All Small Six Which cylinder head?

[Otto]

Took the van for an extended test drive to check my work. The speedometer is now pretty durn close to the app on my phone, so I’m calling that fixed.

The engine ran well with the 160 jet size; I didn’t see any alarming lean readings from the AFR gauge and driveability was excellent. I’m thinking this setting will work for my engine. The van will get driven more when summer rolls around and more time behind the wheel will further tell the story.

Thanks to all that contributed to this project, it’s appreciated. Sometimes it takes a village…

 

[Otto]

Just to follow up with a summer driving update:
I drove the van to a local Econline-centric event at the end of June, and noticed the AFR meter was reading lower than it was when I was testing things out in January. Plus I could tell it was running richer due to the exhaust smell. Having windows that open on the rear doors tends to offer clues on what’s happening in the engine.

I got some new jets in the 1.55mm size as I had drilled the carb’s jets larger. The new jets are one size smaller than the drilled jets that were in the engine. With these new jets, I was seeing 14s and 15s on the meter cruising down the road- this is higher than before where it was only in the 13s with an occasional 14.
On the latest test drive w/new jets installed, the spark plugs look like this:



I pulled #1, 2, and 4 and they all looked very similar. This is after driving at 40-45 mph and turning the key off and pushing the clutch in, coasting off the road. I was able to pull the plugs from the driver’s seat even with a seat belt on!

Any thoughts on the plugs? It seems to run well. The engine is only happy with the idle at around 12.5.

 

[DON]

Plug looks good in the photo
With the idle around 12.5, let it idle for 15-20 minutes and check the plugs again. I would say it it is happy there, leave it and see if any negative issues arise .
Assuming all other aspects are correct- timing mostly

 

[Otto]

I’ve been driving the van a bit since summer hit and am enjoying how the van runs/drives now, but can’t help thinking there might be a bit more to achieve with it. I’m wondering if the ignition timing is optimum for the engine and did some initial data collection. With the vacuum hose disconnected and timing light hooked up, I find the initial base timing to be at 20* btc- seems like a bit much. Sometimes the starter protests when the engine pushes back when cranking.
Idle= 20*
1000= 22*
1500= 30*
2000= 34*
2500= 34*

34 degrees seems to be all the mechanical advance the engine is seeing; if I reconnect the vacuum hose and run the engine up to 2500, the engine is seeing ~48*.
In all the driving I’ve done with the van I’ve never heard it “ping” on regular gas. The engine is stock with the exception of the 2 bbl carb and the DSll distributor. I have the Mr. Gasket #925D kit on the workbench- is it worth it to try changing springs? I’ve read so many of the existing threads with various pro/con arguments that now I’m cautious to try anything.

 

[Frank]

I’ve been driving the van a bit since summer hit and am enjoying how the van runs/drives now, but can’t help thinking there might be a bit more to achieve with it. I’m wondering if the ignition timing is optimum for the engine and did some initial data collection. With the vacuum hose disconnected and timing light hooked up, I find the initial base timing to be at 20* btc- seems like a bit much. Sometimes the starter protests when the engine pushes back when cranking.
Idle= 20*
1000= 22*
1500= 30*
2000= 34*
2500= 34*

34 degrees seems to be all the mechanical advance the engine is seeing; if I reconnect the vacuum hose and run the engine up to 2500, the engine is seeing ~48*.
In all the driving I’ve done with the van I’ve never heard it “ping” on regular gas. The engine is stock with the exception of the 2 bbl carb and the DSll distributor. I have the Mr. Gasket #925D kit on the workbench- is it worth it to try changing springs? I’ve read so many of the existing threads with various pro/con arguments that now I’m cautious to try anything.

Great news!, nothing beats driving the old classics.
The mechanical advance is only 14*, which is why it needs 20* base timing. "Pushing back" while cranking is not good, it puts huge load on the rod bearings and starter. A solution (other than retarding the base timing, which it needs with the 14* timing curve) is to put the ignition on a separate toggle switch. Then crank the engine over (no spark) and flip the ignition on. The inertia of the rotation will overcome the early base timing, it will fire right up. Most race engines use this, as the timing is locked in at a high advance.

