Hey guys, been a while.

My car is a 1970 Ninety-Eight with a 455, either 105k miles or 205k miles, been in the family for 4 generations. I've rebuilt the front end, new radiator and cooling lines, plugs and wires, internally regulated alternator, all new wheel bearings, etc. Dad swears the motor was rebuilt but uncle says the heads have never been off, so who knows. The Q-Jet is original and seems to be running ever richer. Th400 won't downshift by itself in spite of a new governor, but whatever.

I've been bugging you guys about it since I bought it off my uncle when I was 17, and your help has been invaluable, but now I've gotten married and I'm moving from Utah to Texas in a couple of months. Turns out it's really hard to tow something as heavy as a C-Body, so I'm thinking of driving it. D: I know, but I can't afford a decent tow and I REALLY want to pass this on to the 5th generation.

The biggest issue I can see is that it seems to sit around 210 degrees on my coolant temp gauge. Warms up to 220 at a stop light. Winter, summer, whatever, doesn't care. It's got a brand new 2 core [aluminum I think] radiator, a good thermostat, and I flushed the whole block three times. Fan clutch is fine, shroud is there, and I pulled out the condenser just to be sure.

How hot is too hot? Should I be looking at a 4 core rad, or should I start with timing / air-fuel? Or should I just bring a tow rope and pray it makes it?

Or am I just insane for thinking I can get a 46 year old motor to take me another 1300 miles?

Thanks, sorry as always for the super long post.

 

Did you replace the radiator cap? A 2 core radiator is probably a little light for that big car. Check the timing.

 

What temp thermostat is in it?

 

How do you know that your temperature gauge is accurate?

20 years ago, a buddy of mine moved from NY to California, drove it in his '67 Chrysler Newport 4-door (the MoPar 98, or at least 88) towing a trailer.
When he got there he realized one spark plug wire was off and he'd gone the whole way on 7 cylinders and hadn't even noticed.

I wouldn't worry about it.

- Eric

 

Yep, brand new cap - although it does leak a tiny bit from the thermostat gasket, could a small leak do it?

I'll check the timing today - always have a hard time getting that straight. Old chain + someone doing something weird to it 20 years ago means that it acts like it wants 12-14*BTDC, but I've also got a leaking manifold gasket so I have a hard time hearing if it pings. I have at 9-10 at 1200rpm on the marks right now, which might be innacurate, with dwell at 30* according to an old shop meter. But it's always run at 210-220 regardless of what I've got it set at.

 

Good question. Either 165 or 185, and I've honestly forgotten. Usually I go with the colder one. My sensor is in the port in the intake manifold, if that makes a difference.

 

Another good question - what's a good way to test something like that? I might be able to borrow a laser thermometer, that would at least give me an idea of how far off it might be.

Ha! That's awesome. Now that you mention it, I did drive it without a worry for 4 years before I put the gauge in, so it's probably fine.

 

An infrared thermometer would be good, but that, too, would have to be calibrated.

I'm not sure whether this is "kosher," but I boil water in a block pot (they read best from non-reflective surfaces) and see whether they read 212°.
The one I have is consistently 5° off.

Read temps from several places once the engine is warm and the thermostat is open.

- Eric

 

Good idea, I'll see if I can find/borrow one somewhere. In the meantime, I might pull the sensor and throw it in a pot of water on the stove. Pretty easy to tell where 212* is that way I'd imagine - or 207* anyway, whatever boiling is up here in the mountains.

How hot should it be getting? I've heard everything from 180 to 215. My Jeep sits at 205, but I wouldn't use that as a good example of anything, and nothing else I've ever owned has had a numbered gauge. Am I right in thinking 210-220 seems a bit hot?

 

We've had "several" discussions about this over the years, but, in an ideal world, the engine should get as hot as its thermostat set point and no hotter.

In practice, this isn't always the way it happens, even in cars where everything is set up "right," but, really, it should be.

The absolute temperatures that you describe are not unusual, and should not be harmful, if accurate, but the engine should be able to run cooler.

