H855cp

Discussion in 'Small Block Tech' started by 72 gs conv ny, Nov 26, 2014.

  1. alec296

    alec296 i need another buick

    Rockers should be fine but many times has someone posted the math on here for the 284 cam and its dynamic compression . 9.4 is low for this cam and will more than likely doggish low end. Consider the 212 cam at this point of go higher on compression. Also consider decking block any was as he might want to go to the aluminum ta heads later on. Deck height is .023 or more over spec to begin with.and opposite side may not even match. Also drill out passage from oil screen to pump in block to 1/2 minimum. Then get the new Melling 5/8 screen. Since motor will see rpm past 4200 with either cam.
     
  2. alec296

    alec296 i need another buick

    72 engines would not normally use steel head gaskets . they also tend to leak if used without refinishing surfaces. Scallop is at top center of head by center head bolt. There will be 2 almost nickel size coolant ports. I don't have a pic right now.
     
  3. alec296

    alec296 i need another buick

    Jim from trishield built a 350 using the 212 cam with 9.6 compression ported big valve heads flowing around 250 I think. With 1 3/4 headers and ported ta dual plane with qjet and made 360 HP and over 400 lbs with a fairly flats torque line meaning it was steady throughout range. So cam has potential and can run higher compression on it as proven.
     
  4. sean Buick 76

    sean Buick 76 Buick Nut

    68-71 were the only years that used the steel head gaskets. The later engines will not work with the steel gasket. 10.5:1 static compression would put the dynamic compression where you want with the 284 cam....
     
  5. TORQUED455

    TORQUED455 Well-Known Member

    I found pictures of the scallops in the heads and can see why the steel gaskets won't work on a scalloped head. Are the blocks the same in that area, 68-81?
     
  6. alec296

    alec296 i need another buick

    Blocks are different but just a support that meets/covers scallops.
     
  7. alec296

    alec296 i need another buick

    If your trying to avoid resurfacing block just go to h522p pistons. They have a compression height of 1.855. .050 taller the standard 8 to 1. I don't know dish since it also has 4 valve reliefs. I have used these pistons on several 350s . one with a 118 cam. Was not impressed. A 310 cam, again disappointed. But with the rv112 and stock 4 barrel manifold had mighty nice low end. I did not like it with the ta manifold.
     
  8. sean Buick 76

    sean Buick 76 Buick Nut

    No, the blocks are different. The 68 and 69 blocks oil through the block to the heads. Some 72 blocks and all 73-80 blocks have the coolant scallops to support the head gaskets. The 73-80 blocks will accept any 68-80 head.
     
  9. TORQUED455

    TORQUED455 Well-Known Member

    Look Ma, no scallops:

    [​IMG]
     
  10. 72 gs conv ny

    72 gs conv ny Where's this part go?

    I told ya it had steel gaskets, wish I would of kept them:Dou:
     
  11. alec296

    alec296 i need another buick

    Yep. There it is. What did you guys land on build and cam choice?. What rear gear and trans/ convertor will you be running? Can get away with Alittle more in engine with 3 series gears and Alittle more stall. Can even make a stock engine more spunky.
     
  12. 72 gs conv ny

    72 gs conv ny Where's this part go?

    Sticking with the 284 and running the 340-30 Pistons and ring set. 3:42 gears on 14" rims. Stock converter but that will be changed. Not sure on the continued machining, .020 off heads maybe??
     
  13. TORQUED455

    TORQUED455 Well-Known Member

    The 284 cam will be fine with the 3.42 gears, 14" tires and stock converter. Stock valve train will be fine with this cam too, all confirmed by a phone call to TA today. For now, unless something changes, Marc will be reusing the stock intake and stock exhaust manifolds. If anything, headers would be a likely next step. Again, shooting for 9.4 static cr, using 340 pistons and steel head gaskets. I'll have a head tomorrow to cc, and once the pistons arrive, I can check the dish volume, get the block back and check the deck cc. With the 284 cam (which I will degree), headers and TA intake eventually, this will be a nice running street engine. Stock plus we will call it. :TU:
     
  14. TORQUED455

    TORQUED455 Well-Known Member

    Oops, treed!
     
  15. TORQUED455

    TORQUED455 Well-Known Member

    Without the scallops, you can order the steel head gaskets from TA, which eliminates the need for taking .020" of the heads, saving more machine costs and pushrod issues
     
  16. alec296

    alec296 i need another buick

    I would consider cleanup on deck of block if you do use steel shim gaskets . they like a fresh surface to seal well. And still suggest milling block atleast .025. Degree cam as it likes Alittle advance. Jegs has an inexpensive convertor for 149 that might work well for you if you can swing it since you have engine out already would be easy to drop in.
     
  17. sean Buick 76

    sean Buick 76 Buick Nut

    I would still try to get 10:1 or better for that cam...

    72 was the cross over year so some engines had the early blocks and some the later.... Thats why we only suggest steel gaskets on the 68-71 engines as the 72 are not all going to accept the steel shim.... I cannot think of a good reason to use the steel over the fel pro ...
     
  18. alec296

    alec296 i need another buick

    Another reason to mill block first then if he needs more compression after its together then he can do mill heads and won't need to take off as much.
     
  19. TORQUED455

    TORQUED455 Well-Known Member

    I think it is a mistake for this all iron build to go over 9.5:1 and risk detonation on pump gas. Making an octane junky of this mild build isn't very useful. The used 70 high compression pistons that Marc purchased, among other things, have the upper shell of the rod bearings pounded out from detonation. We will try to avoid that situation.

    If the block deck isn't good enough, it will be decked just enough to clean it up but I'm pretty sure it will be fine as-is.

    Decking the block .020 just to to use a thicker composite head gasket is pretty stupid in my opinion. Steel head gaskets were used successfully in millions of GM engines of that period and putting back in what came out will work just fine. I used steel head gaskets in my 455 convertible for over 2 decades and now use Cometics, with no problems what so ever. There are a couple of assembly tricks that I use with the steel shim head gaskets to help prevent leaks.
     
  20. alec296

    alec296 i need another buick

    Understandable that you have a plan. Im sure you are going to consider the 212 cam at that compression as previously stated.
     

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