Have you looked at the springs in the distributor? I would wager there's more advance in the weights than is releasing thru the springs @ 2500 rpm. A lot of stock type distributors have a heavier second spring. On my 300's changing the heavier spring (only) for a lighter one put the curve right in the sweet spot.

 

[Otto]

I have a spare DSll and took this apart to compare and get familiar with it. The light spring had tension and the heavy spring had some slack.

I pulled the van’s distributor and installed one of the 925D kit springs in the advance mechanism replacing the light spring. According to the lore here on the page, the heavy spring’s post gets bent inward 3/32”. I did this and it took the heavy spring completely out of the picture, it was totally slack throughout the full movement of the advance- unless this is the whole point of bending the post. I pulled the post back about half of the distance bent where the heavy spring now came into play in the final movement of the mechanism.

Now the ignition looks something like this:
Idle= 14-15*
1000= 19*
1500= 30*
2000= 32*
2500= 35*

With vacuum connected, total ignition advance is at 52* at 3k rpm.
It might all be in my head, but the test drive this evening was good- very pleased with how it runs. It’s seeing basically the same curve with a lower initial setting. So I guess the kit worked, I think I’ll leave it alone for a while.

If someone sees something out of the ordinary here please let me know.

 

[gb500]

Did you run your mech advance readings past 2500rpm ?

Does it stop advancing at 2500rpm?

 

[Otto]

Yes, past 2500 rpm there’s no more advance. Stays the same.
With the vacuum connected, there’s more.

 

[Otto]

I’m still enjoying how the van runs and made some short trips with it this summer. Overall, it runs very well- it’s smooth, doesn’t hesitate, makes pretty good power for what it is and starts every time. However, it seems to be using more fuel than I think it should. My last little trip was 40-45 miles and it used about ¼ tank (~3.5 gallons). That’s roughly 12 mpg- dismal. I haven’t really quantified the fuel usage by filling the tank and doing arithmetic, but at this point it’s not necessary to realize the van is thirsty.

The engine runs at 165 -170F most of the time, with it reaching 190F in standstill traffic. When it was doing this, the AFR meter cleaned up to 13.5 at idle where it is 12.5 most of the time. Running down a level road at a steady speed with a light throttle, the meter will see high 14s and low 15s. This seems good. At lower engine speeds I’ll see 11s and 12s. Before I start investigating the reason(s) for excessive fuel usage, could it be that the engine is running too cold? Pretty sure it has a 180F thermostat.

 

[DON]

You don’t drive vans for the gas mileage

 

[Frank]

I’m still enjoying how the van runs and made some short trips with it this summer. Overall, it runs very well- it’s smooth, doesn’t hesitate, makes pretty good power for what it is and starts every time. However, it seems to be using more fuel than I think it should. My last little trip was 40-45 miles and it used about ¼ tank (~3.5 gallons). That’s roughly 12 mpg- dismal. I haven’t really quantified the fuel usage by filling the tank and doing arithmetic, but at this point it’s not necessary to realize the van is thirsty.

The engine runs at 165 -170F most of the time, with it reaching 190F in standstill traffic. When it was doing this, the AFR meter cleaned up to 13.5 at idle where it is 12.5 most of the time. Running down a level road at a steady speed with a light throttle, the meter will see high 14s and low 15s. This seems good. At lower engine speeds I’ll see 11s and 12s. Before I start investigating the reason(s) for excessive fuel usage, could it be that the engine is running too cold? Pretty sure it has a 180F thermostat.

It seems it's time to do a careful choke-operation check. A choke plate closed even a few degrees will cause a rich condition. Engine temperature is not going to change the carburetor metering.

