318 Head Headache

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AbodyAaron

AbodyAaron

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Warrenton, VA
I jumped into an old thread and it was suggested I would get better responses creating a new one with my car’s specific specs in mind. For context: my 71 demon is currently running a 318 that is .30 over with forged Keith Black Pistons. Eddy intake, Eddy AVS2 650 carb, Hughes whiplash cam (cam card below), hooker headers to 3” exhaust. Rear end is geared at 3.23. Trans has a small shift kit and stall in it (904 reverse manual valve body). My main question is heads. While the previous owner ported and gasket matched the stock iron heads and Eddy intake what would be the best option for heads for my setup. I’m not looking for a race car here… but the most performance I can get out of a drivable street muscle car. I’ve been looking at 340x heads, Eddy and truck flow heads on the aftermarket etc. unfortunately my knowledge isn’t as deep as it needs to be to make a sound decent decision here. Any help on best bang for the buck would be much appreciate. I can provide as much info as needed to make further suggestions etc.
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If it were myself and looking to keep it as inexpensive as possible, I’d just use a set of stock 340/360 heads and call it good. Some good machine work in making the head as good as possible without porting would be all that I’d do. One of the issues here is the cam is very small.

A few problems here;

You didn’t state what the compression is. What octane are you running it on? If 93, will it run on 87?

You said it’s running an Edelbrock intake. That’s great! Which one? I can make about 6 that will bolt on.

What size tire?

What’s the cars weight?

Stock rockers?

A/C car? P/S? P/B?
 
rumblefish360 said:
If it were myself and looking to keep it as inexpensive as possible, I’d just use a set of stock 340/360 heads and call it good. Some good machine work in making the head as good as possible without porting would be all that I’d do. One of the issues here is the cam is very small.

A few problems here;

You didn’t state what the compression is. What octane are you running it on? If 93, will it run on 87?

You said it’s running an Edelbrock intake. That’s great! Which one? I can make about 6 that will bolt on.

What size tire?

What’s the cars weight?

Stock rockers?

A/C car? P/S? P/B?
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Car is running currently on 92 octane(I haven’t put anything else in it yet as that’s the ethanol free stuff near me)at 9.7:1. The intake is an older style performer.

stock rockers. No AC does have PS and about to upgrade to PB drums (eventually discs).

tires are currently 225/60r14 and 245/60r14 (these will change down the road as well as I upgrade to discs and the 8 3/4 I picked up) but gives you the car as it sits.
 
It doesn't sound like you have a bad combination that most 318 owners strive for. You might gain a bit with bigger port heads and a bigger cam but at what cost? You may then need a higher stall converter and bigger rear gears. And then you will need some bigger tires to get it to hook. That's when most Teen owners step up to a 360 or stroker. Your car, your choice.
 
toolmanmike said:
It doesn't sound like you have a bad combination that most 318 owners strive for. You might gain a bit with bigger port heads and a bigger cam but at what cost? You may then need a higher stall converter and bigger rear gears. And then you will need some bigger tires to get it to hook. That's when most Teen owners step up to a 360 or stroker. Your car, your choice.
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Yeah the ole snowball effect . Thank you for the advice. Just exploring where I’m at and attempting to learn more about it.
 
Lets be careful here. Just so you know this. Keith Black does NOT offer a forged piston. If they are Keith Black, they are Hyperutectic cast pistons, not forged. Icon offers a forged piston through United Engine and Machine. Icon and Keith Black are two completely separate entities.

Now to your question on the heads. If you go to a 340 or 360 style head (same basic difference) you will drastically lower your compression ratio, since the 318 heads have smaller chambers. Plus, most any old iron castings will require a lot of work because they are likely worn out. You will reach out and almost touch aluminum head prices for what you will have in reworking a set of old iron heads.

Lastly, the "X" heads ain't all that. They are basically the same as all the other open chamber smog era castings, but they do have "slightly" better ports and of course the bigger valves. I just wouldn't go the X heads. I'd go aftermarket aluminum. I tell you what I'd do FIRST, though. I'd make DAMN SURE what I HAD was tuned properly and had a good hot ignition curve, initial and total timing set up right and make sure the camshaft was properly degreed and everything else was tuned properly. That in itself can net you some big power gains if it is not properly tuned. If the heads are ported as you say, and you have some good pistons with raised compression, you should have a pretty spanky 318. You "might" already have the best option and maybe it just needs some tuning.

But I reiterate, I would NOT put the 340/360 style heads on it, UNLESS it was a closed chamber aftermarket aluminum head.
 
  • Make sure your car is optimally tuned. Always. This includes that the current parts are functioning as they should. Including compression check, the carb is coming fully open on WOT, initial timing, total timing, the curve, and also jetting
  • Next, looking at heads, I would consider the speedmaster(s), along with the others that have been mentioned. Hey, if your budget includes the TF's, by george do it! IF you go 340/360, cut them to keep the compression relevant
 
RustyRatRod said:
Lets be careful here. Just so you know this. Keith Black does NOT offer a forged piston. If they are Keith Black, they are Hyperutectic cast pistons, not forged. Icon offers a forged piston through United Engine and Machine. Icon and Keith Black are two completely separate entities.

