Running hot

Canadian Poncho · A Poncho Legend!

Running hot

4SPEED427 · A Poncho Legend!

I don't think that all the small blocks have that port above the timing cover. You will see a small square head plug above the timing cover on the passenger side if your block has it.

Todd, you may know that GM has a pretty potent coolant flush that you could pour in and try. That would help clean out crud in the block.

I have heard various opinions on where to mount the temp sender. I'm not sure what I believe any more!

Canadian Poncho · A Poncho Legend!

I'll give that a try first.
Todd

73SC · A Poncho Legend!

Keep in mind that you never saw a "red" light when you had trouble lights. I think factory gauges are not the most reliable in terms of accuracy either, especially 40 year old ones that have been sent in the mail.

I now have two sets of gauges so I am tempted to switch and see how consistent they are. Your idea about putting in a trio to measure accuracy is a good one too.

Canadian Poncho · A Poncho Legend!

I have a suspicion the gauge is right. The car puked some coolant when we got to cruise night last night. I also think overheating may have been the reason the pushrods bent/broke when Ken had the car. I read on a couple of websites overheating SBC's can do that. There also wasn't a bulb in the cluster for the temp light! Chock that up with the fact that there wasn't a thermostat in the car when I got it and I suspect there is a problem. It may have ran much hotter before I got it as the coolant was a rusty brown when I drained it.

-- Edited by 69Laurentian at 11:01, 2008-08-04

427carl · A Poncho Legend!

How about WATER WETTER? or something like that ...unfortunately it wont be long ,and winter will be here Time to put the small block on the engine stand in the garage...

macsleuth · Guru

Running hot, could be run lean!, check timing, check fuel pressure and re-check carb, running smooth during idle is good, but there are different circuits for idle, off-idle, cruise etc. Smooth idle, means running slightly rich, it's ok to rumble a little during idle.
But of course if the block is full of 30 years worth of crap, that won't help with cooling. Water wetter is a good idea after a good cleaning. What temp thermostat are you running?
Do you have enough rad? for your engine/trans combo?
Good luck.

Canadian Poncho · A Poncho Legend!

I hear you Carl. The big block swap is happening this winter. I just want this engine to hold together until then. The engine is the factory 350 which has an Edelbrock intake, 650 Edelbrock carb, L79 cam and dual exhaust. Ignition is later HEI. Nothing too radical. Trans is THM350. I just think this car hates being out of 30 years storage. I notice now the rear main is leaking badly too!

73SC · A Poncho Legend!

How Hot Is Hot?

Most people have been led to believe that 180-190 degrees is ideal, so
they start to panic at about 200 degrees. Wrong. If we assume that
your cooling system can maintain an operating temperature within
about a 30 degree range under most driving conditions, then you should select a thermostat that will keep the operating range in the 190 to 200 degree range. Parts failure on a properly maintained engine should not
be a consideration until water temperatures reach 250 degrees or higher.

Source:
General Motors Performance Parts
Crate Engines
Frequently Asked Questions

-- Edited by 73SC at 23:50, 2008-08-04

67BBSD · Canadian Poncho Superstar!

Todd, have you found a big inch block for between the fenders?-keep it mild or the gas tank will get empty even faster ! I heard about a Canadian Pontiac 396/350 horse today if you have interest.

Ken

Canadian Poncho · A Poncho Legend!

I have located a 454 that I should be able to simply drop in. It's a good runner. It won't be too radical so my mileage shouldn't suffer too badly.

73SC · A Poncho Legend!

Does this mean you will be making custom 454 fender flashes to replace the 427 or will it be our little secret?

427carl · A Poncho Legend!

73SC wrote:

Does this mean you will be making custom 454 fender flashes to replace the 427 or will it be our little secret?

He thinks its 454 out of a 1 ton, but it is a 427! no really C2

Ghost Post · Poncho Master!

Is your cap for sure good and retaining pressure?.

Are you running a fan shroud?.

Any chance there's an exhaust obstruction?.

What suffix is stamped on the pad of your BB?.

Canadian Poncho · A Poncho Legend!

I borrowed a laser thermometer today and took the car for a good run until the gauge read about 225. I did a number of measurements at that point:

Upper Intake at front 199F

Upper Rad Hose 163F

Lower Rad Hose 145F

Head at sending unit 218F

Rear of Intake 213.8F

Rad Fins 145F

Left head at front 194F

Thoughts? I wonder if I have an air pocket from swapping the temp sending units. I might order a 160 degree T-stat and see what that does.

Todd

73SC · A Poncho Legend!

Todd,

My new Rally Cluster temp gauge is reading even worse than yours. It is either the guage or the sender in my opinion. My coolant is good and the car has even run in parades on Canada Day and never overheated.

