276 or 284

J

Jim

Senior Member
I have the parts, but is the extra 8 CI worth the additional work and expense, just wondering. Jim
 
It depends what the expense is to get only 8 more cubic inches. Would probably compute to less than 4 more HP.(unless super charged or turbo charged).


Sal
 
When someone driving a 4 cyl. car displacing less than one half the cubic inches, blows your doors off, then ask yourself the question.:):D
 
Bore it to 3-5/16" unless your going all out with FR cam, crank (4") trip carbs, etc. That way if later on you need a rebuild you can go to 3-3/8" .
 
I have my doubts that you will see any difference in performance because of the 8 cubic inches. If it's a lot more money for those 8, I would pass on it.
 
Well, you said you had the parts . . . so I don't see a cost issue.

A 276 is a 4" stroke crank with a 3 5/16 bore. A 284 is a 4 1/8" stroke crank with a 3 5/16 bore . . . so the bore is the same on both.

If you already have a 4 1/8" stroke crank and the correct rods, might as well go to 284. Where the complexity/cost can come into play is if you don't have the correct rods/bearings for the smaller journals and also need to offset grind a 4" Merc crank to a small-journal 4 1/8" stroke setup.

You can build a 276" engine with a basic 4" stroke 49-53 Merc crank and use the late 49-53 rods. You'll not need to go the "traditional" 91A/21A rods with full-floating bearings or aftermarket H-beam rods . . . and you won't have to offset grind the crank. A rough guess is that this will save you about $1000.

Now, if you buy an aftermarket 4 1/8" stroker crank and it is setup for the larger journals (49-53 rods), then this is not a bad way to go either (except the cost of the crank and the balancing required). Bearings are super cheap (insert bearings) and you'll not have to fuss with full-floater rod bearing setup/sizing. Most "modern" machine shops have never setup/ran full-floater bearings . . . they have no clue as to what they're all about.

Lots of ways to skin the flathead cat! It usually comes down to time and money . . .

B&S
 
Jim, you worked all of your life to have fun in the retired mode so you need to get "in" the retired mode. When you build flatheads, you spend everything you have coming in, less 10% to live on just like we did back when we were racing for a living.
Get with it. You will like it.....
Think 352 ci 8ba block.
 
Well I guess I misled everyone. I have a 4" crank that wil needl offset grinding but have everything else so I will go with the 284 after all, Thanks to everyone for your response. Jim
 
I went 284 on my rebuild, with a Schneider 248f cam, which has a really strong low end. Running 3.27 rear end and never a doubt about having enough low end torque, even starting on steep hills.
 
The bigger the engine, the lower the RPM for peak power, due to the restrictive port flow, so you have to cam and gear accordingly.
 
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