I bought a carb from another member to replace mine (it won't smog anymore) and I am excited to get it installed. I started by comparing the two. They're the same carb, but they're set up differently. There is a device on the back of the carb (passenger side) that the new carb doesn't have, and the wiring is slightly different because of it. The vacuum hoses are also done differently. I've included comparisons so you can see what I'm talking about.

This is all on a 2.6L motor. I suspect that I have a california model or something, and the carb I got is not such. Can I just swap the new carb in, set it up the same as the old one and go? or am I looking at reconfiguring everything under the hood for this new carb? I think the device etc is the altitude compensation unit, and frankly I don't care if that stays or not. I'd be happy to set it up any way that will work!

Here are the pictures.

In this one you can see they are plumbed differently here.



There's the device on the back of the carb I mentioned above. I've looked closer, and it *cannot* be swapped in. I'm going to have to work around this.

Obviously the one on the engine is correct? The 'new' carb may have been for a 2.0l? What is the production date of your Raider, I have a small selection of various year carbs. May also be dealing with the Federal, High Altitude and CA variants of the carb. ??

Russell

I have an 87 Raider FSM that is just for the feedback carb. Maybe it can help you differentiate between the two you have...

Yes the one on the engine is correct. The new one came from another 2.6L raider. I think that the new one is federal, and the original is california spec. From what I'm reading in the FSM, the california spec models have a *different* altitude compensation setup than the federal model. I'm trying to confirm this.

I'm also looking into that FBC FSM, thanks for the tip on that!

I don't have any Federal carbs, but have a few CA spec. <img src="/forums/images/graemlins/wink.gif" alt="" />

Do they have that thing in the back shown in my second comparison photo on the left? The one right behind that green round thingy? I wish I knew what these things were, it would make it easier to identify.

Also by looking at the FBC driveability manual my truck does NOT have the High Altitude compensator, and has the *federal* version of the distributor vacuum chamber.

I'll be able to assess more tomorrow when I pull the carbs from their nooks.

I think the Federal HAC is in the device box on the fenderwell, just an air source to lean out the mixture at altitude.

I think you would be best served to buy a rebuild kit for your carb, plus a new bowl vent valve. Should be less than 150 for the parts iirc. Easy rebuild if you are careful. How did yours fail smog? A kit and a good cleaning should fix you up.

@Russell: Thanks, I'll look forward to hearing what you've got.

Eddy: What I'm trying to identify the differences in is in that thingamajigger that's in the second photo. The carb on the left (old) has it and the carb on the right (new) doesn't. I'm not sure what its called. If I could figure that out, I'd be able to re-plumb the new one around it, I think.

[EDIT] I found it. Its the Mixture Control Valve. Its listed on page 105 of the Raider FBC Driveability guide. I see no mention of it anywhere (need to look closer I guess) and I don't see any diagrams that DONT have it. I'm cOnFuSeD but in a good way. This is fun to figure out.

The truck failed smog with very high HC's at high RPM's, normal HC's at idle. Basically its running super super rich when the secondary opens up, from what I can tell.

That is probably a leaky bowl vent valve.

Kevin