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SO thats what 4bbl is supose to feel like! Silly me.

Discussion in 'The Garage' started by Grim-Reaper, Sep 15, 2002.

  1. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    I have owned Dollar (my 75) for almost 4 years. It was rough when I got it. Numerous problems including a blown tranny. First year it spent in peices on my driveway. Durring that time I cut all the rust and put new floors int. REBUILT EVERY THING BUT the motor. I mean everything, axles, tranny, did some work on the case, distributor, new water pump and the Carb. It drove ok off the line it was all right despite the 3.08's. No rocket like the Lady's 79 but it did fine. Durring that time I fought a ping problem on the hwy. It just sort of ran into a wall. Put a snorkle on it to get it some freash air and for the most part that went away. It however just never really pulled well above 65 mph. Just ran out of steam. I figured the motor was a little tired and with lift 32's, 308's and all just figured it didn't have it in it to do much more. To be honest it topped out about where it was conforatable to drive with the lanky suspension. Much faster and it starts to get white knuckle type of ride. Really got that way with the Detroit.
    Well this spring old Dollar finnay got 4.10's Felt like a rocket at low speeds but still just ran out of steam on the hwy. Religiously shifted at 2800-3k.
    Since I put it back together I had a problem on hills. Get the nose up high enough and bounce and it stalled no fail. The 79 NEVER stalled like that. Difference was the old style Quad carb with the divorced stove type choke. Left me stuck a few times. Well a bug gave me a quad off a 79 he parted. Well I did everything I could with the old carb so I was going to try this "79" carb. Well I don't know what the heck this carb is but the build date says 76 and the emmisions hook ups look like a 76 but I don't think it's a 76. Has torx bolts and that's a 80's thing. So after having this carb sitting around for 6-8 months I got around to rebuilding it Friday night after spend a hour trying to look up a rebuild kit for this thing that according to most places doesn't exsist. Casting is 17067040 is you want to try to find more than a breif list on a Eddlebrock page and one other. Had to guess at the rebuild kit as well as the float settings ad a couple other things. Midnight I have it back together except for finnal set up and convertting it to electric choke.
    So today I go to put this thing on. You name it I had a problem. The screw holding the divorced choke stove to the intake is frozen. Finnaly snaps off so no turning back. If this new carb doesn't run I have to drill out this screw to go back to the old carb. The throttle linkage is goofy. The old carb had the attacment nub permentatly attached. The new carb had this long goofy thing on it. Wasn't going to work with the cable set up on the truck. Hit the parts store for the shorter deal, no dice. Finnaly drill out the hole on the end of the cable and double nut a bolt to make it work. Had to mix and match the fuel fiter cap and run a short filter to get it to hook up to my hard fuel line I don't want to cut. Still worred that the filter has enough spring on it to keep it from pushing off the seal. May convert that to a Steel braid line and AN fittings with a spin on filter.
    So I'm doing the finnal check of things. Something is binding. Cant get the 4bbl open. Cussing I unbolt it.Get it over to the bench and the thing works fine. Cant find any reason for the bind. The intake gasket stayed stuck to the carb when I unbolted it and no problem there. Scratching my head I put it back on. Same damn thing! No 4bbl. CUSS a lot now. Take it back off and the damn thing works fine.
    Now I'm pissed. Get compairing the old carb to the new one. Everything looks the same. I nothing was hitting anything. For a lark I bolt the old cab back down. Guess what....Yep No 4bbl. take it off it works fine. Set hte new one on and by this time my back is screaming form having to stand on the bumper of this 7ft tall pig with one foot and the frame with the other. I find the issue.
    Seems somthing is goofy with my down shift cable. It stops deat just shy of getting the 4bbl open. Go look that the 79. Same exact set up. all the parts look identical. I can get full throttle on it.
    I have been driving that damn truck for 3 years and NEVER hit the 4bbl. It couldn't. So I leave the down shift off. set up the choke, preset the idle mix screws. Start cranking to get the float bowl full. Fires off thrid try with no prime and idles. First good thing of the day. Set the iddle mix best I could. I have a fould plug again so I can only get it to pull down to hair under 19hg. Too hot to throw new plugs in so I take it for a test drive. HOLY CRAP what a difference! get out of the hood and stand on it. 4k shift both shfts! having to back out of it were I was still just getting going before. Hopped on the hwy lay into it and murge at 70mph and still pulling! Guess my old motor is not as tired as I thought it was. Just was running out of air. The point I was hitting the wall I can accelerate!
    So after all the cussing it was worth it. Old cab may well be fine andif it was able to get into the 4bbl it probably wouldn't stall. Well I guess a couple mid night wrech fests are in my future cause I was also supose to get the new Mile Marker shaft replacement part time kit installed to day but my back saying no LOL Need to figure out the deal with the down shift cable too and I have a feeling it's goingto involve dropping the pan on the tranny. That may wait till after Dixie run. I can live without passing gear for a few weeks. .I'll quit babbling now LOL
     
  2. Muddytazz

    Muddytazz 1 ton status

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    Nice to hear you got it running better....now you wanna rebuild mine LOL /forums/images/icons/grin.gif
     
  3. jc71355

    jc71355 1/2 ton status

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    Nothing like the feeling of the secondaries opening up on a 4Bbl. I had a quadajet on my old 71 everyone told me it was junk to get a holey. So I did, BIG MISTAKE. Thing sucked, so I get an Edelbrock, it's better but still doesn't do what the quadrajet would.
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    That's comparing apples to oranges. The Edlebrock 1400 series is a square bore which will outpull a Q-jet on the primaries. The huge diference between the primaries and secondaries on the Q-jet is what makes it seem impressive.

