318 snowball

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SSG_Karg

SSG_Karg

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Ok, so this little project is on the verge of snowballing into a giant pile of wasted money. All comments and advice are welcome. Here goes,
Last weekend I yanked the 318 out of my Duster to replace a leaking rear main seal, replace timing set, and give it a general once over and cleaning. Upon disassembly, I decided to calculate just how low the compression is. I discovered that the flat top pistons, most likely Sealed Power 285ap, are an abysmal .100" down in the hole. Couple that with the '587' casting heads with about 70cc chambers and the Comp XE268 and it is no wonder it was a lazy turd below 2500rpm.
So my question to you is; what is the cheapest and easiest way to gain a little power out of this little nugget?
What I've considered so far is:
1). to swap in a set of KB399s but I don't know if that would require a balance job.
2). Leave current pistons in and have heads shaved .050-.060" and run 1121G head gasket
3). Leave pistons in, leave heads alone, and install Hughes Whiplash cam.
It seems any of these options will cost close to the same, around $3-400 and I'm not willing to spend any more than that. I'm building a W2 stroker that will be taking the place of this little 318 eventually.
Current specs are:
72 Duster probably 3300lbs
4 spd, 3.91, 28" tire
74 318 .030 over
stock crank turned .010/.010, stock rods
Flat top cast pistons w/ 4 valve reliefs (believe they are sealed power 285ap but not sure)
2.02/1.60 J heads with 1.6 rockers
Comp XE268
Torker 340, Holley 650DP
Current combo has gone a best of 13.6@99mph but I'd like to get into the 12s with the teener before I swap in the big stroker.
What would you do?
 
  1. Cut heads .045 and use a .035 thick head gasket. Whatever you had, you'll have more. :)
  2. Go to a nice, dual plane intake. Weiand Action Plus would add low end compared to your current intake. I've had good experiences with the ones I've used. Or, the eddy RPM.
These two mods would make a noticeable difference on the low end torque

P.S. - I've cut heads several times and NEVER cut the intake - always been issue free.
 
318willrun said:
  1. Cut heads .045 and use a .035 thick head gasket. Whatever you had, you'll have more. :)
  2. Go to a nice, dual plane intake. Weiand Action Plus would add low end compared to your current intake. I've had good experiences with the ones I've used. Or, the eddy RPM.
I'm going to cc the heads this week just to see exactly where they are. If I go the head shaving route, I would probably cut at least .050 off the deck surface and .040 off the intake surface just to prevent any alignment issues. This route will depend on machine shop prices.
Click to expand...
 
my experience is the bolt holes line up better when I cut the heads (never cut an intake). Not at all telling you what to do, just remember, once you cut that intake, you make it an orphan.
 
I would advance the cam some if it is not, button it up and live with it until you get your "real motor" done. The times you describe are not all that bad for a mismatched combo
 
318willrun said:
my experience is the bolt holes line up better when I cut the heads (never cut an intake). Not at all telling you what to do, just remember, once you cut that intake, you make it an orphan.
Click to expand...
You have to check, it's not a certainty.
I prefer to cut the intake face of the heads, but...i have had a few ootb I had to cut.
Everything varies.
 
318willrun said:
what rpm do you shift at?
Click to expand...
6200
318willrun said:
my experience is the bolt holes line up better when I cut the heads (never cut an intake). Not at all telling you what to do, just remember, once you cut that intake, you make it an orphan.
Click to expand...
Not planning to cut the intake manifold, would be cutting the intake face of the head.
 
You're building a stroker- I say this is a good time to experiment with a $300 nitrous kit and take that 318 to the Moon if you have to and gain some experience and maybe have some fun..my-2
 
67Dart273 said:
I would advance the cam some if it is not, button it up and live with it until you get your "real motor" done. The times you describe are not all that bad for a mismatched combo
Click to expand...
The new timing set has provisions to advance 4* and I probably will. Will definitely have to check piston to valve clearance.
 
