SBF question ?

I have a .040 bore 69 block that I plan on building for my mustang to 427 cubic in. 13.5:1 compression turn 7500 rpm
My question is should I run a main girdle or 4 bolt main caps ?

Block work is already done less main caps and plan on changing and having all screw in freeze plugs and oil plugs as well.

Just a shot in the dark with the information you post, compression and engine speed will be the deciding factor.

Dave.

LivermoreDave wrote:Just a shot in the dark with the information you post, compression and engine speed will be the deciding factor.

Dave.

I thought about that after I posted it ! I will edit it.

13.5:1 solid roller cam 7500 rpm

Using a C9 block as you mention, main caps may be the better choice. At the stated compression ratio and engine speed you mention, frequent bearing fatigue may be a problem. Too, the main webbing of a C9 block may fail at those levels. It sounds as if you are planing a full race engine. Why not begin your project with an engine block designed for such stress?

Dave.

LivermoreDave wrote:Using a C9 block as you mention, main caps may be the better choice. At the stated compression ratio and engine speed you mention, frequent bearing fatigue may be a problem. Too, the main webbing of a C9 block may fail at those levels. It sounds as if you are planing a full race engine. Why not begin your project with an engine block designed for such stress?

Dave.

I thought about it but already had this block machined . The other reason is I have to many projects going and was trying to put together the parts I had setting around allready paid for. I Have a big block going in a 64 fairlane and a full blown restoration going on my 68 torino that I drove in High School. anyway I figure that a 427 13.5:1 would only be around 700 flywheel hp and this being a 69 block out of a boat would be ok at that level of HP.

In closing may I wish your project well.

Dave.

LivermoreDave wrote:In closing may I wish your project well.

Dave.

Thanks for your help and input. I may just save my pennies and get a aftermkt block

whitefield wrote:

LivermoreDave wrote:Just a shot in the dark with the information you post, compression and engine speed will be the deciding factor.

Dave.

I thought about that after I posted it ! I will edit it.

13.5:1 solid roller cam 7500 rpm

Use a better block at the start. If you make any kind of 427 type power ... you'll break it.

W/that block imo the main caps will not be the downside.It will be the block strength between the lifters. Those blocks are notorious for splitting @high HP,right down the center between the lifter bores.

dfree383 wrote:Rick I think your thinking about the 5.0 Roller blocks.

the 351W stuff is decent, but not the best choice at 700hp.

Dave Whats the most power you have made reliably with a 351W ?

dfree383 wrote:Rick I think your thinking about the 5.0 Roller blocks.

the 351W stuff is decent, but not the best choice at 700hp.

While I haven't split any 351 blocks down the middle, one of my 408" dirt motors did crack ALL the main webs out of it..
But it was a mid- 80's block..
At 700hp..it's not IF it will let go.. just WHEN it will let go.

https://www.429-460.com/t15185-m-6010-c58-frpp-racing-block-1200


Lots better than the stock block.

dfree383 wrote:I've never built a max effort 351W, mostly street stuff, Biggest one was a 420" 10:1 stroker with dart heads for a guy in Washington, never had it dyno'd, but It did run great.

I've had Cleveland stuff in the 500hp range years ago and a number of 347's with factory HO blocks in the same range, never had an issue with spliting blocks.

This is just me thinking out loud I was thinking a N/A engine of this size would handle around 800 hp at 7500 rpm!

my 351 base small block was 688 hp as a 393 with 2 years racing till an eagle/arp rod bolt ended its life. the main girdle prevented the rod from coming out of the block with very minor oil leakage.

dfree383 wrote:Rick I think your thinking about the 5.0 Roller blocks.

the 351W stuff is decent, but not the best choice at 700hp.

A friend of mine split a 408 windsor(70 block) w/lifter galley brace,right down the middle.

I think with any engine a bunch of whether it will survive or not is in the tune. My little 14:1 357 went 8200 a bunch of times and the bearings looked good upon teardown before I sold it. Just a early 70's block and crank. Paid attention to the machine work, clearances, balancing and the line bore and kept a good tune on it. I didn't feel comfortable with the 2 bolt caps on it though...

jbozzelle wrote:I think with any engine a bunch of whether it will survive or not is in the tune. My little 14:1 357 went 8200 a bunch of times and the bearings looked good upon teardown before I sold it. Just a early 70's block and crank. Paid attention to the machine work, clearances, balancing and the line bore and kept a good tune on it. I didn't feel comfortable with the 2 bolt caps on it though...

I figured that a good tune with no power adders it might be ok !
I would really like to know which or if the girdle or main caps would be the better route to go.?

dont do it. it may live 500 passes or one dyno pull you never know. there are cheap sbf stuff floating around everywhere. just pick up an old cup block or used dart or frpp block. heck at that power level the man o war block would be fine but that is a lot of cylinder pressure and lots of stuff moving around in a weak factory block.

we run drysump blocks from Roush but they are 9.2 deck or lower.


but to answer you last question. Neither will help much.

Think you need to consider how much more money you will be spending on the 4 bolt mains (and yes that would be the way to go), screw in core plugs, etc... vs selling the block and putting the money in a good block. One thing I don't like is your block is at .040" over. I'd want a sonic check before putting any more money in it to see just what the wall thinkness is.

I'd agree the tune up matters and you likely can make it live if you are careful, but still is a crap shoot IMO.

On the subject of windsor blocks who makes this one?

http://www.racingjunk.com/Blocks/2723215/FORD-PRO-RACE-4-BOLT-MAIN-BLOCK-COPY-of-DART-.html

The ad is so vague that it reads like an ebay pro comp ad. lol