340 engine runs hot

[Ralph]

I have a 73 cuda 340 auto car and it runs hot, it has been flushed, new radiator, water pump and thermostat.

I am thinking that the exhaust manifold heat riser needs checking next. It may be letting exhaust gas into the manifold at all times.

How can you check this out. The circlular mechanism on the outside and the spring work but real easy.

I am thinking about removing the exhaust head pipe and trying to see if this mechanism is working correctly.

Any help would be appreciated.

thanks Ralph

 

[ramenth]

What's your timing like?

 

[mopar70]

How hot does it run?

 

[moparlee]

Do you have a viscous clutch fan? It may be slipping.

 

[Ralph]

Clutch fan is new.

I have a sunpro temperature guage and its the way the temp goes up really fast and then stays about 195 and when driving goes up to about 205 degrees and then that's where I turn it off and it keeps climbing to about 230 degrees after the engine is off.

The motor compartment feels real hot, and afterwards its real hard to start.

When I got the car the vacuum advance was plugged and the timing was set at 5 degrees below TDC. I have installed a new distributor and have experimented and its works well at 2 degrees below and I have been adjusting the vacuum advance slowly 1/2 turn more advance with an allen wrench and its been starting to smooth out

I have not had time to check the total timing yet but the engine does not seem to have a lot of pep - but I believe its the original 40 year old motor without a rebuilt so that may be the issue, it has 70,000 original miles and it was in a warehouse sitting for some time.

It does not have any backfires, smoke or any other issues. It runs a little rough at this point but not much, everything else is new carb, wires , alt etc

thanks ralph

 

[Ray]

What temp stat is in it?

 

[moparleo]

Go buy your self a IR Thermo gun. They are down to about $30.00 and are great to find hotspots any where, like the thermostat, waterpump, radiator core, cylinder heads, individual exhaust ports etc... This tool will pinpoint your hot spots and help you with your diagnostic testing. Initial timing should be 10-14 degrees with vacuum disconnected, idle about 750-800 rpm. Do this first and then start checking everything else one by one.

 

[Ralph]

the stat is a 185 degree

I like the idea on buying this thermo gun where do you get one ?

thanks to all

R

 

[Ralph]

Moparleo, am i missing something.

The chrysler book states 2 degrees below TDC for automatic cars and i believe 10-12 degrees with vacuum advance, then a total of mid 30 degrees all in ?

your take

R

 

[VeteranCosmicRocker]

Disregard the manual, what Leo says is spot on. Re-connect the vacuum advance after you set timing. What radiator do you have ? hopefully you have a shroud on it, as well.

 

[Ralph]

Got it, will try it

new 4 row copper radiator with shroud.

let you know what happening

thanks Ralph

 

[Ralph]

Leo, you did me a solid.

12 degrees with the vacuum advance plugged and what a difference in the way it runs.

Took it for a 20 minute ride and its 100 degrees and muggy here in the northeast and it ran at 190 degrees for sometime and then about 195 to 200.

I am playing with the vacuum advance allen screw adjustment to fine tune the timing. I have an excel hi po distributor that plugs into the mopar harness.

How do I know when I have to much or too little timing ?

Really thanks for your help

Ralph

 

[moparleo]

First, before you start making vacuum adjustments, you need to determine what your initial timing and total timing should be. The vacuum advance and mechanical advance weights control the curve or how quickly the timing advances. You need to get yourself some timing tape from your local, national auto parts store. Most should have it in stock. This is an adhesive backed degree tape and is numbered from about 20 degrees after TDC to 40+ degrees before TDC. You need to determine actual TDC and mark your harmonic balancer. Install the timing tape to correspond with the timing mark. Again, disconnect the vacuum advance and set to 12-14 degrees advance. Loosen distributor clamp slightly so it will move but not easily. With someone helping you, raise RPM to approx. 3,000 RPM. Check the timing with your timing light and advance the distributor timing until it starts to loose RPM and crap out. This should be roughly 35 degrees. Lock the distributor down. Shut off engine. Restart engine and check where the initial timing is. If it still starts easily, reconnect your vacuum line and enjoy. Fooling with the advance weights and vacuum mechanism should only be made to speed up or slow down the timing advance curve, not to adjust timing. Also, I forgot to mention having your radiator cap pressure checked. You should be running a 16 lb. cap. You should also be running a 50/50 coolant ratio. The purpose of the cap is to raise the boiling point of the coolant. With the cap off, water boils at 212* Under pressure it will be over 220* So it is not overheating at 200*. 200-220 will normal in high temp driving especially at speeds lower than 50 mph.

 

[Ralph]

thanks will work on it

Ralph

 

[marksmopars]

I have a 70 340 and it like 36 total advance. had it on the dino and 35 or 37 produced less HP. I set it at 10 to get it started and then when running at rpm just set to 36 total. Makes life simple and I like things that way. Goodluck!