Need advise from carburetor, distributor, and ignition gurus.

[DieselFJ]

So here is my issue, I have a 72FJ40 with a stock carburetor, Mallory distributor, and a factory ignition coil. At this time all emission equipment is disconnected and all intake ports plugged. The carb was just rebuilt and seemed to be in good condition. Right now I am having drivability issues. I don't believe the components are playing well together and from what I read and understand they probably never will. So here is the question, should I find an OEM distributor and reconnect all the emissions, or swap the carb with a Weber and an MSD coil, or are there other options out there? Is it possible to get the setup I have running right? Any advise would be greatly appreciated.

On a side note, the block is a pre '69, and the rest is '72

 

[Curt]

I would get a dizzy from trollhole, remove the coil from the block as heat is not good for the coil. Also take the carb apart see whats going on in there or buy a trollhole, you never know what the PO has done. Just bought a tercel with the carb rebuilt and the auto choke was not setup at all among many other things.

 

[edwjmcgrath]

I'd get a stock dizzy (or trollhole). Then you're basically stock and will find hundreds of folks with the same setup.
Going to an aftermarket carb is the wrong direction.
That said, what exactly are your drivability issues?

 

[ErikinSC]

Basics - Check for vacuum leaks with a vacuum gauge.
Verify timinig, check / replace points & condensor,
Check spark plugs (regap & make sure not fouled / corroded)
Verify spark while cranking (important to know that you have fire - remove spark plug from block, connect to wire, hold spark plug with rubber glove near ground while someone else cranks rig.) You can also verify spark from coil.... it could be bad.
Fuel filter looks new - but verify that fuel pump is pumping fuel to carb....
Clean carb - make usre jets are open, use carb cleaner and a compressor and blow air thru backwardds of fuel flow direction - dont use cab cleaner on any rubber parts in carb!

Your dizzy looks like is not oriented the same as mine - i dont know if that has any thing to do with running issues - verify the timing and you can move on to points gap after that.

As the others have said - a Trollhole distributor is a good option - I have a non-use dizzy with a Mallory coil & a Weber carb - all new (less than 2 year olds) components and they are working well. If I HAD TO replace my carb - I would almost certainly go with a Trollhole.

HTH.

 

[fhawk5]

Well, looks like most ground covered , but, after all the basics are checked, another good possibility;
1.) Use a stock carb, rebuilt well.
2.) Stock distributor with pertronix instead of points.
3.) (If stock distributor comes up short, go with a DUI , new.)
4.) All new wires.

I am running stock everything, 1969, with the exception I put in the pertronix....And, glad to do it, it runs wonderful. ( I kept the points at the ready in case of nuclear blast. )

 

[DieselFJ]

Sorry for not responding soon, but let me clarify. I rebuilt the carb just the other day, I have rebuilt many Aisin carbs and am very familiar with them, I have no where near the knowledge Jim or Mark has, but I have a good understanding and have been successful in the past, but they all have been in stock configurations. With that being said, the question I have has to do with the vacuum advance/retard of the 72 dizzy and it's relationship to the carb and its functionallity.

So to answer the other questions:
I checked for vacuum leaks, everything looks good. I didn't check actual vacuum pressure, but I will do that.
I verify timing which is per FSM
Has new plugs and wires
Has good spark
Fuel filter is new, gas tanks has been resealed and all lines replaced. Float set in middle of window, fuel pump seems to be functioning well.
Haven't checked dwell, I will do that as well.

Sorry, should have explained the drive ability issues. As it sits now it idles good, but I had to set the choke butterfly partially closed. If I open the choke fully it has a large hesitation right off the pedal and will after fire. With the choke partially closed the problem is still right off the pedal, but now it just feels like there is a lack of power and slight hesitation. Once running it seem okay, but in my opinion it is lacking full power. There is also a larger hesitation between the primary and secondary throttle's opening up. Once in the secondary opens it has good power.

I've never heard of using the stock distributor with Petronix instead of points, I'll have to look into that. I have a stock distributor, but it wasn't functioning and I didn't spend the time to look into it since I had this Mallory.

