Big block chevy main bore

[1961BelAir427]

Another question for all you experts: What, if any is the down side to having a W block align bored to the Mark IV main journal size? Does it significantly weaken the block? If I were going to 4 bolt caps and a stroker would this be a good way to go?
Does a 397/427/454 crank drop right in then or do the counter weights have to be trimmed down to fit in the block? I know there are timing covers made with the bbc crank seal opening. I guess it would effect the timing set used too. Haven't looked into that.
I read where someone said they were thinking of going to the big main size, going to BBC 4 bolt mains on the center 3 caps and keeping the stock 409 caps at the front and back. Never read whether they actually did it or if it was a bad idea.
Thank You in advance. I really appreciate all the great information shared on this site. I can't compensate any individual for the insight you share, but I will make sure to help support our forum when I can....and encourage everyone who hasn't ever donated to step up.
Jason

 

[Ronnie Russell]

Jason, I have in my shop a 409 + .030 , bbc main size with 4 bolt caps (3) Probably needs to go to +.040=.060. Needs one sleeve. I think the owner still has the timing gear set and timing cover for it. I can ask the owner if he wants to sell if you are interested. Oh, and yes, the bbc counterweights need to be reduced to fit the block. The 454 GM crank from this engine is also available but needs one journal repaired. My machinist recommended Diamond cams for the crank repair or maybe you have somebody who could do it.

 

[Ronnie Russell]

Diamond cam ??????? too much medication. Bullet cam company

 

[1961BelAir427]

Ronnie, I posted this question after reading that Jim had some cap walk on his stroker in the Phantom 409 a few years back. I have never had trouble with a 2 bolt block even at 7800 RPM, but I've never build a 409 either so I wasn't sure what I'd need.
Found this post of yours in an old thread: "Hooley, We run 6.10s 1/8 = 9.60s 1/4 e.t.s with 2 bolt mains. Would I like to have 4 bolt mains?? You bet. But since we have had no failures, it just does not seem cost efficient to use the 4 bolt main mod."
I guess maybe I don't need to worry too much about it and just stick with the plan to use the 2 bolt caps with ARP studs.

I'd just thought that if I was going to build a stroker AND go to 4 bolt caps, then why not go ahead and go to the bbc main size? Timing cover is the same price, I already have 3.766" and 4" cranks, and the caps are easier to find for a bbc with aftermarket center 3 around the $100 range for quality parts.

I would be interested in the block and parts IF I hadn't just made a deal for a 63 or 64 passenger block. I haven't gotten the suffix code off the pad yet, but it had HP heads on it and 2x4's. The heads are gone. Seller had bought the whole engine just to put the heads on his '62. Pics are in the "Race Engine Planning" thread. For my planned build would I be better off with a truck block with the notch to clear high lift? If I stick with the passenger block will I have to grind a notch into it? Thinking about this cam: 265*I/270*E dur@.050" - .680" (1.7:1) Lift 110* LSA - possibly with 1.8:1 rockers later which would give .720" gross lift.
From what I've seen HP blocks sell for I might be able to get a truck block and the machine work done plus it might help someone looking for certain numbers/date code.

 

[1958 delivery]

Diamond cam ??????? too much medication. Bullet cam company

Too many Lone Stars, if you ask me

 

[Ronnie Russell]

 

[Ronnie Russell]

Rule of thumb--- .650 lift for passenger block and .735 for truck block. Isky makes a fly cut tool you can use to cut a notch in the pass car block.

 

[Ronnie Russell]

Mike, a few years ago , you would have been correct. Can't drink anymore because of damn medication. Old age is hell.

 

[1961BelAir427]

Sorry to ask a dumb question, but is the following correct? That picture looks like: I'll be alright with the car block with just adding a small notch and should have more compression with it vs. the truck block.

Edit: Typed this between the picture and your other post.

