Builds Clifford is home again- a 1965 FJ40 FST

[middlecalf]

Finally got to pull the 40 out and check the engine tune again. I think fixing that dizzy line leak helped. But it was still not running well enough. Vacuum was almost 19”. A friend suggested I check the dwell and lent me a dwell meter. Sure enough it was a bit less than 35 degrees. It supposed to be between 38-44! So I adjusted the gap to 0.024” and got it right at 40. Engine seems happy when warmed. Pulling almost 20” of vacuum now and it seems best at 12.

Well, finally!

I guess I better pull out the dwell meter and check my new (at time of build) dizzy’s dwell instead of just assuming it is good to go out of the box .

 

[red66toy]

Well, finally!

I guess I better pull out the dwell meter and check my new (at time of build) dizzy’s dwell instead of just assuming it is good to go out of the box .

Hahaha, I know that took forever! I still do have a heat related vacuum leak I believe. The engine picks up better vacuum and smoother idle as it heats up. Although seems right for a old engine. I have no idea where the leak could be, but I will keep hunting. Hoping it's not a hairline crack in the intake or something. That being said, once warm the engine seems very happy so I am going to run it as is for a while.

Definitely check the dwell angle. I had my dizzy restored by an expert in the field and trusted it was perfect. The points gap was set to specs.. but the dwell was still off. Happy I checked the angle and got it to where it was supposed to be.

 

[red66toy]

@mattressking confirmed something I had been suspecting... that I had an exhaust leak. He has good ears. I had a hunch the studs I used on the exhaust downpipe were not correct. Too much shank length. So I had ordered a different style stud from Belmetric. His comment was the kick I needed to dive in last night. Sure enough.. leaking. The shank length was too long and the nut was bottoming out before I could compress the pipe gasket. Replacement studs are in and the truck is running MUCH quieter! Adjusted the valves today as well. Excited for a test drive tomorrow.

Suspect:

 

[red66toy]

Ok hive mind. Could use some help. Truck is running. It is VERY fun to drive again. But I still need to give it a bit of choke or it bogs down when I go to accelerate. With a bit of choke on it runs great, seems happy and accelerates strong. Even up a hill. First idea was that I had a vacuum leak. I cannot find one at all! I have sprayed carb clean all over the manifold interfaces and carb base.
Things that have been refreshed, done to the truck.
1. Had a SD40 carb rebuilt. Done to factory specs.
2. Fresh Remflex manifold gaskets
3. NOS fuel pump
4. New fuel lines
5. Timing, dwell angle and valves adjusted.
6. Rebuilt Dizzy
7. New cap and rotor, plugs and wires.
8. PCV checked
9. new rubber gasket under oil filler cap

So I feel like it has to be one of two issues, not enough fuel or too much air. With regards to the fuel, only thing I can think of at this point is maybe there is a partial blockage in the tank. As for a vacuum leak... that I don't know.

Would love some suggestions, maybe I am looking at the wrong things?

 

[Green Bean]

Ok hive mind. Could use some help. Truck is running. It is VERY fun to drive again. But I still need to give it a bit of choke or it bogs down when I go to accelerate. With a bit of choke on it runs great, seems happy and accelerates strong. Even up a hill. First idea was that I had a vacuum leak. I cannot find one at all! I have sprayed carb clean all over the manifold interfaces and carb base.
Things that have been refreshed, done to the truck.
1. Had a SD40 carb rebuilt. Done to factory specs.
2. Fresh Remflex manifold gaskets
3. NOS fuel pump
4. New fuel lines
5. Timing, dwell angle and valves adjusted.
6. Rebuilt Dizzy
7. New cap and rotor, plugs and wires.
8. PCV checked
9. new rubber gasket under oil filler cap

So I feel like it has to be one of two issues, not enough fuel or too much air. With regards to the fuel, only thing I can think of at this point is maybe there is a partial blockage in the tank. As for a vacuum leak... that I don't know.

Would love some suggestions, maybe I am looking at the wrong things?

As an experiment, what happens if you advance the timing several degrees and take it for a test spin?

