Priya, a very good explanation of the effects of excessive heat on electron flow in an inductive wiring system. I have been working on cars for around 50 years now, and my only qualifications are a Diploma of Photographic Technology and a Production Engineering Degree when I worked for a tyre company in the late sixties. In the eighties, I worked for two manufacturers of diesel engines, Scania and Kubota, so knew a little about their applications from scallop trawlers, repowering buses and trucks to ride on mowers, etc. Most of my car work has been on six cylinder Holdens, including a dragster with a 202 Holden six. Having owned a Corvette for over 20 years (I now have three), I have plenty of experience with basic maintenance on them and have learned some things about them.

My white '74 coupe has the most work done, a Borgeson steering box, Hydroboost and a Holden V8 aluminum/plastic master cylinder. On one of my US trips, I brought home a Sanderson Block Hugger kit and fitted it. When it came time to connect the headers to the rest of the exhaust system I had some concerns about heat soak and filter removal, so I bought some 2-1/2" mandrel bent steel pipe with 45* and 90* bends. I "kinked" the driver side one out and around the filter so, upon removal, I can drop the filter straight down with minimal spillage and ditto upon replacement.

On the passenger side (still LHD) I routed the pipe out and around the starter motor so that the heat soak would have minimal effect on the starter. I agree that this is probably overkill, perhaps not even needed at all, but as I had to complete the exhaust, I could put the pipes where I wanted to, and I did. So far, even in the HOT Australian summers, I have never had a problem cranking the engine when it's hot. But then again, neither do I have a problem with my '74 'vert with a stock exhaust under similar conditions.

As Corvette starter motors, as well as ALL other parts are expensive on this side of the pond, I was merely putting into place what I hope was a small degree of preventative maintenance and hope that some of you Forumites might benefit from it.

Regards from Down Under.

aussiejohn

 

Many L-48 owners have made the big mistake of installing 750 cfm mechanical secondary carburetors because they have read about so many others installing them (the blind leading the blind). First of all an L-48 running at an 80% volumetric efficiency only consumes 405 cfm at 5000 rpm so a 750 cfm carburetor is way too big. As the carburetors increase in cfm size their venturi bores increase accordingly so the fuel mileage really suffers because of low venturi velocity at cruising speeds. But the biggest drawback of using a mechanical secondary carburetor on a street engine is under a sudden throttle opening at a low rpm the engine falls on it's face because it simply cannot accept that much throttle opening when the venturi vacuum of the primaries and secondaries drops to almost zero. That's why only vacuum secondary or AVS carburetors are recommended for street use.

Yes, a mechanical secondary carburetor can be used on a street engine but a vacuum secondary or AVS carburetor offers much better low rpm performance because of the limited throttle opening and that is why the factories have always used them. For stock L-48's I highly recommend using a #1848 465 cfm electric choke Holley because of it's smaller primary venturi sizes or the OEM QuadraJet for the same reason.

 

Your husband has it. Another thing that is not always mentioned is - Full voltage/current may not be available to start with. 30-40 year old wiring, switches, and connections may have a drop across worn and corroded parts, and will have enough power when cool but when heated it may not be enough. Also, mechanical parts in there expand when heated and may cause more strain.

 

Ask an engineer if the glass is half full or half empty. I'd bet the answer will leave your jaw agape.

 

Since the C3 explosion myth hasn't been explained yet..
I will add one. Here is one I heard from an esteemed forum expert.

HEI ignition modules dont need regular heat sink compound, just use RTV.

Now there are specialized RTV heat sink compounds, but this myth says to use regular engine sealant RTV.

But.. the proponent of this myth also says he drilled a hole in his distributor cap and firewall so that a hose connected to his A/C vent will blow cool air on the module preventing overheating...........

If that isn't engineering... I am not sure what would qualify.

I quit now

 

The glass is twice as large as necessary.

 

Forgive my ignorance but, what size is the OEM QuadraJet for a corvette. I could've sworn they were 750cfm (some 850cfm). I also thought that they are all mechanical secondary not vacuum secondary.

 

An engineer friend of mine merely says that the glass is twice as big as it needs to be.

Hardly seems an agape-worthy answer.

Edit: Just saw Priya beat me too it.

 

I'm surprised you want to go there, but since you brought it up...


https://www.corvetteforum.com/forums...onversion.html

 

Sounds reasonable.

 

What if it just looks twice as large...but really the same size!!!

 

"A plug-in is needed to display this content".

 

I know some Q-jets are 750 CFM, not sure about any others. They are all vacuum secondaries and I believe the secondary is a progressive type that only opens enough to meet the engine's demand. Perhaps someone will correct me if I'm wrong.

 

Q-Jets are mechanical secondary carbs, with an air valve that responds to engine needs. I believe most are 750 cfm. There were some 800 cfm models.

I am curious (maybe ignorant?) about the heat soak starter thing. I have certainly experienced it on lotsa GM cars. I don't think it was a problem when they were new. And wasn't a Ford remote solenoid a fix? For full disclosure, I use the high torque mini starters...

And the glass 1/2 full thing? The answer is we don't have enough water in CA. It was supposed to pour today; we didn't get much. I had to wear long pants, though. Kinda cold in winter...

 

An up to date flash player should do it.


And BTW, that 'tube is what I'd call a jaw-dropper.

 

I suppose technically speaking that's mechanical secondaries, but as far as I'm concerned its vaccuum secondaries for all practical purposes.

 

Until today I thought the internal expansion of hot starter parts was the sole reason for a hot motor cranking slowly.

 

The "hot and running" myth has got to be the most foolish myth of all because the factory never did it and neither did the professionals. Its a silly and messy waste of time that accomplishes nothing more than you would achieve from adjusting them cold and NOT running. And then to make matters even worse most people adjust them to 1/2 turn down from zero lash which is 5/8 turn short of what is needed.

 

The so-called "figure 8's" after a rear end oil change is another silly waste of time as it accomplishes nothing more than making the driver feel like he's doing something really beneficial. About the equivalent of doing a rain dance while naked or sacrificing a goat. Its a MYTH guys.