455 overheating !

Yeah I know, it's me again ! O.k Got the car to a driveable state now but I'm experiencing overheating. I fitted new head and valley gaskets recently, cleaned all the ports and waterway entrances/exits and generally made all the waterways that were accessable, as clean as possible. (some were badly clogged up) De-coked the piston crowns and cylinder heads. Assembled the top end of the engine, torqued it down as instructed. The radiator is running free, no apparent blockages. Flushed the whole system twice with radflush. So, what are the symptoms? I hear you ask. The engine will start without hesitation from cold, choke works fine, fast idle, stab the gas pedal once after a short time, it's slows down, stab it again after a little longer, the choke shuts down and it idles like a V8 should. However, after only a short drive, maybe one and half miles or two. it starts to misfire and run a little rough, poor throttle response. It stalls, and is almost impossible to restart, if it does, it pre-ignites badly and stalls again, leave it for a while, start again, select gear and it stalls again. Ignition timing is fine. The engine itself seems way too hot for just a short running time, I think the fuel mixture is evaporating on contact with the inlet manifold, as the manifold is so hot, it's almost impossible to hold my hand on it for more than a second or two. Even the carburettor body is getting very warm. I've taken the thermostat out, tested it in a kettle and it seems to work o.k but I'm going to replace it anyway. One thing I did find that seemed odd when rebuilding the valley/inlet manifold, a hose fitting that screws into it just behind the thermostat housing, it accepts the hose from/to the heater system. the nut size of this fitting is7/8ths the hose is about 5/8ths internal diameter, the odd thing was the internal bore of the brass fitting was about 1/4 to 5/16. It didn't look right, so I opened it out to 1/2 inch ! this is the only thing I have done other than reassmble it all. The cooling system seems to be cycling o.k, I've checked the radiator surface and it is an equal temperature across, getting cooler towards the bottom hose outlet, no hot or cold spots across the radiator. Their are two hoses coming from the water pump casting, one goes to the heater system the other goes to the thermostat housing (just a short right angled hose) this one is on the right of the two hoses (as I look at the engine from the front of the car) does this make any difference which way around they are fitted to the pump? Before the engine work, the car did not experience overheating at all, so it's all a bit odd and infuriating to me. Any help, as always you guys, is greatly appreciated. I wish I could offer some advice to someone about the things I've learned on the restoration, Hey who knows, it's early days yet! By for now, Dave.

 

Hi Dave.

Firstly, when diagnosing an overheating problem, I would like to know what temperature your thermostat is, and what temperature your car's cooolant is getting to.

A 15 psi system like yours and mine should have a boil-over temperature of 247* F.

I have a few questions for you:
1) Are you running an overflow tank?
2) How you tried replacing your radiator cap?
3) Are you using the proper radiator fan shroud?
4)What type of fan do you have? Electric? Directly coupled to the water pump? Clutch-governed?
5)If clutch-governed, can the fan spin freely if you spin it by hand?
6)is your lower radiator hose collapsing under throttle?

Personally, I think there may be a problem greater than the over-heating; to me, this sounds like a symptom rather than the root cause of your trouble.

To get more replies to your question, I have a suggestion:
Post this in the "Street/Strip 455" forum in the V8Buick boards.
Good luck and let us know how things are coming along

 

Hi guys, firstly to Chris's questions;
1. Overflow tank; NO
2. New radiator cap.3.
Radiator shroud is copy of original item, it was in a bad way.
4. The cooling fan is the original clutch type, which runs freely by hand with engine turned off.
5. Lower hose is not collapsing under throttle.
6. Thermostat is 88 degree type, we run the centigrade system over here !!!!

To Larry;
No gauges on the car, only the original 'HOT' lamp in the panel. This does not illuminate during running. the things just feels really hot. Or maybe the lamp ain't working.
I will check the choke set up again when it is running poor. I rebuilt the carburretor at the same time as the top end job. Replaced gaskets, filter and cleaned out the best I could.
Thanks for the info guys, I'll keep at it, gotta get it right. Regards Dave.

 

Heat riser

I would check to make sure that the exhaust thermo bypass valve (heat riser) is not stuck in the closed position. That would send too much exhaust across the intake after "warm up"

Just a thought. Good luck

 

Dave-

Should you be running an overflow, I wonder? The so-called "overflow" tank isn't just to hold "extra" coolant. If the cooling system was designed to run with an overflow tank, a few things happen- firstly, the radiator wants to purge. With the overflow, the purge line is always under the level of coolant, and will purge to the tank. The reverse side of this coin is that the radiator will also want to draw. With the overflow tank, the system can draw coolant, since the purge line is the one at the bottom of the overflow tank. Without it, the system will draw air at atmospheric pressure rather than coolant at system pressure.

The fan should make approximately one revolution when spun by hand. If it pinwheels when off and spun by hand, replace the fan clutch.

It might be good peace of mind for you to install a mechanical temerature gauge. Very easy retrofit.

The idiot light for the temperature gauge in your car should come on when the key is turned to the "on" position, I should think. If it isn't, that may be evidence of the bulb (or should I say "lamp") being burned out.

P.S.
I know you use C. I guessed you were from Jolly Old when I read "carburettor":TU:

 

Have you adjusted the points? Is your coil okay? What is your spark plug gap?

