Head and cam swap, guidance for a newbie?

Discussion in 'Small Block Tech' started by MDBuick68, Feb 15, 2016.

  1. MDBuick68

    MDBuick68 Silver Level contributor

    Had some time to mess with it...
    Wasn't able to test drive but holy crap this thing burns my eyes!!! I couldn't stay in the garage for more than a few min at a time.
    What would cause the strong exhaust smell with burning eyes?

    Here's what I have so far...
    -Reset dwell to 30* per Larry, was at 40.
    -idle 1000rpm in park
    -set timing @ 16* btdc, bumping it up higher didnt really make the idle better. Dropping down under 10-12 starts to stumble
    - turned mixture screws to get highest vacuum ended up 4 1/2 turns out
    -got 16" of vacuum fairly steady. Slight wiggle down to 15"
    -hooked vacuum advance to manifold source and backed off the throttle idle screw to keep idle at 1000. Dies when dropped in gear so I used a ported source and adjusted screw to get 1000rpm. Almost died but Idles in drive now without having to tap the throttle.
    The idle isn't too bad but somewhat resembles a miss. Plugs are new, cap rotor wires and points are less than 300miles old.
    Haven't had a chance to drive it but it sure does burn my eyes like never before!! Very strong exhaust.
    What would cause this??
    Hopefully this info can help steer me in the right direction to get it tuned best I can.
    What do you think?
     
    Last edited: Apr 6, 2016
  2. pmuller9

    pmuller9 Well-Known Member

    Sounds like not all the cylinders are firing.
    Check the plug wire firing order to make sure none have been crossed.
    Then Pull the plugs and see if any are wet or black.
     
  3. MDBuick68

    MDBuick68 Silver Level contributor

    checked firing order, it's correct. Pulled plugs and they all look as new. Not wet or fouled.
     
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Like I said, the Q jet idle system may need some modification. What happens is that the throttle plates are open too much at idle causing the engine to idle on the mains. That causes the mixture to go extremely rich. It's commonly referred to as "nozzle drip". The Q-jet primaries are extremely efficient. It doesn't take much. Generally, lots of initial timing allows you to close the throttle plates enough at idle to eliminate this, but not in your case. If the mixture screws have no effect when turned in, this lends further evidence that you aren't idling on the idle system of the carburetor. The engine may also hesitate when driving from a dead stop. I'd look into getting Mark or Ken to modify your Q-jet.
     
    Last edited: Apr 6, 2016
  5. MDBuick68

    MDBuick68 Silver Level contributor

    Thanks Larry, I've noticed that the mixture screws only have an effect when turned way in, about 1-2 turnes from bottoming out. Car will stumble. I can go all the way out with no real change in idle. I only stopped at 4.5 turnes because that was best for vacuum. And as you said, bringing in more timing would usually allow me to back off of the throttle plates but no, I can put timing up to 20 and I still have to have the idle screw turned in to hold the throttle slightly open. I've checked for vacuum leaks and also cupped my hand over the primaries to see if it would smooth out indicating a leak but it didnt, it stumbled. So I think you're right it could be rich.
    Sorry but I'm not familiar with Mark or Ken, how would I get ahold of them?
     
  6. Joe T

    Joe T Well-Known Member

    Idle circuit needs help... Your going to have to open up the idle channel restrictions and open up the idle tubes to .035 or so. This will also eliminate any off idle stumble.
     
  7. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    http://www.v8buick.com/forumdisplay.php?172-Everyday-Performance-LLC (Ken) (techg8 on V8)


    http://www.quadrajetpower.com/ (Mark) (carmantx on V8)
     
  8. MDBuick68

    MDBuick68 Silver Level contributor

    Got ahold of Mark at quadrajet power today and he pretty much said the same thing about the idle circuit, so we decided to go ahead and have a performance build done for my car.
    We'll see what happens when I slap a new carb on in a few weeks!
    I suprised my 5 yr old daughter today when I picked her up from school in the Buick. Sitting in the line up Of cars with a nice slappin idle a few parents gave me thumbs up and asked all kinds of questions about it. Then this parent and kindergartener walks past and I hear her say ooohhh look at that car! The kid goes wow that's shiny and cool! It's so loud! and it stinks! Hahah
    The new carb cant come soon enough
     
  9. MDBuick68

    MDBuick68 Silver Level contributor

    Ive bought a recurve set with bushing and 3 sets of springs and will recurve the distributor as soon as i get this thing idling ok.
    I decided to mess around and do a compression test, what do these numbers tell me? Seems way low to me. Consistant, but low.
    I have 122 at all holes but 1 and 4 are 121. All plugs removed, Engine warm with throttle wdged open.
    I did a test cold as well @ 120 across the holes.

