What you should know about the boss big bore blocks...

ChevyKiller

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If you are considering getting the new 'boss' or 'big bore' 4.6 block - you should know a couple things...

First, I have had some people ask me why the block has 2 bolt mains even though it has a set-up for 4. The reason is the people this block was originally made for over a year ago was Sutton Performance. Doug over at Sutton discovered early on that the 4 bolt mains actually weakened the web and caused failure in big hp ranges. They had the block remade with 2 bolt mains and have consistently ran over 1100 hp on it with no problems. This is why the block now comes with 2 bolt mains - because it is actually 'stronger'.

The more interesting thing to note is the block has a big flaw from the factory. The main bearings are oversized and have a tendency to conflict with the crank and cause havoc.

Not to worry, there is a solution and it is to call Calico Coatings company at (704) 483-2202 and ask for Jerry. They make main bearings that are narrowed and coated and work perfect with this block. Price is about $160.00 with a 1-2 day turnaround. They come in standard, x's, and 1 under's. For 99.9% of your builds, the standards will be fine but talk to your builder to be sure.

I also strongly suggest anyone going with this block or any high HP applications on ANY block to consider also shelling out the $139 to MMR for the Billet rear main cover/block support (part #400031). This is a good addition to your block (whatever you have) IMO for all big HP builds.

That is all.

CK
 

US-1

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I figured that's why it was two bolt. The two valve engines I built years ago never showed any signs of main cap walk or bearing chatter even when we went to 800 hp.

Are the main journals too small or too large?
 

andyman

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Don't tell me your putting one in your car....
 

cekim

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I also strongly suggest anyone going with this block or any high HP applications on ANY block to consider also shelling out the $139 to MMR for the Billet rear main cover/block support (part #400031). This is a good addition to your block (whatever you have) IMO for all big HP builds.
Any specifics on that? This is not a load bearing plate. If it is taking load, that is not a good thing. The bolts are too small and too few....

So, why do I need more than the cast/machined plate?
 

ChevyKiller

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Any specifics on that? This is not a load bearing plate. If it is taking load, that is not a good thing. The bolts are too small and too few....

So, why do I need more than the cast/machined plate?

Don't be deceived by the pic. The bolts are actually much stronger than stock. The thickness of the plate gives a lot of extra support to the block. It's definitely a good buy for an aluminum block and not so critical with an iron block but in my case seeking in the 1000 rwhp range, I opted to put it on my iron block as well. I would recommend on an iron over 800 and on an aluminum over 600 IMO.
 

ChevyKiller

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Don't tell me your putting one in your car....

Where have you been?...lol

After all the headaches with the block, the car is finally going back together next week. I have this block stroked to 331ci and have the new whipple 3.4HO blower. The Chevykiller is looking to break some 4.6 records...:clap:

Right now, I am looking at some serious weight shaving. If I can get 300-400 lbs off the car - I think I can see 8's...:samuri:

Vids coming soon...:piano:
 

cekim

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Don't be deceived by the pic. The bolts are actually much stronger than stock. The thickness of the plate gives a lot of extra support to the block.
I was actually looking at the stock plate while I typed that (had it on my desk). The bolts are small. So, while it usually doesn't hurt to "brace" (though not invariably as you found with the 4 bolt mains), the bolts themselves are not large enough to take much load. So, you can stiffen up the plate, but if you have tiy screws holding it in, how does that help?
 

ChevyKiller

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I don't understand what you're asking? The brace comes with new bolts and doesn't use the stock ones? They are a lot bigger/stronger?
 

cekim

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I don't understand what you're asking? The brace comes with new bolts and doesn't use the stock ones? They are a lot bigger/stronger?
Ah, so you have to drill and tap new larger holes?

That's my question/issue - the dinky little bolts (and thus holes) the hold that thing on are not load bearing...

So, unless you drill and tap larger holes, I remain skeptical...
 

tlt05gt

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Thats Enough!

Where have you been?...lol

After all the headaches with the block, the car is finally going back together next week. I have this block stroked to 331ci and have the new whipple 3.4HO blower. The Chevykiller is looking to break some 4.6 records...:clap:

Right now, I am looking at some serious weight shaving. If I can get 300-400 lbs off the car - I think I can see 8's...:samuri:

Vids coming soon...:piano:

Man I wanted to run you this Thursday too.....lol I will just tell myself that I would have won so I feel better.LMAO I cant wait to see what that beast can do. Call me when you get ready to dyno pull so I can be there.
:leghump:
 

spyder7724

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good info mark.
I can't get one as they are now on back order but I've decided to go a little different....uh and larger direction. :) more details on that soon.
 

Adam@ST

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back order

The Blocks are on back order due a problem I found with the rear main caps.The rear main cap isnt machined properly for the thrust washer. Ive been on the phone with Ford a few times now.Ford idnt selling any blocks til Rousch figures out the problem and correction.
 

don_w

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Speaking of Mihovetz, I saw him make two passes in Comp Eliminator at Pomona last week. That Cougar is just plain sick. Antime you can put a 4.6L engine into the mid 6's, it is damn impressive.
 

ChevyKiller

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Yep - 6.50 flat - IMPRESSIVE!!! Paul got it on video from the suite...:clap:

At least we know he was giving it all she had as he was chasing to the very end.
 
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