Thanks for the comments
Scott

 

[Pin_Head]

There is no reason it couldn't run fine if the components are working properly.

The problem sounds like your average lack of idle fuel problem either due to a fuel delivery problem to the idle screw and transition slot or an intake vacuum leak. Disconnect the idle fuel cut off solenoid and see if it idles even worse. If so, it is probably a vacuum leak.

What makes you think it lacks "full power"? Compared to what?

 

[fhawk5]

I will say that vacuum is the power robber. I still do nut understand why vacuum gauges are not included in the "dashboard". It is THAT important.

 

[DieselFJ]

There is no reason it couldn't run fine if the components are working properly.

The problem sounds like your average lack of idle fuel problem either due to a fuel delivery problem to the idle screw and transition slot or an intake vacuum leak. Disconnect the idle fuel cut off solenoid and see if it idles even worse. If so, it is probably a vacuum leak.

What makes you think it lacks "full power"? Compared to what?

I will say that vacuum is the power robber. I still do nut understand why vacuum gauges are not included in the "dashboard". It is THAT important.

I didn't have time to put a gauge on it last night, but I will after work today and post the numbers. I'll also disconnect the idle fuel cut solenoid and see if the idle changes.

I'm comparing the lack of power to my other 40's, 55's and 60's that I have driven. It feels like the power curve flattens out, almost like it was pulling a heavy load until the secondary opens up then it feels good.

I found the factory distributor, I am thinking of installing it and hooking up all the emissions to see if it reacts any differently with the factory components.

Thanks
Scott

 

[Downey]

Check wear on the drive gear of the dizzy in case it (for some reason) has a GM drive gear rather than a Toyota drive gear. Back in the day when MAF's original owners sold Delco dizzys they left the GM drive gear on the dizzy, ruined many a dizzy/cam/engine. They have the same number of teeth, same distance apart, but on a completely different phase angle.

 

[salguire]

You won't regret a DUI distributor. The best thing GM ever created, made better by the guys at DUI and it drops right into your block. One wire hook up. If you ever break anything there are hundred of manufacturers of replacement and upgrade parts.

I have installed Pertronix modules in many vehicles and this is a cheap, easy mod if you want to keep the stock look but want electronic triggering performance. Anyone who says they like adjusting points all the time has got a few screws loose.



There are very few people who really know how to set a carb. I will agree with fhawk5 that vacuum is one of the keys to setting timing and carbs. Just remember that any carb that worked great 15 years ago will have to be rejetted 2 sizes larger for the oxygenated fuels that are sold in most of the country. Ethanol additives to fuel only water down your mixture and destroy aluminum parts. Unless you want to burn holes in your pistons you will need to richen the mixture more than just turning a few screws.

 

[Pin_Head]

The original distribtor would be a good idea because of the gear issue mentioned above, but any properly functioning distributor is going to do the same job performance wise on this engine.

You can skip replacing the emissions gear. That won't have any effect.

 

[DieselFJ]

The original distribtor would be a good idea because of the gear issue mentioned above, but any properly functioning distributor is going to do the same job performance wise on this engine.

You can skip replacing the emissions gear. That won't have any effect.

Check wear on the drive gear of the dizzy in case it (for some reason) has a GM drive gear rather than a Toyota drive gear. Back in the day when MAF's original owners sold Delco dizzys they left the GM drive gear on the dizzy, ruined many a dizzy/cam/engine. They have the same number of teeth, same distance apart, but on a completely different phase angle.

I'll pull the distributor and check the wear tonight as well, if I have any questions on wear I'll post up a picture. As for the original distributor, will the vacuum advance on the distributor impact the functionality of the carburetor differently than this non-vacuum Mallory? I am trying to round up a new cap and rotor for my original distributor, hopefully I can get one today.

 

[bertsulli]

Your idle circuit issue could be due to a warped air horn on your carburetor. This is fairly common among the F engine carbs. As far as I understand, the horn warps and sucks in air along the connection to the carb bowl and kills the vacuum in the idle circuit. The main symptom of this is needing to have the choke partially closed in order to idle. Vacuum leaks elsewhere would also cause that.

