318 Build

[73challenger_jm]

I am building a semi-budget 318. I just bought a set of speed-pro .30 over forged pistons on ebay for 200$. I have a 68 318 motor that I hope has a forged crank in it. I think I'm going to use a set of 73 318 rods with pioneer rod bolts and have it balanced. I'm using magnum heads. I have two sets of sealed power .30 over rings(e178x30) that I might use but I am planing on using nitrous. I figured I would need file fit rings. I'm wondering if I will have enough piston to valve clearance to use a .500ish lift cam? I am not decking the block. I bought a a-833 for 200$ and it came with a flywheel. I'm not sure how to tell if its a forged or cast crank flywheel.

[73challenger_jm]

I re-read this and realized it wasn't clear what I'm asking. I am asking if a .500ish cam will work with my pistons if I don't deck it. I don't want to buy 2 cams. I was also wondering if file fit rings are worth the extra money if I'm going to use nitrous. I already have a set of regular rings.

http://store.summitracing.com/partde...0&autoview=sku

[dwc43]

The 292* .508" cam is the biggest cam you can use with stock flat top pistons. Does your pistons have valve reliefs? If not the .500 is too big. Only real way to know is to measure it. A .500 is way too big for a 318 anyways. It will be really slugish off the line unless you have some really steep gears and at least 10.5 to 1 cr. I'd go with a smaller dual pattern cam.

[furz4444]

You should realy check the piston to valve clearance when running a cam that large, also I would check the valve spring retainer to guide clearance and also watch out for coil bind. If your using late model magnum heads they have a different rocker arm ratio also and you may have clearance problems with large cams.

[tenchu80]

It's cool that your'e wanting to build a 318 versus a 340 or 360, but in concern to the nitrous how much of a shot are you going to use? If used repeatedly and anything over a 100hp shot I'd look at forged pistons from JE, and avoid hyperutics, there too brittle for high shots. Also remember that nitrous is based on cylinder pressure, it will find the weekest link and thats where the quality of head gasket and rings come in. Also cams and fuel delivery come into play, for a large shot 250+ they're ground specifically to get the gas out of the chamber as fast as possible. Good luck on your build
look up Engine Masters mag. winter 2006 volume 9 no. 4. they make a 415 horse 318 and that was built for everyday useable power with no bottle.

[rumblefish360]

He has fordged pistons now. Use clay to measure the clearance in the cylinder and prep your heads for lifts over .500. (Or close to it. Better safe than sorry.)

I'm not sure how to tell if its a forged or cast crank flywheel.

No difference. Internal or extrnal is the deal.

A cast crank flywheel (Or 360 cid flywheel, or AKA external balance) has holes drilled in the back of it. There in a weird offset pattern while the flywheel withour any holes in the back of it is a internal balanced flywheel for the 273/318/340 with what ever crank it came with.