73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Thorogood on December 01, 2014, 11:42:03 pm
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Hello!! I'm having issues. I recently did some swaps on my 78 k10. First took out old busted auto tranny with crappy awd transfer case. Put in a muncie with the 205. Then pulled the wore 350 sbc out and dropped in a 454 i cleaned up from a 77 suburban c20. Really like the set-up and the hydro clutch. Problems. I got powdercoat happy and removed my emissions sticker from my air cleaner lid. I don't know what to time it at. Manuals say "refer to emissions sticker", well I'm SOL there. I got it at 8 d. btdc now. Its revving really high when cold, and stumbles in low rpms. The motor is all stock even left the quadrajet on, the motor ran great when pulled. I want to get timing right on before I mess with my fuel system. It should have allot more low end it seems. Tired of stumbling around internet and getting no where. figured to ask the pros. Any help greatly welcomed.
Also found out there is a heavy duty 454 and it is timed different. Idk which one I have, it is a 2-bolt main, but a sticker on the bottom air cleaner housing says heavy-duty.
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If it were mine I would start out with 12 degrees static timing and with the engine at opeating temp putting a vacuum gauge and tach on it and set the idle to about 600/650rpms and then check/note the vacuum gauge. If you have never messed with the carb, I would turn the idle mixture screws in counting and making note of the number of turns to seat them (don't tighten them down) and the turn them back out and adjust it until you get the highest vacuum reading while at the same rpm.
This is just a basic instruction but that is where I would start.
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Thanks will give it a shot.
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Idle fixed and running decent. But now I think it starting to get a ping on mid to high rpm. More of a shudder, think it is my vacuum advance. I got rid of a bunch of stuff the vacuum ran to. Not 100% where it should go. After research from the article posted on this site by the engineer of vacuum advance, i need to have it at manifold vacuum on the bottom of carb because it is now a manual. Going to mess with that tonight. Also I'm starting to see oil pressure drops at idle at running temp. Thats scaring me. Allot of time and money on the motor, that pig goes, im screwed!!! Gonna recheck all my oil pressure lines though. Any info or tips appreciated, thank you!!!
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Phew oil pressure line came loose, good to go there staying above 30 at idle now. The timing runs best at 12, and there is no manifold vacuum port on the carb, just the big one that goes to valve cover. After research I'm guessing my quadrajet is off and not tuned properly. It has a big flat spot mid range. Gonna watch a bunch of youtube vids on how to de-bog a quadrajet.
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Has the Qjet been rebuilt? Glad you fixed the oil line.
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Thanks Captkaos, not to my knowledge, I have not had it rebuilt. While in the suburban the motor ran great, but was an automatic. Well truck WAS running good. Got gas after work, seen the prices were so low I put in premium. Ran great, power all over, went to pull in my drive, clutched it, revved through the roof!!! Can not get it to come down either. Adjusted idle screw till it about fell out, nothing!. Turned the idle mix screws a little each way, nothing! Only way to get it to de-rev was retarding dist. cap. Then took it for a drive and had NO power. Can't win with this thing!! So get to pull the camaro out of storage tomorrow so the wife can go to the doctor and I take her truck to work.
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High idle speed sounds like stuck choke linkage or binding throttle cable.
For the flat spot or bog I would check the secondary vacumn break.If it's
not hooked up or not working secondary opens too fast causing a bog,
more so at low speeds.How about posting some pics of your carb
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Well went out tonight after work. Tore the carb off and inspected it, sprayed the heck out of it with carb cleaner and air hosed it off. No luck runs worse and still idles high. Everything moving freely and smooth. I don't know I'm stumped. Secondary vacuum break? I know carbs for atvs and motorcycles, nothing about vehicles. Time to learn I guess. I have a couple of Holley 650s off of 350sbcs, thinking of buying the adapter plate and throwing one on there. Seems alot easier to tune/rebuild. I'd buy a rebuild kit for it to. Hate to loose my custom powdercoated metal fuel line tho. What you think? I can get pics up tomorrow night, but I need this thing running buy monday hopefully. Should I keep messing with quadrajet? Got the numbers.. 17056212 ABH with 133 under it. is a Rochester R4-4MV. Thanks for the help!!!
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QJets have vacumn pods on pass side,some had 2,1 on front & I on rear ,just depends
on application.Arod from 1 of them will open choke after starting and could also go to
the top secondary plates.When started vacumn is applied retracting the rod,if it doesn,t
the flaps will snap open causing a huge bog,depending on engine speed,lower rpm the more the bog
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Didn't read the other posts, but the choke has to be off for the top secondary flaps to open.
Chris Lucas
73-87chevytrucks.com
squarebody.biz
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Thanks again, couldn't barrow a camera.... I bought the adapter plate. Electric choke holley 650 double pumper going on there. Going to do that tomorrow. No reason to leave it stock I guess. Just my powdercoated lines and air cleaner gonna go :( I will hopefully be able to get some pics. Haven't shown anyone my motor yet, be cool to see what you guys think.
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You are going to hate that Holley on a 4x4 unless you never go off road.
Chris Lucas
73-87chevytrucks.com
squarebody.biz
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I'm not worried about off roading now. Just need this truck going! Kinda screwed myself investing everything into it. Its my only vehicle during winter. Just going to be used for getting me to work. SO got the adapter plate, installed holley. Fired right up, then climbed in rpms. Idling high STILL. Must be intake leak I thought, sprayed all around intake with starting fluid, then around carb, nothing! 2 carbs same issue. Timing at 12dbtdc, idle screw all the way out, printed out a holley initial set-up sheet followed it closely everything but float bowl level check. All vacuum lines triple checked, idk what going on. Try a different distributor? Yelling and cussing at it don't work, haven't hit it with a hammer yet tho. Going to check holley tech to see if they got anything to help.
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HURRAY!!! Got it dialed in, combo of the choke cam, and kick down linkage was not allowing throttle to bottom out at all. Got float levels adjusted, accel pump, hooked up vacuum gauge to manifold vacuum, screws 1 3/4 out. Got to say really happy with it so far, running better than ever, idles great, happy happy happy. Got to say this project was an eye opener, I was overconfident, all I'm a machinist good at working on quads and bikes, gonna b easy!!! Shoot, now its I'm NOT a mechanic, have ALLOT to learn, not doing this again!! but I did manage the swap and it running ok for now. Took allot longer and more money than expected, and had to learn most everything the hard way. Funny we got hit with a big snowstorm in early november, ice scated my camaro while throwing the truck together. Now that its fixed.... NO SNOW. I'm not complaining tho, tired of that crap. Thanks for all info and help, especially Captkhaos!!! Have a great holiday season!!
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Any pics of the motor & of the Camaro?