 

[red66toy]

As an experiment, what happens if you advance the timing several degrees and take it for a test spin?

So the timing is already advanced to 12 degrees. That gave me the best vacuum at idle. Thinking I should try more?

 

[middlecalf]

So now were on the right track, because you still need to get this figured out so then I know what to do with my rig as I have the exact same fault (stumble) and runtime hack fix (choke). I'm not a fan of high(er) timing advance FWIW.

But I do have a bit of a different setup, that being the Offenhauser dual carb setup with two Carter WA1's and you have the single OEM SD40. I suspected too much air given my two carb setup, and the choke closes one of the carbs down air-wise (only have choke cable connected to one carb). But chocking also increases the throttle. Both of those factors impact the airflow through the carb and hence the fuel draw. My suspicion on too much air is linked to that event, transitioning from low speed circuit to high speed - possibly a bit also from idle to low speed. I've messed around a bit with lean drop tuning but haven't completely saucered and blown this so I'm not convinced I've traced that down. I've also sprayed everything to find a vacuum leak, and I've smoked out intake and exhaust system using a vacuum smoke checker thingy. And of course I've replaced the head casket, honed the cylinders and replaced rings with NOS OEM rings, cleaned up the valves and honed the seats and set the valve gaps, new dizzy at start of rebuild (less than 500 miles), check point gaps (but need to check dwell), set timing and idle speed, yadda yadda yadda. And I'm getting 14.5mpg which is pretty good IMO and there's no smoke anymore out the tail pipe. So I'm driving it .

Hurry up though and figure this out, I'd like to eliminate my stumble.

Oh, and I'm not much help either.

 

[Skreddy]

I know nothing about those carbs. Now that the disclaimer is out there. Do you get a good stream from the accelerator pump? (I’m assuming that carb has an accel pump).
Are you running a vacuum retard or vacuum advance distributor? Or neither?
Whenever I suspect a vac leak I disconnect and cap all vacuum ports to rule out those and the accessories they go to.

 

[red66toy]

I know nothing about those carbs. Now that the disclaimer is out there. Do you get a good stream from the accelerator pump? (I’m assuming that carb has an accel pump).
Are you running a vacuum retard or vacuum advance distributor? Or neither?
Whenever I suspect a vac leak I disconnect and cap all vacuum ports to rule out those and the accessories they go to.

Stream seems good! I’ll get a shot of it. It’s a vacuum advance dizzy. The only accessories off the manifold are the PCV valve and the 4WD system. I plugged the 4wd system and it didn’t change anything. PCV system is all tight and sealed. I sprayed carb cleaner around the manifold gaskets, all over the carb. Nothing changed the idle. Vacuum at idle when cold is 16-17, warm it’s almost 20.

 

[red66toy]

So now were on the right track, because you still need to get this figured out so then I know what to do with my rig as I have the exact same fault (stumble) and runtime hack fix (choke). I'm not a fan of high(er) timing advance FWIW.

But I do have a bit of a different setup, that being the Offenhauser dual carb setup with two Carter WA1's and you have the single OEM SD40. I suspected too much air given my two carb setup, and the choke closes one of the carbs down air-wise (only have choke cable connected to one carb). But chocking also increases the throttle. Both of those factors impact the airflow through the carb and hence the fuel draw. My suspicion on too much air is linked to that event, transitioning from low speed circuit to high speed - possibly a bit also from idle to low speed. I've messed around a bit with lean drop tuning but haven't completely saucered and blown this so I'm not convinced I've traced that down. I've also sprayed everything to find a vacuum leak, and I've smoked out intake and exhaust system using a vacuum smoke checker thingy. And of course I've replaced the head casket, honed the cylinders and replaced rings with NOS OEM rings, cleaned up the valves and honed the seats and set the valve gaps, new dizzy at start of rebuild (less than 500 miles), check point gaps (but need to check dwell), set timing and idle speed, yadda yadda yadda. And I'm getting 14.5mpg which is pretty good IMO and there's no smoke anymore out the tail pipe. So I'm driving it .

Hurry up though and figure this out, I'd like to eliminate my stumble.

