318 cylinder head upgrade

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dartswinger71318

dartswinger71318

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I have a 318 in my 71 Dart, I swapped the cam to a step above stock, Edelbrock intake and headers. The bottom half is stock. I am considering a head swap but with the pedestrian 8.5 - 1 compression ratio I want to select the proper cylinder head to not decrease the compression ratio further. Looking for options and opinions.
Thanks in advance.
 
dartswinger71318 said:
I have a 318 in my 71 Dart, I swapped the cam to a step above stock, Edelbrock intake and headers. The bottom half is stock. I am considering a head swap but with the pedestrian 8.5 - 1 compression ratio I want to select the proper cylinder head to not decrease the compression ratio further. Looking for options and opinions.
Thanks in advance.
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Get a 66 or 67 273/318 head and give it some porting and put 360 valves in it... The smaller combustion chambers on those heads will bump your compression up about 0.4
 
Options on the cheap:
  1. Port the 318 heads you have and have a good valve job done....
  2. Get a set of 302 heads, they'll help your compression (my opinion they won't flow any better than what you have and they are often cracked)
  3. get 360 heads and cut them .040, use a fel pro 1008 head gasket. I've never needed to cut the intake to do this.
  4. Magnum heads - which will mean different push rods, lifters and either drill the heads for LA bolt pattern or magnum intake.
  5. My opinion, 1 & 3 are your best choices.
 
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302 closed chamber head casting would help. Not sure what heads you currently have though. 65'
 
318willrun said:
Options on the cheap:
  1. Port the 318 heads you have and have a good valve job done....
  2. Get a set of 302 heads, they'll help your compression (my opinion they won't flow any better than what you have and they are often cracked)
  3. get 360 heads and cut them .040, use a fel pro 1008 head gasket. I've never needed to cut the intake to do this.
  4. My opinion, 1 & 3 are your best choices.
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There's another thread, can't remember which it is, Rockauto has those 302 heads for a reasonable price.
 
Ottmundr said:
There's another thread, can't remember which it is, Rockauto has those 302 heads for a reasonable price.
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they did, not sure if they are still available. To be stone-faced honest, in stock form I've always thought the pre-302 heads ran harder around shift point vs 302.
 
I have 302 heads and milled them to get 58cc, I would check piston height on your 71 the advertise was always different. I been wanting to go the magnum head route only problem is the damn intake would have to be different. 1:6 rocker ratio better flower and bump in comp.
 
Porting an otherwise stone stock LA 318 head?
On the cheap with a little extra money?
Install the 1.88 intake valves and leave the exhaust alone. Port the head and grab a split duration Lunati cam that works for you.
 
675 casting is a good one.
Just mill those .026 to remove 5 cc , shoul be about 63cc at that point, 1cc smaller than a 302. Save yourself the money..cause the 302 does not flow anybetter and any other head.
And for what it's worth... a 273 head is 66.5 CC's roughly. The exhaust port also has a better floor on the 302, 675, 163, 593.
 
Any thoughts on 1.88/1.60 and standing the valves proud in the chamber to use up a little more chamber volume?
 
dirty white boy said:
yup,..and like the chevy vortec heads,..run many a thousands of miles cracked with no issues, but nobody in right mind would bolt on a set known to be cracked...
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Sometimes, yes, they do. It all depends on where those cracks are though.
 
Don't overlook 920 heads. They are a 273/early 318 head. Closed chamber as well Oh and by the way, the head gasket in the picture is a original 273 steel shim gasket.

stock head gasket on 920.jpg
 
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For the build being described here, I’d just reuse the current heads with some mild reworking.
 
dirty white boy said:
more hate for 302s,..but thats what i suggest!
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It's not hate, maybe disappointment, but not hate.
Facts about those castings.
Don't let it bother ya.
No one has a dyno test where nothing but the heads were swapped to show they are any power benefit. It's all theory.
The flowbench shows that they aren't any better. They can be made to be as good as any other ...with tools most people dont have.
Other than that, to own them is nothing more than a badge imo.
 
There are 3 advantages of 302 heads over ... a bit more compression, harden seats, less timing needed ( more timing is negative energy) And as stated MANY times
prone to cracking.
 
If I were building a “mild” 318(call it “around 300hp”), and the core motor I was going use had them on it already, and they weren’t cracked, I’d probably use them.
But it would be pretty much the same case for just about any 318 heads that were on it.

If I wanted to try and “make some power”........ I’d use heads that had higher ootb flow numbers as a starting point.
 
Whoever said that having more timing is a negative needs to stay the fk away from me. lol

Timing is dependent upon chamber shape, and 'mainly octane tolerance', more I suppose as well.. but need I say more.
 
MOPAROFFICIAL said:
Whoever said that having more timing is a negative needs to stay the fk away from me. lol

Timing is dependent upon chamber shape, and 'mainly octane tolerance', more I suppose as well.. but need I say more.
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Earlier combustion pushes back against piston coming up (counter productive) This is the reason why new engines combustion chambers burn faster than their ancestors. 302 head was an early example.
 
66jim said:
Earlier combustion pushes back against piston coming up (counter productive) This is the reason why new engines combustion chambers burn faster than their ancestors. 302 head was an early example.
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in theory my friend. If advancing the timing 'if needed' makes more power ... not a negative.
If what you're saying was so important we all have one degree of timing before top dead center so take that desperate argument for a 302 head and sell it to someone else.
 
MOPAROFFICIAL said:
in theory my friend. If advancing the timing 'if needed' makes more power ... not a negative.
If what you're saying was so important we all have one degree of timing before top dead center so take that desperate argument for a 302 head and sell it to someone else.
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I'm not selling anything? Don't understand your statement it is incoherent Please educate us all.
 
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