Fwiw, I just put a trollhole carb/dizzy in my 9/72 and I'm very happy with it.

As for the original dizzy, are you sure it's vacuum advance? Being a '72, it's likely vacuum retard.

 

[DieselFJ]

You won't regret a DUI distributor. The best thing GM ever created, made better by the guys at DUI and it drops right into your block. One wire hook up. If you ever break anything there are hundred of manufacturers of replacement and upgrade parts.

I have installed Pertronix modules in many vehicles and this is a cheap, easy mod if you want to keep the stock look but want electronic triggering performance. Anyone who says they like adjusting points all the time has got a few screws loose.



There are very few people who really know how to set a carb. I will agree with fhawk5 that vacuum is one of the keys to setting timing and carbs. Just remember that any carb that worked great 15 years ago will have to be rejetted 2 sizes larger for the oxygenated fuels that are sold in most of the country. Ethanol additives to fuel only water down your mixture and destroy aluminum parts. Unless you want to burn holes in your pistons you will need to richen the mixture more than just turning a few screws.

So this 40 is my nephew's, he has been away for a couple years and is due home on October. I am trying to get his Cruiser back to reliable so when he gets home he has something fun to drive. That being said I don't have a lot of cash to throw at it, so going DUI is probably out of the picture since there are a few other things that need addressed. It has been 25 years since I had a 40 of this era and back then I was just a pup and didn't know much about motors etc... Since I have owned and worked on later model 40's, 55's, 60's etc... and most recently everything I own is diesel so I'm trying to dust off the cobwebs and remember how this gas stuff works.

 

[Pin_Head]

The distributor has no impact on the functionality of the carb. The vacuum advance is a way of fine tuning the advance to respond to engine load to avoid preignition or pinging. It is not an inherent performance avantage. I believe that the OEM distributor for '72 is vacuum retard.

 

[DieselFJ]

Your idle circuit issue could be due to a warped air horn on your carburetor. This is fairly common among the F engine carbs. As far as I understand, the horn warps and sucks in air along the connection to the carb bowl and kills the vacuum in the idle circuit. The main symptom of this is needing to have the choke partially closed in order to idle. Vacuum leaks elsewhere would also cause that.

Fwiw, I just put a trollhole carb/dizzy in my 9/72 and I'm very happy with it.

As for the original dizzy, are you sure it's vacuum advance? Being a '72, it's likely vacuum retard.

So I did have some serious warping on the air horn. I did what I could to file it to where it was actually reasonable. I know it wasn't perfect, but I figured it was within a few thousands and the gasket would take up the difference. I am able to idle with the choke fully open, it is just when I initially push on the throttle it cuts out.

As for the vacuum advance, I was thinking it was vacuum retard as well, but wasn't sure, and I'm not sure how that would impact the carburetor without that circuit being hooked up.

 

[DieselFJ]

The distributor has no impact on the functionality of the carb. The vacuum advance is a way of fine tuning the advance to respond to engine load to avoid preignition or pinging. It is not an inherent performance avantage. I believe that the OEM distributor for '72 is vacuum retard.

Ah, that is what I wan't sure about, especially with the emissions control box and it's connections to the distributor and the carburetor. Thanks, that helps clear up some questions I had.

 

[DieselFJ]

So I checked the vacuum and at 700rpm I am at 15Hg's. I did forget to unhook the idle solenoid so I will have to do that after I get the distributer re-installed.
I did notice this metal post when I removed the cap, not sure what would have caused the center electrode to break, but when I removed the cap it was sitting in the body of the distributer.

Once the distributer was out I checked the wear pattern on the gear and it doesn't look good, the pattern is way to shallow and short. Here is a comparison of both the Mallory and the OEM.

I'll work on getting the distributer squared away, then I'll see how it runs.

Thanks

 

[Weber Sarge]

I'd just get a Trollhole distributor - drop it in and 2 wires , nice vacuum advance and simple - works great .
Sarge