Bazza's 318 is running (!!!), but....

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ProjectBazza

ProjectBazza

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Just now, not more than 10 minutes ago, I got Bazza's 318 fired-up, for the first time in over 2 years! No vacuum hoses are connected (everything is plugged), and I haven't even looked at the timing yet, but I need some advice.

During initial start/crank it backfired on me, and I got a puff of white smoke out of the holes in the choke heater. Once I adjusted the distributor and got it to run I noticed a pretty good exhaust leak at these same places (video):



I removed the carb, and this heater, when I had the engine out, and the gasket is brand new. Don't recall the condition of the "bowl" underneath, and I'll have a look at that after I set the timing, check oil and transmission fluid levels, etc, etc.

I'm not a Mopar guy, but common sense tells me there shouldn't be an exhaust leak here, so what should I look for when I tear into this again?

Thanks in advance!

Jim
 
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4spdragtop said:
Could choke bowl be rusted thru?
Click to expand...
Nailed it!

Looks good here:
IMG_4750.JPG


And here:
IMG_4751.JPG


But hold it up to the light and....
IMG_4752.JPG


Guess I'm going parts shopping.

(Again!)
 
To clarify, you would not have an exhaust leak there, only a vacuum leak. The carb and choke are obviously part of the induction system, not the exhaust.

The choke is of course regulated by engine temp. The choke well is just a closed chamber that provides a relatively accurate place for the choke to ‘read’ the engine temp. Can’t imagine there is a rust hole in it without other parts of the intake having similar problems.

The choke mechanism is operated by a bi-metallic strip. When the strip reaches xx temp, it opens the choke since it’s no longer needed once the engine is warm enough.

Regardless of whether the choke is working correctly or not and if you think you have a vacuum leak there, check the choke base and/or carb base and gasket, maybe something got pinched during installation. Also make sure there are no open vacuum ports in the carb base itself.

Could easily be an intake gasket leak too.
 
O
rmchrgr said:
To clarify, you would not have an exhaust leak there, only a vacuum leak. The carb and choke are obviously part of the induction system, not the exhaust.
Click to expand...

Ok, so now I'm confused.

The area underneath this choke bowl is clearly exhaust related, as it's full of black soot as far as I can see. Plus, when I fired it up with this open, it ran just fine (and it sounds kinda bada-***, for a stock 2-Bbl 318):

 
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Yeah, that's the intake manifold exhaust heat crossover, sorry for the confusion. I suppose it could technically be an exhaust leak too but not in the traditional sense like from a manifold or pipe. I'm not sure if the crossover is considered to be part the exhaust system? Maybe it is somewhere, I don't know.

It's obviously related though in that it employs exhaust heat to warm the intake manifold faster on cold starts. It is supposed to work in conjunction with the heat riser mechanisms on the exhaust manifolds that always get rusted stuck.

It makes sense that the choke well rusted out because it is exposed directly to exhaust heat on cold starts which would create condensation. Over time the moisture would eat through the bottom of the well like it did on yours.

I'll shut my trap now, seems like you have it figured out.
 
That choke cup seals the exhaust crossover area under where the choke sits. No vacuum there, only exhaust. Replace the cup and gasket and you should be good to go.
 
That's an older 318 I can tell ... the newer ones (73/74-ish and up) didn't have that cup.
Maybe find a newer intake where choke parts are more available?
I did see someone on eBay a while back that had a few of those, and they were NOS
 
Who wants to go to all that trouble when you can just change the cup. '70-72 model 318's had them.
 
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