I checked my temps like you today, when the highest at the block was 203 the gauge read 260. At idle in the driveway the highest at the engine was 159 and the guage was about 190. We found that about 12 ohms resistance brought the gauge in line.

I am going to check with the parts store and see if the senders come in different ratings for Pontiacs and Chevy. I'm not sure what one I have. I also have a second set of gauges that I could set up and see what's up.

I am not worried about overheating but I don't like seeing the gauge read so high. It is interesting we are both having the same issue. I can fix it with a little resistor but that will be my last resort. BTW I run a 195 degree thermostat as per owners manual.

Your air pocket idea might be worth some attention too. What would you do to address that, open the rad cap and run the motor?

-- Edited by 73SC at 22:34, 2008-08-05

4SPEED427 · A Poncho Legend!

Todd

To me it seem strange that your intake is so hot and the upper hose is so cool. It should be much hotter since the stat should be wide open in an effort to cool the engine. I am no technician, but that's how it appears. The thermostat is new, isn't it? It might be worth trying a 160 if you can find one. I have also had very poor luck with jobber thermostats, and very good luck with GM stats.

Ray

Have you installed the sender that is listed as being correct for your cluster? I am positive that GM has at least two different choices for resistance for the temp gauge senders.

73SC · A Poncho Legend!

Carl Stevenson wrote:

Ray

Have you installed the sender that is listed as being correct for your cluster? I am positive that GM has at least two different choices for resistance for the temp gauge senders.

Thanks Carl, I am going to double check that PN. I have BWD #WT203, listing shows it fits a ton of cars including 1973 Chevelle 350 engine code H & K which is what I have BUT I may need the Pontiac one to match the cluster.

Canadian Poncho · A Poncho Legend!

Interesting Ray! You would think GM would be consistent with sending units to keep costs down! My sending unit is from an early Camaro. I picked it up at Early Birds. If anyone has access to the American Pontiac parts books it looks like I need the sending unit from a 69 Bonneville with the Rally Cluster. Carl, do you have access to these PN's?

I'm less worried than I was but will swap the T-Stat. The car runs so well otherwise since I replaced the carb.

73SC · A Poncho Legend!

The advice I recieved on the oil sender from 77Canamman on PY Forum was that Pontiac used 80 ohm and Chevy used 60 ohm so I got the 80 ohm. Might be a similar situation for the Temp sender, it may be a consistent 60 ohm for Chevy senders and my guages look like they need 80.

We figured we needed about 12 more ohms resistance with a rudimentalry test with a slot car control, which if I have a Chevy at 60 = 72 in total. That's pretty close to 80.

Canadian Poncho · A Poncho Legend!

So as per the post on the other thread, are you going to "spoof" the gauge with a resistor?

Probably the best way to do it would be to put it "in line" on the wire to the sender and hide it with heat shrink tubing..

Todd

4SPEED427 · A Poncho Legend!

I will be curious to see how it works out. I can't see why it won't be right, but the parts book actually says they are the same, so....???

I had a similar problem when I converted my 66 Grande Parisienne to a US cluster with gauges, many years ago. Never did sort it out.

73SC · A Poncho Legend!

Well 65 Camino and I took a run out to a Mississauga cruise in tonight in rush hour traffic. When we got there we took the temperature of both engines. 65Camino has a trio set of gauges and he was showing 215, and we measured 209 at the engine. My gauge was reading 280 or so and the engine was 220. So we proved that taking the temp at the engine is fairly accurate based on 65 Camino's readings.

I have another temp gauge that we will test on the car and see what it reads to confirm or refute the gauge in the car now.

Was also thinking that teflon tape on threads of sender may be making a poor ground. As Carl says checked with Borg Warner today and WT203 is for just about every GM car ever made.

Last resort will be as Todd says, resistor with shrink wrap in wire sheathing.

Going to cottage soon for a rest so may or may not report in before weekend.

-- Edited by 73SC at 23:45, 2008-08-06

73SC · A Poncho Legend!

I can make this short and sweet. Gauge currently in car is bad, it is from the unknown car with 5000 RPM tach from California, cluster stamped 1976. Ran car for 40 minutes, temp at engine 187, temp on gauge 250.

Set up extra gauge from 1973 GTO cluster from South Carolina, the 8000 rpm tach cluster. Temp at engine 187, temp on gauge 190....BINGO ! biggrin

PS: Also got offered a radiator air deflector from my Grafton Ontario parts source. My car is missing this piece. Should help to keep it cooler at highway speeds.

-- Edited by 73SC at 23:16, 2008-08-07

Astro Jet · Poncho Master!

How are you measuring the temp. at the engine?