Finishing up on a 49 Chevy 3100. 350/350 with mild (Erson) cam. Flushed out the stock radiator, put on a 16# cap and a 16in Flex a lite fan because with the placement of the motor a mech fan would not clear the lower radiator hose. Also have Vintage Air condenser and trans cooler in front of the radiator so I'm probably blocking too much air. When it idles, the temp will run up to about 190 and stabilize when the fan kicks on (180 thermostat) but when it's driven or run up to 1750-2000 rpm the temp keeps climbing until it is shut down. Seems to have good water flow, thermostat works, etc. gauges are new and calibrated. Do you think an aluminum radiator with internal trans cooler would solve this or is there something else I should check?
Are you running a HP water pump? They can under certain conditions, flow TOO much water and not allow it to cool down in the radiator. Did you change the pulley sizes?
Confirm your dist. advances are working. Run 10-14 initial advance if you have less and see what happens. A aluminum radiator if a good one will help. The stock-er may have blocked tubes or calcium deposits built up in it.
That's what I was thinking. I've used a handheld infrared thermometer to locate hot spots and blocked tubes blocked before.
OK I'll check the timing. It has an Accell HEI Dist. I had the stock Rad rebuilt and cleaned up and put 1 1/2 flange in the top tank. Thanks for the help! If I go with an al rad what brands do you use? I've seen some up in the $750 range, Cool Craft is about $400 and Champion is about $200. Any experience with any of those?
I would look into replacing the radiator, or at least get it checked out by a radiator shop to see what sort of shape its in. I'm not big on electricic fans myself, would rather have the stock mechanical fan in place. Bob
I have a '52 Chevy Coupe which would run hot on the freeway. Since I was adding A/C, I sprung for a triple pass 4 row radiator. It helped but ultimately, it turns out the distributor advance was stuck and would not advance. Popped in a new distributor with the new radiator and she runs at 160, 180 with the A/C on. I run a mechanical fan with a shroud.
Why not have a radiator shop recore the original? Just flushing a 60 year old radiator won't be enough.
Usually when a car idles without overheating and heats up on the road it's a partially clogged radiator. I had it happen to me.
Just something to think about. My 427 BB Chevy in my 39 Chevy will not run on stright pump gas. It would over heat. I put up with this a a year. Fans, radiator, hoses. water pump One day I was are a racer friend of mine and was low on gas. he said there is a couple of gal in that race gas can. So in the tank it went. driving home I noted the temp was now about 200deg. by the time I got home I was at 190deg. This is about 25deg cooler that normal. I,m now running a mix of 50% race to 50% high test pump. Runs cool and fast. Maybe a higher octane will help. Gas now days is S&^t
This might be the key. When I hooked up the vac hoses I ran them where I thought they ought to go. Of course this was originally a smogged engine and I tore the Camaro apart almost 20 years ago so I really don't remember how the vac hoses hooked up and there are vacuum connections everywhere that are no longer used. I may have the timing off and the vac advance run to the wrong spot. Just have to figure out where it is supposed to hook up on a Qjet. A friend who has had this kind of problem on his El Camino said I should turn the dist about 5-8 degrees one way and try it then move it 5-8 degrees the other way and try it and see what the temp does. At least that will tell if it is a timing issue or the radiator. The radiator was rebuilt "rodded out" is what they called it at the radiator shop and checked so I would be surprised if there is a flow issue. I'm stuck with the elect fan because a mech fan won't clear the bottom hose because of the way the SB sits. At least timing is a helluvalot cheaper than radiators! Thanks for your help[.
SBC lower radiator hose comes down parallel with the block . Clears a fan on millions of others. Got any pics ? Assuming your tune is correct - sounds like an airflow problem or a radiator that is not up to the task
It is the radiator. The stock radiator, is not designed for any obstruction such as a condensor or tranny cooler. You have 2 choices. Recore, or replace. There are many after market radiators. I dont think there is anywhere in this country yet that is experiencing any kind of heat, so if you have an over heating problem now, its gonne be compounded in the summer time with the A/C on... Make sure your lower hose insnt getting sucked shut or collapsed... usually has a sping inside to avoid this. When I replace mine, I am gonna use DISSRAD out of clemmins Mich..... He has an ebay store. He makes-um, they are affordable, and all tig welded.
Here is a pic http://img.photobucket.com/albums/v518/Blacktailer/1949 Chevy/IMG_5398.jpg Hope that works. The centerline of the waterpump is only 4 inches above the bottom of the bottom of the bottom tank and 7 inches from the bottom hose. I could clear a 12 inch fan but it would only draw air from the bottom 1/4 of the radiator because of the way the engine sits in the chassis. I can't see how I could run a mech fan, do you?
Try running it without the thermostat and see how it runs. If it continues, try a 190. Some times running the 180 doesn't let the water slow down enough to cool when going thru the radiator. May be a stuck thermostat. Check in hot water.
asking, what does timimg have to do with overheating ? again asking, Half the time I dont use the Vacum advance
I am with you. I have had the timing so far advanced on my race engines, I needed a pull of to start them or I would eat starters. They never over heated, but this seems to be the question of choice. Go figure. To me reasonably speaking if a few degrees of timing makes that much of a difference in early springtime weather? well then OK!!
I've been told that timing can lead to overheating but have never experienced it myself. My buddy's Elc was overheating when he drove it and it gave him fits for months until he replaced the dist and the overheating probs disappeared. So how do you check flow of a water pump? That was my first suspicion because everything else has been rebuilt/replaced on this engine.
Confirm your fan is drawing air through the radiator, it should be able to hold a shop rag to the front of your grille. That radiator also appears to be a low fin count core (at least on the low res photo) and may not have enough surface area to drop enough heat as your engine makes power.
Zips water pump riser would/should get your fan centered. A custom shroud or modifying that one so it fits the entire radiator might help. Blocking holes in the core support so the air is forced to go thru the condencer & radiator - preventing airflow around the radiator will help.
Should feel pressure on the outlet hose by squeezing it, compared to the feel when cool and no flow due to the thermostate not allowing flow with the cap on. Also open the radiator cap after cool down then start till fan kick in, you can see the water flow current.
You can generally see water circulating in the radiator.... Back in the day, radiators had so many cooling fins per inch. With bigger engines, more cooling fins were needed. With A/C even more were needed. HP more Hot temps more.... ect.... If your radiator is original, it may flow fine, but simply not designed for your applications demands. 300 bucks for a USA made tig welded raditor is a wise choise, and gives peace of mind in my opinion.... Shops can recore yours with a core that is light years ahead of the original. You may be talkin $150 or so.....
The fan is drawing lots of air through the radiator. The shroud only misses the top 1 to 1 1/2 inch of the radiator. The pump is pushing water, didn't know if there was a spec amount but it is definitely flowing. It is the stock 49 radiator so maybe I'll look into having it recored with something that cools better. I'll have to see if I can find a local shop that does hotrods. I'll play with the timing first just to see if that makes any difference since that only costs a few minutes and minimum amounts of blood. Thanks for all of the replies and advice!
ZIPS makes a water pump riser which raises the fan 5 and 1/2 inches ... so a large fan can be run if you want a larger fan. .
Do you know if the Zips riser interferes with the AC comp or alt? I have the Old Air setup where the comp is on the pass side and the alt is now on the driver's side. http://img.photobucket.com/albums/v518/Blacktailer/1949 Chevy/IMG_5413.jpg
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