318 low budget heads change

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4drzdart

4drzdart

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Hi,

I hope it's not because I did not research properly, but did not find an answer to the following question.

This winter I will be working around the heads (intake + headers), so maybe a cheap head change would be worthed.

I have 3 choices, would like your input on if worhty or not:

1 - 1978 360 heads - free
2 - 318 casting 302 - 125$ / pair
3 - 340 casting J (don't know the year) - 250$/pair

All of those are complete, would reuse the valves, but change the seals and use a set of thin head gaskets. If budget permit a cam change is also in the plan.

The engine is a 1972 318, all stock (the compression checked good), Holley 1850, performer intake , headers + dual 2.5" exhaust.

I have a complete 360 but don't have the thousands of dollars needed for a complete rebuild. But for some stock heads and a cam that I could afford, if worthed.
 
You'd be best off with the 302 castings on a 318. The 360 heads on a 318 drop compression and don't offer much added flow that the 318 can take advantage of. The J heads are nice for the big valves and such, but again, you wouldn't see a big advantage with the 318. The heart combustion chambers on the 302 castings are the way to go for a 318.
 
I would normally agree except you did not say what it is you wanted from the engine or how the car is to perform. Free 360 heads is a home run.


What is your gear ratio and tire size?
Do you have a cam in mind for use?
 
I vote 360 head because they are free!! Spend 65 bucks to have 'em milled .040 to help the compression, and the rest of the money you saved by using the free heads can go toward the cam. If your using headers, the 360 heads would see positive flow gains over the 302's. If you add the mild cam, the 360 heads would be even of more benefit. And the '78 heads have hardened seats for unleaded fuel...
 
That's the way I kind of see it unless he is going to use a real mild cam and Hwy. gears.
 
don-vee said:
You'd be best off with the 302 castings on a 318. The 360 heads on a 318 drop compression and don't offer much added flow that the 318 can take advantage of. The J heads are nice for the big valves and such, but again, you wouldn't see a big advantage with the 318. The heart combustion chambers on the 302 castings are the way to go for a 318.
Click to expand...

As Mr. Don-Vee stated,,,,,,,,,

The Casting #302 Cylinder Heads are the easiest choice, as they will bump-up Compression and
will add to the needed Horsepower in the 1972 '318'.

The #302 Casting is a good general purpose 'low-to-mid' Performance Cylinder Head,
which relates to 'functionability'.

But, these Heads have a tendency to 'crack', and usually where you can't see it visually,
under the Valve Seat or between the Valve Seats.

I would never put a set on any Engine without having them pressure tested on an 'AXE' Cylinder
Head Pressure Testing Unit first.

Probably $50 to have the set of Heads 'Pressure Tested'.

Sounds like you want a 'Low-Budget Upgrade', and it wouldn't cost that much for a
basic 'standard' or 2-Angle Valve Job.

If the Cylinder Head Surface is 'square' {flat and not warped at all}, you can get away without
Milling them, and utilize a Thin Cylinder Head Gasket..........

Does that sound like the direction you want to go in........
 
Unless your gonna port the 302's there a waste of time they flow the same as open chamber 318 heads and the compression bump you'll get will be about .5 on your CR which at best is a 2% power increase and from what I understand 318 factory gasket is pretty thin so if you go with an average gasket size you'll lose any gain.

Go with the 360 heads mill them down, the flow will offset the Compression check out the low compression 440 build on here.
 
273 said:
Unless your gonna port the 302's there a waste of time they flow the same as open chamber 318 heads and the compression bump you'll get will be about .5 on your CR which at best is a 2% power increase and from what I understand 318 factory gasket is pretty thin so if you go with an average gasket size you'll lose any gain.

Go with the 360 heads mill them down, the flow will offset the Compression check out the low compression 440 build on here.
Click to expand...

I'd have to agree. Flow trumps compression.
 
