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BBC head gasket bores

  
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BBC head gasket bores

 
jumbo2 jumbo2
New User | Posts: 1 | Joined: 10/12
Posted: 10/15/12
08:46 PM

Picked up some felpro's to assemble my 454 .030 over , the bores are not round and I cant figure out why ? I see copper head gaskets come with round bores ? maybe someone has a part number for round felpros ?

thanks  

pepsi1 pepsi1
Guru | Posts: 1718 | Joined: 09/11
Posted: 10/16/12
03:22 AM

It's possible you did not order the correct Gaskets for the bore size. As you can see the bore increases so the gasket size should also increase.
On the following post I have the Engine sizes versus the bore dia. and stroke.
This is only for the 454 engine size... Grin  Cool  

454 Stock Bore is 4.250
           Over/Bore              Finised/Bore
454          .030                    4.280
454          .060                    4.310
454          .090                    4.340
454          .100                    4.350
454          .125                    4.375

I hope this helps..... Grin  Cool

Bob  

pepsi1 pepsi1
Guru | Posts: 1718 | Joined: 09/11
Posted: 10/16/12
03:32 AM

Jumbo2 I hope this helps. Most big blocks have eye brows cut in the block for valve relief. Grin  Cool

Engine/Size        Stock/Bore        .060/Over            Stock/Stroke
   396                    4.094              4.154                 3.760
   402                    4.125              4.185                 3.760
   427                    4.250              4.310                 3.760
   454                    4.250              4.310                 4.000
   502                    4.468              4.530                 4.000

Bob  

pepsi1 pepsi1
Guru | Posts: 1718 | Joined: 09/11
Posted: 10/16/12
03:53 AM

To Calulate Engine Displacment of an Eight Clyinder Engine
Bore X Bore X Stroke X 6.2832

Bob  

pepsi1 pepsi1
Guru | Posts: 1718 | Joined: 09/11
Posted: 10/16/12
03:56 AM

jumbo2 Welcome to CHP:

Bob  

68scott385 68scott385
Guru | Posts: 1990 | Joined: 10/09
Posted: 10/16/12
06:43 AM

stock GenVI gasket bores aren't round either

could it be to clear the valves as they open on skewed angles from each other?  
68scott385 68scott385 68scott385

Dave632 Dave632
Addict | Posts: 2218 | Joined: 07/08
Posted: 10/17/12
08:41 PM

I used to grind the block where the intake valve opened into the combustion chamber. There was a slight interference there where the head met the block so I tried to smooth out the air flow there. This may not happen with bigger bores. I did not have to do that on my 4.6 bore blocks.
This may be the reason some gaskets are not round. They may allow extra room near the valves.  
[[SUPPORT AMERICAN CARS, STOMP A RICE CAR TODAY.]]

skyeking skyeking
Addict | Posts: 2738 | Joined: 08/09
Posted: 10/18/12
04:31 PM

Laugh Hi Bob,
 for 301.44 [ 302] Chevy
 Try 4v4 x .7854...12.56x3 x 8 = Grin  Grin  Grin  
skyeking

skyeking skyeking
Addict | Posts: 2738 | Joined: 08/09
Posted: 10/18/12
04:37 PM

Try 301.5196..  
skyeking

pepsi1 pepsi1
Guru | Posts: 1718 | Joined: 09/11
Posted: 10/18/12
05:09 PM

Your absoloutly correct Dave.With a 4.6" bore you can put your head in it...LOL...
  When guys open those up for the first time they get a suprise. It's amazing as to what you can do with that bore, before you ever hit water?
  The canted valves and the flow has to go against anything we know about air flow, turbulence!
  Some machinists are afraid to deburr a small block at the deck area before they put the piston rings in the bores. Those burrs can break a Piston Ring, and Scuff a piston skirt if it's not done. I take a die grinder to it and put a good leading edge on it. It really needs a good bevel.

Bob  

pepsi1 pepsi1
Guru | Posts: 1718 | Joined: 09/11
Posted: 10/18/12
05:13 PM

Icon Quoteskyeking:
Try 301.5196..

Noel:
You better not be telling me I've been using the numbers...LOL... Confused
That number should follow suit as long as you know the bore size... Grin  Cool

Are you going to Aloha Country?

Bob  

pepsi1 pepsi1
Guru | Posts: 1718 | Joined: 09/11
Posted: 10/18/12
05:34 PM

Icon Quoteskyeking:
Try 301.5196..

Icon Quotepepsi1:
Noel:
You better not be telling me I've been using the numbers...LOL... Confused
That number should follow suit as long as you know the bore size... Grin  Cool

Are you going to Aloha Country?

Bob


Noel
Your using 1/2 the diamention we normally use...ALOHA...NOEL...

Bob  

redneckjoe69 redneckjoe69
Addict | Posts: 2337 | Joined: 03/10
Posted: 10/18/12
05:59 PM

perhaps our aussie neighbor is useing the cricket,...i mean metric system? lol.
  3 crickets is about a big block, Noel?    Grin

   all the best, hope your doing well buddy!
                           hows the jag running these days?  

redneckjoe69 redneckjoe69
Addict | Posts: 2337 | Joined: 03/10
Posted: 10/18/12
06:05 PM

perhaps our aussie neighbor is useing the cricket,...i mean metric system? lol.
  3 crickets is about a big block, Noel?    Grin

   all the best, hope your doing well buddy!
                           hows the jag running these days?  

Dave632 Dave632
Addict | Posts: 2218 | Joined: 07/08
Posted: 10/18/12
07:20 PM

Icon Quotepepsi1:
Your absoloutly correct Dave.With a 4.6" bore you can put your head in it...LOL...
  When guys open those up for the first time they get a suprise. It's amazing as to what you can do with that bore, before you ever hit water?
  The canted valves and the flow has to go against anything we know about air flow, turbulence!
  Some machinists are afraid to deburr a small block at the deck area before they put the piston rings in the bores. Those burrs can break a Piston Ring, and Scuff a piston skirt if it's not done. I take a die grinder to it and put a good leading edge on it. It really needs a good bevel.

Bob


With the Dart big M they claimed you had .250 left with a 4.6 bore.
The other block I had was a Keith Black which used sleeves. Those sleeves were so hard you could not bore them you had to replace the sleeves if you wanted a bigger bore. On the + side they did not seem to wear much as there was no taper.  
[[SUPPORT AMERICAN CARS, STOMP A RICE CAR TODAY.]]

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