Building 318

[drphiluponya55xr]

Ok I have a 94 magnum 318 I will buying an aluminum air gap intake that fits both la and magnum heads from eBay with a rochester 2g untill i can afford an e85 kit for my holley 4412 I have a 268h extreme comp cams cam and lifter (yes I know the magnums are roller motors) just simply don't have 700 for a new solid roller and this cam has already been purchased so I plan to use it I also plan to get a set of kb 167 hypereutectic pistons .30 over and eagle I beam rods with arp bolts (stock crank) whats everyone's opinions on this setup? I know very little about building engines I plan to leave the heads stock until I can afford valve springs and hardened pushrods just looking for opinions on these items I mentioned and how u think they will work together thanks in advance for opinions and please dont bash my stupidity

[axlebreaker69]

if you can afford it i would change out valve springs, get matching springs for cam, hate to see u go out there and break a spring and knock a hole in ur piston....jmo

[hemi]

I personally would find a 360 magnum instead.The extra torque of the 360 over a 318 is well worth the 360 build ..IMO

[dm440c]

Apr 11, 2012 20:40:55 GMT -5 axlebreaker69 said:

if you can afford it i would change out valve springs, get matching springs for cam, hate to see u go out there and break a spring and knock a hole in ur piston....jmo

ditto 100% .... you should always match the springs to the cam. The XE series has fairly aggressive lift profiles and you want to do this right. Dumb question but.... if you can afford to rebuild the engine with new pistons, ARP bolts, and I beam rods why can you not afford a set of valve springs? Seems like a mismatch of priorities to me. I'd re-think how your engine dollar is being spent in this case.

The KB 167's are good pistons for an LA 318 but be aware that hypers do not like detonation. I would use the thicker (around 0.040") composite head gaskets to get the SCR to a barely manageable level (around 9.6:1 with the Magnum heads) and keep the water in the radiator. Premium gas is a must, consider higher octane such as race gas because you are right on the ragged edge with that SCR and, again, detonation is a hyper piston killer. Don't let it get hot. Personally I think the KB 167's are ideal for street use with LA 360 heads but that's a different story. Another thing you could consider doing in order to manage the cylinder pressures with the Magnum heads is to go with a more radical cam in order to bleed off pressure by increasing the duration. You would want to cheat it towards higher duration/ less lift with this strategy so I would consider maybe getting away from Comp's XE series cams and instead look at the Magnum series. The 280H will bump up the duration a bit without getting into high lift areas and may help your cause. You'll want to invest in some decent rear gears to bring this all together, I'd say 4.30 to 4.88 should be about right.

Overall it seems like an odd selection of parts for a derby engine but do what makes you feel good I guess.

[drphiluponya55xr]

Yes I have since decided to run a stock bottom end and buy valve springs I am in the process of build a ford 9 rear also with 6.00 gear

[drphiluponya55xr]

Thanks for all the great feedback and info also! All appreciated

[drphiluponya55xr]

Could anyone help me with what size should I get on springs or a special spring I need for a magnum engine

[dm440c]

when in doubt, always follow the cam manufacturer's recommendation for springs. They have tech people, use them, they know their product better than you do.

That is a $hit ton of gear. My stock bottom end 318's are pretty happy in the 4.56 range.

If using the stock pistons then use the 0.025" compressed height steel shim head gaskets. Your SCR should be in a nice range that will run good on pump gas. It's more cam than I would choose but it should still work OK with the Magnum heads.