318 head thoughts....

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MOPARJ

MOPARJ

What can I upgrade now?
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Currently running a 73 318, with a Street Demon 600 cfm carb, Comp Xtreme Energy 268 cam, hooker 1 5/8 headers, 2.5" piping, with Dynamax Ultra Flos on my Duster. The intake is an Edelbrock Performer, converter is 2500 stall, 3.21 geared 8 1/4. Currently running stock cleaned up heads, stock valve size. What do you guys think about pulling the current heads off, cleaning them up, adding 1.88/1.60 valves, and running a .028" thick head gasket? Just thinking aloud. Always looking for ways to get more. Makes at least 275 horse now, and at about 43,000 miles since the rebuild 5 years ago. Still burns no oil and has good oil pressure.
 
Yep, what you mentioned will add horsepower, or you could use a good 360/340 head (LOOK OUT! here come the compression screamers!). Both will add horsepower. I personally would find a set of "308" 360 heads. Have them cut .040 thousands and bolt them on. But yes, what you mention will work fine too.,
 
I am your man. I have a set oh already done #302s. 1.88 1.60 3 angle valve job, ported to remove pinch point also bowl work and gasket match, cut .015 to 56cc chambers.
 
mini said:
I am your man. I have a set oh already done #302s. 1.88 1.60 3 angle valve job, ported to remove pinch point also bowl work and gasket match, cut .015 to 56cc chambers.
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Have these been run as of yet? Is the intake face and ports untouched?
 
The 302 heads with the big valves will work the best.and you wont need to worry about thin head gaskets.member saetun has them on his teener with everything else the same as you his car runs rral strong...
 
I was under the impression that you couldn't run a cam like that with stock compression, and the Comp site says 9.something to one.
Did you do something to alter the compression already before this?

just curious because I had somewhat the same plan but using cut 360 heads.
 
TrailBeast said:
I was under the impression that you couldn't run a cam like that with stock compression, and the Comp site says 9.something to one.
Did you do something to alter the compression already before this?

just curious because I had somewhat the same plan but using cut 360 heads.
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You certainly can run up to about the size of an XE268 cam (.477/.480 lift), but that is just about it without a lot more stall and numerically higher gearing. Minimum 3.21/3.23 gearing. Mine runs pretty good with the open chamber heads. Decent torque, although a little soft below 2000 rpm, but pulls right up to 5500 rpm.
 
J, What's the initial timing on your 318?

That will make a huge difference in that bottom end performance.

The 302's in good shape would be a good, though no more shaft rockers. The 340-360 heads would be an easier swap as rocker stuff transfers right across. I have a bunch of 1.88 340-360 heads if you are looking for a pair.
 
crackedback said:
J, What's the initial timing on your 318?

That will make a huge difference in that bottom end performance.

The 302's in good shape would be a good, though no more shaft rockers. The 340-360 heads would be an easier swap as rocker stuff transfers right across. I have a bunch of 1.88 340-360 heads if you are looking for a pair.
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About 17 initial right now. 34-35 total by 3000. Stock cardone replacement distributor. Haven't been running the vacuum advance. Would like to pull a little more mileage out of it as well. I have been thinking about jumping up to a 3.55 or 3.73 gear to help the bottom out, but not sure I want to give up 2800 rpm cruising at 68-70 mph.
 
crackedback said:
J, What's the initial timing on your 318?

That will make a huge difference in that bottom end performance.

The 302's in good shape would be a good, though no more shaft rockers. The 340-360 heads would be an easier swap as rocker stuff transfers right across. I have a bunch of 1.88 340-360 heads if you are looking for a pair.
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Huh? 302 ARE shaft mount heads. I think you're confrooshin um with magnums.
 
MOPARJ said:
You certainly can run up to about the size of an XE268 cam (.477/.480 lift), but that is just about it without a lot more stall and numerically higher gearing. Minimum 3.21/3.23 gearing. Mine runs pretty good with the open chamber heads. Decent torque, although a little soft below 2000 rpm, but pulls right up to 5500 rpm.
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Thanks for clearing that up.
 
I don't get why people still recomend the 302 as the hot ticket for a 318 I wouldn't run any 273/318 head unless the plan was to port them and spend virtual no money on them. Magnum have closed chambers and way better ports, if your looking to do it on the cheap grab a low mileage set off a 5.2/5.9 at the local scrap yard or spend some $$$ on a set of EQ'S. If I was building a 318 for scratch with higher CR pistons 340/360 heads would be an option. But in your situation any mods (port/ mill) you do to the 340/360 heads can also be done to the magnum heads and the mags will always give more CR.
 
I sware by the #302's. So you have to do a little work on them to unleash their potential, you end up with a great head with shaft mount that you can rev to the moon. And you don't have to change your intake.
 
OK... I had them listed as 302 in the picture. Have to look at the casting numbers again.

Stud mount, no oil hole should be a clue.. huh... :)

Lazy today.
 
Yeah. The 302s are shaft mount. I promise. Had many a set.

Hell, why not just grab some RHS heads? That way, you'll already have the good stuff if you ever upgrade to something bigger.
 
mini said:
I sware by the #302's. So you have to do a little work on them to unleash their potential, you end up with a great head with shaft mount that you can rev to the moon. And you don't have to change your intake.
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I agree with if your willin to do the port work but I have a feeling 99% of the people putting 302 heads on are unported there for no real power gains for the time, effort and money.
 
I have a set of 318 heads with 1.88" valves and porting sitting on my shelf for when I may want to run the small port heads.

there's nothing wrong with going in that direction also.
 
318willrun said:
Yep, what you mentioned will add horsepower, or you could use a good 360/340 head (LOOK OUT! here come the compression screamers!). Both will add horsepower.
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The increased flow will trump the compression drop.


I have put many 340/360 heads on a 318.


However, if you want to put 340/360 heads on a 318, the best way to do that is to get a set of 10.5 pistons for a 318, and then with the larger combustion chamber of the 340/360 head, it will end up at 9.2 compression. Perfect for a street motor on pump gas.....
 
What I have noticed is that the 318 head is underrated and a decent head to inexpensively upgrade. I have gone into the low 13's with 360 valves only.
360 valve sizes are an excellent upgrade. Once you enter the word "Ported or porting" a head, the choice is the flow the current head can deliver vs. the flow and cost of a head all ready done for you.

The question is, can you upgrade your current heads cheaper than a set of EQ's RHS's, Edelbrocks, or another set of stock heads? You must figure in the purchase price of stock or Edelbrock heads and then then cost of work.

The RHS/EQ heads can be purchased from one of in house engine builders all done and ready to rock. As well as the other heads or yours if you send them to them.
 
Thanks for all of the advice guys.

On a secondary topic, what gears would you guys suggest? Suggest a bump up to 3.55s or 3.73s? I guessI wwouldn't mind turning 3400-3500 at 65-70mph. Just not sure if its worth the low end performance gains over the current 3.21s.
 
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