360 heads on a 318

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trigger_andy

trigger_andy

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Hello all,
I hope Im not going over old ground here although I feel I will be but I have done some research and thought Id throw it out here and see what the experts think.

I have a '73 340 coming over from the US to the UK in the next month or so and will have that rebuilt to some spec but that will be a project that might take a year depending on funds. In the meantime I have an 318 running smoothly although I feel its underpowered even for a 318. I dont know what mods its had other than its got a 1406 Edelbrock Performer carb and Edelbrock Performer intake. (I have a 1405 calibration kit coming for the carb regardless what I do)

The 318 has standard 2843675 heads but I have a set of 4027596 360 heads and I fancy having ago at porting them and fitting them to the 318 as a small side project. Ive done my research on porting and Im itching to give it ago, if I bugger it up no loss really.

From what I gather the 2843675 heads chamber volume is 67-68-5cc with a minimum recommendation of 60.1cc. The 4027596 heads I believe have a capacity of 71cc so to keep even the same crappy CR I'll need to lose 3-4cc. Ideally Id like to up the CR but as Im not wanting to spend much money on the 318 as I have the 340 coming over in a few months.

So I guess my question is how much can I mill off the 4027596 heads and they will still be usable and a performance upgrade over the 160cmf 2843675 Heads? From what Ive read this head will need 0.0043'' off the head to drop one CC and I'll have to Mill 0.0095" from the intake surface for each 0.010" milled off the deck surface of the head.

Will the Edelbrock Intake and Carb still be usable? Obviously it will be jetted and the springs and rods changed to suit.

I doubt getting 2.02" valves installed will be worth it on an otherwise stock 318 and I also presume unshrouding the Heads will be of much benefit either? (all things planned on the 340. :)

Thanks in advance for the feedback.

Andy
 
I have never seen a 71cc chamber. They always spec out more. Typically around 76cc's. Your compression will be in the 7s with the 360 heads on the 318. Port the 318 heads instead and install 360 size valves.
 
RustyRatRod said:
I have never seen a 71cc chamber. They always spec out more. Typically around 76cc's. Your compression will be in the 7s with the 360 heads on the 318. Port the 318 heads instead and install 360 size valves.
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Thanks for the fast reply. :D

So in your opinion milling the head to the max is not an option? I really do not plan on messing with the 318 heads as I want the car running and on the road as I play around with this side project.
 
It's always an option. It's not how I would do it, but it's an option. You will also have to mill the intake to fit as well. Then, you will have an intake that will work on only one engine.
 
RustyRatRod said:
It's always an option. It's not how I would do it, but it's an option. You will also have to mill the intake to fit as well. Then, you will have an intake that will work on only one engine.
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Again I appreciate the feedback.

I know its not the best approach but its almost free and a practice at porting for me. The Heads are just sitting doing nothing anyway and Im sure most would consider them junk and scrap anyway. I can pick up an intake fairly cheaply I assume and mill that to match, so thanks for that, its not something I had considered. So I'll need to mill the intake side of the heads and mill the intake itself to match?

If this small project works then when I finally have the 340 built the 318 will be sold with the 360 heads, intake and carb. I'll be going another route with the 340.

Given that you believe these heads CC at 76cc then what do you think I could successfully mill off the heads to get good compression but not ruin the actual heads themselves?
 
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RogerRamRod said:
Get some 318 heads to mess around with, so you can still be driving.
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Thanks. :)

But I have these heads here so they are free. I have looked on ebay in the UK and there is no 318 heads currently.

Im wanting to spend as little as I can and to see what a difference the 360 heads will make when machined down and how much the experts think I can machine them down to provide adequate CR.
 
I just cc'd my "587" Jheads, tht are going on my 360. They checked in at 73-74cc. Not a big deal for me because I'm running zero decked flat tops.

I know this doesn't really help the op, but if you were building a 318 from scratch, and wanted to use 340/360 heads, are there pistons available to make up for the compression, or would the block have to be cut drastically to zero deck them?
 