 

[Ronnie Russell]

Yes

 

[1958 delivery]

Mike, a few years ago , you would have been correct. Can't drink anymore because of damn medication. Old age is hell.

Damn, I refuse to get old.

 

[1961BelAir427]

That required notch looks like it would only be about 2 or 3 cc's. I bet the truck notch is at least 10 cc's from looking at pictures. I tried searching for the size and couldn't find it. That should really help make it easier to reach my 13:1 goal.

 

[Skip FIx]

I cc'd my block and had the results here when I built mine. Mock it up and check your valve to block clearance to know for sure. Ronnie has built watymore than me but I think mine was getting close before .600.'65 passenger block and Edelebrock heads. I also used the larger Isky cutter than the valve head to be sure I had radial clearance also, in case I ever add larger valves or a bigger cam.

I looked hard at adding 4 bolt caps but where the outer bolts go there is not that much meat in the main saddles and I felt it might even weaken the block some. Went with studs.

 

[jr.W]

The 2 bolt vs 4 bolt debate has gone on with sbc's also.
What it comes down to is not so much the extra bolts to stop the cap walk but
the extra surface area or the wider cap.
So maybe what is needed is a wider cap that still uses 2 studs?

Quote
(In regards to rats I agree completely but this post was referring to small blocks, not rats & you cannot begin to compare the two in regards to the lower end.
A rat has registers & caps that are both longer & wider then a small block.
It is not the number of bolts, it is the clamping force & area involved that controls weather or not the caps are going to move under a certain load.
A rat & a small block are apples & oranges when you look at the clamping forces on the main caps.
You are talking about 1/2" bolts that are torqued to 100 lbs with about twice the surface area of a small block with 7/16" bolts
I agree completely that a rat can be built to handle a lot of power in a two bolt block,, I have done it many times but a small block is a different animal

I do think 350HP is a little conservative but there are other factors, especially rpm involved.
I have done a lot of honest 400-425 street small blocks with studded two bolts but that in my opinion is about the limit & is probably stretching it in a 350.
A 400 is a little different as it has a lot more surface area to work with because of the larger caps but also has more load at a given rpm due in part to the longer stroke.)
From here.
http://www.chevelles.com/forums/showthread.php?t=38173
Wolfplace was the driver of the sbc top alcohol dragster from the 80's(the car name was David)

To me the main caps on a w engine are small like a 2 bolt sbc not wide like a 2 bolt bbc.

 

[buildit]

Another question for all you experts: What, if any is the down side to having a W block align bored to the Mark IV main journal size? Does it significantly weaken the block? If I were going to 4 bolt caps and a stroker would this be a good way to go?
Does a 397/427/454 crank drop right in then or do the counter weights have to be trimmed down to fit in the block? I know there are timing covers made with the bbc crank seal opening. I guess it would effect the timing set used too. Haven't looked into that.
I read where someone said they were thinking of going to the big main size, going to BBC 4 bolt mains on the center 3 caps and keeping the stock 409 caps at the front and back. Never read whether they actually did it or if it was a bad idea.
Thank You in advance. I really appreciate all the great information shared on this site. I can't compensate any individual for the insight you share, but I will make sure to help support our forum when I can....and encourage everyone who hasn't ever donated to step up.
Jason

I have built one 476" engine with BBC 4-bolt caps on center three, a narrowed 2-bolt BBC cap on the front (to maintain vertical cross section strength), and enlarged the bore of the stock rear cap, as there is plenty of material for there. Another build, that I can't seem to finish, is 527 ci. All main registers were widened to just under BBC width, with 4-bolt BBC caps in the center three and BBC 2-bolt caps front and rear. After redrilling the pan rails to BBC pattern and fabricating a hybrid front cover (upper 2/3 409, bottom 1/3 BBC), you can use your choice of BBC oil pans. I bought a set of used Milodon splayed bolt BBC center caps recently. Mocked them up on another block and the outer splayed bolt does not interfere with main oil gallery in the left pan rail.