Hot motor

[Yvon the french]

Hi, I'am Yves from France, yes not a joke.

 

I just receive from USA an C30 with big block motor (7.4). It's work perfectly but since I remove all the system to reduce pollution, the motor seems to be more hot....It's not dangerous, but more hot!!!

 

If you have any suggestions and explanations..... thanks in advance.

[00Silverado4x4]

If your engine is running hotter, I'd double check your coolant system to include the thermostat. The coolant system may need a flush and/or the thermostat may be getting stuck.

[Yvon the french]

Really thanks for your answer. I will check coolant system and thermostat....

[sahls01gmc]

Nice looking truck! I think it's just a coincidence that it runs hotter. Coolant system might just need to be flushed. Maybe new thermostat. What temp is it running at?

[Duelin]

Big blocks run hot any way. Did you remove or disconnect the egr valve? That will make it run hotter

[Yvon the french]

Yessss anyway, big block run hot.... I will flushed coolant system.

 

But the temp never go over the middle of the gauge..... but before it always stay really under the middle, now it's more between the quart and the middle of the gauge...

[grampadirt]

Check the airflow going through the condensor & radiator,leaves & debris can collect and hinder cooling.Flush with compressed air or water from a garden hose.Even dust on the radiator fins can reduce cooling.You can go one step further and remove top plate holding the radiator and look down between the condensor & radiator and clean there better.I do it often and my big block powered Suburban runs at normal temp even in our 100* summers here.

[ifixedit]

Reviving an old thread here, but it caught my attention. Back in the days of the old ways of reducing emissions, one thing GM did starting in the early 1970's was retard the timing, ranging anywhere from 2 to 6 degrees before Top Dead Center at idle. Retarding the timing by itself will cause a seemingly otherwise normal engine to run considerably hotter. The idea back then was to reduce the timing in order to more completely burn each charge of fresh fuel as it came into the cylinders, however all it really did was kill power and made the engines run much hotter, most notably at slower speeds and at idle.

 

You're first going to want to look at your distributor, I'd assume it is using an HEI distributor with both vacuum advance along with mechanical advance. It will require resetting the initial timing and likely require some re-tuning of your advance curve as well. I would first get an adjustable vacuum advance for the distributor if such a thing is available in France, then I'd look at the springs on the weights that controls the mechanical advance of the distributor.

 

I'd start out with an initial timing of 12 to 16 degrees Before Top Dead Center at an idle of around 700 RPM without the vacuum advance connected. Using a timing light, slowly raise the RPM from idle and observe where the timing begins to move, this is the start of your mechanical advance. Most prefer the mechanical advance to begin around 800 to 1000 RPM, if not it will require lighter springs on the distributor weights. If at idle the timing is moving around and not staying stable that means the mechanical advance is already moving which you do not want and will require stiffer springs on the weights, you want the timing at idle to stay stable. I'd assume if the distributor is stock and has not been touched, the current springs in it are probably adequate to hold the timing from changing at idle. Depending on the number of miles, the distributor may be due for a rebuild or even be ready to be replaced because of worn parts. Once you have the initial timing properly set, you can then re-connect your vacuum advance and see what happens from there. The nice thing about an adjustable vacuum advance is you can then fine tune the vacuum advance part of the advance curve, giving you both good mechanical and vacuum advance at cruising speeds where it is most needed. You may want to look into a new distributor, I just purchased an Accel distributor and I've been very pleased with it, also comes with an adjustable vacuum advance already installed.

 

End result is the engine should run noticeably cooler and also have considerably more power.

 

Oh, by the way, install a taller air cleaner as well, the one shown in the picture is way too short, go with a 3" or even 3-1/2" tall air cleaner.