Builds 1974 FJ40 Restoration Build Thread
- Thread starter JohnJL
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
thebigredrocker
SILVER Star
Dust on the HOOD! Come on man.
Really like your color choice. Body color roll cage is
Really like your color choice. Body color roll cage is
thebigredrocker
SILVER Star
- Thread starter
- #224
Is this Canadian for "Jim can I bring my rig to your shop please"
Last edited:
- Thread starter
- #227
Dust on the HOOD! Come on man.
View attachment 2533359
Really like your color choice. Body color roll cage is
Just to keep it light, lets say its kief on the hood, not just regular dust
What type of distributor is on the engine?
- Thread starter
- #229
Its a DUI with a new cap, rotor, wires and plugs. Its vacuum advance is tapped to the manifold per DUI's recommendation.
Thanks,
John
- Thread starter
- #231
Thank you, its killing me that this backfiring on decel issue is keeping me from enjoying it.!
Beautiful rig, love the colour. Can I drop mine off to you to get the tub redone... If so, I’ll throw the steering column and be there in a Jiffy.
My gut reaction is that it’s a timing issue.
Have you tried hooking the vacuum advance to a ported vacuum source? That’s where it would be connected if I wasn’t a DUI. I’m throwing it out there... but I’ll be honest, I know nothing about DUI. I have been messing around with my points distributor(s) in my 40 for many years. I had the last 10.25:1 SBC running well on 87 octane for 21 years. The current 8.5:1 SBC loves it too.
If you have the original distributor, I’d throw it in, check & double check it’s fully seated into the oil pump, and go for a spin. If it solves the issue, it’ll narrow down the source of the problem. Alternatively, retard the timing a degree and see if it changed the symptoms.
If so, I’ll throw the steering column and be there in a Jiffy.My gut reaction is that it’s a timing issue.
Have you tried hooking the vacuum advance to a ported vacuum source? That’s where it would be connected if I wasn’t a DUI. I’m throwing it out there... but I’ll be honest, I know nothing about DUI. I have been messing around with my points distributor(s) in my 40 for many years. I had the last 10.25:1 SBC running well on 87 octane for 21 years. The current 8.5:1 SBC loves it too.
If you have the original distributor, I’d throw it in, check & double check it’s fully seated into the oil pump, and go for a spin. If it solves the issue, it’ll narrow down the source of the problem. Alternatively, retard the timing a degree and see if it changed the symptoms.
- Thread starter
- #233
Beautiful rig, love the colour. Can I drop mine off to you to get the tub redone...
My gut reaction is that it’s a timing issue.
Have you tried hooking the vacuum advance to a ported vacuum source? That’s where it would be connected if I wasn’t a DUI. I’m throwing it out there... but I’ll be honest, I know nothing about DUI. I have been messing around with my points distributor(s) in my 40 for many years. I had the last 10.25:1 SBC running well on 87 octane for 21 years. The current 8.5:1 SBC loves it too.
If you have the original distributor, I’d throw it in, check & double check it’s fully seated into the oil pump, and go for a spin. If it solves the issue, it’ll narrow down the source of the problem. Alternatively, retard the timing a degree and see if it changed the symptoms.
Hi, thanks for the compliments and the suggestions.
I asked DUI whether manifold source or ported source is correct, they said manifold so I am using that. I do actually have the old distributor in a box, though it hasnt been installed in 20 years. I have switched the vacuum source for the sake of trial and error and found it slightly better on the manifold. I rebuilt the distributor and checked both the weights and the vacuum mechanisms work smoothly. Also just ordered another couple of exhaust gaskets. Maybe air leaking in at the donut gasket?
It was partially de-smogged before the restoration, but still had the computer connected, and it wasnt backfiring before...
Anyone know if a 1974 US market FJ40 uses the "computer" to close the idle solnoid under decel?
- Joined
- Sep 26, 2003
- Threads
- 117
- Messages
- 11,199
- Location
- Lancaster, Ohio, USA
- Website
- www.tlcperformance.com
The 7" of vacuum at idle is low, although a lumpy cam will knock it down. 15-18" would be typical of an F engine.
An AFR reading of 14 is also lean for a good idle on F carb. Peak idle quality will be closer to 13. Lean idle AFR will pull the idle vac reading down as well.
The vacuum advance distributor should be connected to the ported vac fitting on the carb base.
The 69-75 US-spec stock dissy is vac retard, so don't install it.
The computer does not control the ICS on 74. That functionality is on 79-87 USA trucks. ICS power comes straight from the ignition switch, ground is through the body of carb.
An AFR reading of 14 is also lean for a good idle on F carb. Peak idle quality will be closer to 13. Lean idle AFR will pull the idle vac reading down as well.
The vacuum advance distributor should be connected to the ported vac fitting on the carb base.
The 69-75 US-spec stock dissy is vac retard, so don't install it.
