Carb jets for 5280 feet

Discussion in '40- & 55-Series Tech' started by RicardoJM, Nov 10, 2009.

  1. RicardoJM

    RicardoJM

    Messages:
    231
    I have a 1971 FJ40 with the F135 engine. It runs fine, my son drives it every day (5,000 to 6,500 feet elevation) and it does some light wheeling in the mountains up to 12,000 feet. The ignition system is electronic; distributor from 1978 FJ40 and coil/igniter from 1984 FJ60. The current carb base does not have the ported vacuum, so the dizzy is only using mechanical advance. The VSV has been removed. The carburetor was rebuilt (not by me) about 18 months ago when I could not pass emissions. After the rebuild, a local shop was able to make adjustments to get it to pass emissions - but just barely. The best vacuum I been able get out of the engine is 12. I've looked for vacuum leaks (not found any) and have the valves adjusted to spec. The truck runs rich (you can smell it) and averages 10-11 mpg pretty consistently.

    I picked up the FJ40 because I've always wanted to learn more about auto mechanics and over the couple of years I've had my truck I have learned a bunch.

    While the truck is running OK, I really want to get experience rebuilding a carb. To that end I picked up a couple of carbs and rebuild kit a while back. They have been sitting around and now I'm ready to take the project on. My starting point is a H2662 model that has 2I4 (built September 4, 1972) stamped on the air horn. The carb base is not drilled for ported vacuum. The rebuild kit is in a old, beat up Keyster box from SOR which has many numbers; SOR 042-03E, Original Kit No. 04211-60142, Carburetor No. 21100-60202. 60203 and on the side the number K11-358A. While the box has seen better days the two packages with parts are still sealed in their plastic wrappers and in very good shape.

    I have a few questions regarding the jets to use as I put the carb back together. On the disassembly, I managed to mangle the head on the secondary jet and I did not realize the size of the slow jets was different:eek:. In short, I have incomplete information on the jets that were in the carb. I do now have some custom modified screw drivers so I'll not be making the trashed carb jet head mistake again:D. Probably not too big a deal because I am more interested in what jets should be in the carb when I put it back together.

    The jet sizes that were in the H2662 carb are:
    Primary Jet - 118
    Spare in Primary plug - 060
    Secondary Jet - UNK; trashed the head
    Spare in Secondary plug - 141
    Power valve jet - 070
    Slow Jets - 80 and 50; but I didn't make a note of which was on what side​

    The Keyster kit has the following new jets:
    114 - Primary
    180 - Secondary
    60 - Power valve
    50 - Slow jet, but the kit only has one​

    From some other carbs, I've also got a few jets of the following type and size;
    Primary/Secondary - 180, 159, 114, 103
    Power valve - 070, 040 and 060​

    I understand that many variables come into play when deciding which jets are the best starting points for a particular carb, on a particular engine in a particular geography. As I've researched jet size, I have been able to gather that at altitude a smaller primary and power valve jets together with timing advance are the general direction to follow in optimizing a carb.

    Locally, MDH33 has rebuilt a couple of 73-74 carbs using; 112/114 Primary, 180 Secondary and 50/50 for the slow jets with good results. This seems like a reasonable starting point. However, given the subtle changes between 72 and 73-74 I am interested in input from the group as well.

    Given my situation, what recommendations would the group have regarding jet sizing as I put the carb back together? Is 103 a too small starting point for the primary jet? Even though I don't have one, should I look for a 112, 110 or 108 jet as the starting point?
  2. BlackDiamond72

    BlackDiamond72

    Messages:
    209
    I live just west of you at 9000 ft and would suggest that a smaller primary jet is a good thing living were we are, however if you go too small, you'll have no power on hills and you'll be dipping into your secondary all the time. You'll end up with a less driveable vehicle that still gets poor mpg. I would start with a 112 if you can find one and go from there. Jets are cheap. I think you can still get them from Toyota. Try Stevenson West.
  3. COMITX

    COMITX

    Messages:
    23
    Sorry, I don't have carb jet advise for you...but since you live in the Denver area, you might want to consider getting collector plates. Unless the laws have changed, you won't have to get another emissions test as long as you own the vehicle.
  4. BlackDiamond72

    BlackDiamond72

    Messages:
    209
    COMITX is right, get the collector plates, 5 year registration. Its a lot cheaper and you'll never need emissions testing. I believe the cut off is 75 at the moment.

    Or live in a county without emissions!:flipoff2:
  5. COMITX

    COMITX

    Messages:
    23
    I'm with you there! :cheers:
  6. RicardoJM

    RicardoJM

    Messages:
    231
    I got the 5 year collector plates 18 months ago when emissions were required. With this years law change my truck is now emissions exempt, but emissions laws are much like our Colorado weather and will likely change again.

    BlackDiamond72 - were you the one riding with Crispy on the Yankee Hill Run Sunday?
  7. GarageRat

    GarageRat

    Messages:
    668
    Location:
    Colorado
    My 78 T/A has collector plates and the law then was 25 years old or older but I'm sure it's changed ever since I got that done...(anyone know the new laws?). As far as the jets, I'd give it a shot and go from there. Cheap to do. Wish I lived in an emissionless county, Littletons killing me.

    Sure yankee hill was a blast, had a few friends hit it Saturday while I had to work. Looked like some good snow acumulation from the pics.
  8. BlackDiamond72

    BlackDiamond72

    Messages:
    209
    Yep..

    That was me Ricardo. I promise to have my 69 on the road for the next run. Front Range is running near Boulder this Sunday around noon, hopefully going to that.

    I saw your post on the Rising Sun forum today, but didn't want to jump between the two.