Three main factors that could be affecting your engine temperature, specifically, are:
Radiator capacity not adequate (no matter what it's rating is "supposed" to be),
Rubber seals around radiator not in place, allowing too much air to bypass the radiator at highway speeds, and thermostat not opening far enough (I am a fan of the Robertshaw "heavy duty" type).

I have a '68 high compression with an original-style 3-row radiator and a 160° thermostat in my own car, with an unused A/C condenser in place, and a recent highway drive showed that around 80 MPH it nudges a bit above that number, maybe to an indicated 165° or 170°, but that's it.

- Eric

 

Thanks, that all makes sense to me. I'll start by testing the gauge, and then I could try it without the thermostat to make sure that's not the issue.

Considering I'd be driving it in Texas in August, I'm worried about it getting up to a harmful temperature at some point. My personal bet is the cheap radiator, but it probably doesn't help that my water pump is 30 years old - is there any good way to test it short of taking it off and looking at it?

 

Your cooling will be adversely affected by running without either a thermostat or a restrictor - there needs to be some restriction at that point to allow increased coolant pressures in the heads.

The water pump question has been a sticky one forever, but there are water pumps out there that have been more carefully designed than the average rebuilt, such as FlowKooler.

- Eric

 

Good to know. Sounds like I need to do some homework.

Thanks

 

The thermostat open temperature is the temperature at which the thermostat opens, not the temperature at which the engine runs.

There is nothing wrong with operating temperatures in the 210-220 range. At 16 psi, the coolant boils around 250F, and you are well below that.

 

I agree here. My 350 will get up 210-215 if I'm sitting in traffic. That's going off of a cheap dash mounted gauge in the intake port on a 90* day. On the highway at 70mph it's around 200. 75-80 it's a little hotter. Knock on wood, I haven't even remotely gotten close to overheating. Mine a stock radiator, and I do have a thermometer radiator cap, but that's not super accurate.

It'd say the car will be fine. Make sure all your fluids are topped off, that you have some basic tools, a spare tire and small hydraulic jack(cause bumper jacks are a joke) and head on out.

 

You might think about taking a round trip of 150-200 miles or so before you leave. If you don't have any problems on that trip, you are probably good. How old are you tires?

 

Do you mean it won't downshift at WOT? If so, the TH400 uses an electric downshift switch so the modulator won't affect that at all.

 

That makes sense. Guess I just thought it was ususally lower on an older system that wasn't necessarily designed to rely on higher pressure - hence why my Jeep has a 195* thermostat in it, etc.

 

Well that's a whole other issue. My pedal switch is dead, so I have that wired to a switch I can hit manually. What I mean is that it'll go 1-2-3 and then maybe back down to 2 at a light if I'm lucky, but usually just sits in 3 after that until I shift down with the handle or hit my switch.

At least it's shifting at all now, it was stuck in 1-2 alternately for a long time, my third vacuum modulator finally fixed that. Stupid TH400 valve magic.

 

Good idea, and good question - two are brand new thanks to the worst alignment job I've ever personally seen, one is about 2 years old, and the other one... let's just say I should probably be able to blow holes in it at this point. So I should probably get that replaced.

 

That's good to know, thanks.

I guess what's hard is that there seem to be two groups - us guys with cars running at anywhere from 205-220, and then the guys who have to put a hotter thermostat in so they don't get too cold. What's the difference, I wonder? I mean there's a huge gap between 210 and 165, there has to be something obvious I'm missing. Is it pumps? Bad radiators? Old motors?

 

Make sure you tuneup is set right. This does not require changing parts, just cleaning the old parts and setting everything right. Put a bottle of water wetter in your radiator and go.