I would be thinking around 74 cc's for the 360 heads. The amount of milling to remove 1 cc will be around .005" per cc. So removing .035" would do it fine, and you could remove more with no problems. I personally would go .050-.060" and other have reportedly removed more. IIRC , I have read of someone milling so much as to remove the open area of the chamber, which is .090" deep! Maybe some searches will give better info there.

And the minimum numbers that you find for chambers is not a 'recommendation'; it is the minimum to which a racer can mill heads and still be in compliance with NHRA rules. The listed minimum cc number allows every racer to equalize their head chamber volume to the same minimum size. It is not an absolute minimum for the head itself.

Be aware that thicker head gaskets (than stock, shim metal gaskets) are what you can buy nowadays, so you would want to buy .028" head gaskets (Mr Gasket 1121g). Unless someone knows of a thinner one.....
 
Awesome, thanks for the reply and info, there is a lot of confilicting and confusing info out there. I started make a word doc and its filled with such varied views even on FAO.

Do you have an idea what I would need to mill to get the CR up over what it is now? You suggest milling .050-,060" I like the sound of that, what would those numbers give me?

Im a little confused if I just mill the Intake or the Intake and intake face on the Cylinder Head as well?
 
I like what you said.
First, If I read it right, your going to give home porting a shot. Love it. Much to be gain by doing it. 2nd, I've NEVER lost performance by putting 360 heads on a 318. I've cut the 360 heads .040 and never had an issue with the intake bolting up.
3rd, I totally understand doing up a set of heads on the side and keeping the car drivable.

Here are some home porting videos I made for a project I did here for FABO that may help you.




 
318willrun said:
I like what you said.
First, If I read it right, your going to give home porting a shot. Love it. Much to be gain by doing it. 2nd, I've NEVER lost performance by putting 360 heads on a 318. I've cut the 360 heads .040 and never had an issue with the intake bolting up.
3rd, I totally understand doing up a set of heads on the side and keeping the car drivable.

Here are some home porting videos I made for a project I did here for FABO that may help you.




Click to expand...



Thank you! :D I actually read your whole thread a few times and its what got me seriously interested in starting. :) Thanks for adding the vids, handy for me to easily find again. I cant watch them just now as the oil rig Im working on has worse than dial up speeds but I very much look forward to watching them when I get home.
 
trigger_andy said:
Do you have an idea what I would need to mill to get the CR up over what it is now? You suggest milling .050-,060" I like the sound of that, what would those numbers give me?
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.050-.060" would certainly get you a few tenths of a point over stock. The best you could have stock is around 8.0-8.2. Starting at 8.0, and cutting .060" and using the .028" thick gasket will get you up to 8.2-8.3. Beyond, that, you need a piston change or deck work. Sealed Power 526 is the best price for a low cost cast unit. (But it does not sound like a piston change is in the plan for your 318; very understandable.)

How you would mill the intake and then go back and use it on the 340 is not making sense. If you mill off of the head surfaces instead, you take .0095" off of the intake faces of the heads for each
.010" taken off of the head's surface to the block. (This is per the Direct Connection engine mods book). Milling the intake is a different number.
 
nm9stheham said:
.050-.060" would certainly get you a few tenths of a point over stock. The best you could have stock is around 8.0-8.2. Starting at 8.0, and cutting .060" and using the .028" thick gasket will get you up to 8.2-8.3. Beyond, that, you need a piston change or deck work. Sealed Power 526 is the best price for a low cost cast unit. (But it does not sound like a piston change is in the plan for your 318; very understandable.)

How you would mill the intake and then go back and use it on the 340 is not making sense. If you mill off of the head surfaces instead, you take .0095" off of the intake faces of the heads for each
.010" taken off of the head's surface to the block. (This is per the Direct Connection engine mods book). Milling the intake is a different number.
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Ok, so even 0.60" and and .028" gaskets will not giving me much more CR but the bigger valves and small amount of port work will help the little bugger breath better. :)

Sorry, I must have mislead you. I have no intention of using any of this on the 340. The 340 will not use a single item from what I have for the 318. I meant that when I sell the 318 it will be sold with the 360 heads on so its irrelevant if the work done will not fit on anything else.