I think it was SirDan that took an early 70s 318 and slapped on a set of 360 heads with a 340 cam and a 4 speed...he seemed pretty pleased with the general performance. And I'm inclined to agree with the part about having them shaved and using a shim head gasket...if you have the cash to spare afterwards, I bet the Lunati 256/262 Voodoo grind would be great in a cruiser.
 
Thanks for all the inputs. :thumbup:

The car will not see the track, but I would like that it can lay some rubber and get off a corner with ease :D .
The tires are 235/60 r15, the gears need to be change this winter and I am leaning toward 3.23 or 3.55 depending on the deals.

From your comments, I think I will go with the 360 heads, and check if i can have them milled a couple of 0.01.

I will for sure look to change the cam, but I have no idea of what cam I would need to help it breathe better with that combo. One thing for sure, is that I like the lumpy engines, not too extreme but a little is nice.
 
I'm currently running e 318 with 360 heads, performer intake, carter 625 carb, headers with 2.5" exhaust and a mystery performance cam. Car has a 904 trans with about 2200 stall converter, and 3.23 gears in a sure grip 8.75 rear end.

Bottom line? The car goes pretty good; I certainly have no complaints. Plus, thanks to the low compression I can run 87 octane fuel with no issues. That is a huge bonus if you like to put a lot of miles on your car. Where I live it adds up to a difference of about $8 per tank.
 
autopar3000 said:
I'm currently running e 318 with 360 heads, performer intake, carter 625 carb, headers with 2.5" exhaust and a mystery performance cam. Car has a 904 trans with about 2200 stall converter, and 3.23 gears in a sure grip 8.75 rear end.

Bottom line? The car goes pretty good; I certainly have no complaints. Plus, thanks to the low compression I can run 87 octane fuel with no issues. That is a huge bonus if you like to put a lot of miles on your car. Where I live it adds up to a difference of about $8 per tank.
Click to expand...

That sure looks a lot like what I would like to do to my car. Did you had any work done to the heads?

and yes running 87 octane is a plus ...
 
Nope, heads are bone stock small valve 360 heads. The only non-stock item is the thin Mr gasket ultra seal gaskets, but those probably don't add much more than .25:1 additional compression. If I ever have them off I'd probably get them milled a bit, but for now I'm not gonna fix what's not broken.

The only thing I didn't mention is that I'm running a Mopar orange box for ignition.

To be honest I lied a little when I said I had no complaints. I'd like to have a little more torque down low, but I think the bigger runners that come with the bigger heads impact the fuel/air velocity, so more torque with my current setup might be hard to come by.

I'm thinking about getting a cam expert to give me some advice on which cam would be best matched with the rest of my setup, because we all know the wrong cam can kill a good motor and the perfect cam can make an engine perform stronger than the sum of its parts. The cam I currently have is probably just "OK".

I think if you get the perfect cam for your setup you can maybe find that extra torque I have been looking for.

So, how about it FABO cam experts? What would you recommend for the setup that me and 4drzdart currently have (or 4drzdart is soon going to have)? The basic setup is described above, and the goal is to maximize hp and torque while having a lumpy idle yet maintaining drivability. Any ideas?
 
That's the 'draw back' with the 360 Cylinder Heads mounted on the 318.

'Low-End' Torque.

You need more Cam with the 360 Cylinder Heads, or the gain is about 'equal'
on the Steet.

#302 Heads.....................{Better Bottom-End and Low-End Torque}
#360 Cylinder Heads........{Better Mid-Range and Higher RPM's at Top-End}

If you're not changing the Camshaft........... ???
 
I'm not sure.

Years ago, I had the same cam which is presently in the Dart, in my old Landcruiser. The cam is an unknown independent mechanical regrind that's supposed to be "about the same" as the 68 340 cam.