Now to your question on the heads. If you go to a 340 or 360 style head (same basic difference) you will drastically lower your compression ratio, since the 318 heads have smaller chambers. Plus, most any old iron castings will require a lot of work because they are likely worn out. You will reach out and almost touch aluminum head prices for what you will have in reworking a set of old iron heads.

Lastly, the "X" heads ain't all that. They are basically the same as all the other open chamber smog era castings, but they do have "slightly" better ports and of course the bigger valves. I just wouldn't go the X heads. I'd go aftermarket aluminum. I tell you what I'd do FIRST, though. I'd make DAMN SURE what I HAD was tuned properly and had a good hot ignition curve, initial and total timing set up right and make sure the camshaft was properly degreed and everything else was tuned properly. That in itself can net you some big power gains if it is not properly tuned. If the heads are ported as you say, and you have some good pistons with raised compression, you should have a pretty spanky 318. You "might" already have the best option and maybe it just needs some tuning.

But I reiterate, I would NOT put the 340/360 style heads on it, UNLESS it was a closed chamber aftermarket aluminum head.
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Thank you for the details. I didn’t know KB didn’t make a forged piston. That was me quoting the previous owner’s list of modifications (guess that already makes me wonder…..). I should have specified this in the opening but the car is actually way more alive than I expected a 318 to be and I wouldn’t call it an absolute dog by any means because the cars weight is so low it seems to do a lot with less than I’m used to in larger classics? I was simply looking at what is on the car and what might make the biggest gain per dollar. Usually in my experience that’s always tied to a head combo. The car runs great as it is but like most people here…. I’m always looking for more.
 
AbodyAaron said:
Thank you for the details. I didn’t know KB didn’t make a forged piston. That was me quoting the previous owner’s list of modifications (guess that already makes me wonder…..). I should have specified this in the opening but the car is actually way more alive than I expected a 318 to be and I wouldn’t call it an absolute dog by any means because the cars weight is so low it seems to do a lot with less than I’m used to in larger classics? I was simply looking at what is on the car and what might make the biggest gain per dollar. Usually in my experience that’s always tied to a head combo. The car runs great as it is but like most people here…. I’m always looking for more.
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then you are tracking the right rabbit .... heads (do we know what was all done to the 318 heads - porting you mentioned? bigger valves??) It might be worth it to pull them and see "where we are" in the current state
 
AbodyAaron said:
Thank you for the details. I didn’t know KB didn’t make a forged piston. That was me quoting the previous owner’s list of modifications (guess that already makes me wonder…..). I should have specified this in the opening but the car is actually way more alive than I expected a 318 to be and I wouldn’t call it an absolute dog by any means because the cars weight is so low it seems to do a lot with less than I’m used to in larger classics? I was simply looking at what is on the car and what might make the biggest gain per dollar. Usually in my experience that’s always tied to a head combo. The car runs great as it is but like most people here…. I’m always looking for more.
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The heads are where it's at, there's no doubt. But for your 318, IMO, that ain't X heads. lol
 
318willrun said:
then you are tracking the right rabbit .... heads (do we know what was all done to the 318 heads - porting you mentioned? bigger valves??) It might be worth it to pull them and see "where we are" in the current state
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the heads were ported to the gaskets on the intake and on the intake/exhaust sides of the heads. The previous owner had some pictures of the work. He’s not a pro, just a guy in a garage like most of us. The pictures showed what I’d expect from a weekend warrior, rough grind and not polished. They’re also fitted with the larger valves (2.02/1.60). looks like a standard 3 way valve job with the bigger valves. there doesn’t seem to be any bowl work at all far as I can tell.
 
AbodyAaron said:
the heads were ported to the gaskets on the intake and on the intake/exhaust sides of the heads. The previous owner had some pictures of the work. He’s not a pro, just a guy in a garage like most of us. The pictures showed what I’d expect from a weekend warrior, rough grind and not polished. They’re also fitted with the larger valves (2.02/1.60). looks like a standard 3 way valve job with the bigger valves. there doesn’t seem to be any bowl work at all far as I can tell.
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If he installed larger valves, I'd be surprised if there wasn't any bowl work. But if not, there is a gainer for ya
 
2.02 in the 318 heads?

Stay with the 318 heads and have them ported. Your don’t head wise. There’s no benefit to upgrading the intake at this level.

Run as much advance as you can then limit the centrifugal advance (springs inside the distributor) to a max of 34*’s. It may - MAY like more (36*’s) but that requires a dyno or a drag strip to find out.

Tune that carb razor sharp and your good to go.
 
AbodyAaron said:
Also, while we’re here. Love your YouTube channel. Was able to source my rear end with that info very quickly and easily
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He's got a nice channel for sure. He's worked real hard on it. Lots of good info.
 
The magnum heads would be a fairly inexpensive upgrade and keep some compression.
 
I would tune what you have to the 10th degree. The next thing would be to pull the heads. Check and see what you have. Do a fresh valve job and check the springs real good. I think the 2.02 is too big for the 318 bore unless you chamfer the top of the intake side of the cylinder bore. I have run 360 heads with the 1.88 intake and a light decking with great results.
I like the cam you already have. Maybe throw some 1.6 rockers on it.
 
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