Stock block, largest stroke recommended

[liljohn2724]

I have a 1977 Motor home block that has a 4.25 stroke. I have broken a valve on my Edelbrock victor max wedge head. I will need pistons and was thinking about changing to a 4.50 stroke crank. I have replaced the caps to billet caps and I will need to go to .055 over. I would love to go to a new block but it is not in the finances, 5100 is a lot of money for cast block. My Coronet weighs 3300 lbs and has been back halved with ladder bar and a 9 inch. I will be running 15:1 compression and full roller cam. Is this a good idea? Or should I save and go with a Callies block? What are your thoughts.

 

[493 Mike]

How much power are you aiming for? Is this race only?
Mike

 

[Hemirunner]

I have a 1977 Motor home block that has a 4.25 stroke. I have broken a valve on my Edelbrock victor max wedge head. I will need pistons and was thinking about changing to a 4.50 stroke crank. I have replaced the caps to billet caps and I will need to go to .055 over. I would love to go to a new block but it is not in the finances, 5100 is a lot of money for cast block. My Coronet weighs 3300 lbs and has been back halved with ladder bar and a 9 inch. I will be running 15:1 compression and full roller cam. Is this a good idea? Or should I save and go with a Callies block? What are your thoughts.

A stock block will take a 4.500 stroke combo, but in a race application and at the power level you’re planning, failure is highly likely. I’d save for an aftermarket block.

 

[33 IMP]

I'm gonna use a 4 3/8, with a girdle in a stock block, but I've got a 4.625 crank in the closet.
I think a 543 is reallypushing it in a 15 to 1 race application with a stock block. I would be tempted to put together a lightweight 4.25 crank combo, use the stock block, and then either use the saved money on cylinder heads, or continue saving for a good block. You have a light car for a b-body, for the small premium over a callies, I would consider indy aluminum.

 

[HEMI-ITIS]

Don't gamble with the good parts you have and go to an aftermarket block!

 

[liljohn2724]

How much power are you aiming for? Is this race only?
Mike

Yes it is a race only car. I am trying to make the most power available with the parts I have. My 512 motor made 680 to the rear wheels.

 

[33 IMP]

If you are making that power with a 512, I think you will be disappointed with the expense/power increase of going to a 543.

 

[oldkimmer]

I’m building a stock block 543 with just over 11-1 compression. .625 lift solid roller. 1.6 rockers. Max wedge ported Indy SRs. Super Victor intake and a 1250 Dominator. Should only have to twist it to 6500. U will need to notch the bottom of the cylinders and grind clearance at the oil pick up boss. Plug the hole and run external oiling. I’m gonna run the Milodon single line system. Hope this helps u make a decision. Kim

 

[Cojohnso1]

I have have never seen a 4.5" stroke RB block in the wild. What rod were you considering?

 

[oldkimmer]

Mine is 7.100 rods. Kim

 

[33 IMP]

Im using 7.1 BBC rods in my 4 3/8 combo too. The whole build is built around using pistons I got dirt cheap. Yeah, really stupid, I know!

 

[Cojohnso1]

Damn. Those pistons must be like pancakes. (Assuming you not above the hole?) I run 6.7 rod with RB 3.75 crank in my 451 to very near 0 deck. (Block was not decked. So I'm sure there is some discretion and variation.) I know it's a B short deck. But the Ross pistons are definitely lower profile. With 4.5 on a 7.1 rod? Doesn't leave alot of profile room? Would love to see a pic of piston/rod combo?

 

[33 IMP]

I think Kim's setup is for a rb block. Mine definitely is. Dished piston, and the pin isnt even in the oil ring .

 

[Hemirunner]

Damn. Those pistons must be like pancakes. (Assuming you not above the hole?) I run 6.7 rod with RB 3.75 crank in my 451 to very near 0 deck. (Block was not decked. So I'm sure there is some discretion and variation.) I know it's a B short deck. But the Ross pistons are definitely lower profile. With 4.5 on a 7.1 rod? Doesn't leave alot of profile room? Would love to see a pic of piston/rod combo?

They’re typically 1.32 to 1.35 CH. plenty to not have the rings in the pin bore. Some of the SBC and BBC stroker stuff is 1.10 CH.

 

[oldkimmer]

I think Kim's setup is for a rb block. Mine definitely is. Dished piston, and the pin isnt even in the oil ring .

Mine are for a RB block. The oil ring is in the pin. Which in reality is a non issue. The first and 4th pics are the 543 piston. The 2 and 3 pics are a 505 piston. The 543 uses a 7.1 rod with the 4.5 crank. The 505 uses a 6.8 rod and 4.25 crank. Kim

 

[dvw]

My oil ring is below the pin. 4.50" stroke, 7.10" rod. Previously it ran BME aluminum 7.15" rod. The pin was below the oil ring as well.
Doug

 

[Hemirunner]

My oil ring is below the pin. 4.50" stroke, 7.10" rod. Previously it ran BME aluminum 7.15" rod. The pin was below the oil ring as well.
Doug

Good application for pin buttons. I’m definitely gonna be using pin buttons in my next one.

 

[oldkimmer]

So I would imagine pin buttons will throw the balance out. I think I have heard of them but I forgot about them. Where would I find them? Thanks. Kim

 

[polyjohn]

Hi Little John,

(512ci motor in a street car 'at 600hp' in avatar)

I am medium sized John and we did the 543ci when it first came out in the early 2000's.
Piston slap if is the biggest problem with the 'short skirted' pistons!
Then there is the external oil-feed issue with the bigger than 4.250 crank.

But most of all was the ''CAP-WALK'' of the big strokers.
The 2 bolt caps just aren't up to the job and over 600hp they is POOR at best!

So we did some 'program cap' conversions and it worked very well indeed...
But the mis-informed and bias arguments has turned folks away from them???

I hear all the time folks saying ''its gonna be fine'' NO ITS NOT!!!

Unless you use very high octane and tune to the MAX, its gonna bash the CAPS!!! like this...

 

[Hemirunner]

So I would imagine pin buttons will throw the balance out. I think I have heard of them but I forgot about them. Where would I find them? Thanks. Kim

No, they’re specific to a custom piston. You have to order them with the pistons and they’re accounted for in the piston weight when balancing.