'72 Starting problems

[Drummer72]

My '72 does not easily start when the engine is hot. Cold start is not a problem so I guess the choke is working fine. THe engine is the original 350 block with a Quadrajet carburator. I assume it's the mixture which probably too rich. Can anyone confirm and give some hints on the best way how to solve the problem.

Jeroen

 

[Jack]

have you hugged your condensor lately?

First WELCOME to CACC! Well ... not a whole lot to go on here (actually possibilities are quite broad) ... and since no one else has taken a stab at it, here goes:

Repeat, this is only a stab:
If the car's huffing black smoke out the exhaust then the carb's rich for what could be several reasons ... if not, then you have other trouble. Your 72 probably came equipped with a distributor having points & condensor inside it. Condensors do fail & often exhibit failures more when hot than cold. Have you considered replacing your condensor? This'll be a very cheap & easy thing to try. If your distributor has been replaced or retrofitted with a new electronic/HEI type (no points nor condensor) then replace the module inside distributor ... also cheap & easy. And keep a spare new module on hand.

If the car is huffing black smoke then I'll hope someone else here at CACC will walk you through carb setup ... I'm better with ignitions than carbs.
JACK:gap

 

[Drummer72]

Jack,

Thanks for the reply. Let's narrow down the options. First of all there is no black smoke whatsoever, ones running everything goes very smoothly. No hick-ups either when I hit the pedal.
The capacitor sound like a good starting point. I will try a new one as this seems like worth the try for just little investment.

The feeling I am getting though is that the carb gets not enough air and just floods the engine when warm. Too little air or too much fuel perhaps.
If it is the carb, can anyone advise what's the best way to tackle this?

 

[69MyWay]

How fresh is your tune up? Good plugs, wires, and coil wire?

Also, if you get in after it is warm and hold the throttle to the floor when you start, does it start right up? If so, it might be a tad rich.


First, knock out the basic tuning items and let us know what pops up.

 

[Drummer72]

Thanks, I'll get back the moment the wheather improves. This might take a while, it ain't particularly Florida over here.

 

[Nut]

Jeroen,

My old '72 had the exact problem; drove me crazy too. Turned out being an over heated starter motor. The header on the right side was heating up the starter motor. I put a heat shield around it............ problem when away.

............. Nut

 

[Drummer72]

That is very helpfull. It is true that the starter motor gets overheated fairly simple. How did you solve the problem exactly?
Was it by using this insulating fabric that some of the shops offer or did you use something else?

Jeroen

 

[69vettester]

I have a similar problem, but only when hot starting at high elevation. my carb is set for sea level. It acts like the fuel evaporates in the lines when I stop the motor for a few minutes and try to start again in a few minutes. At first I thought it was flooding, but no black smoke belches when it starts to fire. Also I have to set there idling and lightly reving for 20 seconds. If I take right off it will hesitate intermittantly perhaps because air bubbles, are in the line where it comes close to the exh. manifold.
Like I said, this condition only exists up at 4K on up elevation.

Good luck
Tom

 

[Nut]

Jeroen,

This was a long time ago, but I noticed that Eckler's sells something similar to what I used. Stock #33895. It's a heat blanket that wrapped around the starter. I don't remember using velcro to attach it, but I also bent up some light gauge sheet metal into a shield as well. Hope this helps.

Regards............ Nut

 

[desertsled]

Starter prob.

When I bought my 79 from the original owners it started right up. Of course it did it hadn't been started in a couple of hours or days. After I drove around town for a while I decided to stop and get gas after fueling I would turn the key and not even get turn over. It was 60 degrees out and the engine was not over heating so I waited 10 minutes with the hood open and it started up this would happen always. On my car the exhaust manifold Y pipe is located directly under and slightly to the side of the starter. Heres what I did....
1. Went to pep boys and bought a lifetime starter and then I tryed it out and it still gave me the problem.
2.Checked voltage on battery not only was the battery to small but it was only putting out 12.3 volts after replacing the battery with a larger and stronger unit I have never had this problem again.

I would sugest you check those 2 possibilities in reverse order that might save you 50 dollars.

p.s. I also saved my new starter by running true dual exhaust this routed the pipes away from the starter.

 

[Tim73454]

Not sure if this is your problem but I had the same thing with my 73. The starter was new and it would start fine cold. Once it got hot it would not start until it sat and cooled for about 30 minutes. The battery also looked new but it was only a 650 amp battery. I replaced the battery with a 1000 amp orbital Exhide battery ($149.00) and have had no problem since hot or cold.

Just a thought....

Tim73454

 

[Drummer72]

Starter problems

Thanks to all of you guys,

Many of what all of you described is what I experience too. The tips you gave me all look very usefull. When the wheather improves I will try them out.

 

[Drummer72]

Starter Problems solution

After all of the great advise I got from all of you I've been able to locate the source of the hot starting problems and the solution for it. Above the starter motor there is a solenoid mounted that has a dual function. First of all it slams the starter gear forward onto the flywheel. Second it activates the starter. Especially when you're using headers the pipes get awfully close to the solenoid. In my case as close as only 4 cm (~1.5 in.). The immense heat from the exhaust ofcourse heats up the solenoid up to a level where it gets jammed and the engine just won't start. While driving the solenoid usually gets sufficient driving wind to keep it more or less cool. It will at least keep it below the temperature where the solenoid core gets stuck. However, if you stop the engine for while the headers will radiate a lot of heat which often is enough to jam the solenoid's moving parts. What also happens often is that the first two or three attempts the starter motor will work but then will suddenly stop. This is caused by the extra heat generated in the starter and solenoid which will just tip it over and everything gets stuck.
There are two ways to solve this problem. The first one is to get ayourself bigger battery. The voltage drop of the battery itself when cranking the engine is less then with smaller types and this is in a lot of cases just enough to fire it up. However, in my opinion this is not the most elegant way because it does not take care of the problem itself. To prevent overheating of both the starter and especially the solenoid I have installed a heat shield. It is a simple sheet of aluminium bent around the solenoid and the starter motor. On the front side of the car it is bolted to the bracket that also holds the ground lead. On the other side, closer to the flywheel, it is held in place by the starter mounting bolt that goes all the way up through the starter casing onto the engine block.
I have driven it now for two weeks and all seems to be working great.

 

[Nut]

Jeroen,

That took a while to find and fix but I'm glad that you solved the problem. Heat can do some amazing things to Electrical and Mechanical parts. GE huh. What division of GE to you work for? We have an Aerostructures division of GE Engines on the same property as my company. Even though I love my '81, I sure wish I still had my '72.

Take Care............. Nut

 

[Hijinx]

Most older Chevy's have this problem. Once the starter and solenoid get older, they do not tollerate the heat well. The heat shield will definately help. But there is another way to rectify this problem and one I use on every older Chevy I own. You can get a remote solenoid from Summit. It does not take the place of your current solenoid, but is in addition to it. I installed mine high on the firewall. It has additional post for accessories. The best part, other than the starting issue, is that it is much easier (read handier) to attach a remote starter when your working on your Vette. Check these out, they are well worth the $25 or so they cost.