Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

HEI swap ...need help

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by LKJR, May 14, 2003.

  1. LKJR

    LKJR 1/2 ton status

    Joined:
    Apr 18, 2000
    Posts:
    2,116
    Likes Received:
    0
    Location:
    Lubbock, Tx
    ok guys, I just swapped in an HEI unit out of an 81 model. put on new plugwires, and I lined up the rotor with the old one when I replaced it. well now I'm not getting any fire, it rolls over and I've turned it a hundred times it seems like, but all I ever get is backfire through the carb or gas blowing out of the carb. I hooked the yellow wire up to the connector on the HEI unit. Am I missing something. HELP.
     
  2. big pappa b

    big pappa b 3/4 ton status

    Joined:
    Jan 3, 2003
    Posts:
    6,328
    Likes Received:
    0
    Location:
    Falcon, Colorado
    If you're getting backfire and popping thru the carb chances are that you either have the distributor 180 degrees out or at least off a few teeth. When you took out the old one did you mark where the rotor was pointing and aim the new one at the same spot or just drop it in?
     
  3. 69K5

    69K5 1/2 ton status

    Joined:
    Nov 10, 2001
    Posts:
    1,544
    Likes Received:
    0
    Location:
    Monroe, LA
    you are probably off one wire. rotate all your wires one spot over to the right (counter clockwise). there is a different starting point for the #1 between points and hei. also you need to put a stronger wire on the coil side. the stock wire isnt big enough. put a bigger fron the fuse box.

    hope it helps

    nathan
     
  4. LKJR

    LKJR 1/2 ton status

    Joined:
    Apr 18, 2000
    Posts:
    2,116
    Likes Received:
    0
    Location:
    Lubbock, Tx
    [ QUOTE ]
    I lined up the rotor with the old one when I replaced it.

    [/ QUOTE ]

    yes I put the hei rotor in the same spot the points was at, I tried rotating the wires counter clockwise already, I'll try the bigger wire trick tommorrow.
     
  5. 69K5

    69K5 1/2 ton status

    Joined:
    Nov 10, 2001
    Posts:
    1,544
    Likes Received:
    0
    Location:
    Monroe, LA
    if its backfiring im 90 % sure that its off on the starting point. as long as the rotor is pointing at the #1 wire when you start cranking on it, and the order is right. it ought to fire off. mine gave me hell for like 3 days. /forums/images/graemlins/mad.gif i swapped em every direction. i thought it was one spot over it might have been 2. i know i tried both. good luck.

    nathan /forums/images/graemlins/grin.gif
     
  6. JohnSPledg

    JohnSPledg 1/2 ton status

    Joined:
    Feb 22, 2001
    Posts:
    141
    Likes Received:
    0
    Location:
    Baton Rouge, La
    If it is the original engine, you are probably one cylinder off in the firing order, in 74 (i think) GM changed the firing order by one cylinder. I had the same problem in my blazer, but it was because the previous owner swaped in a 305 and retained the points distibutor, I didn't bother to mark the distributor position and when I put it where it should have been for a 72, it was off by 1 cylinder. This was of course in my younger, less informed days. Now I know better, but only from experience.
     
  7. LKJR

    LKJR 1/2 ton status

    Joined:
    Apr 18, 2000
    Posts:
    2,116
    Likes Received:
    0
    Location:
    Lubbock, Tx
    is there a way to test this HEI unit somehow? I've got the rotor lined up and I've got an 8 gauge wire going straight from a 12 volt source to the BAT terminal on the HEI unit. I"m at a loss, I heard something from someone about when it sounds like it's trying to roll over on itself to do something but I don't remember what. I'm getting that much.
     
  8. jasonkh2tg

    jasonkh2tg 1/2 ton status

    Joined:
    Mar 27, 2003
    Posts:
    139
    Likes Received:
    0
    Location:
    MPLS MN
    Was the moter turned at all once you removed the points distrubitor..if so just turn the engine with a breaker bar on the damper tell your sure it's on the compresion stroke then 0 it out on the damper and pointer...then remove the cap on the HEI point it to the 1 cylinder in the cap and drop it in..that will give you a exactly TDC...put all the plugs back in and wires and start the engine it will be running a TDC then advance it to you desire...Also keep in mind that running spark plugs with points are gapped about .035...you may need to gap them more or buy a plug that was for a HEI most I think are around .045..
     
  9. MJF

    MJF 1/2 ton status

    Joined:
    Nov 1, 2001
    Posts:
    694
    Likes Received:
    0
    Location:
    Campbell, CA
    When I did my hei swap, I had almost the same problems. I eventually pulled the dist, pulled the #1 plug, & turned the motor until it made compression on #1. Then I started all over & dropped the dist in with the rotor pointed at #1.

