Mk4 or Gen 6 BBC?
Thread Starter
Burning Brakes
Joined: Apr 2002
Posts: 1,105
Likes: 114
From: Lawrenceburg, KY
Mk4 or Gen 6 BBC?
I'm starting to look for a BBC to toss into my SBC 79. This is going to be a temporary engine (just something to get the vehicle running) while I keep working on other parts of the vehicle. If I try to "build" the BBC I'd like, I'd be several years getting anything done. So this is a stop gap to keep moving in the right direction.
I'm running a Holley Sniper Stealth fuel injection and in-tank fuel pump, so I don't need the mechanical fuel pump boss on the block.
A number of the local wrecking yards have both Mk4 and Gen 6 BBCs available, so I need to figure out what I go with. I'm inclined towards the Gen 6 because:
Is there a reason I should go with the Mk4 engine? I have to buy a new flywheel (since my car was an automatic and I'm swapping in a T56), so this is entirely blank slate.
I'm running a Holley Sniper Stealth fuel injection and in-tank fuel pump, so I don't need the mechanical fuel pump boss on the block.
A number of the local wrecking yards have both Mk4 and Gen 6 BBCs available, so I need to figure out what I go with. I'm inclined towards the Gen 6 because:
- it's a roller lifter block
- 9:1 CR
- 1 piece rear main seal
Is there a reason I should go with the Mk4 engine? I have to buy a new flywheel (since my car was an automatic and I'm swapping in a T56), so this is entirely blank slate.
Last edited by ChrisLSx; Jan 19, 2021 at 09:43 PM.
Le Mans Master
Joined: Apr 2001
Posts: 5,941
Likes: 281
From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
I'm starting to look for a BBC to toss into my SBC 79. This is going to be a temporary engine (just something to get the vehicle running) while I keep working on other parts of the vehicle. If I try to "build" the BBC I'd like, I'd be several years getting anything done. So this is a stop gap to keep moving in the right direction.
A number of the local wrecking yards have both Mk4 and Gen 6 BBCs available, so I need to figure out what I go with. I'm inclined towards the Gen 6 because:
Is there a reason I should go with the Mk4 engine? I have to buy a new flywheel (since my car was an automatic and I'm swapping in a T56), so this is entirely blank slate.
A number of the local wrecking yards have both Mk4 and Gen 6 BBCs available, so I need to figure out what I go with. I'm inclined towards the Gen 6 because:
- it's a roller lifter block
- 9:1 CR
- 1 piece rear main seal
Is there a reason I should go with the Mk4 engine? I have to buy a new flywheel (since my car was an automatic and I'm swapping in a T56), so this is entirely blank slate.
plan on using an electric pump that is no issue.
as for the roller cam, mark 4 blocks are easy to add it. The screws are in the block for a stepped nose cam. You just need link bar lifters.
Thread Starter
Burning Brakes
Joined: Apr 2002
Posts: 1,105
Likes: 114
From: Lawrenceburg, KY
the biggest concern would be lack of a fuel pump boss on the gen 6 blocks. If you
plan on using an electric pump that is no issue.
as for the roller cam, mark 4 blocks are easy to add it. The screws are in the block for a stepped nose cam. You just need link bar lifters.
plan on using an electric pump that is no issue.
as for the roller cam, mark 4 blocks are easy to add it. The screws are in the block for a stepped nose cam. You just need link bar lifters.
I realize I can always convert a mk4 to a roller cam.
Drifting
Joined: Aug 2004
Posts: 1,883
Likes: 124
From: Lubbock TX
Gen 6 is also priority main oiling and every one has 4-bolt mains. Easy cam retention and OEM lifters to about .625" or so lift. To me, it's a no-brainer. I only have a half dozen or so stacked in the corner and I grab every one that comes up at a reasonable price. Oh, and if you fall in love with a 1-piece RMS crankshaft, a $100 adapter lets you use it in a Gen 6 block. Can't go the other way.
Thread Starter
Burning Brakes
Joined: Apr 2002
Posts: 1,105
Likes: 114
From: Lawrenceburg, KY
Thread Starter
Burning Brakes
Joined: Apr 2002
Posts: 1,105
Likes: 114
From: Lawrenceburg, KY
Gen 6 is also priority main oiling and every one has 4-bolt mains. Easy cam retention and OEM lifters to about .625" or so lift. To me, it's a no-brainer. I only have a half dozen or so stacked in the corner and I grab every one that comes up at a reasonable price. Oh, and if you fall in love with a 1-piece RMS crankshaft, a $100 adapter lets you use it in a Gen 6 block. Can't go the other way.
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Race Director
Joined: Jun 2000
Posts: 10,046
Likes: 675
From: FL
Gen 6 all day. This coming from a guy who has a 496 based on a MkIV block. The fuel pump and clutch stud drove my thinking but now I am running EFI and could easily swap to a hydraulic T/O bearing. I have been living with a small but annoying rear main seal leak for about 5 years now. Would love to have the one-piece RMS.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
If starting from scratch the Gen6 is the better choice because of the main seal......but remember these blocks when running ANY aftermarket head will require the right head gasket:
https://sdparts.com/i-21078748-victo...mk4-heads.html
The Victor Reinz gasket is excellent......as is the Fel Pro which I believe is part # 1047
Jebby
https://sdparts.com/i-21078748-victo...mk4-heads.html
The Victor Reinz gasket is excellent......as is the Fel Pro which I believe is part # 1047
Jebby
Thread Starter
Burning Brakes
Joined: Apr 2002
Posts: 1,105
Likes: 114
From: Lawrenceburg, KY
If starting from scratch the Gen6 is the better choice because of the main seal......but remember these blocks when running ANY aftermarket head will require the right head gasket:
https://sdparts.com/i-21078748-victo...mk4-heads.html
The Victor Reinz gasket is excellent......as is the Fel Pro which I believe is part # 1047
Jebby
https://sdparts.com/i-21078748-victo...mk4-heads.html
The Victor Reinz gasket is excellent......as is the Fel Pro which I believe is part # 1047
Jebby
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Unless you are using over 400 shot of nitrous....or 12-13 psi boost....MLS gaskets are unnecessary. At $100 a side.....it is something to consider.
Jebby