    I am interested in your jetting experimentation as I would like to follow suit. I haven't had mine running more than in the driveway and a little around the neighborhood so I don't really know how rich or lean it is yet. New carb rebuild could have changed things a bit. I however didn't have any extra jets on mine, PO musta stole em!

    Keep us informed! :hillbilly:
  9. FJ40Jim

    FJ40Jim The Cruiser Whisperer SILVER Star

    Messages:
    8,077
    Location:
    Lancaster, Ohio, USA
    What is an H2662 carb? Is it an Aisan carb?

    Assuming that the carb in question is a 1973 federal Aisan, the jets to start with are 114/180 & 50/60, and 60 PV.

    While you're at it, install a ported vac fitting to enable the vac advancer. It is useful at high altitude because the engine wants more advance.
  10. RicardoJM

    RicardoJM

    Messages:
    231
    The H2662 is what is what is stamped on the metal tag. This tag is held on by one of the air horn screws. It is an Aisan carb. I know your knowledge of Aisan carbs is very extensive - are the build date and metal tag values consistent with a 1973 federal?

    I understand the ported vac fitting would improve things. I've not looked very hard for a machinist locally.
  11. FJ40Jim

    FJ40Jim The Cruiser Whisperer SILVER Star

    Messages:
    8,077
    Location:
    Lancaster, Ohio, USA
    The metal tag is a number from a rebuilder. The correct Toyota tag would be stamped 60202 or 60203.

  12. RicardoJM

    RicardoJM

    Messages:
    231
    The rebuilt carb has been in service for just over a week. It has been up to 9,500 feet on a snow run. I could not find a size 60 idle/slow jet from Toyota or a local carb shop. I went with the following jet sizes:

    114 - Primary
    180 - Secondary
    60 - Power valve
    50 - in both slow jets

    There is a very noticeable improvement in the operation of the choke and starting of the engine. The last couple of days the temps have been in the single digits. Above idle the truck runs about the same (maybe a bit stronger) as it did with the older carb.
  13. PabloCruise

    PabloCruise SILVER Star

    Messages:
    12,279
    Location:
    Northern Colorado
    So these jets would be good for Denver altitude in a '73 Fed Spec Aisan, any comments on how different the needs of a '78 Fed Spec (9/77 build date) Aisan are from these - same altitude?
  14. FJ40Jim

    FJ40Jim The Cruiser Whisperer SILVER Star

    Messages:
    8,077
    Location:
    Lancaster, Ohio, USA
    A 78 is a very different vac secondary carb with very different jet sizes.
  15. subzali

    subzali

    Messages:
    2,776
    Location:
    Denver CO
    TJ, it would probably be best to start with the stock jet sizes, get an O2 sensor bung welded into your exhaust pipe, and use a wide-band O2 sensor to fine-tune it. Otherwise you're just shooting in the dark.
  16. RicardoJM

    RicardoJM

    Messages:
    231
    Jim C said it well - very different. When you're ready TJ both Marco and I have the zeitronix zt-2 units. Any exhaust shop can install the bung. We can hook the unit up and you can get all the AFR details. That said, having used it on my rig the same results can be achieved using the lean drop method with a vacuum guage.
  17. spectre6000

    spectre6000

    Messages:
    212
    Location:
    Coal Creek Canyon, CO
    I just ordered some jetting gauges and reams as well, and can close/open whatever jets will fit the holes to work. I also have a lead on a complete set of stock jets for my stock and complete 11/73 1.5F, and I'll let you know how it pans out and pass on the info. It sounds like we're close geographically and doing the same project at the same time... I sense a group workday project.

    I have a stretch of road picked out that's dead in the middle of my altitude needs for dialing. I advise having a good idea of what range of altitudes you intend to jet for (try to keep the spread around a max of 2,500'), and find yourself a low traffic stretch of road that you can really stomp a little in. I.e. I live just under 8k' and regularly drive as low as 5,200', so 6,500' is my middle ground, and there is 2 mile a stretch of 72 going west from 93 goes from about 6,400'-6,600' before it gets curvy and has parking lots at either end (a bus stop and what I think is a bike launching lot). Straight with a slight grade helps so you can get an idea for acceleration and power. That said, the wideband setup would be ideal to eliminate quite a bit of guess work.
  18. I live like you but rarely go below 6,000'. I often drive to 11,500'. I have an 84 2F with sea level jets right now. I'm really keen to hear what jets you decide on. I have a vacuum gauge but no O2 sensor.

    Josh
  19. subzali

    subzali

    Messages:
    2,776
    Location:
    Denver CO
    I'm sticking with the stock jets. Works well enough up to 13,207 feet on Argentine Pass (I haven't driven up to the tops of Mt. Evans, Mt. Antero, Mt. Bross or Pikes Peak yet though).

    :meh:
  20. spectre6000

    spectre6000

    Messages:
    212
    Location:
    Coal Creek Canyon, CO
    Subzali, may I have an opportunity to turn you into a believer in the church of the fine tune? With any luck I'll have a set of sea level jets, a set of stock altitude jets for my year, and one extra set to dial in with the reamers, and some time to do some tuning (hopefully with some decent weather to match...) within the coming weeks. I live about 7 miles up from the stretch of road referenced above, and I'll be basing my operations between there and the aforementioned parking lots. An assistant is always a plus to operate stop watches, monitor widebands (if I can get my hands on one), work cameras (I think I might be pretty terrible at gauging what's going to be of interest for these sorts of things), etc.

    We'll get a baseline with the sea level jets, then swap for the factory spec altitude jets and get a new baseline, and then see if we can make any progress from there (given that the altitude jets are for my exact engine combo and altitude, I doubt we'll be able to get too terribly much better, but I'll have a set of jets specifically for the purpose of fine tuning).

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