Ok, Im with you on the head milling. :) But just to clarify I will or will not need to mill the intake faces as well?
 
I personally wouldn't worry about final number on compression. For what your doing, I'd simply cut the heads .040, and not worry about the intake.
Flow over compression any day
 
318willrun said:
I personally wouldn't worry about final number on compression. For what your doing, I'd simply cut the heads .040, and not worry about the intake.
Flow over compression any day
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Really? Interesting, thanks. :)

I may just do that for easiness sake but if the heads are already in the shop would a few more cuts make a big difference to the cost? It seems like a cheap way to get a few extra HP with no extra work for me.

I'll be installing over the winter and driving all next season with the 318 so would be nice to squeese a few more ponies outta the old girl, but if you dont think its worth the hassle then maybe I'll just take the .040" off and enjoy as is. :)
 
Point is, I don't know how far you can cut heads before you HAVE to cut the intake. I'm saying I have not had a problem at .040 off the heads with the intake sealing/lining up. I usually use the .038 thick Fel Pro head gaskets. If you cut the intake, then it becomes an orphan. I wouldn't.
Again, I'd cut the heads .040, mildly open up the bowls, make sure to freshen up the valves. I don't think you will be disappointed.
 
318willrun said:
Point is, I don't know how far you can cut heads before you HAVE to cut the intake. I'm saying I have not had a problem at .040 off the heads with the intake sealing/lining up. I usually use the .038 thick Fel Pro head gaskets. If you cut the intake, then it becomes an orphan. I wouldn't.
Again, I'd cut the heads .040, mildly open up the bowls, make sure to freshen up the valves. I don't think you will be disappointed.
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Ok, I think you've sold it to me. Thanks for the advice. :D

When you say freshen up the valves you mean lapping or machine work?
 
trigger_andy said:
Ok, I think you've sold it to me. Thanks for the advice. :D

When you say freshen up the valves you mean lapping or machine work?
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Well, valve grinding is great. In fact, you can spend more money on the valve job and get a 3 angle, or even a 7 angle, and be more effective. Often times the exhaust valves need to be replaced. check the valve guides for slop. I just installed new exhaust valves and lapped. They need to hold alcohol. And no light should come through. I did a video also on lapping valves that show these checks. Valves that seal is a MUST for power, gas mileage and the running of the car.
 
318willrun said:
Well, valve grinding is great. In fact, you can spend more money on the valve job and get a 3 angle, or even a 7 angle, and be more effective. Often times the exhaust valves need to be replaced. check the valve guides for slop. I just installed new exhaust valves and lapped. They need to hold alcohol. And no light should come through. I did a video also on lapping valves that show these checks. Valves that seal is a MUST for power, gas mileage and the running of the car.
Click to expand...

OK, then I get home I'll strip the heads down and have a look. Looking forward to watching your vids too. I'll see what the local shop charges for 3 angle valve jobs, they have all the gear and a great reputation then take it from there. :D
 
I have the same 596heads on my 410 stroker that were on my 318 and it did 13.7 in the 1/4 mile. Isn't that about what a stock 340 abody would do in the day ?
 
j par said:
I have the same 596heads on my 410 stroker that were on my 318 and it did 13.7 in the 1/4 mile. Isn't that about what a stock 340 abody would do in the day ?
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Thanks for the feedback.

What work did you do to the heads and engine to get those numbers?
 
j par said:
I have the same 596heads on my 410 stroker that were on my 318 and it did 13.7 in the 1/4 mile. Isn't that about what a stock 340 abody would do in the day ?
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I'll say no to the stock 340 running 13.7's. Maybe if it had todays drag radials and at least headers, then maybe. And that would be the lightest duster with factory 3.91's. Actually, by 1973, the best times/speeds recorded for the 340 Duster with 3.21's were very low 15's at 93 mph. I ran this with my low dollar 318 (threw under 500 at a 318 2bbl) and 2.76 gears. And I believe the best times for the 1974 360 Duster were 15.80's bone stock from the factory.
Now we all know there was a lot more potential waiting to be released in these beast. A few cheap mods and a guy was off to the races :)
 
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