I can't drive 55

[zerotreedelta]

PO “says” they didn’t have the issue…..

Keeping up the House MD theme, "the patient always lies"

Definitely curious on the mech advance numbers as it's one of the remaining concrete tests that's easy.

With the mismatched heads, the lower compression ratio is ripe for a turbo or centrifugal supercharger though.

 

[45Dougal]

I religiously stuff shop towels into the intake because I am certain I'll drop a nut or washer...

Did we finally find the problem!

 

[MatthewMcD]

Keeping up the House MD theme, "the patient always lies"

Definitely curious on the mech advance numbers as it's one of the remaining concrete tests that's easy.

With the mismatched heads, the lower compression ratio is ripe for a turbo or centrifugal supercharger though.

The borescope arrived so I'll post some photos this afternoon.
I'll finish up the carb installation and get the mechanical advance numbers too.

 

[MatthewMcD]

Random thought for the day, if the PO is incorrect. Is it possible to mate a 3-speed transfer case to a 4-speed transmission and would that be a problem?

Are there marks or indications on the transfer case that can confirm that it is a 4-speed case?

 

[Grayscale]

Found this: Heat Riser Block Off Plate - Fits 1969 - 1/1975 3-Bolt Style 4x Applications (EGEXHRPE) - https://cruiserteq.com/heat-riser-block-off-plate-fits-1969-1-1975-3-bolt-style-4x-applications-egexhrpe/

Not clear on what this mates to and what it is for.

It sandwiches between the intake and exhaust manifold. It keeps your intake from being directly exposed to exhaust gas, because the exhaust 'heat riser' flap has broken off and is somewhere.

Back to the Rochester base plate, you had that one vac hose with a torx screw in it, that is a good source to tap manifold-vacuum, instead of ported vacuum, on your distributor advance. It probably will kick-in after the starter gets the engine firing on its own.

 

[Green Bean]

Random thought for the day, if the PO is incorrect. Is it possible to mate a 3-speed transfer case to a 4-speed transmission and would that be a problem?

Are there marks or indications on the transfer case that can confirm that it is a 4-speed case?

Yes, you can use a 3-speed transfer case with a 4-speed transmission. 3-Speed Transfer Case to 4-Speed Transmission

 

[pb4ugo]

Here's an article on tcases from 4wheel and offroad magazine from years ago.

T-Case Tech

 

[island45]

3 spd case/4 sd case, same in high range, 1/1. Correct? And how 'bout running that boroscope up the tailpipe and performing an automotive colonoscopy? Don't forget to dump a quart of marvel mystery oil down the intake at idle the night before......

 

[MatthewMcD]

Here's an article on tcases from 4wheel and offroad magazine from years ago.

T-Case Tech

Comparing my TC to the photos I have either a 3 Speed '70-'75 or a 4 Speed '73-'78.

Interesting in the "Common Problems" section:
"The two-wheel-drive-to-four-wheel-drive shift collar is often installed backward, which will lock the case in four-wheel drive (the tapered side of the sleeve always goes to the rear.)"

 

[Pighead]

3 spd case/4 sd case, same in high range, 1/1. Correct?

Correct, just a slightly lower low range.

 

[RevISK]

Comparing my TC to the photos I have either a 3 Speed '70-'75 or a 4 Speed '73-'78.
View attachment 3750982

Interesting in the "Common Problems" section:
"The two-wheel-drive-to-four-wheel-drive shift collar is often installed backward, which will lock the case in four-wheel drive (the tapered side of the sleeve always goes to the rear.)"

Trying to remember who mentioned this to you early on …

 

[Skreddy]

I think you’re chasing non-existent problems looking into the t-case or transmission.

If that is the open chamber head (which it appears to be), the compression ratio is garbage on that F block. I’ve never heard of domed pistons for the F so the only way they could’ve bumped the CR back up is to deck the block and/or mill the head. Even if that was done, that head still is larger diameter combustion chamber than the F bore not a good shape for a good burn with flat top pistons.

Using a CR calculator with stock bore and stroke, 0 deck and .5mm gasket thickness…
To get stock F CR of 6.8 would be a 108 cc head combustion chamber volume.
To get stock 2F CR of 7.8 would be a 130cc combustion chamber with a 30cc domed piston (guessing on volume).
So assuming that chamber on the F head: 5.8 CR. That’s a power robber for sure.

 

[fyton2v]

Hey now, there's no call for bringing math into this thread.

 

[MatthewMcD]

Borescope shows flat pistons. (This is #3)

Running up the tailpipe I just see a clean muffler.

 

[45Dougal]

I think you’re chasing non-existent problems looking into the t-case or transmission.

If that is the open chamber head (which it appears to be), the compression ratio is garbage on that F block. I’ve never heard of domed pistons for the F so the only way they could’ve bumped the CR back up is to deck the block and/or mill the head. Even if that was done, that head still is larger diameter combustion chamber than the F bore not a good shape for a good burn with flat top pistons.

Using a CR calculator with stock bore and stroke, 0 deck and .5mm gasket thickness…
To get stock F CR of 6.8 would be a 108 cc head combustion chamber volume.
To get stock 2F CR of 7.8 would be a 130cc combustion chamber with a 30cc domed piston (guessing on volume).
So assuming that chamber on the F head: 5.8 CR. That’s a power robber for sure.

You don't account for a PO brazing a couple of quarters on top of each piston though

 

[RevISK]

I know just enough to be dangerous around these things. As one of the two humans active on this thread to have laid hands on Matt’s rig, I’ll just say it just feels like it’s in the gearing.

Maybe when Kelly @77mustard40, who I’m certain far surpasses my meager knowledge, checks the truck out, we’ll have a sense of resolution.

It really isn’t that the truck is just slow, something is holding it back.

I was just over there loaning him a brake reservoir cap, there has been more fact finding.

 

[45Dougal]

Borescope shows flat pistons. (This is #3)
View attachment 3751047
View attachment 3751048

Running up the tailpipe I just see a clean muffler.
View attachment 3751049
View attachment 3751050

Do you have a mirror so you can see upwards?

 

[77mustard40]

I know just enough to be dangerous around these things. As one of the two humans active on this thread to have laid hands on Matt’s rig, I’ll just say it just feels like it’s in the gearing.

Maybe when Kelly @77mustard40, who I’m certain far surpasses my meager knowledge, checks the truck out, we’ll have a sense of resolution.

It really isn’t that the truck is just slow, something is holding it back.

I was just over there loaning him a brake reservoir cap, there has been more fact finding.

I'm starting to dream about a 40 I've never seen, its worse than Work Dreams. Has the condition of the emergency brake been raised in this discussion? I know its a long shot since they mostly barely work as opposed to actually impeding forward movement.

 

[island45]

You don't account for a PO brazing a couple of quarters on top of each piston though

OK, I concede on the muffler... Dangit.

 

[MatthewMcD]

Do you have a mirror so you can see upwards?

This is a bit closer than the camera is designed to focus. To me, the head looks flat, but I haven't seen it opened.