I can't drive 55 (1 Viewer)

[MatthewMcD]

As far as timing goes, was that mechanical only (no vacuum advance)? This was my timing map that was intended to replicate factory, albeit for the 2F vs older F...I don't have that FSM.

Looks like I ramped from 9-10 base (slightly more than factory) up to 22-23 by 3200RPM at WOT (basically the top row) to account for the mechanical advance, and then you can see how it brings what would be vacuum advance as you go down the rows to the lower MAP readings.

At least for the 2F, advance starts around 1000RPM flywheel (500RPM camshaft), but only getting to around 8-10 mech' advance by 1800 RPM.

View attachment 3748398View attachment 3748399

Original post re: timing:

FiTech/Sniper Distributor ???

forum.ih8mud.com

I am confused by Distributor RPM vs. flywheel RPM.

 

[zerotreedelta]

I am confused by Distributor RPM vs. flywheel RPM.

The crank spins two rotations for each rotation of the camshaft (and distributor). The FSM did everything in distributor rpm vs crank RPM, for better or worse, so you have to double it to get engine rpm.

 

[MatthewMcD]

Finished the installation of the donor carb from @knuckle47. Thanks to @RevISK for donor parts that helped me complete the installation.

I rechecked the timing, idle and idle mixture. Then took it for a test run.

This is the raw video, the real run starts after I turn it out of the sun. You can hear the carb whistle!


I am sad to report that it has same, EXACT, performance.

I chatted with @cruiseroutfit and I'll order a clutch tomorrow. While I am waiting for that I'll get the fuel pressure measurements and order a fuel pump rebuild kit, because I haven't rebuilt that...yet.

 

[zerotreedelta]

Video is private - you'll have to flip to to unlisted or public.

Any luck testing the mech timing advance with the vacuum advance disconnected?

 

[77mustard40]

Matt I’d encourage you not to throw parts at it. Let’s figure this darn thing out. If fuel delivery was inadequate then you’d feel a stutter as the carb became fuel starved. If it were the clutch there would be obvious slipping resulting in a revving motor that didn’t translate to movement. What part of Austin are you in, I’d like to stop by to meet the patient.

 

[chubot]

You aren’t driving around in low 4 are you?

 

[aging fleet]

Wild, was really expecting the old carb to be what was stifling your top speed.

 

[knuckle47]

Wow! . I am sorry this did not provide the solution for this nutty problem. I was hoping and sitting here ( working in the garage on that new room) waiting to read the news.. I’m saddened as well..but clearly there are more than a few people interested in getting this behind you

 

[zerotreedelta]

RPMs match what one would expect for high-range - from what I could see, it peaked around 2100 in 4th around 45. It makes all the right sounds for a 40 at least.

Looked like you did the 3-4 shift at 2500. I usually let it eat a bit longer, more like 2800...a later shift might give it a helping hand in 4th, but it should still gain speed/RPM either way. Given the RPM holds, doesn't seem like a slipping clutch at least (although the splitting/delamination may be worth dealing with anyway).

Presumably that was a WOT pull in 4th? When you let off, how does it coast?

I'd also think that fuel supply starvation would cause a more severe/harsh effect...but never can tell I guess. I'm down to either the mechanical advance is basically all in at idle (so when you set timing, it's basically inop/disabled)...or something mechanical causing a sort of binding/drag.

Very very strange, but the haystack is shrinking at least.

 

[RevISK]

Matt I’d encourage you not to throw parts at it. Let’s figure this darn thing out. If fuel delivery was inadequate then you’d feel a stutter as the carb became fuel starved. If it were the clutch there would be obvious slipping resulting in a revving motor that didn’t translate to movement. What part of Austin are you in, I’d like to stop by to meet the patient.

I’d like to join or we can do it at my place since I’m not far from him and have good testing grounds.

I said this early on and I’m still thinking it has something to do with his gearbox.

 

[77mustard40]

I’d like to join or we can do it at my place since I’m not far from him and have good testing grounds.

I said this early on and I’m still thinking it has something to do with his gearbox.

Maybe I’ll get off my ass and bring you your springs.

 

[BOBWhite74]

I guess the Saga continues...
I hate to repeat this but I'd say keep bumping up (advancing) the timing until you get the performance you want. I know It says 7 degrees in the book but remember that is with new gears and tight bearings and bushings, usually once an engine gets broken in it the timing gradually retards.

Also I hate to nitpick but I don't recommend you rest your foot on the clutch even in between gear changes. I know its a hydraulic clutch and it probably doesn't matter but it will at least save you a STERN talking to if you ever give an older guy a ride

 

[Skreddy]

Good point, I did not disconnect the vacuum advance, so this is a "combined" number. I need to do more testing once I get the engine running again with the Weber.

Did you ever disconnect the vacuum source to the advance can when setting timing? And plug the vacuum source when timing.

 

[Mr. Green]

I originally was guessing at a 4Lo situation but you confirmed RPM so that's out. Still, seems weird that you just lack power in 4th vs the other gears. Brakes aren't dragging, are they?
Hope you figure this out! Maybe go back and review original problems... like the shift linkage. Has got to be a clue.
I applaud your persistence.

 

[Grayscale]

The Weber 32/36 DGEV ported vacuum kicks in somewhere at 1.5 turns in on the idle speed screw. I really doubt that an F can idle on that amount of throttle, or no way on a 2F at my altitude. So, by unplugging the vac line, you'll be able to kick-up the static timing, as your probably at two turns in on the idle-speed screw, is my guess. Replacing the vac line, you'll likely idle with vac advance. Simple, small victory.

The valve lash was set when the motor was still hot? I can't actually turn wrenches to set that fast, but, I can reheat, and the recheck them before the pushrods get cool. In your video with the valve cover off, why was the head orange on the inside?

 

[MatthewMcD]

Did you ever disconnect the vacuum source to the advance can when setting timing? And plug the vacuum source when timing.

Yes, I do that normally while setting the timing. Just forgot when doing the test of the advance mechanism this time around.

 

[MatthewMcD]

Video is private - you'll have to flip to to unlisted or public.

Any luck testing the mech timing advance with the vacuum advance disconnected?

On the list for today.

 

[MatthewMcD]

Matt I’d encourage you not to throw parts at it. Let’s figure this darn thing out. If fuel delivery was inadequate then you’d feel a stutter as the carb became fuel starved. If it were the clutch there would be obvious slipping resulting in a revving motor that didn’t translate to movement. What part of Austin are you in, I’d like to stop by to meet the patient.

Thanks! I know it needs a new clutch and I can guess that a fuel pump rebuild is in the future. So I am not worried about the work not being necessary. Since we addressed the carb, it feels like moving to the powertrain is the next logical step. It will allow me to better assess the state of the transmission and transfer case out of the truck.

I'll PM you my details.

 

[MatthewMcD]

I originally was guessing at a 4Lo situation but you confirmed RPM so that's out. Still, seems weird that you just lack power in 4th vs the other gears. Brakes aren't dragging, are they?
Hope you figure this out! Maybe go back and review original problems... like the shift linkage. Has got to be a clue.
I applaud your persistence.

Wheels spin freely in back (I need to adjust the rear brakes). The fronts drag very slightly.

 

[MatthewMcD]

In your video with the valve cover off, why was the head orange on the inside?

No idea, that was the first time I had the Valve Cover off.