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Technical 6-71 Blown 355. First time start up procedures after sitting for a LONG time?

Discussion in 'The Hokey Ass Message Board' started by Mr. Sinister, Apr 30, 2021.

  1. squirrel
    Joined: Sep 23, 2004
    Posts: 55,942

    squirrel
    Member

    why? It won't make boost until it's under load, and the throttle is open a ways...which doesn't happen during break in.

    the upper pulley looks larger than the lower one, although the photo may not be quite in proportion, so you can't be sure without counting teeth. But that doesn't really matter if you're just breaking it in, it still needs the throttle open a ways to make significant boost, and that means you need to have a it in a car or a dyno to get into boost.

    And having the blower overdriven or underdriven is not what makes it a race or street engine...I've put a whole bunch of miles on a blower with a little bit of overdrive. The more important thing is the ratio of engine size to blower displacement....if the blower is small compared to the engine, you need to overdrive it to get much boost. If it's big, then you need to underdrive to limit boost. The little B&M type blowers are all overdriven about 2:1, because they're so small, and they're street blowers, mostly.
     
  2. Thanks Jim.
    So ultimately it will be just fine breaking in with the blower spinning away. I plan to do it in the car with my good fuel and cooling systems.
    I have not been able to figure out the valvetrain in the engine, but it's an 80-85 4-bolt 350 block. The cam number on the build sheet does not come up as anything. I'll need to put all the gaskets under the blower manifold as it's just sitting on the engine, so I'll figure it out then.
     
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  3. squirrel
    Joined: Sep 23, 2004
    Posts: 55,942

    squirrel
    Member

    Be careful installing the blower, you need to make sure the intake manifold is flat where the blower sits (using a straight edge). Then when you tighten the blower bolts, they take little torque, and follow the tightening pattern a little at a time. Make sure it spins freely after you torque it down, if not, you need to start over, from the "intake must be flat" part.

    BLOWER INSTRUCTIONS.png
     
  4. Thanks again.
    I printed out the manual that would have come with the blower, and have read through it a couple times. I'll probably invest in the aluminum stud kit for the blower. It needs a couple of carb stud kits and some fittings, and I don't think he has a linkage for the carbs either as this was built as a spare engine for a car he sold.
    The builder has a great reputation here locally so I'm pretty confident everything will be fine. I plan to get it installed, all set up and broken in, then have someone put a good street tune on it (6-8 psi I think will be plenty). I've got my N/A combo pretty dialed in, but I'm not going to chance this. My intention is to learn how to tune a boosted combo so I can do it myself in the future.
     
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  5. Hollywood-East
    Joined: Mar 13, 2008
    Posts: 1,993

    Hollywood-East
    Member

    Highly recommend lathe turned valve locks...
    I read the build sheet.
    Most important part of an "econo' blower build!
    Especially in an eng. That's sitting with psi. On the valves for said years...
    Either way a Ben Franklin is a Very cheap insurance policy... Ask me how I Know

    I'm a cheap bastard, ya know stock 882s, no studs/guides, Single "HD" service valve springs, But expensive locks... Broke a spring at 7400 rpm, it Held.. missed/popped like a Bitch, But got me home, Air up cyl., Stuck new spring in.. Done!

    Good Luck, You'll Love it!!
     

    Attached Files:

    Last edited: May 25, 2021
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  6. squirrel
    Joined: Sep 23, 2004
    Posts: 55,942

    squirrel
    Member

    I lost a stock lock on a blown 454 about ten years ago...got really really lucky, damage was minimal...the valve head broke off the stem when I was trying to pull it out of the head. I've used good locks since then.
     
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  7. Good advice. I'll see what's on them when I start digging into it. Nothing is listed but I'd be a little surprised if there were stock locks in there, but I've been surprised before.
     
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  8. Why not put a single 4 barrel intake and break it in unblock?
     
