I'm finally getting around to building the 383 turbo motor for my 69camaro. The QUestions I had was that I plan on trying to get about 800 HP out of the motor. I was talking to the Machine shop that might build the shortblock, and they said that if I use a GM production block, they recomend using steel caps. My questions is that since I'm already gonna buy Main caps and a block, would I be better off By a 2 bolt block and convert to the 4 bolt splayed caps or just get good caps for the traditional 4 bolt blocks? Also Is converting the 2 bolt over to the splayed four bolt expensive. Thanks for your time.

Paul

 

For that kind of power, skip right to a GMPP CNC Bowtie block with 8620 4-bolt caps on all five mains. Everything is where it belongs, it mega-tough, and only needs clearancing for the stroke, boring and honing. For about $2500 you'll have a great foundation that's much stronger than any producton block.

Besides, it'll handle a 4.16 bore.

Using a 4.125 bore and a 3.50 crank, you'll have 374 cubes, no clearancing, lower piston speed, lots of bore area for better breathing, and room for a couple of rebuilds. Unfortunately your machine shop won't have much to do!

My $.02.

 

I worry about the concerns about "expensive" and 800hp forced induction small blocks in the same paragraph! It will be exepnsive no matter how you do it. The block prep and parts needed to build up a strong stock block gets the cost into near the same range that the old stroker is talking about for a Bowtie (or aftermarket) block. And the end result is not as durable by a long way.

But if you must use a stock block, I'd say there is not a huge difference in strength between a 4-bolt block upgraded with good straight main bearing caps and using splayed main center caps. The cost of the conversion from a 2-bolt to 4-bolt splayed caps will vary a lot between different shops. Why not just ask the place you have been talking to? A good part of the cost will be align boring and honing the new caps, which will have to be done in either case. But there is additional machining to convert to splayed caps. Maybe a couple of hundred bucks, as an offhand guess.

Rich Krause

 

I know it is going to be pricey but what i meant was is it worth the extra cost to convert to splayed bolts over the straight bolts. I also wanted to get the input from you tech guys not just machine shops wanting the business. I've been slowly working on this project and i'm at the point now where within the next month I would like to have the shortblock done. One other thing i saw was that Milodon offers caps that are for the 4 bolt blocks but have angled outer bolts. How those that work, do they drill and tap new holes and fill in the old ones or what? Thanks again

Paul

 

Those caps you are speaking of are splayed caps. The milodon caps you need for your block are the straight 4-bolt, if you go to 2bolt and convert to splayed you want the ones with angled outers.

BTW that bowtie block sure sounds like a good deal, you are looking at over $1500 in machining and assembly, not to mention $215 for caps. You can get blocks out of Jegs and Summit I believe all ready to go, no honing even required.