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Author Topic:   400 4bolts vs 400 2bolt
fridge
Member
posted February 22, 2001 11:51 PM
i was wondering what everyone thought about 400 4bolts compared to 2bolts i know that a 350 4bolt is better, but i heard that in a 400 they aren't because the outside bolt is in between the cylinder walls which are closer because of the bore. thanks


tls88mod
Member
posted February 23, 2001 09:24 PM
2 bolt 400 blocks are a stronger block because they have more material in them. They also work well if you use splayed main caps.


mtnman
Member
posted February 24, 2001 02:41 PM
Mod93,

If you have a 400 2-bolt which is the ideal block to have, you should have if fitted with splayed caps. I don't know of anyone around here that runs a motor without them! You could leave it two bolt I guess if you want to blow the bottom end off the thing. Also check the block for the nickel content. A high nickel content means a stronger block. For all the guys running stock caps check the bottom for a "NF" casting on the bottom of the cap. This stands for Nodulated Forged which is a very strong "stock" cap.

chomme
Member
posted February 27, 2001 01:09 PM
Mod racer, The Extra cost of doing a splayed cap block is around $400. but if you need to line hone the block you have now you can deduct another $80. because you would have spent that much to keep it a 2 bolt anyway.
I would NEVER, EVER, think of putting a $2500 crank kit in a block that didn't have splayed caps....by the same token I wouldn't put a cast crank kit in a splayed cap block.you would have too much to loose.....you will spend money on tires, fuel, tear offs, and a ton of other things..........this $400 is CHEAP insurance. If you don't blow the 2 bolt to pieces it will be worth a lot less than if it had splayed caps.
In my opinion splayed caps are the cost of racing, and it's one of the few parts where when you sell the thing you can get your money back........A SPLAYED CAP BLOCK HOLDS IT'S VALUE...........
save money some where else, I'm sure you already have, but look again........Jeff


MOD RACER#93
Member
posted February 27, 2001 08:09 PM
I have a 377, with a 4 bolt main which we have put studs in. 13:1 compression, should a carry a bucket around to pick up parts? I sure hope not!


fridge
Member
posted February 28, 2001 09:05 PM
all i have is a 400 4 bolt block, do you think i should put money into it or just build a 355


GnarlyCar
Member
posted February 28, 2001 10:50 PM
Sell your 4-bolt 400 block to a street rod guy and go find a 2 bolt one and have it fitted with splayed caps. The outer bolts in the factory 4-bolt makes the main bearing webbing too weak to take the HP that a mod motor will make. Awkward Jeff was right..it's nothing to spend $400 on tires that'll be gone next month, but so many of us are afraid to spend that same $400 on something like a splayed cap block. Seems pretty simple when you really think about it. The cost of racing.. chalk it up as one of the "gotta-haves" like a helmet or sweet graphics job.

Matt

Roadhzrd
Member
posted March 01, 2001 02:57 AM
$400 sounds kind of high. the caps are $100 for the cheap ones and all they do is bolt them in with the old two bolt holes and step drill with bushings and tap the splayed holes before they align bore.


chomme
Member
posted March 01, 2001 10:05 PM
Chomme,
I was just thinking the same thing earlier today. Seemed to me that after all the sweet tricks we gotta do to a stock block to make it race ready, we'd have spent about the same as a decent aftermarket block with all that stuff already done. You just confirmed my suspicion.. Any chance that the authors of any of our rulebooks will ever figure that out??? Fat chance..

Matt

MOD RACER#93
Member
posted March 01, 2001 10:33 PM
quote:
Originally posted by Roadhzrd:
$400 sounds kind of high. the caps are $100 for the cheap ones and all they do is bolt them in with the old two bolt holes and step drill with bushings and tap the splayed holes before they align bore.

roadhzrd, Like anything in life you get what you pay for.......I know a shop that will put the caps in the block, then align the thing for about $250......the problem is that they don't fit the caps properly first.
All blocks are a few thousands different at the parting line for the main caps.....the after market caps need to be set into the block then measured for fit.........the set up in the mill and faced off where needed...
the final fit needs to see the step sit flush, then the outside need .002 clearance.
then drilled and taped.........the cheap shop won't torque the outside of the cap before align boring..........then you take the thing home and torque the bolts.....the bore is about .0005-.00075 out of round....
a 1/2 thou may not sound like much but when the oil clearance is 2 1/2 that 1/2 is 20 percent......and now thats a ton.......
This is why a good shop will charge a fair price........$400 is fair where I'm from.
$250 is no bargin when you have problems...you could have saved the $250 and just raced it with 2 bolt mains.

you can also reuse the same caps from one block to another by clipping the cap and re-fitting the cap to the new block, the problem with this is unless this is a very EXPENSIVE set of caps with all the machine work that needs to be done you are money ahead to just my the new ones
Jeff

[This message has been edited by awkwardjeff (edited March 01, 2001).]

modbob35
Member
posted March 02, 2001 07:31 PM
Is it the main caps or the block that is weak on the 4 bolt main 400's? Or combination of them both. Already have engine built is there any solutions? Thanks


awkwardjeff
Member
posted March 03, 2001 01:39 AM
It's in the block, there is nothing you can do to make the block stronger.....If you can measure the webbing at the bottom of the bore they are a bunch thicker in a 2 bolt block.


MOD#11
unregistered
posted March 03, 2001 01:38 PM           
Just put block filler to the bottom of frost plugs and run it.