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  9. greybeard360
    Joined: Feb 28, 2008
    Posts: 2,074

    greybeard360
    Member

    • Advance:
      • 2
    • Application:
      • 1955-1995 CHEVROLET 262-400
        ,
      • 1957-86 262-400 1987-94 305/350 NON HYD.ROLLER
    • Brand:
      • Erson Cams
    • Cam Type:
      • HYDRAULIC FLAT TAPPET
    • Duration @ .050:
      • 230/230
    • Duration Advertised:
      • 284/284
    • Gross Lift:
      • .453/.453
    • Lobe Center:
      • 114
    • Make:
      • Chevrolet
    • Part Name:
      • Engine Camshaft
    • RPM Range:
      • 2000-4800
    • Valve Lash:
      • .000/.000
    The new part number is E110042 Erson. Still available from PBM Erson. I have used Erson cams since they were still Sig Erson. Great cams!
     
  10. landseaandair
    Joined: Feb 23, 2009
    Posts: 4,485

    landseaandair
    Member
    from phoenix

    I'd think that cam would be fine even with stock valve locks. Might need more lube on the lifters and lobes if it hasn't been broke in yet and squirt some oil on all the valve stems through the springs. Seen more than one motor that sat for years and was re fired that seized dry guides. Also don't set the blower belt with zero slack cold. Aluminum grows with heat and belt will be extremely tight when warmed up. Usually around 3/4" in or out, 1 1/2" total cold. A little play hot 1/4" in or out, 1/2" total.
     
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  11. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,264

    gimpyshotrods
    ALLIANCE MEMBER

    I would buy the $100 borescope on Amazon, and get a look inside. If you see anything suspect, tear it down and take care of it now.
     
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  12. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,264

    gimpyshotrods
    ALLIANCE MEMBER

    I do not understand the fascination with doing this.

    I have never taken a blower off for a break in, and I am about 40-deep.

    I am building a 354 Hemi with a 6-71 now, for myself, and won't do it on that one, either.
     
  13. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 9,214

    mgtstumpy
    Member

  14. Man this blew up overnight!!
    Thanks to everyone for the input. I'm sure this boat anchor will be fine, but it sure never hurts to be careful!!
     
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  15. The quick and dirty, overfill it with oil so the crank is partially submurged, turn it by hand to pick up some oil on the rod and main bearings, oil the blower and crank it over with the starter with the coil wire out, put the coil wire back, drain the oil, put 5 quarts back in it then fire it up.
     
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  16. AmishMike
    Joined: Mar 27, 2014
    Posts: 968

    AmishMike
    Member

    If rocker arms bolted tight then some valves very open for 15 years. Those valve springs may now be weak. Had similar deal ended up replacing broken valve springs after running and seeing high revs
     
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  17. Baumi
    Joined: Jan 28, 2003
    Posts: 3,043

    Baumi
    ALLIANCE MEMBER

    On your second set of pics of the engine it seems like you actually have two different heads . One has two arrows pointing up, the other a rectangle with one peak on top... I did no research, but I guess both are 76 cc 350 heads with 1.96/1.50 valve from the factory. Just a wild guess, but I think you may have more like 74-76 cc chambers than 64 cc , as the late accessory hole camel humps had.
    Maybe a good thing, you could run more boost , having less static compression with the 350 heads.
     
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  18. Baumi
    Joined: Jan 28, 2003
    Posts: 3,043

    Baumi
    ALLIANCE MEMBER

    Mr. Sinister and loudbang like this.
  19. Both heads have the same markings, there’s a picture of the front and rear markings there.
    They probably are low compression smogger heads, but they’ve had the right work done to them according to the build sheet.


    Sent from my iPhone using H.A.M.B.
     
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  20. Long overdue update:
    Well, my buddy Gene passed last Spring and the engine and all his mountains of other cool shit went to his brother.
    We were working out a schedule for me to do the engine swap at his place, but he had a couple cars he was finishing taking up his shop space. As his health declined, his projects got put on hold. None of it means shit compared to the death of a good friend, but that's how this story finishes.
     
  21. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 2,872

    427 sleeper
    ALLIANCE MEMBER

    Sorry for your loss Brother. It's never easy to lose a friend.
     
    Mr. Sinister likes this.

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