Eagle Race Car! 81 SX4 Project

[blk-majik]

Is the choke butterfly,on top of the carb, closing all the way when the engine is cold and the accelerator pushed? If not the choke control is not working properly.  Have someone hold the choke shut with a screwdriver or some thing and try starting. If it fires and makes vaccum the choke pulloff should open the choke 3/16" to 1/4" and then the choke control should slowly open the choke as the engine warms up. Check for vaccum hoses that are disconnected or cracked causing a vaccum leak. Pumping the accelerator petal should pump gas into the intake and get the engine to fire even with a vaccum leak.

the butterfly is fully closed when the accelerator is pushed, and when it's not pushed. I put a screwdriver in it to make sure it stayed close, just to make sure (even though I can see it when starting the car). No dice Any particular vac lines to prioritize? We reduced a lot of the vacuum complexity, so a bunch of them are just plugged. Not really sure what's essential and what's just for emissions

Sounds like you need to pull the carb and rebuild, it's probably gummed up. Especially since if you dump a little fuel down it's throat it fires, but wont when it's line fed. When you rotate the throttle, look down into the carb (don't try to start), do you see fuel spray from the nozzles as you rotate the throttle lever? If not you may have a bad or weak accelerator pump, a rebuild kit supplies a new one, or at least new seals and spring for the current.

i think you're right. I'm not seeing/smelling any fuel when I rotate the throttle by hand. If I rebuild, it'll be a first for me. I guess I just need to man up and get to it I found some good guides online. Any recommended resources to make sure I do it right? and dont mess up anything else in the process?

if anyone else has any other ideas in the mean-time, I'm all ears. Thanks everyone!

[GRONK]

A rebuilt carter is still a carter.  I have some cheaper Motprcraft options and I'm open to trades if you're on a budget.  I can help you get fixed right w/o spending a lot of time on it.

[blk-majik]

That's something I'd like to to do, just not yet. We'll need spares of everything at the track anyway, so I want to get everything working with what I have before I start upgrading. Even if we replace it, I'd like having a working backup And its a good learning exercise

[blk-majik]

Here's a few resources I found that might be useful to others:

Carter BBD 1-1/4"Service Manual: http://u225.torque.net/cars/SL6/docs/BBD_Manuals.pdf
Is this the exact carb that comes with on the 258?

Here's an overview video going over how the carb works:
http://www.youtube.com/watch?v=Wd6ekdW2jPM

The first 4 parts of a video series showing how to rebuild this sucker, by the same guy:
http://www.youtube.com/watch?v=-VMk3VI7sYs
http://www.youtube.com/watch?v=01nt0m9xW_4
http://www.youtube.com/watch?v=rgGLaWSoghM
http://www.youtube.com/watch?v=9qgBfgz1rz8

If anyone can find the rest, please share

[shaggimo]

Honestly the carter non feedback, is probably one of the simplest carbs I've ever tinkered with/rebuilt, simpler being a snowmobile or ford 9N tractor  . The napa rebuild kits are dirt cheap, get a new float while you're at it, the kit will come with a nice blow up of the carb, along with a couple important adjustments that are needed. Take your time pay attention to where stuff goes and keep your work area clean, you'll be set.

[Baskinator]

I agree with shaggimo. I rebuilt my Carter BBD a few weeks ago (first carb I've ever rebuilt) and it was actually pretty simple. I completely disassembled it once just to see if I could do it and thoroughly cleaned it out with compressed air and carb cleaner, then did it a second time with the actual kit and a chemical dip. Considering you're building a race car, and I knew absolutely nothing about cars before this past summer, you should have no problem.

I used a Chilton's manual for reference, but the kit came with the same diagram as in the book. It also gives you all the specific measurements and adjustments needed, and provides a small ruler/straight edge for that. My kit was the GP-Sorensen from Advance Auto I believe, and it has all the necessary gaskets (plus some extra), as well as a needle and seat, check balls, and new accelerator pump.

Here are before and after pictures of my Carter. Not the best pics, but you can see that it looks a lot better.

Before:

After:


I would suggest taking lots of pictures and using little baggies to put parts in and label. If you want, I have a bunch of pictures of the innards of my Carter before I cleaned it somewhere in my album: http://s1237.photobucket.com/albums/ff479/Baskinator/

[blk-majik]

Thanks, good stuff

I agree with shaggimo. I rebuilt my Carter BBD a few weeks ago (first carb I've ever rebuilt) and it was actually pretty simple. I completely disassembled it once just to see if I could do it and thoroughly cleaned it out with compressed air and carb cleaner, then did it a second time with the actual kit and a chemical dip.

What did you dip it in? I think I'm going to need to do that

I got the ball rolling last night. I ordered a rebuilt kit from NAPA - Their Echlin brand. They also had a Mileage Plus variant, which is a Echlin sub-brand, but I've heard they're not as good, so I went all-out There wasn't a list of what's included, so I also ordered a new brass float, leather accelerator pump, and needle & seat. I think I'm good to go!

