302 heads for 318

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Small_Block

Small_Block

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I plan on putting 302 heads on my 74 dart 318/904. My question is if I decide to do this and a cam will it be a waste of time if I don't put an intake and a 4bbl immediately? I was hoping to do the heads and cam and still retain the stock intake and 2bbl for a little bit until I save enough to get the remaining parts. Will the stock 904 tranny hold up fine with the new additions?
 
I'm running a stock 904 with the exception of a shift kit, it's held up so far.
 
If your plans are to add a 4bbl later, then put your 2bbl back on and drive it till ya get the intake and carb.... Just don't expect much of an increase in performance with that 2bbl on it..
 
It will run fine, you just won't see a performance increase until the engine can breathe through the 4bbl
 
Personally I would collect all of the desired parts and then do the changes.
 
Long story short.Heads and cam won't show a huge jump with out the carb but the carb won't show a huge gain without a better exhaust.You have to move more air IN and OUT to get a huge gain.But doing the heads and cam is fine but adding the 4bbl and headers will show up better.Keep in mind the pistons are a big HP killer in the 318.If you put the 2bbl back on try not to over jet it as you want the A/F ratio to be right more than just throwing jets at it.
 
mopar410 said:
Long story short.Heads and cam won't show a huge jump with out the carb but the carb won't show a huge gain without a better exhaust.You have to move more air IN and OUT to get a huge gain.But doing the heads and cam is fine but adding the 4bbl and headers will show up better.Keep in mind the pistons are a big HP killer in the 318.If you put the 2bbl back on try not to over jet it as you want the A?F ratio to be right more than just throwing jets at it.
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Exactly. When I did mine I bought a piece at a time until I had everything, cam with accessories, headers, intake and carb.

Installed everything, broke the cam in properly and let er rip.

And if you are doing a cam swap, might as well throw a new water pump on it too while you are there.
 
To answer your questions, yes, you can do the cam and heads and retain the 2 barrel. Yes the 904 will be fine.
 
Bad Sport said:
Exactly. When I did mine I bought a piece at a time until I had everything, cam with accessories, headers, intake and carb.

Installed everything, broke the cam in properly and let er rip.

And if you are doing a cam swap, might as well throw a new water pump on it too while you are there.
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I agree why do it twice on the intake? also agree on waterpump if you dont change it then you prob will down the road sooner than later been my experience,I'd wait and do it all at once including a good roller timing chain and headers,what cam you go with?
 
thanks for the quick replies! The only thing currently done to it is 2.25 piping with an x pipe and turbo mufflers. This car is my daily driver so I was hoping to retain reliability and reasonable gas mileage. Plus I'd love to have a little more power under the hood just to play around with and maybe have a chance against my dad in his 68 cougar. Also I have a quick question about electronic ignition, my car was equipped with it from the factory but would it be beneficial to put on an aftermarket ignition?
 
Not sure what cam to go with...any suggestions? Im looking for good low end torque and something that won't break the bank.
 
HEI upgrade would help. Contact Trailbeast on the board here, he makes kits.

http://www.forabodiesonly.com/mopar/member.php?u=19664

Like rbdart pointed out, doing the intake and 4v at the same time would be a good idea as you will be removing the intake anyway.

You already have dual exhaust so that will help. A 600 cfm carb should get you what you want, or have RustyRatRod build you a Thermoquad.
 
Ditching the turbo mufflers for a different type will free up a noticeable amount of hp
 
The cam is the weaks part for performance in a 318
A cam will make a huge difference even with a 2 bbl because even a 4 bbl is only used as a 2 bbl 99% of the time. A stock 2bbl will be a restriction (mainly at wide open throttle) and cost some HP over a 4bbl but will flow enough fuel and air for your mild 318, my cousin's stock car's with a build 360 runs only a 500 cfm 2bbl (class rules) making close to 400hp. Side note 2bbl and 4bbl cfm ratings are different so a guesstimated 800 cfm 2bbl equals 600 cfm 4bbl.
 
RustyRatRod said:
This would be a nice one.

http://www.summitracing.com/parts/dcc-4452759ac/overview/make/dodge
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Perfect cam for your combo and you can run your stock covertor,the 904 tranny should be fine,good low end torque and mild street manners for your 318 with 302 heads,headers,intake[have you got one or still looking?] 4bbl carb,even if you have to use a factory cast iron 4 bbl intake they work great as well,a good thermoquad[thats in good condition and functioning properly] will be a good choice for a carb for power and fuel economy they will far outperform any edelbrock carb in every way has been my experience,as far as ignition if your stock one is workng good use it and if you suspect it's crapping out on you then go to the internet and look up Skip White in Tennesse for a new HEI self contained distributor they are plug and play 2 wire hook-up and does away with the old ignition box[brainbox] and ballast resistor,they are tested to 12,000 rpm,have roller bearings and parts are cheap and readily available and they flat out work and are trouble free and the best part is they are less than 60bucs to your door,I have and am using these distributors for about 8 yrs so I know they work,and you will have better start-ups and quicker acceleration and fuel economy,they also have adjustable vacuum advances..bottom line gather your parts and try to get it all done at the same time it will be worth it in the end.....
 
