Project Patina-November 1968 FJ-40

wngrog

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I have been enjoying having the 40 back together for some early morning rides.
94373A9C-F945-47C8-BFC1-6A4E5E57BF9D.jpeg



I’m still not right on the carburetor. It’s so sad to me because it was a perfect specimen before I took it off for the header change.

It drives great but it smells rich and gurgles off idle.

 

Pacer

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I have been enjoying having the 40 back together for some early morning rides.
View attachment 2035159


I’m still not right on the carburetor. It’s so sad to me because it was a perfect specimen before I took it off for the header change.

It drives great but it smells rich and gurgles off idle.

I feel that may not be the carb, sounds more to me like miss.
Check each header tube temp while running with an IR thermometer or....
Pull each sparkplug wire one at a time...
You know the drill.

Check all around the intake and carb base with brake clean to find leaks....
 

wngrog

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I feel that may not be the carb, sounds more to me like miss.
Check each header tube temp while running with an IR thermometer or....
Pull each sparkplug wire one at a time...
You know the drill.

Check all around the intake and carb base with brake clean to find leaks....
I agree. I chased down a few vacuum leaks. Changed the plugs.

I will hit the header tubes. That’s a great idea.

Unplugging DUI charged plug wires while running does not appeal to me.
 

wngrog

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I feel that may not be the carb, sounds more to me like miss.
Check each header tube temp while running with an IR thermometer or....
Pull each sparkplug wire one at a time...
You know the drill.

Check all around the intake and carb base with brake clean to find leaks....
I just ran IR over it. For sake of even numbers 1-4 were 500* , 5 was 350* and 6 was 180*

I am going to check the valves and rods
 

wngrog

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It was good before the header change. Something you did with that is the culprit.
Yep. I’m trying to redo everything I touched.

Of course I never ran an IR over the headers before.

Here is the video of hot motor at idle. Ignore the knocking sound. That’s was the hood rod hitting the hood.


This led me to believe #6 was not getting good spark. I replaced the (new OEM) plug with one out of my 60. And I replaced #6 wire.

This is the after video from the swap but the spark was the same before I swapped

 

wngrog

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So. Good spark. That led me into the valves to make sure they were correct and no pushrods were mushroomed.

This cover has not been off since @offr0adlim0 adjusted the valves 2 plus years ago.

I snugged up a couple bit for the most part the valves were good.

Check out the Oiler on the very last arm. It’s a bit excited. Never seen that before. All the rest are oozing as advertised


Not seeing anything else to check, I capped it and took it for a drive.

I’ll say it is 90% as before. Likely runs better than 98% of carbureted 40s out there but it’s still a bit off. Not sure what to check now.

Once at operating temp and driving temp you can see the headers are still HOT as hell 1-4, HOT on #5 and hot on #6. 50% less heat coming out of #6.

I’m going to go check and see what the Warthog does

 

wngrog

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All the cylinders are just as hot as the others on the Warthog FYI

I needed to get vacuum leak out of my head. I have been thinking I possibly cracked my intake manifold somehow when I had it off.

So I read up on the vacuums and the 2F. Found an awesome article. Read it.


Here are the Ciff’s Notes

2C66F46C-2F70-49EE-8889-E133B40C62CF.jpeg


Hooked up the MityVac to the carb spacer and everything checked out as it should. Low on the vacuum scale here at sea level but in range


I could not tell if I was in the “poor spark plug gap” area with +1 or if that was just vibration so I pulled all the plugs. Again. Regapped them to closer to the DUI spec range of .040

While I was in there I broke out the timing light and checked the signal on all 6 wires.

Idle was at 550 with the timing at 7*

DUI recommends up to 13* so I bumped the timing. Idle purring at 650 now.

Retested the vacuum and picked up a few


Took it for a final (hot as hell) spin up the road and it’s running great. I think I’ve dialed most of what has been ailing me out.

I still have a bit more gas fume at idle than I had before. Idle is mostly smooth.

I checked the headers after the drive and #6
Was still 150* cooler than the hottest pipe. No idea what that is about.

Last thing on all this. Checked the compression during all this and it’s a steady 120 across all cylinders. This is a rebuilt (of unknown quality) 2F with about 10,000 miles on it. Never has smoked or used a drop of oil.

Weird.
 

Pacer

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So. Good spark. That led me into the valves to make sure they were correct and no pushrods were mushroomed.

