Should i stick with the 2 bolt caps with ARP studs? or switch to the 4 bolt splayed caps?

This is on a 383 stroker that should be putting out 450+ hp n/a and around 600-650 on nitrous.

it seems to me that the splayed caps would be a good thing to have? they are just so expensive.

will they hold the crank tight under the load nitrous puts on? cause i know it will move with the 2 bolts.....

 

4 bolt hands down, not up for discussion, not debatable...the end!

 

Some engine builders question splayed vs. straight 4-bolt cpas. But at that hp level you do need a 4-bolt cap, IMHO.

Rich Krause

 

personally i think RPMS are more stressful than power output- well thats what it seems like anyway. Use ARP fasteners no matter where you go with it

 

block is hottanked before machining correct? cause you ahve to have the caps to align hone it right?

 

chevyboy_z28, What he said

 

who makes the best cap for the money and how much is machine work usually go for?

splayed or straight better?

 

heres a good set http://www.racenet.net/eng/oliver-caps.php but i wouldnt buy em from racenet ive heard bad things about them.

 

dude, your going to break a crank before you even break a regular 4 bolt main. Billet splayed 4 bolt mains are overkill. spend you money elsewhere

 

is the machining cheaper and the parts cheaper on a straight 4 bolt main? i assume it is since its straight holes not crooked ones LOL

 

these are for a 2 bolt register block (no machining required) will require a line bore, as any 2-4 bolt will, have a set off a regular 4 bolt main bolt too. Pics too.

Eric

 

A line bore is about $300-450 + another $300 for the drilling of the outer 2 holes. IMHO not worth the money you need a stronger crank before you should worry about the mains. I have seen the 2 bolt with arp studs hold up to about 700 rwhp with out any problems but the crank was a diffrent story(scat 9000).

 

Just called up the machine shop, and he told me that i really didnt need it. He runs his 406 sbc all the way up to 9200rpm with 2 bolt mains and studs.

 

Several things to consider here, first the engine builder with the 406 2bolt, 400's have bigger main caps than all other sbc, so you can get away with that but I doubt 9000rpm from a 406.

Secondly you're planning on NOS right, then without a doubt get the splayed or straight 4 bolt conversion done.

Thirdly go to SDPC.com you can get GM billet splayed caps for $50.00 ea you'll need 3 center and a billet front cap $55.00 best prices going and the best part is with these caps as opposed to some others you will still be able to use your dipstick. With some of the othe caps ( Milodon comes to mind ) you can't get the dipstick past the cap.

 

This is what I've heard. The reason they use 2 bolt caps is because they are cheaper to make and use nickel and are really just as strong as a regular 4 bolt main. Any truth to this? Also, if you need 4 bolt mains to hold down a crank that is trying to bust out of the block, I'd think you have problems elsewhere. Unless you're pushing an 800hp sprint car motor, why bother?