    At any rate Grim that was one helluva novel.../forums/images/icons/grin.gif good to hear you finally have a properly working carb again!

    rene
     
  5. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    It really isn't that hard. $15 for a rebuild kit. Mostly what happens to them is they get sediment in the float bowl and it boogers up the jets or plugs a passage. That and air leaks.
    Most parts stores have a Rochester manual. It has good information and a good section in the front of how a carb works. There is also another book by Doug Roe (sp) that is excelent. Once you have done one you will wonder why you were affraid of it. Just dont do anything without reading the book and/or the supplied sheet with the rebuild kit. There are a couple things that should just be left alone and if you remove them you screw up the factory setting. Biggest two being messing twith the secondaires top door spring and there is a stop for the primary mettering rods that should also be left alone. A rebuild is best describbed as a through cleaning and new seals. That usualy fixes them.
     
  6. Muddytazz

    Muddytazz 1 ton status

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    I've built a few q-jets before, just that i have never messed with removing the jets...call it being scared LOL
     
  7. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Well that's the kicker. The old carb it looks like was working fine other than the nose up stall problem. With working secondaires that may not be a problem any more. I just never caught that down shift cable problem in 4 years LOL.
    Only thing I can think is it's the wrong cable for the bracket. What I'm going to need to do is find out if GM used a different cable on anything and either buy the right cable or right bracket. The cable has a fray so even though it's more work I'll probably replace it.
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    That's usually how I find all the probs on my truck...replace something I'm sure is no good and find out it's something I never thought of.

    At least yours stays running on a hill.../forums/images/icons/wink.gif

    Rene
     
  9. Brian85gmc

    Brian85gmc Registered Member

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    Crap, thanks grim. Mine does the same thing.

    I'll get on that cable pretty soon
     
  10. Twiz

    Twiz 1/2 ton status

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    BWAAAAAAP! = /forums/images/icons/grin.gif

    You know about the lil' down-shift cable adjustement lock thing, right?
    Should be a just behind the carb/cable-bracket on the down-shift cable. Looks kinda like a box. It's a two-pronged deal that pops up and allows the cable-houseing to pull out/in as needed, then locks the cable-houseing in-place.
    Pop the lock and hold the throttle to WOT, then lock it in-place.
     
  11. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    The down shift cable on a TH 350 and TH400 adjusts as follows.
    Pull the release up. That takes the slack out of the cable. Relatch it. it is designed as a ratchet. Give it full throttle and your done. As such it's bottomed out on my truck. there is no adjustment left. There is not enough travel or it is not the correct one for the application. Hard to say what happend durring the first 22 years of it's life before I owned it but something has been swapped or is hooked up wrong.
    Your dirrections are correct for a 700R4, That trasmission uses a TV cable. Sort of a throttle possition sensor for the transmission. It effects how much line pressure and shift points. You can play with that set up a little and get a littl more aggressive shift at different RPM's but you can also screw up and blow the transmission it it's way out.
    Those dirrection are not correct for a TH350, Th350c, Th400 and TH400c. The Down shift in those trasmissions could care less about anything other than full throttle and that initiates a down shift if the RPMs are within range. The rest of the shift is controled by a "Modulator" that works off intake manifold vacuum. Full throttle eguals less vacuum so the tranny holds gear longer. If you would like me to explain how to adjust the modulator I'll be happy to do so. /forums/images/icons/smile.gif
     
  12. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    </font><blockquote><font class="small">In reply to:</font><hr />
    If you would like me to explain how to adjust the modulator I'll be happy to do so.

    [/ QUOTE ]
    Smart-ass /forums/images/icons/grin.gif

    Rene
     
  13. reddog64

    reddog64 1/2 ton status

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    um isnt th400 electric???
     
  14. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Ahh your the observent one. Yes and no. The 80's ones are electric but the 70's are still cable. The 80's ones have a lock up converter also /forums/images/icons/smile.gif
     
  15. reddog64

    reddog64 1/2 ton status

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    how do i know which i have... it was in a 78 but.. you know how that goes...
     
  16. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Ohh hell you got me. I got to thinking about it and I think your right. they use a swtich and a solonoid to kick down even as far back as the 60's I remember looking at a Pontiac with a TH400 and noticed the switch on the gass peddle, talking to the owner, he told me it was the kick down.
    Scratch my previous comment.&lt;inserting foot into mouth&gt;
     
  17. reddog64

    reddog64 1/2 ton status

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    the guy's i have talked to all say i need a kit from summit that mounts to the gas peddle that when presssed "so far down" it will kick it down a notch...

    so i thinkin like you, there all electric???
     
  18. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Hmm I haven't found any info on GM truck but I did find some on cars. My bet is this is the same switch used in the truck.
    http://www.captiveculture.com/share/share_weekly/weekly_html/05.html
    Nows seeing that I now understand why that bracket is under the dash of our trucks. It's sole purpose is that switch. Good old Generic Motors.
    /forums/images/icons/smile.gif
     
  19. TONYP

    TONYP 1/2 ton status

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    I bought a rebuilt q-jet from a guy down the street for $125.00, it runs great. just need to adust the choke for the somewhat winter we get in so cal /forums/images/icons/smirk.gif
     
  20. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I had an old 65 Buick Wildcat with a variable pitch convertor TH400. The switch on the throtle linkage went to the tranny and the stator pitch changed under full throttle. I don't recall the kickdown details on that tranny...but if you removed the convertor switch mechanism and manually moved to the closed position you had a 2500 RPM stall convertor. Moved out real good for a heavy car!

    Rene
     

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