SteveH
Hard Core 4+
CarQuest had a kit for my '78 in stock last year - $50ish. It did contain the secondary diaphragm. Not sure whose kit it was, but it was repackaged in a CarQuest box.
The Quest for more power
- Thread starter subzali
- Start date
I checked the operation of the TP diaphragm tonight (among other things). I hooked it to manifold vacuum and it retracted, as I suspected. It remained in the retracted position as long as I held vacuum on it, but returned to its rest position when vacuum was removed.
Rezarf
Hard Core 4+
So are you popping wheelies yet or what? 
I'll find out Sunday morning how it really does. Turns out CJ7 Matt is going to come on the Argentine Run, so we'll be able to "race" up I-70 
. I'm hoping to at least keep up with him, if not outrun him due to my gearing advantage. I hope to also have a speedometer cable installed by Sunday, so I'll be able to get some speed readings in addition to rpm readings.
. I'm hoping to at least keep up with him, if not outrun him due to my gearing advantage. I hope to also have a speedometer cable installed by Sunday, so I'll be able to get some speed readings in addition to rpm readings.
I'll find out Sunday morning how it really does. Turns out CJ7 Matt is going to come on the Argentine Run, so we'll be able to "race" up I-70
I can see it now.....
I'll find out Sunday morning how it really does. Turns out CJ7 Matt is going to come on the Argentine Run, so we'll be able to "race" up I-70
I can see it now.....
Okay, after a couple runs up I-70 to Georgetown, I'm very happy with the results...
Going up to Beaver Brook/Mount Vernon Canyon, the lowest rpm I got to was about 2600 rpm (58 mph). For most of the climb, my tach sat at about 2750 rpm (62 mph). On the first flat, my tach climbed up to about 3250 rpm (73 mph). On the way back on Floyd Hill, I got caught behind someone going a little slow and my tach dropped to about 2400 rpm (54 mph). I dropped the tranny into 3rd, ran it up to 3700 rpm, then upshifted to 4th again and was able to hold 2700-2750 (61-62 mph) the rest of the way up the hill.
From memory, I used to only be able to do about 48-50 mph, with spurts up to maybe 55 mph on the first flat spot going up Mt. Vernon Canyon. I'll have to double check my notes though. In any case, big difference. I can definitely feel it in my butt meter as well.
Going up to Beaver Brook/Mount Vernon Canyon, the lowest rpm I got to was about 2600 rpm (58 mph). For most of the climb, my tach sat at about 2750 rpm (62 mph). On the first flat, my tach climbed up to about 3250 rpm (73 mph). On the way back on Floyd Hill, I got caught behind someone going a little slow and my tach dropped to about 2400 rpm (54 mph). I dropped the tranny into 3rd, ran it up to 3700 rpm, then upshifted to 4th again and was able to hold 2700-2750 (61-62 mph) the rest of the way up the hill.
From memory, I used to only be able to do about 48-50 mph, with spurts up to maybe 55 mph on the first flat spot going up Mt. Vernon Canyon. I'll have to double check my notes though. In any case, big difference. I can definitely feel it in my butt meter as well.
kurtnkegger
Rising Sun Member
Matt, I'm going to have to talk to you this coming meeting so you can school me on what/how to check for more power. I am currently running like you describe your conditions from past.
I'm just enough of an idjit, that I'm getting lost in the thread...
I'm just enough of an idjit, that I'm getting lost in the thread...
Rezarf
Hard Core 4+
Add a dash a purple and you're close Matt 
kurtnkegger
Rising Sun Member
Alright Matt, Tore in to my linkage, and set up...My bracket at the carb was openned up, and getting the linkage to not operate quite right. Going to hit the bracket, and the linkage with the welder, and get things tightenned up. Doing the paperclip thing, I only get about 1/4 inch of travel. How do I manually create vacuum to it?
Every hose I've sucked on gets me nowhere...I feel like Linda Lovelace....
Every hose I've sucked on gets me nowhere...I feel like Linda Lovelace....
The vacuum comes from inside the secondary diaphragm housing. If you take the housing off the carb you'll see the hole. It leads to the area right at the venturi, so there is no vacuum unless there is air running past the carb venturi. If the paperclip is traveling at all then you're in good shape, as far as I can tell. Will you have your 40 tomorrow night?
kurtnkegger
Rising Sun Member
Planning on bringing it. Since my bracket was openned up from wear, I rounded the hole, and put a brass bushing in there for the pivot point. I filled the worn away groove in the shaft with a little weld...smoothed, and made a couple of aluminum washers for spacers to keep everything in place.
It should only take a few minutes to install...and then I'll have to readjust the throttle linkage...only after lengthening it for enough travel to move the gate did I discover the worn out carb bracket.
It should only take a few minutes to install...and then I'll have to readjust the throttle linkage...only after lengthening it for enough travel to move the gate did I discover the worn out carb bracket.
Attachments
Rzeppa
Rising Sun Member
What is this throttle positioner diaphragm business? I know FI needs to know the TP, but this sounds like something else. Does it have any function at idle, or is it only for throttle positions above idle? I need to look this up when I get home and see if it might have something to do with my 60 stall at idle problem...
The TP diaphragm holds the throttle plate slightly open when decelerating at high speeds, to prevent an overly rich mixture. I think it also has a function as a choke breaker on some models.
- I'm not sure Radar is old enough to get the reference
Totally over my head, but I have a feeling it's something I shouldn't look up on my work computer
Rzeppa
Rising Sun Member
I checked my manual and there is no reference to a throttle positioner diaphragm. On my 60 I have 3 vacuum diaphragm actuators on my carb: secondary, AC idle kick up, and choke breaker. The choke breaker just opens the choke a little bit when it is fully closed; once there is vacuum from the engine running it allows a little bit of air to get past the choke butterfly. I don't think it does anything to the throttle, when the choke is closed, the throttle is already partially open from the fast idle.
Jeff, it looks like your 60 carb is a little different than my '77 FJ40 carb:
FJ60 carb:
'77 FJ40 carb:
On my carb, the choke breaker diaphragm also controls the fast idle screw, or throttle positioner. This doesn't seem to be the case with yours.
By the way, this is different than a throttle positioning sensor. It's not detecting throttle position in any way, but it's rather holding the throttle plates open at certain times.
FJ60 carb:
'77 FJ40 carb:
On my carb, the choke breaker diaphragm also controls the fast idle screw, or throttle positioner. This doesn't seem to be the case with yours.
By the way, this is different than a throttle positioning sensor. It's not detecting throttle position in any way, but it's rather holding the throttle plates open at certain times.