Machining for 4 bolt mains

[lalessi]

Hello. I am new to the forum but I have had casual experience building several FE's dating back to 1967. I have acquired a C4AE-6015-A short block that has 4 bolt main bosses cast-in but not machined. The engine is a .030 over 390 I believe, and it is rough due to weathering. I am planning on building a stroker with as much displacement as I can get away with. The engine is for my 1957 Ford Custom and will strickly be for the street focusing on "talking points" and sound. The car (3500 lbs) has a stock 390 in it now with a wide ratio toploader and 3.89 gears. I am looking at a Comp cam 282/.571 solid lifter cam and I am designing for a 6000 rpm redline.  Has anybody added 4 bolt mains  to an engine like this after the fact? Any comments?

[afret]

Here's some info:

http://www.network54.com/Forum/74182/thread/1281147705/who+sells+the+Pro+Gram+%28sp-%29+cross+bolt+main+caps+--

I sent a 428 block to Rob's shop in Colorado to install a set of the Pro Gram caps.  He did a super job and it turned out great. 

You can also just install cross bolt caps on #2 and #4 caps and leave #3 alone if you want to save some money.

[cammerfe]

I have a C4 block under my workbench right now to which cross-bolts have been added. I'm the 3rd owner of the engine; it started life as a solid lifter 330HP 'PI' engine. I bought a set of 427 main caps at a swap meet.

It's a straightforward Bridgeport sort of machining effort. I got a set of spacers with the caps, including a couple of spares and it was still found necessary to make several more in order to be able to properly fit things together. The work was all done in Roush's Prototype Shop and they sized them to 4 decimal places. (I just dug a couple of the extras out of my desk as I was writing this.)

Depending on your intended end use, it might be worthwhile to go to the steel ProGram caps. But since they are intended to fit into a 'vanilla' block you'll then need to machine off the internal 'knobs', and have no need for spacers. But you'll still have the extra webbing.

My own block had very little core shift. I now have it cut .040 oversize. As a general rule of thumb, don't bore more than necessary. Cylinder wall strength is more important than the relatively small displacement increase you get from boring. You may find it worthwhile to talk to someone such as Barry at Survival regarding your plans.

Is your block completely drilled to oil the lifters?

KS

[lalessi]

Thanks for the info to date. The block is drilled for hydraulic lifters. I would probably use 427 main caps as well, no point in machining off the existing bosses in my mind. I took a 62 Mercury block in my first build and put stock new 428 pistons and a 428 crank when you could buy 'em from Ford. I had no issues at all back then but we didn't do sonic tests back in 67. Because the block is so rough I am thinking about going straight to the stock 428 bore and then doing the sonic thing before I do the 4 bolt main caps. The block passes the "drill bit" test.

[jmlay]

I would not bore before cross bolting or sonic. I would sonic first, no sense is wasting good money after bad.

[lalessi]

The cylinder walls are very pitted... I don't think I can sonic check it first. If it wont bore out to 4.13, I don't want to spend a lot on maching for the mains. I got this short block for a song for the cross bolted bosses.... Love the idea of a cross bolted "428". I am not racing or trying to maximize HP....cruising with a flair?!

[Bad Byrd]

I would still Sonic the cylinders and then decide to punch the hole size and then go from there. As far as the cross bolting goes, if your intent isnt to push it hard then why even bother with the cross bolting?

[lalessi]

 I will try to have the sonic test first on second thought. I will talk to them first. My machine shop doesn't do sonic testing though. I just want to say I have cross bolted mains.... I am sure I don't really need 'em. i really don't need a new engine when you get down to it, or so my wife likes to point out. I really enjoy getting the feedback, thanks again.

[Bad Byrd]

Gotcha!

[Ratbird]

My 390 with a 428 crank and 410 pistons was bored .030 and revs to 6000 for a red line. The builder used new high quality fasteners and said they should hold up fine. The builder ask why I don't just keep it a 390 and build it to whatever HP and torque I wanted. But I'm like you, I wanted it o be a little different "just because". That's why I went with a 410 (actually 416).

I keep hearing that Barry (on this site) makes a GREAT stroker kit that'll take you up to 445ci. That to me sounds like a tried and true way to go. All the engineering and testing has already been proven.



Just a rookie's 2 cents.

Dave J 

[lalessi]

Planning on a 4.25 stroker kit. This block is already 4.080 and at least one cylinder is pitted. I hope it will clean up period. Since I have had luck with an old block going out to 4.13, I figure this one may too! Thinking maybe the webbing and the cross-bolted bosses indicate a thicker wall. I want 455 cubic inches at least....one more than a 454 BBC!!! "No substitute for cubic inches", an old mantra. As a retired engineer I am back in my second childhood....

[Heo]

I have exactly the same block exept mine is not
bored for hydraulic lifters and it wont take a 4.13
bore  if you want the cyl. to bee .100 thick

[Bad Byrd]

I think it is the luck of the draw, not that is completely applicable but I have a 406 cross bolt block that is 4.160 and it has well over .100 everywhere. I think the thinnest I saw was .116

[Heo]

a 406 at 4.16 is 030+
a 390 at 4.13 is + 080
406 and 390 is different castings

[BH107]

Cylinder wall thickness is a completely different conversation, and it really is luck of the draw. We have one 406 block that will go to 4.23 without being too thin, and I had another that was thin at 4.16 due to core shift. 390 blocks are the same way, some can go more than others, but personally I think its foolish to max them out if they don't need it.