Small_Block said:
4bbl's don't always cost you gas mileage. When your going to the store to get bread, your only using 2 of the 4 barrels. So, in a sense, a 500 cfm would only be 250 cfm puttn around town, or cruisn 55 mph. The only time them 4's are open is when your foot is down. Jett'n is important too. A good dual plane intake and a 500 or 600 cfm 4bbl won't be a gas killer, unless it's jetted rich. Another option would be a spread bore, given real small barrels in the front (for daily driven), and whoppers in the back when ya need it...
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You've got the right idea. Everything can work just fine, but I agree with keeping it all in one swap, though.

The primary barrels on the carb I went with are smaller than the 2bbl carter that was on the Scamp.

I eneded up rebuilding the low end, because I discovered the factory cam was trashed from new oil (no phosphorous).

The cam that Rob suggested from Summit looks like a bump up from a stock 340 cam, with a good split duration for full exhaust like you have.

The one I'm running is a .461/.489 with a quick ramp and puts the cam right where the limits of those heads are at, without cutting the guide seats for more retainer to stem seal clearance, so that Summit cam should work great with a new set of lifters and correct springs.

All together, I think I've got about a $1300 in the top end of the motor, with the carb, intake, what the cam set is currently going for and heads with valves are going for.

I spent some money on pistons and machine work. I got the heads for free and I had the cam sitting for another engine build for years, so it wasn't as much out of pocket.

I think you should get the parts as you can afford them and get them all ready to do the top end of the engine.

Just out of curiousity, what oil are you running? I haven't found a decent oil that isnt chalked full of extremely high levels of detergent, suitable enough for any ZDDP additives. I'm running Brad Penn's Penn Grade.
 
If you look around and have a little patience you can do really well in the parts department.
I also have a 318/904
It took me almost a year, but this is what I got and what I paid.

Edelbrock 2176? dual plane in near perfect condition = 60
Edelbrock 1406 600cfm electric choke like new = 40
Edelbrock spacer/insulator = 20
Chrome air cleaner = 10
Fabricated alum valve covers = 60
1 5/8 Hedman aluminized headers = 210
Double roller set = 40
MP purple cam and lifters (new) = 100
HEI ignition = 25
Yellow 8mm Accel wires = 45
2.5 aliminized dual exhaust with X = (with flowmasters) = 250

Mine is set up all about fuel economy since I daily drive it all over the county, and is getting an Innovate wideband A/F kit for down to the knat's *** tuning.

The plan is to run what I have right now except for the cam and timing set, and pick up a 360.
I'll have the 360 heads milled and put them on the 318 while I do the bottom end of the 360 over time.

Once the 360 bottom end is done and has the cam and timing set, then the 360 short block will go in with all the stuff that is already on the 318 now.
One weekend and there ya go.
 
Thanks for all the advice! I'll just wait to gather the all the parts then put them on. Where is the best place to get these heads? Junkyard? I was going to get them from a local O'reilly's for about 250 a piece with a $65 core charge, everything thing is included but I feel like it's a bit pricey. I have checked the local junkyards and haven't found any small block dodges to scavenge the parts from.
 
Small_Block said:
Thanks for all the advice! I'll just wait to gather the all the parts then put them on. Where is the best place to get these heads? Junkyard? I was going to get them from a local O'reilly's for about 250 a piece with a $65 core charge, everything thing is included but I feel like it's a bit pricey. I have checked the local junkyards and haven't found any small block dodges to scavenge the parts from.
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Same thing I went through, and no way was I paying 500 for them.
That's why I decided to get a whole 360 and use the heads on the 318 temporarily.
I figure to do the heads once and then use them on the 318 for now, and then put them on the 360 when it's ready.
They will be milled for the compression on the 318 and be higher compression heads when they go back on the 360 later.
 
You'll be paying for heads with parts you won't exactly be using at O'Reilly's.

The valve springs will go away. You will need the matching valve springs for that cam. If you get rotator valve retainers with the heads (some have them, some don't), you'll want standard retainers to use the springs that go to your cam.

If you get a set from the bone yard, the faces of the seats on the valves are likely going to be pitted. They have inductive hardening, so the intake and exhaust seats usually survive and don't need more than lapping compound, but check them closely.

The valves that were in the used 302s that I built had quite a bit of pitting on the exhaust side and some on the intake. I would have refaced the valves, but the seat faces were pretty expanded from use, so I dumped a set of stainless valves in.

The valves that I got were standard stem and checked out just fine. The guides were in good shape. I just lapped the seats until all of the bright streaking on the new valves were gone. Sealed just fine.

When I did the valve swap, I lost the flat faced valve and it bumped the CC in the chamber up to 62cc. The advertised cc is 59, I think it's closer to 60.

When I put mine on, I had a problem with gasket seal on one side. I ended up taking them back off and having them squared up and cut .010". I'd suggest getting them checked out by a good head builder, even if you end up doing the work.
 
I don't think the 302 head swap is worth it unless your milling and porting not much gain for the money. You'll get about .5 CR if you use the same thickness gasket as factory and from what I could find out there fairly thin 0.02?' if true a with a standard gasket you would see no increase in CR. If you mill about 0.020" off your heads you would equal the compression bump 302 heads will give you anyways and 1 CR point is said to be 4% HP increase so .5 would only be 2% which on a 200-250HP engine would be 4-6 HP which equals a $100+ per HP. So unless you get a low mileage set for free or close too it I don't think its the best swap get a set of Magnums or better yet EQ's.
 
Unless your heads need replacing spend the money on the carb and intake and do your swap now. Plus headers and gears (depending what you have now) swap I'd do over head swap.
 
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