318: What Will It Make?

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I would guess about 300/300 give or take about 15hp, depending on your ignition, your tune (jets, timing, curve, cam advance, total cyl. psi, etc.) and your exhaust system, but that's with a known 60cc head.

If you want to motivate at this altitude, it's all about torque and keeping a good vacuum signal. Get those valves open and closed quick.

Also, what pistons are you getting a zero deck out of? Are you milling the block? And how are you getting 60cc out of a 973 head? Milling?

The reason I ask is because I'm running a set of KBs and they sit .011" down and my 302 closed chambers with the same valves came in at 62cc. They were 61.5cc after milling .010" to square them up and I radiused the chamber edge to knock the hard lines off and got them back to 62cc. They would be closer to 61cc with flat faced valves. I wound up with 9.65:1 static.

I'm willing to bet that the car runs somewhere near a mid 14 up at Bandimere on those figures, with a good tune and 973 heads (usually 65-67cc). A friend was running 14.9 on an 8:1 318 with 973 heads, a 2300 stall and a 3.91 8 3/4 in a car with little to no interior in a '72 Dart with full headers and shorter exhaust, on a .444 cam.

You're probably at the same weight, higher compression. If you are running KBs, expect .011" from zero, unless you go .010" under or so on the factory deck height.
 
Good to see another Coloradoan!
Ill give you my combo that I used to run at Bandimere. Car was a '74(3500lb) Dart with a 318/904 3.91 gears and a 3500 stall and 195/75/14 tires. Traction was not a issue. I actually ran faster with better 60ft with those little tires then Mt ET streets(28").
Rebuilt 318 with 9.0 compression, Compcams XE 262 cam, magnum heads, Chinese airgap intake, headers, 750 holley DP. Car ran a even 15.0@92mph all the time. Ran 14.7's@93 at Douglas, Wy.
Hope this helps :)
 
DaveBonds said:
I would guess about 300/300 give or take about 15hp, depending on your ignition, your tune (jets, timing, curve, cam advance, total cyl. psi, etc.) and your exhaust system, but that's with a known 60cc head.

If you want to motivate at this altitude, it's all about torque and keeping a good vacuum signal. Get those valves open and closed quick.

Also, what pistons are you getting a zero deck out of? Are you milling the block? And how are you getting 60cc out of a 973 head? Milling?

The reason I ask is because I'm running a set of KBs and they sit .011" down and my 302 closed chambers with the same valves came in at 62cc. They were 61.5cc after milling .010" to square them up and I radiused the chamber edge to knock the hard lines off and got them back to 62cc. They would be closer to 61cc with flat faced valves. I wound up with 9.65:1 static.

I'm willing to bet that the car runs somewhere near a mid 14 up at Bandimere on those figures, with a good tune and 973 heads (usually 65-67cc). A friend was running 14.9 on an 8:1 318 with 973 heads, a 2300 stall and a 3.91 8 3/4 in a car with little to no interior in a '72 Dart with full headers and shorter exhaust, on a .444 cam.

You're probably at the same weight, higher compression. If you are running KBs, expect .011" from zero, unless you go .010" under or so on the factory deck height.
Click to expand...


Yes, the heads have been milled to 60cc. The piston is a cast Sterling...can't remember the part#, but the deck has been cut as well. They were supposed to zero deck it but I won't know until I put the rot.assem. together. If it IS a true zero deck then the comp will be around 10.7:1 with a .039" compressed gasket. If I fudge the comp height down to .050" in the hole with the same gasket, comp should be a little over 9.5:1, which will be fine.
I test fit the heads and intake on the block and it all lines up near perfect, which I was hoping for as the heads are gasket matched.
 
That's quite a close shave. Don't forget to correct pushrod length. It may affect geometry a bit, too, so I'd blueprint it a little, before buttoning it up. Watch for pushrod clearance on the head, too.

What do the chambers look like, now? If they've got a closed end on them, you may want to run the FelPro .039s to get some quench and keep your 10.7 on premium.

