427 bbc?

[79centurion]

Can I make a 427 out of a 454? The 396 in my boat has crower crank and rods, so I would like to reuse them. Is there a custom piston I need, or does a .060 427 piston work? I have a .060 454 block. I want to be able to cuise at high rpms and not worry like I do with my 396.
Dan

[SmokinLowriderSS]

As far as making it, put your 396 crank in it. All use the same rods, use 396/427 pistons.
396- - 4.094x3.760 stroke
427- - 4.250x3.760 stroke
454- - 4.251x4.000 stroke
As far as high-rpm running, orriginal factory rev limits were the exact same for the 396 & 427 Mk-IV, the 454 was about 500 RPM lower (due to the heavier larger-bore parts whinging back & forth and arround and arround). Kind of pointles to go to 427 just "to spin it high RPM all day long" when the 396 will do it just the same. There are some HP gains to be made tho from the increased displacement. 'Course, if you have the rest of the 454, why cut yourself in half? Take all the displacement and power gains and balance it to spin like mad.
My $0.02

[fc-pilot]

Go for it. A 427 is the bore of a 454 with the stroke of a 396 (in theory). Granted the 427 did come before the 454, but that is the combo. I would make sure to check the length of the rods that you have. Many aftermarket rods are longer than standard so that is one thing to think about. Finding pistons should not be a problem at all. Having a factory stroke with a factory block I don't see any problem. You just need to know the rod length and go from there. It should be a stout piece when done.
Paul

[79centurion]

I have a complete 454, but it has a stock cast crank. The 396 has a good steel crank, so I though that would be the way to go to save some money.
Dan

[WannabeRacing]

If you have a crower crank and rods, use them! Check the rod length like FC stated. Then order pistons to what it is.
Should run forever.

[ECeptor]

I have a complete 454, but it has a stock cast crank.
Dan
Rumor has it the stock 454 cast crank is good to 6,000rpm. How high are you going?

[79centurion]

Mine pulls to 5,000 rpms right now, but I cruise around 4,000 rpms. My 396 is good for about 6800 rpms. When I do this I am going to add more hp, so I am sure the rpms will go up. I just dont trust a stock crank at 4,000 rpms for a long period of time. I am sure it can hold up, but since I have a good crower crank, I would rather use it.
Dan

[lilrick]

"no replacement for displacement" ....:D

[ECeptor]

Mine pulls to 5,000 rpms right now, but I cruise around 4,000 rpms. My 396 is good for about 6800 rpms. When I do this I am going to add more hp, so I am sure the rpms will go up. I just dont trust a stock crank at 4,000 rpms for a long period of time. I am sure it can hold up, but since I have a good crower crank, I would rather use it.
Dan
There are 1000's of 330hp 454 Mercs out there that will turn 4,000rpm hour after hour and their cast cranks are good to go. I won't shy away from it for that reason.
I was just thinking the extra inches would be worth it, imho.

[lilrick]

is your 454 block a two or four bolt main?

[79centurion]

Its a 2 bolt main. The block is a 73 hi perf. block
Dan

[lilrick]

,i wouldn't worry about forged verses cast cranks at this point. Depending on the potential Hp of this mill, All parts must be considered. There are limitations on every part of the engine, including 2-bolt mains. Unless this is an all out race deal' I would consider thecubic inches over the forged deal. It's better to make your torque down low verses higher RPM's. just my.02

[SmokinLowriderSS]

I have a complete 454, but it has a stock cast crank. The 396 has a good steel crank, so I though that would be the way to go to save some money.
Dan
Unless you are going to try to spin it 6k mile after mile, run that cast crank.
Unless you figure to approach 600HP steady, NA, run that cast crank.
I have a 78 Hi perf 454, 2-bolt main, used to be nominally 330 HP, ran 4,850 RPM for 27 years, for MILES at a time. Used to digest another 75HP Nitrous spinning 5200 for fairly lengthy bursts (up to 30 seconds), never was a problem.
It's on a budget-limited upgrade plan, now turning an honest 400HP, 5000 RPM, and not a problem. A local racing engine shop has been on my consultation stops (including upcoming head work) and they have zero concerns with me digging 500+ NA HP out of it, another 100 nitroused, spinning below 6-grand max. If I wanted to run her above that, they tell me the story changes. That cast BBC crank is damn strong, as long as you aren't wanting to wind it to the moon, and 5-grand isn't that far.
It's all up to you tho.

[fc-pilot]

If you plan on spinning the bigger RPM's I would go with the crower crank (just my opinion). I also would have your block converted to four bolt mains also. Spinning those RPM's is often a little more than the two bolt blocks like to deal with. You often times see odd wear on the bearings if you try to get away with it. For nothing else it is good insurance and would allow for things like juice in the future. It is your deal so go with what you feel comfortable with. Just remember, safety first.
Paul