porting and valve questions about 318 heads

Posted By: rxod

porting and valve questions about 318 heads - 07/02/10 08:21 AM

I am rebuilding a '73 318 for my daughter's Swinger. I had the block line honed and bored to .040 over, squared up with .010 off the deck, added new KB 167 pistons to get zero deck height, all balanced. I will be using 318 Edelbrock Performer manifold and 600cfm carb. Since this will be a daily driver, I want to use the original stock #675 open chambered heads. The CR is at 9.5 with these 64cc heads and .040 gasket, which is good. My goal is to have good low end torque for her driving and decent high RPM power(6000rpm-ish) for my driving (ha). Does anyone have some advise for porting these heads and perhaps changing to 1.88/1.60 valves as opposed to 1.78/1.50 stockers. I don't want to lose the velocity by hogging out the ports too much but want to increase the flow. Is there a way to port match without going to gasket size?
Of course the next question would be what cam and springs to use? As always, thanks for your advise.

Posted By: scratchnfotraction

Re: porting and valve questions about 318 heads - 07/02/10 12:10 PM

I done a homepocket port on the bowls and bumped up to 1.88/1,60 valves

just cleand up the cut line in the bowls and blend it good

gasket matching the intake ports and intake to the gasket size(no tin 318 gaskets)felpro 1213 gaskets

I run a lunati 60710 roller cam in my 360 headed 318 and like it for a daily driver

i would suggest comp 901-16 springs,they are a single with damper,drop on no machine work,use stock seals and retainers( they will match up with any lunati sb cam)

next I would add a stock High stall torque converter,that will help the 318 out a lot

alnog with headers and I would try for a better intake like an LD4B and the 600 carb

I had good results on the last home port jog for a 318

my currant set up is

88 360 headed 318 4-v cop modor low comp and high mailage,never had the heads off it yet

600 carb
LD4B intake
lunati voodoo roller cam
258/264
207/213
.485/.485
headers with 2.5" duels
hs.lu a999 trans
8 3/4-3.23 gears
29x15x15 M/Ts

knocks back 18 mpgs and merges in traffic with attude in my 85 stepside truck

just remember that a 318 is ez to over cam so cam choise is the key to a good driver and not a dog out the hole

Posted By: rxod

Re: porting and valve questions about 318 heads - 07/02/10 07:03 PM

Thanks for that info. I'm trying to use what I got for now. I can always do a head and cam swap later on when she retires it as a driver. Thats why I built the bottom end well. I guess I may be better off with some 302 heads from what I've read, but I don't really need the higher CR with the pistons I'm using. They do have better swirl and quench I'm told. You are definately right about over camming. She will get more pleasure with more low end torque, especially with the 2.76 / 8.75 posi rear. I would like to be able to wind it out to 5800-6000 rpm without floating the valves. Thanks for the tip on the felpro gaskets. I have the tin ones and they looked to large to gasket match with. I already have the Edelbrock manifold and it has the smaller ports to better match her heads.

If I give her too much power, I might create a monster!! She already has driven my hemi cuda and got quite a thrill when I told her to go for it. (had to tell her to "back off")

Posted By: dulcich

Re: porting and valve questions about 318 heads - 07/03/10 01:39 AM

Quote:

I don't want to lose the velocity by hogging out the ports too much but want to increase the flow.

If you ported the heads until every interior port surface of cast iron is one molecule away from breaking into the water jacket you would not affect velocity in a way that will make you lose any noticeable torque.
-dulcich

Posted By: 70AARcuda

Re: porting and valve questions about 318 heads - 07/03/10 05:31 AM

Quote:

Quote:

I don't want to lose the velocity by hogging out the ports too much but want to increase the flow.

If you ported the heads until every interior port surface of cast iron is one molecule away from breaking into the water jacket you would not affect velocity in a way that will make you lose any noticeable torque.
-dulcich

interesting way to say 318 heads have small ports...LOL

Posted By: HotRodDave

Re: porting and valve questions about 318 heads - 07/03/10 06:49 PM

I built a 318 with the KB 167 pistons and .039 quench distance and 302 heads and I used the smallest cam I could find and it was fine on pump gas. I did run premium but the MPG was up so much from the high swirl, tight quench... that it was much cheaper to operate than the original low compression openchambered 2bbl motor. If you run any kind of performance cam with that combo it will bleed off enough cylinder preasure that you could still use low grade pump gas so I say deffinately go with the 302 heads, they are cheap and work very good even OOTB. That motor was very snappy and pulled hard to 5000 RPM and that was stock valve sizes and no porting. It was probably makeing 300hp or so. A little port work 1.88 1.6 valves and a slightly bigger cam and you should be makeing an easy 350 very streetable hp on 87 octane. I would use an comp cams XE252 cam, close to a 360 2bbl cam but a hair less duration and a hair more lift, it should keep your TQ up as well as build good HP. The real high rod stroke ratio of a 273-318-340 helps it pull a little harder in the higher RPM range than the cam and heads alone would suggest.

In short don't be afraid to run the 302 heads on that short block give it a little cam, port work and slightly bigger valves and kick some 5.0 butts

PS I would even mill the heads .030 or so for more comp and run 91 octane if needed.

Posted By: rxod

Re: porting and valve questions about 318 heads - 07/04/10 01:46 AM

Quote:

Quote:

I don't want to lose the velocity by hogging out the ports too much but want to increase the flow.

If you ported the heads until every interior port surface of cast iron is one molecule away from breaking into the water jacket you would not affect velocity in a way that will make you lose any noticeable torque.
-dulcich

noted

Posted By: rxod

Re: porting and valve questions about 318 heads - 07/04/10 01:51 AM

thanks hotroddave, I think I will go the 302 head route if I can find some locally.

Found a good article on porting various small block heads.

Chrysler small block cylinder heads casting differences and porting

Posted By: patrick

Re: porting and valve questions about 318 heads - 07/05/10 01:53 PM

another option, vs. buying used heads, or putting bigger (new) valves in are to pick these up from hughes:
Enginequest 318B "Iron Ram" heads

they basically flow OOTB better than a max ported 318 head with 2.02/1.6" valves will flow, are new, and have a nice spring package on them. you can find magnum rockers used for about $30-40 from the junkyard or fleabay, or about $90 new from rockauto, just get some 7.625" or so pushrods, and you're good to go. for a driver cam, I'd look at a lunati voodoo 60400 or 60401, or a comp XE250 or XE256