This cover has not been off since @offr0adlim0 adjusted the valves 2 plus years ago.

I snugged up a couple bit for the most part the valves were good.

Check out the Oiler on the very last arm. It’s a bit excited. Never seen that before. All the rest are oozing as advertised


Not seeing anything else to check, I capped it and took it for a drive.

I’ll say it is 90% as before. Likely runs better than 98% of carbureted 40s out there but it’s still a bit off. Not sure what to check now.

Once at operating temp and driving temp you can see the headers are still HOT as hell 1-4, HOT on #5 and hot on #6. 50% less heat coming out of #6.

I’m going to go check and see what the Warthog does

Is it possible you switched number 5 and 6 spark plug wires at some point?
 

Pacer

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All the cylinders are just as hot as the others on the Warthog FYI

I needed to get vacuum leak out of my head. I have been thinking I possibly cracked my intake manifold somehow when I had it off.

So I read up on the vacuums and the 2F. Found an awesome article. Read it.


Here are the Ciff’s Notes

View attachment 2035625

Hooked up the MityVac to the carb spacer and everything checked out as it should. Low on the vacuum scale here at sea level but in range


I could not tell if I was in the “poor spark plug gap” area with +1 or if that was just vibration so I pulled all the plugs. Again. Regapped them to closer to the DUI spec range of .040

While I was in there I broke out the timing light and checked the signal on all 6 wires.

Idle was at 550 with the timing at 7*

DUI recommends up to 13* so I bumped the timing. Idle purring at 650 now.

Retested the vacuum and picked up a few


Took it for a final (hot as hell) spin up the road and it’s running great. I think I’ve dialed most of what has been ailing me out.

I still have a bit more gas fume at idle than I had before. Idle is mostly smooth.

I checked the headers after the drive and #6
Was still 150* cooler than the hottest pipe. No idea what that is about.

Last thing on all this. Checked the compression during all this and it’s a steady 120 across all cylinders. This is a rebuilt (of unknown quality) 2F with about 10,000 miles on it. Never has smoked or used a drop of oil.

Weird.
Well, the fumes at idle are definitely from the misfiring #6.
 

Pacer

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Have you sprayed brake clean all around your intake manifold to look for the crack?
 

wngrog

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Have you sprayed brake clean all around your intake manifold to look for the crack?
That’s where I’m afraid this is going to end up.

I replaced the bungs on it I am using for the brake booster and I redid all the plugs with pipe sealant.

I just picked up a fresh can of starter fluid.

I could have cracked it.

So, if it did have a crack in the intake. Why would that manifest in a #6 misfire?

Also, was my vacuum test done wrong? Why would a manifold leak not have shown up to there?

F42F2348-37D6-44C4-9548-CB0443EF6B1F.jpeg
 
Last edited:

Pacer

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That’s where I’m afraid this is going to end up.

I replaced the bungs on it I am using for the brake booster and I redid all the plugs with pipe sealant.

I just picked up a fresh can of starter fluid.

I could have cracked it.

So, if it did have a crack in the intake. Why would that manifest in a #6 misfire?

Also, was my vacuum test done wrong? Why would a manifold leak not have shown up to there?

View attachment 2035745
You can use the starter fluid to check for leaks.

With the engine running, squirt starter fluid at the base of the carburetor and around each place where the manifold attaches to the cylinder head. Listen for a stumble or change in RPMs it will help you zero in on any leaks.
 
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I would do a leakdown on 6. I know compression looks good but I would still do one. Do one cold and another one at full run temp. The carb is common to all cylinders. If you had a rich issue there you should have more than one cylinder running rich. Besides on inline engines the fuel tends to lean out at the ends of the manifold.
 

wngrog

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You can use the starter fluid to check for leaks.

With the engine running, squirt starter fluid at the base of the carburetor and around each place where the manifold attaches to the cylinder head. Listen for a stumble or change in RPMs it will help you zero in on any leaks.
Yeah. I exhausted my 1/2 can finding what I thought were the leaks in the booster hose and that pipe fitting.


I quit for the day...actually for a few days.

Carb has been off twice to put new gaskets on. Thought that was the culprit. Changed the the booster bung and hose. Thought that was it. Resealed that bung pictured above.

Still don’t understand how a leak in the intake would make #6 miss
 
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