Topic: Engine timing / Fuel Mixture Question

[blackdiamond]

My problem is that ever since I installed my Weber Carb (4wheelparts.com - K874?) my truck only runs well on quality premium fuel.  It starts to ping and just run rough on even mid grade fuel.

I thought that my engine timing might be advanced and I might be able to retard the timing and run regular grade fuel.  The timing was, and is, retarded (8 degrees advanced rather than 12) so when I set it to stock specs the pinging got worse.

My next idea is to richen the mixture of the weber (not sure what jets to get) so that I can advance the timing and not run too lean.  If I understand things correctly, it seems like I should be able to get the weber rich enough to back off to midgrade fuel and advance the timing closer to stock specs.

Does this make sense to anyone or do I have my head in a dark place?  Any suggestions on what jets to get, I don't know what comes in them stock?

I make no claim to be a mechanic, but I am trying to learn.

[germ]

Get fuel injection!... just kidding had to say it

Erik

[Uncle Jesse]

Where does it say that the timing should be 12 degrees advanced?  If I remember correctly on my 84 I ran the stock 5 degrees of advance, then with the idle advance hooked up to the distributor it went to 12.  The actual distributor timing should be 5 degrees though.  I ran a weber on that truck and ran midgrade.

It looks like I don't have the paper with the custom weber jet sizes on it either.

[blackdiamond [OP]]

Where does it say that the timing should be 12 degrees advanced? If I remember correctly on my 84 I ran the stock 5 degrees of advance, then with the idle advance hooked up to the distributor it went to 12. The actual distributor timing should be 5 degrees though. I ran a weber on that truck and ran midgrade.

It looks like I don't have the paper with the custom weber jet sizes on it either.

Sounds like there is more to know, I thought my service manual said 12, will have to look.  I don't have any information on Weber Jets, can you post it?

[mudmaster]

Is it the 32/36 Weber? My runs great with it on regular (lowest grade) fuel. Is it adjusted properly? If not try this site: redlineweber.com   It's what I used and I've had no problems for the last 4 years.

[blackdiamond [OP]]

Is it the 32/36 Weber? My runs great with it on regular (lowest grade) fuel. Is it adjusted properly? If not try this site: redlineweber.com   It's what I used and I've had no problems for the last 4 years.

It is a 32/36 carb, I think it is a K874 kit but not positive.  The only real adjustment on it is the idle mixture screw and it runs fine at idle.  I really think that it is just running lean, but I don't know what jets are in it to know what jets to get.  I have used that site before, but will look again.

[mudmaster]

I got my used so I don't know what jets are in it. I thought there were 2 adjustment screws? It's been a while though. Good luck

[blackdiamond [OP]]

I got my used so I don't know what jets are in it. I thought there were 2 adjustment screws? It's been a while though. Good luck

I am pretty sure that there is really only idle adjustment screws, I have been working with tech support off and on for a while, but I have been wrong before.

[Ferg]

79-82 - 8* BTDC @ 950 RPM vac adv off
83 - 5* BTDC @ 950 RPM vac adv off
85 22R - 0*BTDC @ 950 RPM vac adv off
85 22R-E 5* BTDC w/terminal T grounded

[blackdiamond [OP]]

79-82 - 8* BTDC @ 950 RPM vac adv off
83 - 5* BTDC @ 950 RPM vac adv off
85 22R - 0*BTDC @ 950 RPM vac adv off
85 22R-E 5* BTDC w/terminal T grounded

Thanks, what does BTDC stand for...I'm not the sharpest tool in the shed?

[Uncle Jesse]

btdc=before top dead center

I ran a used weber as well, and the guy I bought it from helped me rebuild it and jet it.  I couldn't tell you what the jetting is though.  They do sell a weber carb that is pre jetted for toyota 22r's, so go searching for that info.  To find out the jet size I believe you'd have to get into the carb and look on the actual jets.

There should be both an idle speed and an idle mixture adjustment.

[blackdiamond [OP]]

btdc=before top dead center

I ran a used weber as well, and the guy I bought it from helped me rebuild it and jet it. I couldn't tell you what the jetting is though. They do sell a weber carb that is pre jetted for toyota 22r's, so go searching for that info. To find out the jet size I believe you'd have to get into the carb and look on the actual jets.

There should be both an idle speed and an idle mixture adjustment.

You are correct about the two adjustments, I have played with both of them.  Now I am working to get the rest of it up to speed.

[Uncle Jesse]

I just found some info I had packed away in the corner.

On my carb, this is what I ran:
Float Adjustment - 19/16" or 41 mm
                           2" or 51 mm

Main Jet - 130
Secondary Jet - 155
Emulsioning Tube - F50

Primary Air Corrector - 175
Secondary Air Corrector - 190

I also have a scan of an exploded view, parts list, troubleshooting chart.  I'll post a resize of the exploded view.  Let me know if you need  any of this, I will scan it fullsize then email it

[Duffil]

btdc=before top dead center

I ran a used weber as well, and the guy I bought it from helped me rebuild it and jet it. I couldn't tell you what the jetting is though. They do sell a weber carb that is pre jetted for toyota 22r's, so go searching for that info. To find out the jet size I believe you'd have to get into the carb and look on the actual jets.

There should be both an idle speed and an idle mixture adjustment.

it would be a K8749 if I remember right...but Weber has been on strike for like 16 months now...the supply of 033B carbs has been depleted..i couldn't find one anywhere between Cali and NYC...

[llamas]

if it helps i live at 4800' ele. and use .115 main jet runs great i got jets from CARBS UNLIMITED 1800-994-CARB  good luck!

[blackdiamond [OP]]

if it helps i live at 4800' ele. and use .115 main jet runs great i got jets from CARBS UNLIMITED 1800-994-CARB  good luck!

Impressive reply...over 3 years after the previous post!  That truck has been parted out.

[BLACKDOG]

Impressive reply...over 3 years after the previous post!  That truck has been parted out.

bd is getting sassy of late!! 

[blackdiamond [OP]]

bd is getting sassy of late!! 

Not really trying to be sassy, but this newbie shouldn't ever be accused of not using the SEARCH feature!

[boobap]

...and now 5.5ish years...