need some help
+ Reply to Thread
Results 1 to 12 of 12

Thread:
need some help

  1. #1
    Junior Member
    Join Date
    Jun 2011
    Location
    tucson az
    Posts
    6

    Default need some help

    how ya doin folks.....have a few questions about head clearance on a bbc 427...i have a late 60's 427...30 over with speed pro pistons with a .140 dome....i have a mid 80's set of open chamber truck heads ....my question is will these need any work to be used on this motor? im using a comp cams 292h cam and springs.. it looks pretty close but i cant afford to f#$% this motor up...hahahaha...just looking for an answer that a simple mind like myself can understand. this is going in my 74 rogers 18 foot cyclone.....any input would be greatly appreciated. thank you all and have a great season.
    Last edited by cyclone bil; 03-03-2013 at 12:09 PM.

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Some guy obnoxious001's Avatar
    Join Date
    Dec 2007
    Posts
    3,571

    Default

    Quote Originally Posted by cyclone bil View Post
    how ya doin folks.....have a few questions about head clearance on a bbc 427...i have a late 60's 427...30 over with speed pro pistons with a .140 dome....i have a mid 80's set of open chamber truck heads ....my question is will these need any work to be used on this motor? im using a comp cams 292h cam and springs.. it looks pretty close but i cant afford to f#$% this motor up...hahahaha...just looking for an answer that a simple mind like myself can understand. this is going in my 74 rogers 18 foot cyclone.....any input would be greatly appreciated. thank you all and have a great season.
    Did you try fitting the head to the block with no head gasket and make sure there is no interference?

  4. #3
    Junior Member
    Join Date
    Jun 2011
    Location
    tucson az
    Posts
    6

    Default

    not yet...it just looks sketchy....i mean the dome clearly comes over the deck.....and the combustion chamber on the head literally seems to have no space between the valve edge and the head surface....ill be doing that this afternoon...but ive done a little research on the heads and it turns out they are the peanut port heads and they may have been milled a time or two....i think im just gonna try and find a reasonably priced set of heads that still have some combustion chamber left...lol

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    Senior Member 67weiman's Avatar
    Join Date
    Dec 2007
    Location
    Surprise, AZ
    Posts
    985

    Default

    Set the head on and turn it over by hand. You won't hurt anything.

  7. #5
    Some guy obnoxious001's Avatar
    Join Date
    Dec 2007
    Posts
    3,571

    Default

    Quote Originally Posted by cyclone bil View Post
    not yet...it just looks sketchy....i mean the dome clearly comes over the deck.....and the combustion chamber on the head literally seems to have no space between the valve edge and the head surface....ill be doing that this afternoon...but ive done a little research on the heads and it turns out they are the peanut port heads and they may have been milled a time or two....i think im just gonna try and find a reasonably priced set of heads that still have some combustion chamber left...lol
    OK, I read right over the "truck heads" in your first post,, maybe go for some 781 or 049 oval port heads.

    If you do put one of the heads on to check,, make sure to put a couple of bolts in loosely so you don't have a chance of the head falling on the floor.

  8. #6
    gn7
    gn7 is offline
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,975

    Default

    Quote Originally Posted by cyclone bil View Post
    not yet...it just looks sketchy....i mean the dome clearly comes over the deck.....and the combustion chamber on the head literally seems to have no space between the valve edge and the head surface....ill be doing that this afternoon...but ive done a little research on the heads and it turns out they are the peanut port heads and they may have been milled a time or two....i think im just gonna try and find a reasonably priced set of heads that still have some combustion chamber left...lol
    Thats a valve to piston issue, not a head to piston issue. You can mill the heads till you hit water with those pistons and not have a head to piston problem.
    But if they have been milled a couple times, with a cam that long, you could very well have a exhaust valve to piston issue, and possibly even a intake valve cleanance problem. TRWs are not know for overly generous valve clearances, specially on the exhaust side.

    Bolting a ahead on without a gasket will tell you if you have a chamber problem. But sufficient valve clearance? No way!



    100% free webcam site! | Awesome chicks and it is absolutely free! | Watch free live sex cam - easy as 1-2-3

  9. #7
    Junior Member
    Join Date
    Jun 2011
    Location
    tucson az
    Posts
    6

    Default

    Quote Originally Posted by gn7 View Post
    Thats a valve to piston issue, not a head to piston issue. You can mill the heads till you hit water with those pistons and not have a head to piston problem.
    But if they have been milled a couple times, with a cam that long, you could very well have a exhaust valve to piston issue, and possibly even a intake valve cleanance problem. TRWs are not know for overly generous valve clearances, specially on the exhaust side.

    Bolting a ahead on without a gasket will tell you if you have a chamber problem. But sufficient valve clearance? No way!

    ok...i put one of the heads on and turned the crank,,,,,there isnt any interference.....let me ask you this...whats your opinion on using some thick cometic gaskets? pure and simple, i just cant run out and drop a ton of money on some heads at this point.

  10. #8
    Senior Member
    Join Date
    Apr 2012
    Location
    Tucson
    Posts
    127

    Default

    Sounds like you need to check your piston to valve clearance. A lot of YouTube videos if you need help.

  11. #9
    Senior Member
    Join Date
    Dec 2007
    Location
    New Jersey
    Posts
    307

    Default

    Not that I know anything - but won't those heads really choke that engine? The ports are tiny, intended help generate torque at low RPM (from what I have read).

    Doug

  12. #10
    Senior Member 67weiman's Avatar
    Join Date
    Dec 2007
    Location
    Surprise, AZ
    Posts
    985

    Default

    I think the OP is trying to use what he has. I would clay the reliefs, set the heads on with a cheap .041 gasket, a few bolts/ studs in to hold it in place, mock up one cylinder with pushrods and all, rotate the motor over 2 revolutions and if nothing binds, pull it and measure the piston to valve clearance.

    Bil, you NEED to know piston to valve before knowing if a thicker gasket will even work.

  13. #11
    Member
    Join Date
    Jan 2012
    Posts
    30

    Default piston clearance

    Quote Originally Posted by 67weiman View Post
    I think the OP is trying to use what he has. I would clay the reliefs, set the heads on with a cheap .041 gasket, a few bolts/ studs in to hold it in place, mock up one cylinder with pushrods and all, rotate the motor over 2 revolutions and if nothing binds, pull it and measure the piston to valve clearance.

    Bil, you NEED to know piston to valve before knowing if a thicker gasket will even work.
    be sure to use either a light valve test spring or a solid lifter . The hydro lifter can colapse while rotating the engine and checking v to p . Also I have ran into on a 454 L2349 piston would hit the chamber on a 781 or 049 you sure need to check

  14. #12
    Senior Member SoldHondaBoughtHondo's Avatar
    Join Date
    Oct 2009
    Location
    Lake Havasu az.
    Posts
    4,318

    Default

    Have you run that block before? It seems like the deck isn't all that thick on some of those older castings, add a few years worth of lake/river water and the threads for the heads are often times dead
    Just something else to check, pulling threads out of the block is a pia when you are trying to bolt a set of heads on.

    Speed pro uses TRW type forgings? My 427 trw's barely cleared .635 x 260 @ 50..
    "A liberal paradise would be a place where everybody has
    guaranteed employment, free comprehensive healthcare, free
    education, free food, free housing, free clothing, free
    utilities, and only law enforcement has guns. And believe it or
    not, such a place does, indeed, exist: It's called prison."

    Sheriff Joe Arpaio
    Maricopa County Sheriff's Office

+ Reply to Thread

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in

Tags for this Thread

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95