 

x2 Oldscutlass, improper timing will make the 455 run hot, I wonder if the chain has worn or slipped?? Anyway here's some brain food from Oldsmobile FAQ:
Every increase in timing advance results in an increase in spark plug temperature. One chart I've seen put out by Champion Spark Plugs indicates plug temperature increases in percentage about one number higher than the advance figure. For instance, if your timing is 2 deg BTDC, plug temp will be roughly 3 per cent higher than at TDC; at 4 deg BTDC ,plug temp will be roughly 5 percent higher than at TDC and so on. This increased spark plug temperature is one cause of preignition. The spark plug itself becomes the hot spot that contributes to the problem. Other contributing factors to pining are excessive carbon deposits, poor or low octane fuel (at least lower octane that the compression ratio requires), some fuel additives, excessively lean air/fuel ratios, etc.


Car most like has A/C is there a radiator shroud??

 

I put a bottle of water wetter in my 54 and have not seen any difference. Some of the stuff I read on it is that it work better in pure water. If you have a 50/50 coolant/water mix then it is not very effective. I think it is used by the circle track guys a lot.

 

Good question, I've always thought the timing seemed a little weird. Could it be too retarded? When I got it, it was at like 16*btdc according to the timing marks, but other than a high-ish idle it loved the extra timing. I got scared and moved it back to 10 ish. I really need to check TDC

Car has had A/C completely removed. It was junk when I got it unfortunately. This includes the condenser, took it off to remove any extra restriction on radiator flow. Fan shroud is still there, seems to pull well through the radiator.

 

I'd never heard of it until today, looks interesting. I siphoned out half of my coolant and replaced it with distilled anyway today, so it might be worth a shot.

In other news, I went ahead and replaced the thermostat. Old one didn't move much - only 2 years old but looked like garbage. Spent a bit more on [already forgot brand] - and it did seem to take longer to hit 200, but it definitely wasn't magically a refrigerator like some of your cars. I'll tilt the car over and burp it properly tomorrow and report back.

Also want to note that my radiator actually looks like the 3-core, not the 2-core - I have a terrible memory and it was two years ago so I'm not 100% sure. I do remember it being a bit thinner than the original though so I wouldn't be surprised if that's the issue.

 

I agree. You know a lot of the guys running 190 all the time, they do have electric fan conversions, or other. Do you have a link to the guys who put in hotter t-stats? It'd wager they have all kinds of modifications, fans, high volume pumps, etc. I worry about mine sometimes, but it's unwarranted. Like I said, knock on wood, I've never had a problem. A new radiator should help. The spectra radiator at Autozone(At least for the cutlass/442) seems to be good, really good. My radiator is due for replacing, if I tug on the hoses, I can see the neck of the radiator flex a bit, so it's getting old/weak. I do have a pump master replacement waterpump, just a factory replacement style. I have the oddball 5.072" shaft, so it was the only one I could find.

I do have a shroud, which I saw you do too. Keep it. It helps. Something else to consider is the accuracy of the gauge too. Mine is a cheapo sunpro gauge, I put it in there just to have because for a while my temp idiot light didn't work. If the gauge is old, it could be off.

Just cruise easy. Leave at an off time. Try to avoid rush hour times if you can. The two core aluminum radiator should flow the same or better than the factory one. I wouldn't go change the radiator out to a replacement 3 or 4 core just for this drive. Maybe down the line if you go through the motor etc.

Can you find the link and post it? it'd like to read this. That's interesting.

My car loves additional initial timing too. I've got hei, but my initial is like 18*+. It's off the timing tab on my 72 Rocket 350. I can't explain it. I had a 4 page thread about it a couple years ago and I never was able to figure it out.

 

Yes, retarded timing can cause the engine to run hotter (or maybe I should say advanced timing makes the engine run cooler - it's all relative). When I go for emissions testing, I decrease the initial timing from 18º to 10º (HEI distributor) and the engine heats up to ~200ºF during the test. Once I leave the facility, I set the initial back to 18º and the engine temp comes back down to 180ºF.

 

I'll have to look up some links for you, I don't have one offhand. I'm sure you're right though. @MDchanic, what's your car like? He mentioned that it runs at 160-170.

