At idle the 180 degree stat will help keep engine temps down. So it is worth a try for daignostics. But I would not leave it in long term . The hotter you can run an engine the longer the engine life will be.

All the manufacuters have experimented with high operational engine temps. Ford did one such test in the early 80's to see if they could reliably operate an engine at 250°F coolant temp, we were able to do it and it resulted in better efficiency and lower emmsions and longer cylinder bore life. At the time standard lube oils were not robust enough to handle the temps and aerospace spec stuff was needed (Think rocket engine turbine pump lube oils) and the cooling system needed significant modification (reverse flow heaver construction rad higher quality hoses etc etc) in the end cost was prohibitive for the gain realized.

Instead of a 180 jump way down to a 160 provided you are not needing the vehicle as a primary and need the heat (it is winter and all) If you can not get a slow crank with the 160 stat then you know it is almost definitely a thermal expansion mechanical interference issue.

So that then comes to what in the engine would cause that.

There are only 3 maybe 4 areas that could generate enough drag/force to do this, Cylinder bores, crank bearings rod and main, camshaft bearings (Less probable) and early combustion.

If there is anything I missed please chime in.

Not sure if it could the trans but I would not take it off the table.

 

I get what your saying with operating temps, and I honestly don’t know what’s in it, but I’ll pull off the water neck and check it out tomorrow.

tge part that kicks my butt is days like today where I can’t seem to replicate the problem. All I can say is “more often than not” it’s got a sluggish crank after shutting down for more than 5 minutes on a hot engine. That’s why it would make “sense” to be a sticking vacuum advance, but this goes against all common sense so far...

maybe be worth noting, I lowered idle to around 600rpm, it was around 1000. and I also have to put on a external carb throttle return spring, the one on the carb isn’t cutting it keeping the blades closed after pumping gas to prime for cold start.

 

Another thing worth mentioning is that it has the cast iron manifold on it, I didn’t see conclusive enough results to justify the edelbrock performer aluminum manifold. I was told by running the aluminum manifold with a plate over the heat crossover would help lower intake air temps. Possibly helping. Like I said though, power gains and cost kept me from putting the edelbrock on. If there is any help in solving this problem, I’ll coin it, but if it’s only weight savings, and the heat crossover blocking is negligible, I’ll keep my stock intake.

 

The Edelbrock intake will yield more power but really the limiting factor on the 385 Series are the exhaust ports they are terrible just try to get your finger though one. Some basic porting will go a long way in helping the engine breathe.

Whats better than blocking the exhaust crossover off in the intake is to run an intake baffle pan , this will do more for HP by keeping the hot oil off the bottom side of the intake. See below.

 

I’m not hurting for power, and I haven’t seen any honest gains in torque over the stock manifold. Only reason I was kicking it around was the ability of the aluminum to dissipate the heat better, even more so with the heat crossover blocked. If that sounds like barking up the wrong tree, I’ll pass, and keep stock manifolds. I think we can all assume heat seems to be a decisive factor in this problem.

 

It seems to be but if it thermal expansion swapping the manifold wont change it as will be an expansion issue in the block.

You may be on to something with the distributor if the breaker plate was a tight fit it might hang up. I've never seen it happen or heard of it but hey at this point....
It is not going to hurt to swap in the old one, it would be one more thing stroked off the list one way or another.

 

 

Have you been back to your favorite gas station? As suggested, if this is heat related, maybe it's just a few degrees difference one way or the other. Perhaps working the engine exactly in that manner is enough to trigger the fault.

 

i cast my vote, FWIW, for trying the 160 thermostat on a temporary basis for troubleshooting. Cheap and easy, just like me...

 

Good thinking to check the starter temperature. Was this after a drive, with max ambient heat, or just at idle in your driveway? You want to check it after a drive, to hopefully replicate the fault conditions.

One last question about any slow cranking with the current starter. This is very important, as I want to establish an accurate timeline about when this starter began to misbehave. After you installed this starter, but before the 20 minute crank-a-thon, did this starter exhibit any slow cranking? For the moment, I'm not super concerned about the times the starter hesitated before cranking. I'm more concerned about when it did engage but turned slowly. I still think there's a real possibility this starter was heat damaged from all that repeated cranking. An accurate timeline will provide some answers.

 

I’m sorry I’m being difficult buying into superstitions or internal binding. I’m like that guy that just saw a ufo and is trying to logically reason his way out of unseeing it!

ill bite and put in the 160, heck, go all out? I’m gonna pass on the aluminum manifold, until someone tells me otherwise how it is to solve my problem. I may be convinced to put the stock dizzy back in as well, or at least pull apart the vacuum canister. It’s funny how I was tinkering with the dizzy today on the vacuum advance and the armature and had no problems.....

ill go to the possessed gas station after work tonight and fill up with 93, and drive/crank/start/curse the heck out of it this weekend after the other thermostat is installed. I may as well pick up the ir thermometer too, that may be an interesting tool to use!

 

 

Pay attention to this clue. This is huge. I'm not saying there's no internal binding present. Could be a combination of things. But if your present starter never cranked slowly until after the crank-a-thon, well, um, just remember starters have duty cycles for good reasons.

So what next? Heck if I know. Internal binding? New starter turned marginal from exceeding the duty cycle? I'd just hate to see you rush blindly down one path when the present root cause is not there, or is a combination of things.

 

Very Interesting conversation on piston clearances and as a long term owner of a piston slapping 2000 Suburban I can relate (but in an opposite way). When it’s cold and you first start it the pistons slap so bad you’d think it was a diesel! It used to bother me about 70k miles ago but now I just drive on!

When it’s bone cold the clearances are sloppy and that’s when it slaps the most, and when it’s good and hot the clearances tighten up and it doesn’t slap.

BUT in between cold and hot there can be more or less or less slap depending (in theory) on the relative differences in temperature between piston and engine block / bore.

For exapmple, shortly after start up the piston warms and expands into the cold bore, clearances tighten up and it doesn’t slap. But then when it’s about half warmed up (on the gauge) it’ll lightly slap again as the bores start to expand. Then it’ll stop again once everything (including oil) is fully up to operating temperature.

So if it acts up hot, and also under the “warm piston / cold block” scenario, that could support the tight piston theory.

Also, long time ago I had a vehicle with a bad spot on the flywheel and every so often I’d get starter gear clash when that bad spot on the fly wheel lined up just right (or wrong if you prefer) with the starter.