Ive got a 350 in my cruiser and I've always had problems runnin hot. 180 thermostat, custom aluminum radiator (i think 4 core), headers, electric fan etc. I usually run about 190 around town but on the highway cruisin above 2600 RPM it gets hot!. I was goin about 2750 for 20 min or so and then it creeped to 220 then shot to 240. I pulled over and shut her down and lifted the hood to find that radiator fluid was everywhere, it doesn't generally leak and Im thinkin it started spewing earlier, say around 220. Any suggestions? Thanks

I was just about to start a long thread with pics ect about how I concquered my cooling problem:D

I'm running a 350, and have a new 4 core FJ-40 radiator with a shroud from EPOCHS made for the 350. I just got a Flex-A-lite fan and added some material to the shroud and I can't get it above 175 no matter how hard I flog the motor. Another thing I did was to remove a little material from the fender-wells, you can see the pics in the "New Radiator" thread ;)

Its probably the fan not pushing enough air, is there any way u could remove some of the innner fender for more cool air. U could get a mechanical fan or a better electric.

Also, you might want to get rid of the headers. They contain too much heat under the hood. I use ramshorn exhaust manifolds and have a Griffin aluminum radiator with a TBI motor stock fan and a radiator shroud. My motor does not get over 210 or 220 degrees driving on the freeway at 100 degrees. BTW, I have a 195* thermostat.

Charles

I am/was in the same boat!

mild 305, 4-core from JT outfitters, 195 thermo, GM FWD OEM electric fan.

I switched the fan to a black magic P/N 150, which is the highest flowing electric fan I have seen (2800cfm). Added water wetter, and cut the rear of the inner fenders out. Better, but still overheats on the highway at 2500 and above.

Then, I raised the rear of the hood about 3/8", and pulled the fan AWAY from the radiator, and angled it down. Preliminary testing shows that around town, it's right around 195-200, and I couldn't get it above 210 with the fan OFF on a short stretch of back road. I'm driving it to work tomorrow, so I'll know for sure it it works!

My thinking is that the electric fan is blocking the air from getting out of the rad... moving the fan away (~1" bottom, ~2" top) from the rad will let the air go around the fan if need be, but that sucker moves enough air to still pull air through the rad for low speed work. I'll know about trail perofrmance friday evening.

Also, I don't understand a cooler t-stat, unless your temp gauge is dead on 195 all the time. If you are running say 215, obviously you are at/beyond the cooling system's capacity... I don't see how opening the t-stat sooner would help. Always wondered that.

Also, I'm sure it's not easy for the engine to turn 35" Boggers at 70, while pushing a 4500lb brick through the air... I'd get hot too!

Well, what your problem is, is that the water is flowing too fast through your cooling system. It is too efficient! The water is not staying in the radiator long enough. GM makes a part, what it does is restrict water flow, I do not know the name of it. What it does is slow the coolant down and allow it too stay in the radiator longer and cool off more. This will solve all of your overheating problems. I will try to post a part # or get the exact name of the part. This is a common problem with V8 engine swaps in all vehicles.

PLEASE PLEASE PLEASE get that number... the local GM guy is a moron, and all I can find on-line are restrictors that REPLACE the t-stat... I dont' want to lose the t-stat if at all possible...

My cruiser head buddy said that cutting 3 fins off the water pump vanes would slow the coolant down, too... I'd rather get the restrictor.. :p

Another solution I have heard about, but have not tried myself is removing blades from the water pump. Obvioulsy you have to take the water pump off and dismantle it. Remove everyother blade by grinding it down. This will slow down the rate of flow through the pump and make the water stay in the radiator longer.

If you check the chev manuels, you will find that most v-8 engines have about 23 qts of coolent, while the stock cruiser uses about 18. If you increase the radiator size of the stock cruiser it will run cooler. I ran in the deserts of calif. with an over size radiator and never hit 200. It does create a problem trying to put in sag powersteering since the radiator drops down in the frame where the steering shaft goes through the frame crossmember. The only option for power is the scout or truck conversion. Another odd condition is the temp of the exhaust. The 2f at 700 rpm idle at operating temperature is a little over 100 warmer than the v-8 at 700 rpm, even though it is more volume than the six. An old friend, and I do mean old, (bought a new car before wwII) said as a youth they would build hotrods and found that the heavier engine blocks would run cooler than the lighter ones. Because of the mass of the block they did not absorb heat as fast, therefore more heat went out the exhaust, and the engine would run cooler. Considering what the f and 2f weigh compared to a chev v-8 he may have been correct.

Find the part # yet????

for now you could add a high preashure
radiator cap.

I think mine was 18or20lb
But you will not be able to buy one at the local parts store.

got mine from sumit or jegs.