Will do - and I do still need to test my gauge, I wouldn't be shocked if it was off, I think it's an old Sunpro as well.

I remember that thread, I read through it while trying to figure out my own issue. In my case, everything should be stock, but parts of the family claim they had some farmer rebuild the motor 20 years ago, so he might've done something odd. It does have great compression for its age so I wouldn't be surprised. I just wish I could hear it correctly to tell if it was pinging, but everything rattles and my ears are bad, and I still haven't managed to plug the manifold leak on cylinder 7.

 

I'm starting to think I need to figure that problem out. Mine will act like it's too advanced if I go near 12 - hard hot starts, high idle - but man does it drive great. So then I retard it, and its idle goes back down, but it acts like it's running rich, fuel burning out the tailpipe, no power...

When I got it, the thing had been tuned by some guy at a carb shop who is now dead. I wish I could figure out what he did, because I could burn one of the back tires at will and got 15mpg. Never been the same since, in spite of my years of Q-Jet rebuilding, timing setting, etc. Followed every guide and manual out there and it still sucks in comparison. I figure I either broke something, or he REALLY knew his stuff.

 

I've got a non-rebuilt 1968 high compression 350 with a small cam and mildly ported heads (actual compression about 10:1, if I recall), with an old-aftermarket brass 3-row radiator with a 7-blade fan (forget the diameter) and fan shroud, and just switched from a super-heavy-duty fan clutch to a heavy-duty fan clutch, running a Robertshaw 160° thermostat (lower temperature to reduce detonation).

On yesterday's 300 mile run, I found that the temperature got as high as about 180° on sustained 85 mph uphill portions, other than that it says rock-steady at 160.

- Eric

 

MDchanic that's nice!

 

Thank you.

It ain't much, but it runs.

- Eric

 

squeek,

what'd you end up doing?

 

Renting a big-*** trailer and pulling it behind a uHaul. Well, that's the idea anyway - pick it up tomorrow, I'll keep you posted. Hopefully we get there without anyone driving off a cliff or turning into a fireball.

 

If you do it drunk, on bald tires, with a parakeet loose in the truck, you'll have better stories to tell...

- Eric

 

Eric lives in Maine also, whole different ball game from here in Tejas. My car, with a 180* thermo runs 190# all day long on the highway and in traffic can get up to 220* I don't worry about it. I have a flex fan with no shroud behind a cheapy 2 core aluminum with plastic tank radiator. Been that way for a few years now and I drive it regularly.

Good luck with your trip.

 

I'm starting to think I need to figure that problem out. Mine will act like it's too advanced if I go near 12 - hard hot starts, high idle - but man does it drive great. So then I retard it, and its idle goes back down, but it acts like it's running rich, fuel burning out the tailpipe, no power...
==========================

Sounds familiar
like my 403 => High compression
like the SOB SBC this week

the ported dist'r vacuum thing started in '68 I believe as an emission thing, patched by a TVS to alleviate overheating at idle... by advancing the timing - duh.

SO, a good way to fix this is to set the max timing with all mech and no vacuum to 36 degrees. Run the MANIFOLD vacuum to the dist'r just like the '65 Delta 88. Then adjust idle and mixture for highest vacuum.

With no vacuum before starting, the engine cranks w/o that faltering backpedaling crap. with vacuum after starting , the timing advances and the raw fuel out the exhaust issue and the overheating issue goes away.

So.... how do you like manifold vacuum to the distributor now? Sounds attractive?

 

Hmmm, - I have mine hooked to the port on the distributor, got rid of the electronic... whatever the hell it was that controlled it. Haven't tried just straight advance though, just that port so I have the off-throttle advance. I'll mess with it more when we get down there. Leaving tomorrow, I'm so damn tired.

 

Good to know, appreciate it. I figure at this point I'll blame 46 years old + cheap autozone parts and forget about it. Put it up on the curb the other day and burped the coolant like crazy until the rad is 100% full with no air, also removed the condenser - get about the same numbers you do now.