Looks perfect/Runs like dookie!

Joined
Feb 22, 2020
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55
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Wichita Kansas
I have an all stock 77'. The rig is in great shape but acceleration is lacking (feels like its dragging until you punch it then you get what you expect). As part of the trouble shooting, I've replaced all vacuum lines (and rerouted ones that were incorrect), rebuilt the carb (thanks Pinhead for the youtube video), and put all new parts on the distributor (cap/rotor/points/wires/advance, etc...). It's still not performing and I'd appreciate any insight. My goal is to keep it stock however soon I may add a bullet.

Ignition - I've attempted to set the timing at 7* past TDC (timing light set to zero when shot using #1 plug wire bb lines up with timing mark) at what "feels" like a reasonable RPM. I really don't know the exact RPM's as my inductance gauge on my multimeter won't hold a constant value. Also tried using a multimeter on the negative side of the coil also and once again no joy! Any suggestions on getting a good RPM reading?

Carb - It's a 77 federal carb. As in the photo below, inboard side has the idle mixture, rear has the idle adjust, fast idle, and choke adjust. Further to previous threads, I've backed off the idle mix screw 3 turns from full in and adjusted the idle set screw to what "feels" like the correct idle RPM. I screwed in idle mix until slight change and then came back out 1/4. Not sure idle mix is having much of an impact. Put the cover back on and took for a spin.

Still runs like dookie! Underpowered (but not running rough) unless you stomp on it. Also, idle was fluctuating when I came back in.

Thoughts/suggestions?

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1911

chupacabra
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Parker County, Texas
Adjust the valves, adjust the points, set the timing, in that order. Sounds to me like not enough advance on your timing, but no way to tell from here.
 
Joined
Feb 22, 2020
Messages
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Wichita Kansas
Thanks. I should have mentioned that the head was rebuilt and installed this past year. It was installed/adjusted and then run and then adjusted again. I adjusted the points again today.

It feels to me like a timing issue as well. I have it set at 7*. If I advance the timing until the vacuum gauge max out and back off slightly, its like 22*. I suppose I could try adjusting the carb based on that timing setting.....? Thoughts?
 
Joined
Feb 22, 2020
Messages
55
Location
Wichita Kansas
I would need to check the pressure at idle.

Is it possible I have put the dizzy back in a tooth off? When I adjust the dizzy to "best pressure" on the vac gauge it reads like 25* past TDC. Not knowing if that was a smart thing, I turned the dizzy back to 7* per the book but it really pulls the engine down like its not correct. If I didn't have a timing light I would have left it at the 25*. All the carb adjustments for idle etc... are set for the supposed 7* mark.
 

fjc-man

SILVER Star
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Mar 21, 2014
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Commerce City, Colorado
Do you have a Mitivac ( hand operated vacuum pump ) ? If so, apply vacuum to the vacuum advance unit at idle and see if the engine speeds up. At the same time, you’ll know if the diaphragm in the advance unit is good if it holds the vacuum and doesn’t leak down. You could also try the paper clip on the secondary diaphragm rod “trick” to see if it’s actually opening the secondary side of the carb under load.
 
Joined
Feb 22, 2020
Messages
55
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Wichita Kansas
The advance mechanism is new. I did verify it works.

I kinda think I'm just using the wrong base TDC number. She runs best at idle at 25*. I think I must have the dizzy off a tooth. Is that the symptom?

The carb idle adjustment, lean idle mixture, etc... is all based on the timing being correct. Thoughts?
 
Joined
Oct 2, 2015
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321
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Port Orchard, wa
She runs best at idle at 25*.
Mine runs best way off the BB also. Almost doesn't run with the BB lined up on the mark. I've read several other threads similar.

I think I must have the dizzy off a tooth.
Pretty sure this isn't a thing. Gear on the shaft can line up with any gear on the cam as long as distributor body (and cap) is correctly oriented (AND THE OIL PUMP DRIVE IS ENGAGED). The reasons for moving this would be for the vacuum diaphram to not hit the engine side, etc., as long as the rotor passes under #1 wire on the cap at the right time, not really an "off a tooth".
 
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May 14, 2016
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Arizona
Is your distributor points or something else ? Also, what is vacuum gauge numbers at idle. I.E. 18 / 20 or whatever
 

thorslc1977

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Aug 14, 2012
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434
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Tehachapi Ca.
Have you checked to make sure your advancer unit is still working? Also does breaker plate rotate smoothly? Is the mechanical advance system working properly - springs/weights are there and everything lubed and moving freely?
 
Joined
Nov 1, 2004
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Iowa
mine pull 17"-18"

I agree with above recommendations to check/adjust valves as baseline - easy to do...
 

Pighead

Stop calling it an FJ
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Aug 31, 2004
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Camino
14" of mercury at idle when tapped into the top of the manifold. Does that sound correct?
it might be a tad low, we haven't asked about your altitude though. I'm at 5k'+ and pull 15"Hg at low idle on a 16 year old engine rebuild...
As to your timing, I don't know why but my timing seems to like to be so far advanced beyond the window that I no longer can time by the BB. I time by vacuum.
I've heard (here) that the farther away from the build date, the farther away from the FSM you get. So don't think of the FSM specs as carved in stone.
It might be time to put the book down and learn to tune it by ear, vacuum and SOP...(seat of pants)
 

Purpleaction

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Jul 19, 2011
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773
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FL
When I think of some of the advise from the elder statesmen on this forum I would consider myself somewhere just a hair north of a neophyte. That being said, valves, carb, timing/ valves, carb, timing is legitimate. I also think that the effectiveness of these processes assume a basically normal functioning carburetor and no vacuum leaks.
 
Joined
Feb 22, 2020
Messages
55
Location
Wichita Kansas
Got tired of playing with this and went with the nuclear solution. New MSD ignitor and coil, Pertronix magnetic pickup, New plug wires, cap/rotor, and desmogged (and carb rebuild). She starts hot and cold immediately now, idles perfectly, accelerates with power at all rpm's, and is much quieter. In the event anyone ever wants to take her back original (after I'm dead of course cause you're not going to get it otherwise) not a single wire has been cut or hole drilled and all the parts are in a plastic tub. For me though no more headache and she's an enjoyable ride vs a garage queen.

Part sources
MSD = MSD Performance Products - Official Site
MSD Tray = Amazon productPertronix = PerTronix Electronic Ignition Systems | Point On Performance
Desmog kit = A Toyota Land cruiser specialist with parts and service
Plug Wires = Taylor Spiro-Pro Spark Plug Wire Sets 74252



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