Oh, and I'm not much help either.

Haha, I am not giving up! Ok well stopping short of ripping major things apart.
I hope I can solve this and it helps you as well. Sounds very similar though. I wish I had dual carbs.

Edit: ok @middlecalf I may have to change my dedication to solving this issue now. hahaha

 

[63cruiser]

For what it’s worth, I had Jim C rebuild my SD40 carb and he could not get it to run perfect on his “test rig” without a little choke. I think he uses a 2f on his 60 series with a manifold adapter to run the older carbs. He knows how well his rig runs so the only variable is the carb. He then adjusts it from there. He could not adjust mine without the need for a little choke. He suggested that we could dig deeper but it could ruin the carb. I didn’t think losing my matched carb was worth it. I figure if one of the Carb Gurus couldn’t get it to run perfect without a little choke, then I was going to accept the results. I just run a little choke. Starts every time and restarts after warm. I suspect if you try for perfection with one of these old rigs, you may end up disappointed.

 

[red66toy]

For what it’s worth, I had Jim C rebuild my SD40 carb and he could not get it to run perfect on his “test rig” without a little choke. I think he uses a 2f on his 60 series with a manifold adapter to run the older carbs. He knows how well his rig runs so the only variable is the carb. He then adjusts it from there. He could not adjust mine without the need for a little choke. He suggested that we could dig deeper but it could ruin the carb. I didn’t think losing my matched carb was worth it. I figure if one of the Carb Gurus couldn’t get it to run perfect without a little choke, then I was going to accept the results. I just run a little choke. Starts every time and restarts after warm. I suspect if you try for perfection with one of these old rigs, you may end up disappointed.

Thank you for this! That is super helpful to know. Maybe this is as good as it gets and there is nothing really to dig for.

 

[locklaw]

Thank you for this! That is super helpful to know. Maybe this is as good as it gets and there is nothing really to dig for.

I have the same symptoms on my SD40 and after enough fiddling and rebuilding, I came to the same conclusion and now worry about other things.

 

[middlecalf]

Did all the same stuff you’ve done Chase, plugging/capping everything, getting squirts of fuel, …. and same results. Maybe this is as good as it gets.

 

[RodrigzCrzr]

I have the same results with a recent SD40 carb.
On a 65 FJ40.

 

[red66toy]

I have the same results with a recent SD40 carb.
On a 65 FJ40.

Thank you! It’s great to hear I am on the same page as others.

 

[middlecalf]

Another early morning thought: do you still have a functioning exhaust heat deflector thingy in your exhaust manifold? I wonder if this is having a cold vs. warm impact on your stumble? My deflector was removed sometime in its past by a PO so its always open, and another difference with mine is having the dual carb setup so neither carb sits right over that heated spot but out a bit on the intake manifold. I measured the IR temps of the carb bases after a drive and the forward carb was ~95-deg F and the aft carb was ~102-deg F. The outside temps have been 24 to 38 deg F here with all this “test” driving. Not sure what’s “spec” with this deflector system or what impacts it has on fuel delivery/vaporization.

 

[ceylonfj40nut]

Finally got a chance to tackle the brakes again. The pump for my pressure bleeder died so I had to wait for a new one to come in. I was able to get a lot of air out this time. A combination of pumping the brake pedal and pressure system helped. Also, thank you @cruisermatt for planting the seed of doubt on the brake adjustment maybe being not quite right. I think they were adjusted too loose.
Need to pick up a new battery tomorrow so I can finally fire this truck back up! Thanks @Kleatus for always answering my text questions.
View attachment 3280011

This section looks like a place air bubbles may get trapped. Avoid inverted U-shapes.

 

[ceylonfj40nut]

If you stick a vacuum gauge on the manifold or other vac source, what does it read?

 

[RodrigzCrzr]

I’m sure you have checked it. But make sure the tube on the base of the carb was solid and not with any movement. I found a vacuum leak there. And what I did I laid some RTV around where the tube come out of the base. Sealed it up and made vacuum gauge go up a few points.

Oh never mind I zoomed in on the last photo and noticed you did that already!