318 Build

[pressedham]

I have a 318 spare motor,25 years old.
A friend suggested a rebuild.
He suggested punching it out 60 over, put roller cam and top end
and change out crank with new MT pistons. 600 cfm holley carb and headers.
He said this would make a nice little street machine, not to exotic, around 300 hp.Is it worth doing. A fully running 340 around here is very expensive.

 

[OldVart]

Hey pressedham, that's a lot of work and $$$ to put on a 318, especially .060 over and a roller cam. There should be lots of 360's around the Ottawa area, and you'd be a LOT of dollars and cubic inches ahead to start with one of those. 400 hp isn't that hard to pull from a well built 360. What car are you putting it into?

 

[Mark Nixon]

One of the biggest no-nos on a smallblock is max-boring it, thinking you'll get more cubes and better power.
Overboring too much can lead to heating problems and power loss due to cylinder flex (losing ring seal).

My favorite 318 recipe, before I had access to 340s:

Early 318 LA block ('67-'72).
1.88 intake valved 360 'J' heads, milled .010 (deck cleanup).
1966 CAR poly head pistons. (Hard to find in oversizes these days, but look).

When used with a FelPro (blue) headgasket this build yields a calculated compression of @ 9.6:1.

Depending on cam selection, adding valve reliefs may be necessary, though I never used larger than a .470" lift cam in the (3) 318s I built with these pistons.

I also suggest, if you can, use the lighter, full-floating 318 connecting rod ('782), as they are plenty strong for the horsepower the 318 will make and they really work to lighten the reciprocating weight. These along with a cast (slightly lighter) crank will really help the 318 to rev well.

When I built these 318s, I used a stock 340 iron intake with a '71 Thermo-Quad carb, got 18 MPG with 3.55 gears, along with a 4 speed and still did my fair share of bow-tie and blue oval killing.

It's no 340 or 360, but then again, it ain't no slant six, either.

Mark.

 

[moper]

I wouldnt ask that friend for engine advice....If they cant get 300 hp from a pump gas, stock headed, basic performance rebuild, small cam 318, find a new machine shop.

 

[rumblefish360]

Tell your freind to take a long walk off a short peer. He is bad news. A roller cam and .060 over for 300 HP. He's gotta be kidding you. (And us!)
Keep boreing down to a min. 600 cfm and a performer intake (T-Q's work well on there)
Mill heads for better compresion. (9-1)
Comp XE262H would do great.
Headers help alot.