I once had a smogger mid--70's 318 in the FJ-40, with 340 J heads, and seemed to me it was a little doggy "at the bottom." LC had 4:11 rear, A-833 4 speed and Jeep transfer case

The present 318 in the Dart is a similar engine, (mid 70's smogger) except stock heads. Headers, 727 TF, and 3.7X rear gear, runs about 3300 at 70. It seems to me it's a LOT better at bottom end with the little heads, but I'm not sure it "gave up" much on the top end, either. The fact is, for what I have into it, it's fun to drive.

In other words without taking measures to gain back the lost compression, I'm not convinced the "big heads" are worth it. These smogger engines are already low compression, and run just fine on cheapest fuel I dump into it. I'm not sure I'd want to lose any more compression for bigger ports..
 
Correct 67 Dart 273

The 1972 318 has a Compression-Rating of {9.23 - 1}, and that is with
the Piston set at below deck -.056",,,,,,, and a .036" Thickness Head gasket.

Of course, we know that it is nowhere near that Ratio,,,,, out of the Factory.

And the 1972 318 Heads {Stock} are 'Open-Chamber' with CC's in the 68 Range.

Those 360 Cylinder Heads {73 CC Chamber's @ Stock} will just devour the
Compression Ratio level, though they do offer a nice Flow with the right Camshaft.
 
Ok,

so I called a shop in my area, and they ask 200$ for milling both head (including intake face), have the heads magnaflux and check them for leaks. Sounds fair ...

Can't seem to find the info, but I read somewhere that each 0.01" milled remove ?cc in the combustion chamber of the head. Anyone knows on a 360 head?

Also, if I have the head mills by 0.05", the intake side need to be milled also. I have found this chart http://www.mymopar.com/downloads/intake_head_milling_chart.jpg ... anyone can confirm these numbers?

Based on my shop manual, I have an amazing 8.4:1 compression from the factory ... :banghead: better not lower that number
 
.020 on block side and .019 on the intake side. it is about 1 cc per .005 milled off the block side. This should get you down to 68-69 cc on the largest chambers. This is for untouched heads. I said .020 since that is up to "no extra charge" for milling at my machinist. My numbers are for Chrysler small blocks taken from the Chysler racing manual. I have used these numbers for 30+ years and have never had a problem. The numbers are for every .010" removed from the block side remove .0095" from the intake side of the head. It takes .0048" to reduce chamber volume 1 cc. The chart you looked at was for big block heads.
 
We cut a set of 360 heads .045 once and did not cut the intake side at all. The bolt holes for the intake actually lined up better as our machinest suggested they would
 
If you are running a manual trans the 360 heads will certainly work better. The torque issue does show up more with the automatic. I had 360 heads on my 75 Dart and went to mildly ported 302 castings with new small stem valves and saw little difference other than the $ out of my pocket. The 360 heads actually pulled stronger on the top.
 
I had a 72 318 , milled the heads put in a mild cam ,headers , holley intake with a thermoquad and the car pulled well . Did great burnouts with the G-60 Kelly Supercharger bias ply tires . 318 is a decent engine , plenty of fun on the street .
Good luck with yours , ans above all have fun .
 
You sure about those factory compression ratings?

My info shows 8.6:1 starting in 71. The last year for 9.2 was 69 until the "pre mag" roller 318 with the 302s.
 
First, if you want success, you need to throw the term "low budget" in the garbage can. If you want any type of performance boost from heads, it costs money. Period. It will always cost more than you plan. You might be better off buying new aftermarket castings, depending on the condition of what you have available. If you constrain yourself to "low budget" you may as well scrap the car hobby and take up tiddly winks.
 
First of all, FORGET the '302's. Unless heavily worked (ported) they will not do one single thing in your quest for improved power.

Moving on, I would be prepared to spend some $$$$. I would bolt a pair of these on.

'915 Ported (243 cfm @ .450") bronze liners down to 11/32" 2.02/1.60 S.S. valves, milled to 59 cc, milled intake face to correct, machined guides for lift and positive metal clad Viton seals, etc.... J.Rob
 

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