BBC tall deck build up

[prairiehotrodder]

what would be the best way to take advantage of a 427 tall deck buildup? As far as getting the most cubes out of it? 4.375 stroke? Do they have thick cylinder walls? How much over bore will they handle?
thanks
Brian

[pdq67]

Some people say that they will bore .125" over, but I would definitely sonic check to be sure.

Now, as for a crank, again, some people say a 4-5/8" crank will fit but you really have to grind heck out of the bottom end.

Now I figure a 4-3/8" crank should almost drop right in and if not, it probably won't take all that much grinding.

Try these.

4.350" b x 4.375" s = 520.+..

4.375" b x 4.375" s = 526.+..

4.350" s x 4.500" s = 535.+...

4.375" b x 4.625" s = 556.+...

pdq67

[bigjoe1]

I did a few way back when. 060 over was the rule, but I have heard of as big as 100 over--- The ones I did were 4.375 with a 060 overbore---512 inches--- No problems


JOE SHERMAN RACING

[racear2865]

4.375 x 4.375 no problem. whole bunch cuttin for 4.5
reed

[pamotorman]

when you grind for rotating assy clearance watch you don't grind thru the main oil gallery .

[Steve Haaf]

Would a quarter fill of grout help in supporting the cylinder walls and not finding water when grinding for clearance?

[Sweet P]

Some people say that they will bore .125" over, but I would definitely sonic check to be sure.

Now, as for a crank, again, some people say a 4-5/8" crank will fit but you really have to grind heck out of the bottom end.

Now I figure a 4-3/8" crank should almost drop right in and if not, it probably won't take all that much grinding.

Try these.

4.350" b x 4.375" s = 520.+..

4.375" b x 4.375" s = 526.+..

4.350" s x 4.500" s = 535.+...

4.375" b x 4.625" s = 556.+...

pdq67

"4.375" b x 4.625" s = 556.+..." your math is off, this is a 588 but in a production 427 you'll never get to that large of a bore.

.060 over was done to a lot of those blocks, I too heard that guys were going larger.

An acquaintance of ours used steel rods and creative machining to get a 4 3/4" crank to fit, so the story goes.

We ran them with 4 1/2" strokes and alum rods (read big!) and many years ago I did once break into the oil passage but we epoxied it together. I since have slowed down and only machined off what I need to.

[FC-Pilot]

Have done a couple with 4.5 " stroke and would do it again. It does take time to get right and not hit oil. for me it would depend on what parts you might already have, or be able to get a deal on. the 4.375" stroke is what I would probably do if I were starting from scratch as it would provide a little more "insurance" while clearancing the block. I would probably not go crazy on the bore size as it my be nice to bore it again later for a freshen up.

Paul

[RAS]

Congrats on the tall deck block. Back in the early 70s these blocks took a .060 overbore and ran all year long on 86% Nitro. Sometimes 88%. So a .100 over is still safe on gas. Spacers for the intake and an adjustable collar on the distributor and your all set, unless you have one that's made for your engine. I'd go 4 1/4 and .100 0ver. You can always sleeve a cylinder if it's border line. On fuel, these blocks rarely had two cylinders the same bore! Sleeves were common. The block was pretty tough. Never saw Chadwick or Bourgeois hole one. Good luck.

[pdq67]

Per Wallace Racing here --

http://www.wallaceracing.com/cid.php

"Your Engine with bore of 4.375 and stroke of 4.625 is 556.22 CID".

A 588" engine can be a 4.625" b x 4.375" s = 588".

I would really love to build one and just might do it??

He, He!! Before I die.... Just like my next old junk301..

pdq67

[Alan Roehrich]

If you use steel rods and a 2.2" rod journal crank, most of those blocks will accept a 4.5" stroke. At 4.625", as many as maybe 1/2 of them will have problems with the main oil feed gallery, grinding for clearance will often create a leak. Using small block 2.1" rod journals has been done, but the journal overlap is small, or even non existent.