The computer does not control the ICS on 74. That functionality is on 79-87 USA trucks. ICS power comes straight from the ignition switch, ground is through the body of carb.
thebigredrocker
SILVER Star
There was also this
- Thread starter
- #236
Thank you for the reply and suggestion. When I took the rad and accessories all off to check cam timing again I had a careful look at the cam gear based on this suggestion. There arent any visible indications of the outer gear walking. If the cam timing was off by enough to effect vacuum that much, should I be getting such good leakdown figures though? Leakdown was 5-7% on all cylinders with good, consistent compression ~150 psi.
- Thread starter
- #237
Maybe some progress, maybe not...
I re-researched my vacuum connections and found that I had the carb diaphram vacuum tube connected to the vacuum port on the front of the carb base. I noticed that that diaphram was working its linkage on the 2ndary throttle when vacuum varied, so it was working. I pulled my "Evaporative Emission Control Device" and noted one hose connected to the carb base port, and the diaphram has a separate connection to the device. So in my re-assembly I may have assumed attaching the carb port to the carb diaphram was an acceptable deletion of that device. I seem to remember thats how they are plumbed on typical generic asian (not Aisin) carbs. I will likely rebuild/restore the EECV once the motor is running just right, I believe its function is really to manage the purging and venting of the charcoal canister and gas tank. I have all the pieces. I really want to get the motor running properly before adding that back into the troubleshooting mix.
In any case, I plugged off the carb base port and disconnected the 2ndary carb diaphram. Connected the dizzy vacuum to the intake manifold along with the manifold vacuum gauge. Plugged the new carb vacuum tube as DUI insists the distributor wants intake vacuum signal, not port vacuum signal. (interesting side note here, in my experimentation with vacuum plumbing I notice when the distributor vacuum advance is connected to carb port vacuum, and timed to 13degrees, when I then change the dissy vacuum source to the intake I have to adjust the distributor ~4 degrees to get it back to 13 degrees at idle.)
They just salted the roads here, so just warming up in the driveway and doing some gentle donuts around the lot in the snow to test the differentials and transfer case. It pops in the exhaust on throttle-off still. Starts perfect and idles smooth if lean as noted above. Cooling system, heaters, radio, wipers, lights all work perfect!
I re-researched my vacuum connections and found that I had the carb diaphram vacuum tube connected to the vacuum port on the front of the carb base. I noticed that that diaphram was working its linkage on the 2ndary throttle when vacuum varied, so it was working. I pulled my "Evaporative Emission Control Device" and noted one hose connected to the carb base port, and the diaphram has a separate connection to the device. So in my re-assembly I may have assumed attaching the carb port to the carb diaphram was an acceptable deletion of that device. I seem to remember thats how they are plumbed on typical generic asian (not Aisin) carbs. I will likely rebuild/restore the EECV once the motor is running just right, I believe its function is really to manage the purging and venting of the charcoal canister and gas tank. I have all the pieces. I really want to get the motor running properly before adding that back into the troubleshooting mix.
In any case, I plugged off the carb base port and disconnected the 2ndary carb diaphram. Connected the dizzy vacuum to the intake manifold along with the manifold vacuum gauge. Plugged the new carb vacuum tube as DUI insists the distributor wants intake vacuum signal, not port vacuum signal. (interesting side note here, in my experimentation with vacuum plumbing I notice when the distributor vacuum advance is connected to carb port vacuum, and timed to 13degrees, when I then change the dissy vacuum source to the intake I have to adjust the distributor ~4 degrees to get it back to 13 degrees at idle.)
They just salted the roads here, so just warming up in the driveway and doing some gentle
donuts around the lot in the snow to test the differentials and transfer case. It pops in the exhaust on throttle-off still. Starts perfect and idles smooth if lean as noted above. Cooling system, heaters, radio, wipers, lights all work perfect!
Your leak test will only show you the condition of your piston rings and if your head gasket and valves still seal. It does not show if your timing is correct.
- Thread starter
- #239
Maybe some progress, maybe not...
I re-researched my vacuum connections and found that I had the carb diaphram vacuum tube connected to the vacuum port on the front of the carb base. I noticed that that diaphram was working its linkage on the 2ndary throttle when vacuum varied, so it was working. I pulled my "Evaporative Emission Control Device" and noted one hose connected to the carb base port, and the diaphram has a separate connection to the device. So in my re-assembly I may have assumed attaching the carb port to the carb diaphram was an acceptable deletion of that device. I seem to remember thats how they are plumbed on typical generic asian (not Aisin) carbs. I will likely rebuild/restore the EECV once the motor is running just right, I believe its function is really to manage the purging and venting of the charcoal canister and gas tank. I have all the pieces. I really want to get the motor running properly before adding that back into the troubleshooting mix.
In any case, I plugged off the carb base port and disconnected the 2ndary carb diaphram. Connected the dizzy vacuum to the intake manifold along with the manifold vacuum gauge. Plugged the new carb vacuum tube as DUI insists the distributor wants intake vacuum signal, not port vacuum signal. (interesting side note here, in my experimentation with vacuum plumbing I notice when the distributor vacuum advance is connected to carb port vacuum, and timed to 13degrees, when I then change the dissy vacuum source to the intake I have to adjust the distributor ~4 degrees to get it back to 13 degrees at idle.)
They just salted the roads here, so just warming up in the driveway and doing some gentle
All my vacuum connections...
