1974 FJ40 Distributor Issues (4 Viewers)

[cptmackay]

Hello,

I have posted here before and have found the community to be quite helpful.

I have a 1974 FJ40 that has been misfiring and running rough. It starts out with one or two misfires and gets worse over time. I am 99% sure it is the dizzy. Every time I have these issues I replace the rotor in the dizzy cap and the problem goes away for about 50-100 miles or about 8 hours of run time. Then the issues repeat, I notice fouling on the points and rotor. I also notice some play in the rotor probably 5-10 degrees or so. When I take the rotor off it is chewed up on the inside. My question is, should I replace the entire Dizzy with a DUI dizzy or should I attempt a rebuild? I am pretty sure the previous owner put an aftermarket dizzy in so I am not concerned about losing an OEM part.

Because of the Play I am thinking the gear at the bottom has worn out and should be replaced. But I want to know if any one else has experienced anything similar.

Thanks!

 

[igotta40]

Got any pictures to illustrate your description?

 

[Jonathan Hanson]

I don't know if that's your problem, but years ago I replaced the stock points distributor on my 73 FJ 40 with a late-model large-cap distributor. You also need to buy a newer side cover for the block with the indent for the distributor cap, but it's a far, far superior unit, and virtually maintenance-free.

 

[cptmackay]

Here are the pictures. The Open Distributor, the Underside of the Rotor, The points and the top of the rotor. After the last time I ran the truck I opened the dizzy and checked the rotor, I wiped some soot off the rotor. So it had more build up.

/

 

[cptmackay]

I don't know if that's your problem, but years ago I replaced the stock points distributor on my 73 FJ 40 with a late-model large-cap distributor. You also need to buy a newer side cover for the block with the indent for the distributor cap, but it's a far, far superior unit, and virtually maintenance-free.

Which distributor did you use? Was it from a 40 or a 60?

 

[charliemeyer007]

I bet the bushing is worn more than the gear. I don't like dizzy caps with aluminum contact's.

I have a Delco in my 72, I need to make a new bushing to take out some of the slop, it doesn't eat caps or rotors yet, but its sloppy IMHO.

 

[cruisermatt]

19100-61080 Is what you want.

 

[65swb45]

/this\

To make matters worse, it looks like you’re supplying vacuum to the retard diaphragm.

Get a vacuum advance dizzy and hook it up to a vacuum advance port on the carb and call it done.

I have new and refurbished vacuum advance dizzies in stock if you would like to get one from me.

www.marksoffroad.net

 

[cptmackay]

Thanks for everyone's help. What is the advantage of using a Vacuum Advance Distributor vs supplying vacuum to the retard diaphram?

Are these Toyota Vacuum Advance Distributors more reliable than an all electric ignition?

 

[cstav86]

Mark is a solid resource if you need the carb work to add a vac advance port too.
@4Cruisers can also supply a vac advance distributor. He builds them custom. I can speak first hand to his work, it's quality.
I run a DUI and it is no better than a stock distributor with pertronix.

 

[65swb45]

Thanks for everyone's help. What is the advantage of using a Vacuum Advance Distributor vs supplying vacuum to the retard diaphram?

Are these Toyota Vacuum Advance Distributors more reliable than an all electric ignition?

You can read about the benefit of the vac advance dizzy on the FAQ of my website.

 

[45Dougal]

I'm running diesel, so sparks aren't something I worry about on the 40, but when I replaced my suzuki points for electronic ignition, it completely transformed the bike.

I'm not a purest for LC parts, but more purest for LC ethos. If you want something you can fix in the bush with a cigarette packet and a shoelace then get a new points dizzy. If you want something that's reliable and just works then get electronic - your AAA will get you home anyway for that 1/1000 time it fails.

 

[Jonathan Hanson]

Which distributor did you use? Was it from a 40 or a 60?

I believe it was from a 40. The later large-cap distributors are extremely robust and reliable, and have a cap secured by screws and a venting system to keep the inside dry. Far more water resistant than any points distributor with a clipped-on cap.

 

[Spike Strip]

Thanks for everyone's help. What is the advantage of using a Vacuum Advance Distributor vs supplying vacuum to the retard diaphram?

Are these Toyota Vacuum Advance Distributors more reliable than an all electric ignition?

I have a mid-74 FJ40. I'm running the -61080 Distributor pictured above. This is your easiest and *best* upgrade. The stock Vac retard dissy is a vestigial smog item and chokes performance and mileage. The 61080 is a genuine Toyota points distributor so it will be a plug and play. It's amazing that it's still available. If you want an aftermarket electronic ignition, Mark (65swb45 above) is a Pertronix dealer so he can install the correct one in the distributor for you.

FWIW, first thing I did when I got the truck was ditch the Vacuum retard dissy for new Toyota unit.

Mark's Off Road: 818-953-9230

 

[65swb45]

Based on what I’ve seen in the last 10 years, the large cap electronic dizzy would be a near-last choice at this point.
1. New units are not available anymore, so you’re looking at buying something that’s at least 35 years old.
2. A significant number of them have advancer diaphragms that don’t work, and stock replacements are nla.
3. You’re competing with stock 60 owners who NEED that distributor to stay on the road in states that require emissions testing.
4. If you live in a damp environment, the holddown screws can become a liability. I have seen dozens of cases with snapped screws. Never happen with the clip on.
5. Once the oring is gone (close to half are) the much touted waterproof design is basically gone.

Shall I keep going?

 

[cruisermatt]

Based on what I’ve seen in the last 10 years, the large cap electronic dizzy would be a near-last choice at this point.
1. New units are not available anymore, so you’re looking at buying something that’s at least 35 years old.
2. A significant number of them have advancer diaphragms that don’t work, and stock replacements are nla.
3. You’re competing with stock 60 owners who NEED that distributor to stay on the road in states that require emissions testing.
4. If you live in a damp environment, the holddown screws can become a liability. I have seen dozens of cases with snapped screws. Never happen with the clip on.
5. Once the oring is gone (close to half are) the much touted waterproof design is basically gone.

Shall I keep going?

agreed on all count's except for #5 since the O-Rings are still available new

 

[roadstr6]

@4Cruisers made up a batch of single port advance diaphragms a couple of years ago for the big cap distributors. I bought several to use as spares on my desmogged, low altitude trucks. He may still offer this service. I've heard too many horror stories about the DUI units. I just won't use them.

 

[cruisermatt]

@4Cruisers made up a batch of single port advance diaphragms a couple of years ago for the big cap distributors. I bought several to use as spares on my desmogged, low altitude trucks. He may still offer this service. I've heard too many horror stories about the DUI units. I just won't use them.

OP would also have to change his pushrod cover to use big-cap... and track down a coil/ignitor to run the big-cap. I just don't see it as worth it to track everything down when there's a single-purchase distributor available that will outlast the rest of the truck.

Maybe I am biased since I also sell 19100-61080's
OP should buy one from Mark though.

 

[cptmackay]

Wow Thanks Guys, There is some great info here. So it sounds like the 19100-61080 is probably my best bet.

 

[Spike Strip]

@cptmackay

btw, I have a Calif-spec '74 FJ40. Don't know if yours is Cali-spec, but there are differences from the Fed-spec trucks from that year, on the carburetor. Post a picture of the base of your carb, right next to where the Mixture adjust screw is. If you have this port, you are golden. If you don't have it (Fed Spec does not), you will need ported vacuum for the dissy vacuum advancer to work. Mark's Off Road can fix that, too.

Good luck.