-Bob Cunningham

 

Thanks folks. Replies to suggestions;
Larry, the car is a 73 model (May if that helps)
Pat, what is an exhaust thermo bypass valve ? and where should it be mounted ? I know for a fact the E.G.R system has long since gone, before I got the car. The ports at the back of the inlet manifold have been capped off.
Chris, what do you mean by 'pinwheeling' ? the fan seems to run freely enough(I'll double check it though, you've got me thinking how freely). I fully intend to fit a gauge anyway, 100 % now ! Mechanical better than electrical ?? Yes, the hot lamp does come on when the ignition is first switched on.
Bob, New coil fitted, plug gap is set to 63 thou (1 mm) Will double check timing.
Jason, the car has 89,000 kilometers recorded (55,000 miles) don't know if it's original or travelled round the clock once, twice, three times !! It's seen no use in the last 9 years, and spent it's first ten years in Spain and who knows where in Europe, it came to England in 1983. The internals of the engine look in very good order, camshaft doesn't have a mark on it, only light carbon on the piston crowns, no 'step' on the upper part of the cylinders. It runs silent at tickover and has know knock or clunks under load. I'm off down the garage now to apply the suggestions you've all made. Once again, many thanks for them all. Watch this space folks, Dave.
P.S what's wrong with carburretor Chris ? or maybe it's just my naff spelling !

 

Mechanical gauges are more accurate than electrical. Plus they work when the electrical system dies.

By 'pinwheeling' I mean this:

with the engine cold and off, spin the fan. It should make about one revolution. If the fan spins so freely it does perhaps 6 revolutions ("pinwheels") then seriously consider replacing the clutch on the fan

Nothing at all wrong with 'carburettor'. That's how you folks spell it. Over here we use one "t", so it was a giveaway that you were from the other side of the Atlantic.

 

Dave

A non HEI stock 455 distrib. engine plug gap is 30/1000". Sometime around 73 they did go to an HEI at the factory and I am not sure what yours has. If it has an HEI it sure could be more than 30 but 63 seems like a lot.

 

It's now 4 hours later;
re filled it with water and some flushing solution.
Re-gapped the plugs to 40 thou. It's a non HEI type ignition.Double checked ignition timing, it was a little advanced, backed it off to 4' BDTC, as recommended on the settings sticker on the front panel by the hood catch. drove for a while to get the choke off and it ran a little better. Got home, wouldn't start from hot, Aaargh ! Put another new coil on and it fired up almost straight away, hmmm. Tried it again, with air filter out, not any different. But now it's starting better from hot, drove it again, very' fluffy' on pick up when you give it more than a cautious gas dosing. Stalls altogether if I really punch it !
It is seeming more like carb. problems, does anyone know the correct setting for the two screws at the front corners of the carb. I counted the turns in, this = 2 and a half, so I backed them out to 3, tried it, no real change, tried 3 and a half, no difference really. I think the carb needs a thorough going over and setting up all over again. As always, all suggestion are welcome, Thanks again guys. I'm off for a beer now, and an English one too, Cheers and bottoms up !!

 

Dave-

The 'hot start' problem is common. Particularly after say, a stop for fuel, the car is hard to start because the starter can get heat soaked. Do you use a heat sheild on the starter at all? It can be a difficult install sometimes, but it can be done- even on my car with the 1 and 7/8 inch primary header tubes. Tight but you can do it with the engine in.

For the carb idle circuit setting, I suggest you invest in one of the most basic, cheap, and useful tools you can buy for your car- a vacuum gauge. Set idle timing and idle speed. Turn off car and set idle screws to 2 turns out. Hook up gauge to full vacuum port and start car. Set one side's idle misture by turning screw in or out and looking at the gauge. At maximum indicated vacuum, you are set. Turn screw one quarter to one half turn back in after max vacuum. Reset idle speed, then do the other side just as you did this one. You should be seeing maybe 10-15" Hg on the vacuum gauge, depending on your height above sea level of course. The needle should be fairly steady (I assume you have a stock type camshaft).


Are you using an old harmonic balancer, or did you get a new one? Old ones may 'walk' on the rubber isolator and give you incorrect timing information. Just a thought.

Have a Belhaven at the pub.

 

Hey thanks Chris, just tried a small experiment with the car. I pulled off the pipe connecting the advance/retard unit to the carb. I have a vaccum/suction if I put my thumb over the pipe, good news huh ? If I connect a pipe to the A/R unit and suck for all I'm worth, it changes the engine running by.............. absolutely nothing, surely this is not right I thought. I dug deep and removed the item from the distibutor (fiddly little job that was) If I suck as hard as I can, the actuating arm doesn't move a jot, not at all. If I suck and move the arm (which is very stiff) I lose any vaccum I've managed to create and I can hear air flowing through the unit. I just contacted Daytona Parts in Florida, they supplied the rebuild kit for the carb. And asked if they might supply a new A/R unit. Failing that, do you know of a local supplier that would ship such an item to the u.k? The only numberso the A/R unit are; MS 440 18. Am I onto some thing here, or just blowing or is it sucking, into the wind. Any thoughts ??? Dave.

 

Hi Larry, yeah I guessed it was a dead one, just needed a bit of confirmation. I can't get to NAPA website, from the u.k, keep getting directed to some management consultant site !!! I've searched all over the distributor ( without removing it) and cannot find a single reference number, strange. I thought I would replace the points, condensor and rotor arm at the same time, maybe even the cap. Do you know of any other parts suppliers that may help me out? I'm a little concerned I can't see any numbers, or is this a common thing? I reckon it's the original fitment distributor. Thanks again, Dave.