"Buick 306 CI V7" or "Cylinder #7 just going along for the ride"

Discussion in 'Small Block Tech' started by 72skylark, Jun 25, 2002.

  1. 72skylark

    72skylark 4 Doors of Fury!

    "Buick 306 CI V7" or "Cylinder #7 just going along for the ride"

    Well, I've never been able to get my car to idle perfectly smooth, and I just figured it was this or that, nothing big. But when I changed my plugs everyone looked normal, except #7 was wet, and didn't look like his brothers. So I put the new ones in and started it up. I unplug #7, hear the MSD arching elsewhere, but no change in idle quality. I pluged it back in and unpluged a different one, and idle got rougher. So I whip out the old compression gauge. It read a nice 25 PSI, another cylinder read 155. So.... I thinking burnt exhaust valve...
    It still runs pretty good on 7 cylinders. I figure since I have to pull a head, and want to change the timing chain also, I'm going to do a few things while I'm there. New cam and lifters, I'm thinking the TA 212, anyone run this? it says stock gears/stock converter ok, do the 2.56 stock gears work OK? I'm going to also do some headwork, mill the head/home port/ valve job. What is the most I can mill the head, without having to worry about valve train problems? Can I get it up to a good 9.5 (or higher)?

    I'm thinking the problem probally originated last summer, it was running 230-240 degrees, unknown to me until I installed a temp gauge. I'm hoping it's not a cracked head... hoping for just a bad valve, unless someones got a nice set of worked up heads lying around???
    hopefully the gas milage will pick up a little... just drove to Oklahoma and back to connecticut, got 16.5 MPG without AC, 15.5 with AC, and 12 MPG creeping in traffic going through NY... yikes! this was cruising between 75-80....
     
  2. Mike Atwood

    Mike Atwood The Green Machine

    I am running the TA212, and the stage 1 DP intake with 3.23 gears and a stock converter. I am pretty happy with it. out of the hole it isn't much to talk about though with a stock converter. I would recommend a 2500 stall converter to really make it run.
    90% of my racing is rolling from about 25mph, so it works out great for me. Did you guys know that those new vettes fishtail real good but don't move as fast as they look. :grin:
     
  3. TXGS

    TXGS Paint by numbers 70 GS 455 4spd

    Would expect to see a burnt exhaust valve. I also had this problem. but they do run much better on 8 cylinders. 256 gears are great for highway use but i probably would look for a posi in the 308 - 323 range.
     
  4. Michael Kise

    Michael Kise Member

    Hello,
    Easy way to tell if it is a burnt valve or bad rings is too put a few squirts of oil in the cylinder and then check the compression again. If the compression comes up it is worn rings, if not it is probably a burnt valve or cracked head. Thought this may help narrow it down until you get the heads off:grin:
    Thanks, Mike
     

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