There are a few high compression 360s up here, running KB pistons that do fine on mid grade. One of them belongs to Khalid. You can get away with a lot more up here on 10.7:1 and you will notice more HP for the return by keeping it that way.

If you've got a closed chamber, use it. Keep the quench and the .039 gaskets. You won't have to worry about ping up here on premium with that comp ratio. You're gonna lose a little bit with ring height cc and total, actual CC as well as other dynamics, aside from altitude.

Depending on the LSA of the cam, the ramp and open/ closing degrees, you can also try to play around with the cam to mess with total cylinder PSI. You might benefit from buying an adjustable cam timing gear to play with it. but I'd start at 3° adv.
 
The heads still have a little bit open chamber.

As far as the rockers, they line up pretty good on the stems. The rollers line up a little past center so that when the rockers push down on the valves, the rollers end up on the center of the valve; already checked it :) Also got a pushrod length checker to make sure of the pushrods.

Cam is .465/.465 228/235 @.050" 110 lobe sep 106ICL
Cam info here: http://www.lunatipower.com/CamSpecCard.aspx?partNumber=30402
 
That setup should work good.

I wouldn't go any looser than .039" on the gasket. I depth checked a set of those heads that I've got out in the garage and with a .050" shave , you definitely still see a little open chamber edge there. I'm running 1121G Mr.Gaskets .028" on .011" down giving me .039" total compression distance. With 62cc chambers and high ring lands of the KB pistons, I landed just about 9.65:1, because those pistons have 5cc valve relief sets in them. That may be something you may want to consider doing, if you're concerned about total compression, but don't want to lose your compression distance.

I'd suggest measuring the depth of the chamber's closer end to the mating surface, to see what your total depth is, added with the gasket.

If you get a valve notching fixture and put some reliefs in the tops of your pistons, you might gain a lot of different benefits, including the ability to go larger on the cam if you ever wanted to and be safe on your chain, but mostly in the total CC gain and ability to drop to an .028" gasket for quench and lower compression to mid 9s at the same time. I know that the .039" fel-pro gaskets are twice the price of the .028" 1121Gs.

You could use them with the added CC of the reliefs and this is an easy, inexpensive DIY deal;

http://sbftech.com/index.php/topic,15194.msg147014.html#msg147014

If you put any bare SB head on as a guide and simply mark a depth to stop at, on the stem of the valve/ tool, you're money. You don't need to put specific size valves in. As long as it's a 3/8 stem and you can grab the end with a drill chuck and see your stop mark as it gets to the edge of the guide, it's easy.

I've seen guys do this with a homemade spark plug piston stop that is set to tdc, for each cyl and a vacuum hooked up to the opposing valve port with very minimal cleanup. I was going to do this on a set of flat tops that I had, until I discovered they were extremely low compression pistons and I ditched them for the KBs that already had the notches.

What sold me on the 318 is the combination of stroke to bore ratio lending itself well to closed chamber and/ or quench benefits, without skyjacking the static compression ratio. So you get the benefit of good compression ratios, in the mid to upper 9s, while still getting the piston and head close enough to get the benefits of quench, which keeps detonation away, and is awesome for where we live and for hill climbing.

I have a used valve or two with good stems if you wanna give this a go that I can send you for free. You just set the bare, clean head on the block. You don't need to use a gasket. Just put some masking tape on the deck surfaces , covering the oil passages and put a towel or some rags in the oil galley, then take the vacuum out of the intake or exhaust port and clean the piston when you switch the valve to do the next notch. You only need to set the head on the block with a single bolt in the middle, to keep it stationary on the dowels.
 
300 corrected should be doable.

For reference my 318 made 352hp on the dyno with 10.39:1, thumpr cam 227/241 @ .050 and 2.02 J heads with a bowl blend. performer RPM and 1-3/4 headers.

I've since went 254/254 solid cam and a bit more porting and it feels noticably faster with my best ET being 13.96 @ 98 in a 67 valiant (never raced before, bloody hot aussie summer day, running a little rich with a super restrictive twin 2" exhaust system, heavy 5 blade truck radiator fan. could use more stall etc and any other excuse you can think of)
 
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