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-   -   timing (http://www.risingsun4x4club.org/forum2/showthread.php?t=4728)

jolee 09-05-2007 08:17 PM

timing
 
I have a 1980 fj 40 with original 2f engine with a weber carb i use 36 jets in Kansas and 32 in Colorado. I would like to change the timing to see if i can get a little more power i have 33x10.5x15 tires. In Kansas highway speed of 60 to 65 is no problem. When we go get up in the Dillon and Frisco area 45 is about top speed. Any ideas on where timing should be.

Thanks Jeff

Rzeppa 09-06-2007 01:11 PM

Optimum static timing will vary greatly from one rig to another. Among the many factors affecting optimum static timing are compression, octane, valve adjustment and timing, carb jetting, centrifugal advance and vacuum advance/retard, smog versus desmog versus partial desmog, and others.

In general, higher elevation requires more advance. Even at sea level, the stock 7 BTDC is retarded from optimum power and mileage in order to get best emissions.

I can do 75MPH no problem on I-70 between the passes up there in a stocker. I can even stay around 45 or so going up the passes.

I am currently running about 13 on my 71 (with stock F) and about 9 in my non-USA stock 1978 (the centrifugal advance seems to be higher in that distributor). My 76 runs best at around 12, but that was fully smogged with the original vacuum retard distributor. I haven't run it yet with the non-USA vacuum advance distributor I installed.

Here's my 25-year-proven method to best power and mileage:

First make sure everything else is in good order. Carb is jetted properly, reasonably clean (BG 44K is GREAT stuff!), no vacuum leaks, smog equipment is operating properly, valves adjusted, air cleaner is clean, etc.

Next set idle mixture and idle speed to optimal, then adjust static timing while idling (any vacuum hoses to dist are disconnected) to best RPM, readjust idle speed as needed.

The reconnect any vacuum to dist, go up biggest high speed paved hill you can find and note terminal speed. Go back down, listen for backfiring, note throttle crispness, general performance. At bottom, advance about 2 and repeat. Keep playing with it until you get best terminal speed up hill with little to no knocking, no backfiring downhill and best throttle response. Once you're there, tighten down the dist and enjoy 16 MPG and best performance. Happy cruisin'!

SteveH 09-06-2007 02:10 PM

I doubt a 1980 LC has a vac retard distributor, but if so, remove and plug the 'retard' line. Put a slotted dummy cap over the dist port to keep mud wasps, dirt, etc. out of the hole.

If you have the later dist. with two ports (one for the main vac advance and one for the little extra bit of advance), be sure they're on correctly. Use a vacuum gauge and rev the engine to check that both ports are getting the correct vacuum. Put a hose on the dist. adv. port and suck on it to be sure the diaphrams aren't ruptured.

Your jetting may be too rich at higher elevations, but that is a separate issue from the vac advance setting. Many old FJs won't exactly go 65 around Dillon, so join the club in the slow lane. Blow the doors off an old VW Bus if you need to feel the power you have! ;-).

Steve

Rzeppa 09-06-2007 06:21 PM

A stock, USA-spec 1980 "should" have a dual vacuum advance distributor. I have seen so much over the years and continue to (such as factory white spokers!!!) that I will preface my posts with "AFAIK" regarding what year came with what, more often than not.

As Steve wrote, it "should" have the fully electronic dual vacuum advance, with main plus a little extra advance. In any case, set the static advance where it runs best under dynamic conditions.

corsair23 09-07-2007 12:44 AM

Hmmm....so not to hijack the thread but say a person bought a 40 from CA that came with a weber carb, and brought it to CO, should said person consider changing out the jets and tweaking the timing? Keeping in mind that said owner currently knows squat about carbs, what jets are in said carb right now, and little to nothing about timing. Oh, and that the furthest said owner has driven the 40 is to RMC and back :hill:

SteveH 09-07-2007 11:08 AM

A real redneck can just smell the exhaust on a pre-emission vehicle and know whether it's running rich. Look for black smoke, sooty tailpipe, sooty plugs, and a raw smell to the exhaust.

My attempt at rejetting a '76 FJ55 carb was disasterous - I used one-size bigger jets and it ran very rich and crappy and was undriveable. I know even less about rejetting a Weber carb. My '78 FJ has stock, sea-level jets and only gets rich and boggy around 12-14K feet of elevation, where I too-rarely tread with it.

Anyone doing all this would ideally have access to a factory emission manual, a timing light, a vacuum gauge, and ideally, a CO/emission tester.

I would work on timing first, and then worry about rejetting. A sea-level setup on a good carb will run ok at 5000' (Denver) and you'd rather be too rich than too lean (from a valve life standpoint). Get the timing right, drive it some, talk to others, and only then worry about rejetting.

corsair23 09-07-2007 11:56 AM

Thanks Steve :thumb:

Red_Chili 09-07-2007 01:21 PM

Weber carbs are fun to jet. Like motorcycle carbs. Very precise. Put one on a Chevy LUV once with an Offy intake manifold and had a great time with it. But I am a minitruck redneck so I'll go away now...

pdjohns 04-28-2013 02:46 PM

Timing on a 73 FJ40 with no smog
 
Hello. I just had to replace my distributor on my FJ. I had a late model distributor and ignition coil. I switch everything to the same year. (73 distributor and ignition coil now). It misfires every once and while and will bog down. I have no smog stuff on the engine. Right now I have a vacuum from the manifold going directly to the distributor. Is this correct or do I even need the vacuum line for the distributor?
Thanks!

Rzeppa 04-28-2013 10:34 PM

Quote:

Originally Posted by pdjohns (Post 231972)
Hello. I just had to replace my distributor on my FJ. I had a late model distributor and ignition coil. I switch everything to the same year. (73 distributor and ignition coil now). It misfires every once and while and will bog down. I have no smog stuff on the engine. Right now I have a vacuum from the manifold going directly to the distributor. Is this correct or do I even need the vacuum line for the distributor?
Thanks!

No, that is not correct. Yes you do. Here is the skinny on Land Cruiser distributors:

http://rzeppa.org/tech/jimcdist.htm


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