 

[Otto]

You don’t drive vans for the gas mileage

Ain't that the truth! I was hoping it could at least match my 6.0L 3500 Express, it will get 17 mpg. The "New for 1961" adverts claimed "Up to 30% better mileage than 1/2 ton panels", so I was hopeful...

 

[DON]

17mpg IF you don’t go over 65-70 mph!!

 

[Frank]

17mpg IF you don’t go over 65-70 mph!!

Wind drag (and stopping distance & impact inertia) is doubled at 70mph vs 50 mph.

 

[Otto]

I had a new 195F t-stat on the shelf and installed that into the van’s engine. Took the van for a drive over the weekend and had some observations: driving along on flat road at a steady speed, I see 10” Hg vacuum and around mid 13s on the AFR meter- this is light throttle around 2K rpm, just cruising along anywhere from 45-55 mph. Vacuum never really reads higher except coasting down hills where it will read 20” +. Still uses more fuel than I think it should.

The vacuum and AFR readings seem to have an inverse relationship where one will drop and the other rise depending on what the throttle is doing.

I’m also curious about the engine temperature- the gauge in the dash is reading right in the middle of the range, and the temp gauge with numbers will still read ~160 ish running down the road and climb no more than 190F when stopped in traffic. The stock gauge sender is in the back of the cyl head while the other gauge is installed in a tee inline with the heater supply hose outlet. This is where other engines I’m familiar with measure temp, so the rear location seems odd. Shouldn’t the hottest coolant be leaving the front of the cylinder head?

 

[Otto]

17mpg IF you don’t go over 65-70 mph!!

70 is about as fast as I generally drive it. Pulling our 16' car trailer and my jeep loaded, it got 12 mpg.

 

[DON]

I’ve had a ford van with a six, Chevy van with a 350, another with 4.3 v6, and Nissan NV with 4.6 v8, empty- none got over 20 mph.
I gave up trying to to achieve that and started going for performance. If they were going to get bad mileage, at least it would tow good. The NV was the best for towing

 

[Frank]

: driving along on flat road at a steady speed, I see 10” Hg vacuum and around mid 13s on the AFR meter- this is light throttle around 2K rpm, just cruising along anywhere from 45-55 mph. Vacuum never really reads higher except coasting down hills where it will read 20” +. Still uses more fuel than I think it should

This indicates late ignition timing. Van or not, 10" vacuum at 2K rpm is either: dragging brakes, flat tires, 25mph head wind- or late ignition timing.

 

[Otto]

This indicates late ignition timing. Van or not, 10" vacuum at 2K rpm is either: dragging brakes, flat tires, 25mph head wind- or late ignition timing.

Something is going on, just don't know what. Tires inflated, brakes not dragging (actually felt the drums to check), and I thought the timing was ironed out in post #106. The van is 3200 lbs. and aerodynamic as a garden shed powered by a small engine, so maybe that's just how it is. But it should do better than 12 mpg. Puzzled.

 

[Frank]

Something is going on, just don't know what. Tires inflated, brakes not dragging (actually felt the drums to check), and I thought the timing was ironed out in post #106. The van is 3200 lbs. and aerodynamic as a garden shed powered by a small engine, so maybe that's just how it is. But it should do better than 12 mpg. Puzzled.

It's possible. I'm only speaking from a long time of watching vacuum gauges mounted in the vehicle. I drive off of it. An inline 6 turning 2000 rpm @ 10" of vacuum is considered a moderately heavy load. The small engine may be working that hard relative to the aero drag, but if it were me, I'd advance the timing by loosening the distributor hold down and gently tapping the distributor with the 1/2" open end wrench to move the vacuum can 1/4" in the advance direction. Lock down and try it. Keep doing this till pinging is heard, then go back 1/4" and you then know timing is perfect for those highway conditions. I just did this last week, ironically. Had to make a rare interstate drive for work in an old F150/300 engine. The engine was pinging slightly. Retarded the timing using the method above, took about 2 minutes in a rest area, ran perfect the rest of the way.