I can't drive 55

[pb4ugo]

I don't know. I was running the Big Cap dizzy for a long time, but I had switched springs and the advance mechanism. I just put in this small cap points dizzy with the pertronix.
So, it might take a few days to dial in this dizzy and I don't know exactly how to measure total advance...

Sounds like your base timing plus mechanical advance was all in at idle.

 

[knuckle47]

As for advance…I am new to the EFI and Hyperspark combination but the beauty of it is dialing up the timing settings. I was at 7* as recommended but I am at 12* base timing and 32* WOT. Each time I bring the WOT a point or two higher, I’m waiting for that “ping” but nothing yet. I don’t know how far I can take it but I will keep pushing it

 

[BOBWhite74]

Here is what the book says but it's older and probably not directly applicable.

I don't think your dizzy has an "octane adjustment" but the "ping" adjustment that I put a box around is pretty general for all engines. To understand the feeling of timing adjustment you really ought to drive an old model T or similar vintage tractor that has manually adjusted timing.

 

[45Dougal]

Not sure about the shaft bearings.
Condenser is brand new.
Haven't tried anything with the air filter.
Gas cap? No.

I'll check the brakes next.

Coil is new as is the resistor. Do you mean hot to the touch?

I'll try the "dip test" next time I am out.

Shaft bearing is easy to check - just wiggle the rotor arm side to side and see if you can close up the points.

I don't want to steal Charlie's line, but New doesn't always mean good.

Yes, hot or smoking; we seem to get a lot of fried coils and resistors in here.

You could try poking an endoscope up your exhaust to check for mice - I got a cheap one from a local tool store; very handy.

 

[4x4veteran]

I moved this to a separate thread to apply some focus.
My original question is, why is my top speed in 4th gear ~45-48 mph?

Background:
5/75 chassis with an estimated 68-70 F (PO said .5F but others have doubted that).
4 Speed transmission
32" tires

Vacuum advance on the distributor appears to work fine. At idle if I pull additional vacuum, it advances the timing noticeably. I pulled the plugs and they look amazing.

It has a mini-truck conversion to disk brakes in front. When raised the wheels turn easily. I recently rebuilt the knuckles and installed new calipers. (It drove this way before all that.)

Jacked up the rear driver's tire and rotated it. The drive shaft turned 2 1/8 revolutions for each turn of the wheel.

There are no vacuum lines associated with the Transfer case and the front drive shaft turns freely in 2H.

I ordered a tach so I can get some real RPM numbers to help the investigation.

The vacuum advance on my distributor.
View attachment 3741150

Are you saying there is a loss of power or just high revs at 45 mph?
No power could be not enough fuel to engine.
Slipping clutch could be loss of power and higher rpm's.
With 4:11 / 31-10.50 / 15 and stock three speed I am doing about 55mph @ 2500rpm.
Done a lot of work on make my 1970 FJ40 to make it go straight and it holds the road pretty good at 80mph, but 45 to 55 mph is a lot more comfortable.
Made a lot of trips across the U.S. at 55mph and it really doesn't take that much longer.
Relax and enjoy the scenery.

 

[knuckle47]

I drive on fairly congested roadways and as you know, there are people that fly by you on a roadway only to sit at the next traffic light 30 seconds before you get there. On the other hand I have driven on some empty roads in many areas and diving at 60-65 and I’ll cover 60 miles in that timeframe. Other times I have driven at 75-80 and it took me 56 minutes…not gaining all that much and dumping fuel much faster.

It still fun to push it but …I still wanna get Matthew’s issue solved

 

[MatthewMcD]

Are you saying there is a loss of power or just high revs at 45 mph?
No power could be not enough fuel to engine.
Slipping clutch could be loss of power and higher rpm's.
With 4:11 / 31-10.50 / 15 and stock three speed I am doing about 55mph @ 2500rpm.
Done a lot of work on make my 1970 FJ40 to make it go straight and it holds the road pretty good at 80mph, but 45 to 55 mph is a lot more comfortable.
Made a lot of trips across the U.S. at 55mph and it really doesn't take that much longer.
Relax and enjoy the scenery.

I am not in a hurry, but I feel that the truck is working too hard.

 

[MatthewMcD]

I drive on fairly congested roadways and as you know, there are people that fly by you on a roadway only to sit at the next traffic light 30 seconds before you get there. On the other hand I have driven on some empty roads in many areas and diving at 60-65 and I’ll cover 60 miles in that timeframe. Other times I have driven at 75-80 and it took me 56 minutes…not gaining all that much and dumping fuel much faster.

It still fun to push it but …I still wanna get Matthew’s issue solved

Exactly, I am not looking to "go fast" in my '40. But I am pretty mechanical, and I know there is "something" holding her back. Before I depend on her for everyday use, I want to be sure that, mechanically, I have done everything I can to have it running right.

I'll check the brakes today and take another look at the mechanical advance mechanism, points gap and a few other items.

 

[Grayscale]

Carb needle and seat, or incorrect float levels? In other words, fuel is restricted.

