What is the concessus on splayed main caps for a street/strip big block. I would think the Oliver Billet would be stronger.

Milodon ductile iron $229 for the 3 center + $92 for the front cap =$321.
Or Oliver Billet $325 for all 4?
I also see that eagle has a set of the 3 mains in billet for $89.

The eagle mains are advertised as "Fits 2-bolt block cap register without machining". Other than a line bore is there any other machine work that has to be done with the other caps?

And, none of the conversions that I found have a rear 4 bolt cap. Will a new GMPP rear cap for the early blocks work?

Thanks

Tom

Why? Big Blocks don't have trouble with the mains unless you make some serious HP.

Tom,

Not necessary. Once you get that high in power 1000 HP+ where 4 bolt caps are necessary, an aftermarket block should be on the shopping list

Biggest thing to make sure you check, extra good and could require new caps, is to make sure those babes are almost a force fit in the block. By that I mean, they are designed to snap in the last 1/8" or so. If they don't they will walk around and you will have issues. What kind of steam to you pan to make with this engine?

Well, I got a deal on a 70s 454 that I just couldn't pass on. 1000 is the magic number. At the rear that is.

TK

I wanted a little extra insurance here so went with a 2-bolt main stud kit!!

pdq67

So sounds like you will have a big blower or NO gas. Yea, if this is your goal I'd get the most expensive steel Oliver caps should work well. Sould have caps 1 to 4 and then buy a GM 4 bolt cap. I'd find a local machine shop with a machinist that has done line boring and honing on a number of Mark IV blocks, talk to him and see if he can get the job done. I would also let him drill and tap the new holes for the outer bolts. You could do it by hand but would need some kind of jig to get and hold the correct angle. Remember before you cut the new steel, make sure they snap in place. Good luck.

Just my opinion but,,,
Putting on all five caps is not a walk in the park. It is not cheap properly done by a performance shop.
Now you have a block with good caps that should have the lifter bores indexed to be sure that they are right. Again, not cheap.
You have just put a huge dent into the price of either a Dart or Merlin or GM Bow Tie block that has,,,,,splayed caps, lifter bores that are very acccurate, is better material & has thicker cylinders that can go to 4.600 if you are so inclined.
For a 1000+HP engine I know what my choice would be ;)

I agree the aftermarket and Mark-6 Bow-tie have a better oiling system and are a far better starting point for 1000+ HP

I personallly like the main cap conversion if you are gonna rev up a high power combo. I don't like studs with the stock caps as sometimes they will walk a bit with the studs IME.

But like most guys have said... if you want 1,000 hp it is probably wise to just buck up for the aftermarket block.

Oooooh Tom, 4.6" bore and a short stroke should really make that bigarse blowermotor HUM! Hope all is well with you and your bro' !

Originally posted by 427L88:
Oooooh Tom, 4.6" bore and a short stroke should really make that bigarse blowermotor HUM! Hope all is well with you and your bro' ! With that setup 1000hp is easy!!! (not cheap, but easy) :D

I had a bad experience with a 4 bolt splayed conversion on a 400sb. Never again! The Milodon caps don't have a standard height and they come with Home Depot style grade 8 bolts :( At least for SB. ARP did not have a stud kit for them. Hop Sing says the Eagle ones are made by the Fing Fang Fu Machinery works. If the number five cap is not the original getting the thrust correct is next to impossible for any kind of longevity on the street. This is my experience and I'm not a pro but the new blocks do sound pretty sweet to me :D

last thought from down South.... If you really do plan to make that kind of steam and use an old Mark IV block...... whatever you do grout the block and don't bore more than 60 over.... cause it's going to do the internal watoose in an effort to kill itself:eek: The Geberal made jugs Siamese (later on) for a good reason. graemlins/hurray.gif