What you need is a bigger fan, you need a Lincoln Mark 8 fan.3500 cfm more than a black magic and a lot cheaper too. Got mine last week from a place in Texas $140 plus shipping. Give them a call Houston Performance 281 893-6080. Later

I'm tellin you guys, you gotta try the Flex-A-Lite fan. It only costs $20 and it pulls so much air it's incredible. I saw a dramatic change in the running temps after I put it in ;)

bigger water pump?
After a buddy of mine fabbed his k5 blazer into a buggy w/ rear mounted radiator and dual eletric fans, his 350 ran hot so he got a higher flow/volume water pump and now she's run's juuuuuust fine!

OK, I lost all of the part #'s but what it is is the restictor that replaces the T-stat. I also called up a friend of my dads that races circle track; used to run the mechanics at a Chevy dealership, he said if the restrictor does not cool it under 190, then buy a high flow pump. He also said that the restrictor should solve it, especially if you have an aluminum radiator. The reason for this is because the radiator in the Cruisers are smaller, hold less fluid, so the coolant flows through faster than a larger radiator. The faster it flows through the system, the less time the radiator has to cool it. The restrictor will slow the flow of coolant down and the radiator will be more efficient.

Please correct me if I am wrong: I have always heard that a restrictor slows the flow of water through the system. So the amount of longer time is pends in the radiator is good, but it also then spends longer time in the block giving the coolant more time to get hotter as well.

I have heard to solve the problem in the cruisers that you want the largest capacity radiator you can fit, high volume water pump, and a good fan/shroud combo.

I currently am rebuilding me cruiser and am putting a 97 Vortec in it. I had previously a 350 that ran hot. I kept the origional radiator and added a high voilume water pump and a black magic fan. I never had a problem when crawling infact when the fan would kick on I could watch the guage drop to about 185. However, I still ran hot on the highway. This I determined was from two causes. 1) obstructed airflow to the radiator at higher speeds - possibly from my front bumper and the small grill area of the cruiser. 2) obstruted airflow leaving the engine compartment - Engine to close to the firewall. Just gets like an oven in there and with the airflow at highway speeds it creates a air dam not letting the flow leave the engine compartment.

What I plan with the Vortec I am installing is: 2 core (big 1" cores) Aluminum radiator, the 19 inch Vortec mechanical fan with the serpentine belt, custom made shroud, possibly some inner fender trimming depending on my placement of the vortec. Plus the vortec has an engine oil cooler.

Greg

At highway speeds the problem isn't the fan. The fan is for when you're travelling slow.
The problem is that there isn't enough air flow over your engine and out of the engine bay.
My truck was doing the same thing. Ran right on the thermostat all day at slow speeds but as soon as I hit the highway it would crawl up to 220-230+.
Trying raising the back of your hood so air can get out.
I've heard a 1-2" body lift works really good to improve flow.
I cut out my fenderwells and it didn't really help that much.

I raised the back of my hood little, and it seems to have worked well so far, in addition to NOT putting the fan right on the rad...I spaced it back about 3/4"... it lets air go around ti at high speeds.. so far, so good! 215 degrees at 70mph on 35" boggers!

ok, i picked up a box of restrictors today. what size to use? 5/8", 3/4" or 1". Also, if the restrictors dont solve it, why the high output pump? I thought we were trying to slow the water down not speed it up?? Thanks

Let us know if the resstricers worked cause I had the same problem. Running a 350 with stock 3core rad. stock pump, and 15" rigid fan it would over heat at slow speeds. I put a custom shroud on and that helped alot. It still got hot but would take much longer to get there. Kinda would like to know what works cuz I have the motor out now for a rebuild and i would like to get the correct cooling stuff the first time. 25"x19" 2 row aluminum radiator is first. My tape measure says it will fit past my saginaw conversion with custom mounts.

BTW, whats the correct way to mount a aluminum rad? The universal ones dont have mounting tabs so am I supposed to drill holes in top and bottom flanges and bolt to that or make a mount that sandwiches it in place?

You could make a custom radiator mount like this:

http://www.lslc.org/austinbios/blumenthal/Dulciena.html

3rd picture down.

To make a long story short, I took my stock one, cut it in half width, put a half inch angle iron it. Then cut in half length way welded in one and half inch sq tube. If you want a real detailed report, let me know.

Remember, measure twice, cut once. :smokin:

Ok, I tried the smallest holed restrictor. It (obviously) takes for ever to warm up and rarely gets above 180 in town but when i get on the highway and run 2900+ it gets up to 240. Should i try a different size restrictor or what? Is it likely that maybe my water pump is shot, doesn't leak or anything but I have always had problems cooling my 350 and I've try many different thermostats, fan combos and i did cut out rear fenders.