Used 100 shot. Can be had for under $400.00. W/o lifting the hood, all your friends will be in amazement.All you did was remove the air cleaner and bumped the timing. Slick!.
 
j par said:
You're building a stroker- I say this is a good time to experiment with a $300 nitrous kit and take that 318 to the Moon if you have to and gain some experience and maybe have some fun..my-2
Click to expand...
I like the way you think brother! Unfortunately, a friend of mine wants to buy the 318 when I get the stroker done so I can't grenade it. Would be fun though.
 
SSG_Karg said:
I like the way you think brother! Unfortunately, a friend of mine wants to buy the 318 when I get the stroker done so I can't grenade it. Would be fun though.
Click to expand...
Oh I wasn't thinking anything over a hundred and fifty shot. Nothing that would kill it, just something to have fun. At any rate, I'm glad you got a laugh.
 
If you're going to machine them not a bad idea. Ya, piston a mile down the hole and the big chambered heads really kill it on the bottom end. With the cam probably 7:1 dynamic compression. Not good for bottom end. The heads flow but you have to rpm it to get them to work.
 
SSG_Karg said:
Ok, so this little project is on the verge of snowballing into a giant pile of wasted money. All comments and advice are welcome. Here goes,
Last weekend I yanked the 318 out of my Duster to replace a leaking rear main seal, replace timing set, and give it a general once over and cleaning. Upon disassembly, I decided to calculate just how low the compression is. I discovered that the flat top pistons, most likely Sealed Power 285ap, are an abysmal .100" down in the hole. Couple that with the '587' casting heads with about 70cc chambers and the Comp XE268 and it is no wonder it was a lazy turd below 2500rpm.
So my question to you is; what is the cheapest and easiest way to gain a little power out of this little nugget?
What I've considered so far is:
1). to swap in a set of KB399s but I don't know if that would require a balance job.
2). Leave current pistons in and have heads shaved .050-.060" and run 1121G head gasket
3). Leave pistons in, leave heads alone, and install Hughes Whiplash cam.
It seems any of these options will cost close to the same, around $3-400 and I'm not willing to spend any more than that. I'm building a W2 stroker that will be taking the place of this little 318 eventually.
Current specs are:
72 Duster probably 3300lbs
4 spd, 3.91, 28" tire
74 318 .030 over
stock crank turned .010/.010, stock rods
Flat top cast pistons w/ 4 valve reliefs (believe they are sealed power 285ap but not sure)
2.02/1.60 J heads with 1.6 rockers
Comp XE268
Torker 340, Holley 650DP
Current combo has gone a best of 13.6@99mph but I'd like to get into the 12s with the teener before I swap in the big stroker.
What would you do?
Click to expand...

So just out of curiosity, what was the compression ratio?

I’m also impressed it ran as good as it did for what it is!
 
prorac1 said:
So just out of curiosity, what was the compression ratio?

I’m also impressed it ran as good as it did for what it is!
Click to expand...
Well I haven’t measured the combustion chambers yet, but using the factory numbers for these heads and using 5cc to account for the eyebrows and crown of the piston, came out to between 7.5-7.9:1. :eek:
I’d love to raise it a full point and test before advancing the cam 4 degrees to see how much difference it makes.
 
toolmanmike said:
If you're going to machine them not a bad idea. Ya, piston a mile down the hole and the big chambered heads really kill it on the bottom end. With the cam probably 7:1 dynamic compression. Not good for bottom end. The heads flow but you have to rpm it to get them to work.
Click to expand...
Yeah, it’s really soft in the lower rpm range but it really comes alive above 3000rpm and pulls nicely to 6000. Which is great at the track with the 4 speed but around town I have to slip the clutch more than I would like. Hopefully adding a little squeeze and advancing the cam will remedy some of that.
 
Run a 26 inch tire as said above and swap the intake to a rpm-ag.
Mill the heads.
What intake are you running on the stroker?
 
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