The order isn't here yet, but I pulled the carb to get ready. I can't believe how gunked up it is! This weekend I'm going to pull the intake manifold as well. I'm almost tempted to just yank the entire head at this point. Maybe I'm a bit too used to more modern engines that like to be impeccably clean, but I can't believe how much gunk was in the intake system! Before I do anything stupid and make thigns worse, please someone let me know if this looks excessively dirty and is reason to worry, or if my is just showing

Here's what I started with


After pulling the carb off, I noticed a ton of built-up on the intake manifold inlet runners. I also noticed a good bit of puddled fuel in the intake manifold. Odd design with the pillars... never seen that before Is this puddling normal? What about the build-up?


The bottom of the throttle plates wasn't any better. Should I worry?


Here are the passages from the bottom:


And from the top:


The housing:


The IM with the gasket removed and ports blocked (like its going to help...)


Notice all the oil burnt on the exhaust manifold and getting everywhere else. I think its time to invest in an aluminum valve cover!

[ammachine390]

The little pillars is the intake manifold heater. A lot of carbureted GM cars from the 80s used intake heaters too, but they called them Early Fuel Evaporators (EFE). Its purpose is to prevent fuel puddling when the engine is cold. Once the engine has been ran for a little bit and everything heats up, probably very little fuel actually puddles.

[shaggimo]

  Man that carb is nasty, it would be a good idea to clean the intake too. You can soak the carb in a bucket of carburetor parts cleaner, (can be found at advance auto), by just removing a couple protruding parts the whole carb will fit in the bucket. I let the one off the sx4 sit in it for 5 hours, but you may need to leave it in the longer, lol. Another trick I have heard of, (have yet to try though) is soak it in antifreeze apparently it does the same cleansing, but at a far cheaper price than carb parts cleaner, (again I can't verify, because I haven't tried it yet, but will within the next couple weeks  ).

[GRONK]

I've never heard of antifreeze working.  I don't think it's corrosive enough.  I have personally used kerosene with success but nothing will beat a gallon of carb cleaner.  It's reusable and comes w/ a basket so I recommend the $$$ route.  It will be better and cheaper in the long run.  I also recomend a good media blast session with a mild glass bead.  That caretr bbd will look brand new again.

Of course you will need compressed air etc......

[blk-majik]

Good call on blasting. I'll obviously have to break everything down pretty well to blast it, but are there any parts that should NOT be blasted? If not, I'll just go to town on anything that isn't shiny

I have a decent compressor, but don't have my own blasting gun and no longer have access to a cabinet. Is a cheap-o harbor freight gun good enough, or is this one of those times where quality makes a difference?

Seeing as how much stuff could beninfit from a good abrasive beating, I'll work on building something like this, but maybe a bit bigger so it can hold the entire head if needed. Seems like a good investment anyway

[priya]

I have a decent compressor, but don't have my own blasting gun and no longer have access to a cabinet. Is a cheap-o harbor freight gun good enough, or is this one of those times where quality makes a difference?

I've used a variety of siphon type blasters and been greatly frustrated by their poor performance.  I bought a pressurized pot sand blaster and the difference is night and day.  They use a great deal of air but if you're not blasting something like a frame and just doing smaller stuff it works for intermittent use very well.  Uses a lot of sand too, but then it does so much better of a job.  I ran mine on a 12 cfm @90 compresser and it worked well for most stuff but for continuous use on very large areas I spliced in my 6.3 cfm@90 compressor for a total of over 18 cfm.

Edit:  I just noticed you were talking about media blasting a carburetor.  In that situation a pressure pot blaster might be overkill but I also wonder if a siphon blaster is going to do the job on that corroded carb with glass bead.

2nd edit:  In looking at that carb again I think it might be toast.  I think what you're going to find is that any blaster/media that is strong enough to remove the corrosion is going to damage the carb and any media/blaster that isn't going to damage the carb isn't going to be aggressive enough to remove the corrosion.

[blk-majik]

I'm kinda hoping the solvent soak will do most of the dirty work and blasting will most be for finish. The gunk isn't on there too hard. I can scrape it off, I'd just rather not do that since I end up scratching the metal when I try. We'll see. Worse case, I'll have to upgrade

[GRONK]

You would be surprised what a light dusting of even a mild glass will do to corrosion.  I'm affraid your throttle plates are trashed but will still work (just not the best)  You can buy a cheap-o-harbor freight blaster w/ a bag of glass media.  It will work great on small projects like carbs and small parts.  

You need a beefy compressor or will have to go in shifts.

For what you are doing a very inexpensive blaster will work well.  I used HF blasters for years, I just went through 1 cabinet and 4 guns/year.  I now have a $1500 compressor and a $4K Snap-On blast cabinet but use aftermarket guns and mademy own pickup.  I love it.

See if anyone local has one you can borrow.  I don't recommend blasting needles unless you are very carefull.

Make sure to really wash/clean/blow out everything good when finished.  You can't make sure enough on this.

After everything is finished and ready for reassembely, coat everything with a silicone spray.

[blk-majik]

I almost got everything torn down, but my vacuum piston seems to be stuck. I can't just lift it out for some reason. It seems to be stuck on something in the air horn. Is that normal? Is there a trick to it? Theres corrosion everywhere, so I can't really tell where 1 piece of metal starts and the other ends I tried prying a bit, but I REALLY dont want to break the assembly.