 

[knuckle47]

Matthew…once again< if you want try that Weber I took off of my 40, my truck ran well with it…I delayed the install of the Holley Sniper almost 16 months because the Weber was doing so well.

I WILL GLADLY SEND IT TO YOU TO TRY. that may prove to be a good starting point and I have a new base gasket I add to the box… yours free. (If you can guess the number I’m thinking of between 68 and 70) ..haha. Pm me if you want to give it a try

 

[knuckle47]

It’s in the mail guys….lets hope it helps

 

[RevISK]

It’s in the mail guys….lets hope it helps

Amazing Knuck’s, that is so awesome of you. This community is astounding.

Which Weber is it?
I’ve become something of an unwitting expert at tuning Webers so I’m on duty again. Happy to help and Matt lives very near.

I’m about a week away from turning Japanese, I really think so. Carb wise that is

 

[knuckle47]

I’ll say that I have no idea which model Weber it is… on the other hand, if you happen to get involved …please let me know which one it is…I believe it’s a 36.
Once warm, it ran very well.. until that time, if you stomp and the pedal it will cough once. I also discovered after I had removed it, the timing was low by 6 degrees. So I hesitate to say the carb was the issue. Possibly between slow timing and something else, it caused the hesitation but once warmed up it was non-existent. Enough for me to put off installing the Sniper EFI for almost a year and a half… I hope this will prove something…like that Matts 40 is a speed demon…

By the way…by warmed up, I mean maybe 3-4 minutes

 

[RevISK]

I’ll say that I have no idea which model Weber it is… on the other hand, if you happen to get involved …please let me know which one it is…I believe it’s a 36.
Once warm, it ran very well.. until that time, if you stomp and the pedal it will cough once. I also discovered after I had removed it, the timing was low by 6 degrees. So I hesitate to say the carb was the issue. Possibly between slow timing and something else, it caused the hesitation but once warmed up it was non-existent. Enough for me to put off installing the Sniper EFI for almost a year and a half… I hope this will prove something…like that Matts 40 is a speed demon…

By the way…by warmed up, I mean maybe 3-4 minutes

Awesome, thanks.
I’ll help him install or at least tune it as he needs or wants.

My Weber is insanely fickle.

 

[Pighead]

30* !

OK, maybe not 30* with this new to me earlier dizzy. Took the Pig into town for beerrun and I could get the start of a little clatter, so I backed it off a little in the parking lot. I'm thinking somewhere between 20 and 25* works with this dizzy and the Pertronix.

 

[pb4ugo]

I think your mechanical advance springs are probably too weak. I've been playing with centrifugal advance on my sbc for about a yr. I usually set my timing by its total advance, which is base timing plus mechanical advance. My 40 cruises around 2000 rpm at about 60 mph, so I've been trying to get my mechanical advance all in around 2000 rpm or a little more, for efficiency and power. I think it's currently all in around 2300 rpm. I purchased a spring kit for it and installed the lightest spring and found it advanced instantly off idle and then didn't retard the timing when it returned to idle. For me that's too aggressive and opted for a slightly stronger spring set. After that I can adjust base for my desired total advance.

 

[MatthewMcD]

Shaft bearing is easy to check - just wiggle the rotor arm side to side and see if you can close up the points.

I don't want to steal Charlie's line, but New doesn't always mean good.

Yes, hot or smoking; we seem to get a lot of fried coils and resistors in here.

You could try poking an endoscope up your exhaust to check for mice - I got a cheap one from a local tool store; very handy.

Shaft bearing appears fine. Cannot close the points. I checked the gap while I was in and it's 0.018".
The coil is hot to the touch, but I can hold my hand on it.

I checked the brakes, front, rear, and parking. All wheels turn by hand. The driveshaft turns easily with the parking brake disengaged.

Oh, and I filled it up at the gas station. Opening the gas cap and it sounded like I opened a soda can. Can't tell which way the pressure was going.

Tomorrow is muffler day.

 

[MatthewMcD]

I think your mechanical advance springs are probably too weak. I've been playing with centrifugal advance on my sbc for about a yr. I usually set my timing by its total advance, which is base timing plus mechanical advance. My 40 cruises around 2000 rpm at about 60 mph, so I've been trying to get my mechanical advance all in around 2000 rpm or a little more, for efficiency and power. I think it's currently all in around 2300 rpm. I purchased a spring kit for it and installed the lightest spring and found it advanced instantly off idle and then didn't retard the timing when it returned to idle. For me that's too aggressive and opted for a slightly stronger spring set. After that I can adjust base for my desired total advance.

I am not convinced that my mechanical advance is working correctly. I finally found the notes in the FSM about the order of advance for the mechanical advance. I'll check that after I eliminate the muffler.

Do you have details on the spring kit? Or was that for a different distributor?

 

[Cal40]

I am not convinced that my mechanical advance is working correctly. I finally found the notes in the FSM about the order of advance for the mechanical advance. I'll check that after I eliminate the muffler.

Wouldn't measuring total advance with an adjustable timing light rule this out for the most part?

 

[MatthewMcD]

Wouldn't measuring total advance with an adjustable timing light rule this out for the most part?

That's the plan. The timing light arrived today.