    I got all confused at first because the manual shows that the #1 on the dist is in a different location for hei & non hei. Since I was totally confused & it wasn't starting it made sense to just start all over.
     
  10. LKJR

    LKJR 1/2 ton status

    Joined:
    Apr 18, 2000
    Posts:
    2,116
    Likes Received:
    0
    Location:
    Lubbock, Tx
    dosen't it make two rotations to every time it fires one for compression and one for exhaust? how do I know which one I"m on if that is the case?
     
  11. Don

    Don 1/2 ton status

    Joined:
    May 30, 2002
    Posts:
    1,778
    Likes Received:
    0
    Location:
    Spokane Washington
    Remove the driver's side valve cover, roll the engine over by hand, [with a 1/2" drive ratchet,with the dampner bolt] watch the rocker's on #1 cyl, driver's side, front, watch as the exhaust close's, and as the intake move's down, and back up, now watch the degree mark's on the dampner, slowly roll it up till about 10 degree's before TDC, then set the rotor to #1 cyl. on the dist cap.

    Reinstall valve cover, and fire it up, then set timing with a light. /forums/images/graemlins/eek.gif
     
  12. chevyracing

    chevyracing 1/2 ton status

    Joined:
    Sep 8, 2001
    Posts:
    2,589
    Likes Received:
    0
    Location:
    Colorado
    [ QUOTE ]
    If it is the original engine, you are probably one cylinder off in the firing order, in 74 (i think) GM changed the firing order by one cylinder. I had the same problem in my blazer, but it was because the previous owner swaped in a 305 and retained the points distibutor, I didn't bother to mark the distributor position and when I put it where it should have been for a 72, it was off by 1 cylinder. This was of course in my younger, less informed days. Now I know better, but only from experience.

    [/ QUOTE ]

    ?????????????????????????????
     
  13. jasonkh2tg

    jasonkh2tg 1/2 ton status

    Joined:
    Mar 27, 2003
    Posts:
    139
    Likes Received:
    0
    Location:
    MPLS MN
    You don't even need to take the valve covers off...If you got the plugs out just put your finger over the number 1 cylinder and you will be able to feel compresion when it's on the compression stroke....easy as that...
     
  14. LKJR

    LKJR 1/2 ton status

    Joined:
    Apr 18, 2000
    Posts:
    2,116
    Likes Received:
    0
    Location:
    Lubbock, Tx
    FINALLY!!!!!!!!!

    it ended up being a combination of things. 1 I got some bad info on firing order, I had the order right but I had my odd / even cylinders backwards. Also the distributer was 180 off I lined up with the notch on the dampner but it was on the wrong cycle. so all is well, I still need to find where it's supposed to be at with the timing but I think I'm gonna replace my plugs first just to make sure there isn't anything in the way like that to keep it from running right. it still acts like it's stumbling a little when it idles. and it takes a bit to start.
     
  15. Don

    Don 1/2 ton status

    Joined:
    May 30, 2002
    Posts:
    1,778
    Likes Received:
    0
    Location:
    Spokane Washington
    Any Chevy V8, No1 cyl. on driver's side front.
    Firing Order, 1 8 4 3 6 5 7 2
    Distributor rotation, Clockwise, to advance, turn counter clockwise, to retard turn clockwise.

    Probably around 8* before will get it running. /forums/images/graemlins/eek.gif
     
  16. '72brett

    '72brett 1/2 ton status

    Joined:
    Dec 3, 2002
    Posts:
    166
    Likes Received:
    0
    Location:
    northwest Iowa
    Problems with stumbling yet? I don't think this would be the problem, but is there a chance that the valves are set too tight?
     
  17. LKJR

    LKJR 1/2 ton status

    Joined:
    Apr 18, 2000
    Posts:
    2,116
    Likes Received:
    0
    Location:
    Lubbock, Tx
    It idles it just has a slight stumbling sound to it.
     
  18. LKJR

    LKJR 1/2 ton status

    Joined:
    Apr 18, 2000
    Posts:
    2,116
    Likes Received:
    0
    Location:
    Lubbock, Tx
    running a new wire to the HEI unit from the ignition, where should I run it from? accessory? does that have full power during cranking?
     
  19. stu

    stu Registered Member

    Joined:
    May 2, 2003
    Posts:
    59
    Likes Received:
    0
    Location:
    Bucks County, PA
    you should have two links on you fuse box. One is hot all the time. the other is hot with the key on and the one you want to connect to. By the way I did this to a 71 2wd I had. one problem I had was I kept plowing the control module. keep 1 or 2 with you just in case. it was no fun breaking down when you on the road and no autoparts nearby.
     

Share This Page