    Makes me nervous. Is something wrong?


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  10. alec296

    alec296 i need another buick

    If none are lower then 115 and none higher then I
    135. Hot. Then you should be fine there. Odd that its not running well compression seems to be good and vacuum at 15 ish is about normal for that cam. Check your spark plugs for extra black or wet soot then Install back in same holes and run again and recheck
     
  11. MDBuick68

    MDBuick68 Silver Level contributor

    Ok, 120 cold 122 hot. It concerned me because many years ago when I checked compression on it (if I remember right) it was higher, something like 150 or so. Im not familiar with the what and why of compression #s. Does the bigger cam have something to do with the numbers being different this time around?

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  12. alec296

    alec296 i need another buick

    Cam will change compression pressure some. Can go up or down depending on cam design. Yes it does seem abit low. But they are even .
     
  13. pmuller9

    pmuller9 Well-Known Member

    The intake valve closing point determines the Dynamic compression ratio and the cranking pressure.
    If the static compression is about 8.5 then the TA 212 cam will have a DCR around 6.6 which will give you a low cranking pressure.
    It would have been fun to check the stock cam timing but you might find that it closed the intake valve about 18 degrees earlier which would give you the old 150 PSI reading.

    If you want to raise the Static compression ratio to 9.5:1 later on, that will restore the 150 PSI readings.

    The fact that the cranking pressure is the same for all cylinders is the important part.
     
  14. MDBuick68

    MDBuick68 Silver Level contributor

    Spark plugs are clean and dry. Ive pulled them a couple times in between running.
    It is odd it runs like it does, it just doesnt feel right...it has me out in it checking all sorts of things whenever i have time.
    Which brings me to another concern...
    I decided to pull the rockers and use the dial indicator on the push rod tip to measure the cam lobe lift, I get between .293-.295 or so. Multiplied by the 1.55 rocker ratio gets me very close to the cams spec of .459 for valve lift. Pretty consistant across the board. Heres the sinking feeling in my gut.. All but #7 exhaust, that one only reads .220 which is only .341 lift. I even repositioned the indicator and ran the numbers a couple more times. Same thing. When i changed my oil it wasnt fresh and clean either, it had what looked like darker swirls mixed in. Possibly fine metallic. Cant be good can it?:(
    Did i just find a problem?


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  15. Extended Power

    Extended Power Well-Known Member

    Sounds like one of the lobes got wiped out.
     
  16. alec296

    alec296 i need another buick

    Definitely worth looking into . Hopefully something simple. I never see a cam go that fast. Maybe week lifter.. Close valve on that cylinder and check how loose pushrod is . Any lifter preload.
     
  17. MDBuick68

    MDBuick68 Silver Level contributor

    Damn what a buzzkill. Not the way I hoped my first cam install would go. I'll bolt up the rockers and check that tonight Andre. Ao just get both valves closed and see if the pushrod feels tight?
    Another thing i noticed and again not sure if its normal or not, when the rocker shaft was removed i pushed on the pushrods and only the #1 lifters felt bouncy, i can compress them. The rest are solid and dont move. (On that head at least) Why is that?



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  18. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    .070 difference is a lot. You should be hearing noise from that rocker. Maybe the lifter is bleeding down.
     
  19. MDBuick68

    MDBuick68 Silver Level contributor

    Thats what i thought too Larry, but i didnt notice anything out of the ordinary when it would idle, other than it idling like crap. But no slaps. I measures it a few times and everytime it was consistent. Now i did see the 2 spongy lifters on #1 bleeding down while turning the crank with the rockers on. I could watch the dial needle slowly retreat. Aside from the low reading on #7 are those 2 spongy lifters bad? Or is it just because the motors not running and pumping them up? Still figuring out how it all works

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  20. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    If the lobe was worn down .070, that would eliminate the lifter pre load and give you valve lash, and that would give you noise. If the lifter was bleeding down excessively it might not be noisy, but you wouldn't get full valve lift. Let's hope that's what it is.
     

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