ray

[BVR421]

The closer you can copy the factory AC/HD cooling systems the better it will cool. Fans, shrouds, seals around shrouds and radiators, air dams under front etc
Best upgrade I ever made on my street cars is a piece of tape covering the temp gauge. Millions and millions of Pontiacs with only an idiot light and no gauge spent their entire lives at 200-250 degrees and had no problems. Neither did the drivers as they didnt know and didnt care.

[chiphead]

This thing has an edelbroke carb? Is it tuned correctly? Running lean results in higher combustion temps, and that heat goes into the cooling system.

Ditto on the HD fan clutch and A/C fan blade. Are you running the correct A/C water pump pulley? It's about 6" diameter.

As I've said before, a large 2-core aluminum radiator from PY solved all my problems. Even my 4-core desert cooler couldn't keep my 400 below 205. Now I'm 170-180F in all weather. After you check everything else, then it's all about the heat exchanger.

[mtnbktrek]

thx 4 all comments! i have a brand new hd fan clutch to put on w/stk fan and the water pump pulley is 6'', the edelbrock carb i think is going byebye this spring i just rebuilt a q-jet as far as in depth carb tuning( jets/metering rods) i am tring to find a local guy that knows his stuff and wouldnt mind working with me on that this summer...i spoke to edelbrock this past summer a few times about the carb which was bought brand new and they told me not to mess w internals (jets/metering rods) that out of the box is best performance just set idle air for each side and the base idle, which i did and at a 1/8th mile it would fall flat on its face like it needed more fuel i have a high volume mech pump(new) that edelbrock recommended to fix 1/8th mile prob but thats another story