'302 Head Work

[RAMM]

I have been coming around FABO for awhile now and am constantly surprised at how much interest their is in 318 builds and 318 cylinder heads. Now I have to admit, I understand the appeal of seeing what you can do with a 318 'cuz you already have it and are "bucks down".

So a couple of weeks ago my soon to be 17 year old son comes to me and says "He wants to fix up an old Mopar with me for his first car". I am shocked/excited and impressed seeing as how he never seemed all that interested in anything but video games and girls. I must've raised him right after all--insert tear here. Long story short I have a line on a decent t-top F-body so now being an engine guy I'm thinking "How can I build the kid enough power to have fun with, be driveable,get decent mileage (we are @ $4.66/gal) and do it as cheap as possible?"

At first I was thinking straight up 318 build with a small cam and tall gears. Naww-that wouldn't be any fun and I seem to like to do things the hard way. I've always wanted to build a 3.58" stroke 318 and after a buddy gave me a spun 318 I figured, here's my chance.

Now as I'm tearing the 'teen core down I'm thinking EQ Magnums OOTB but then I notice it has the '302 closed chamber heads-score! Then I notice the block has a flat tappet cam but is a roller block-second score!
So the build as it stands now is going to be a 3.93 x 3.58 resulting in 347 cubes.

To make a long story longer I formed a game plan on how to set the heads up and here it is. J.Rob

Step one - Give grungy nasty cores a spin in the Jet Wash. Then a ride in the Roto-Blaster. Check.

 

[RAMM]

Step two involves the guides and the valves. Since this is a budget build and since I have a few sets of used OEM Magnum valves here at the shop that is what will be used. So in order to utilize the 5/16" stem diameter of the Magnum valves I have to bore and ream the chunky 3/8" guide to accomodate an iron .437 o.d. .312" i.d. guide insert. No problem I'll just use my trusty Sunnen VGS-20. So to be clear I will be using a 1.92/1.6 valve combo in these '302's. Yes I will be turning the 1.625" exhaust valve down as I feel it is too large for no good reason anyways. J.Rob

 

[RAMM]

Since I am very interested in how well a '302 casting flows vs a '302 casting that has had a quick valve job cut for a 1.92 valve I am only doing the one intake for now. I will flow an untouched stock port with a stock valve and valve job. Here it is on the VGS-20. J.Rob

 

[RAMM]

So on to the flowbench it goes for a before and after comparison only a few minutes apart. I use a SF-1020 so don't get too hung up on the numbers as they are not what you might expect. The flowbench when used this way is a great comparison tool. The stock valve port flowed as follows:

Tested on a 4" bore @ 28" water

.1 48.2
.2 86.9
.3 130.2
.4 165.3
.5 175.3

I won't worry about the exhaust just yet.

Here's a shot of the Magnum valve compared to the stock 1.78 valve. J.Rob

 

[RAMM]

Here's what the 1.92" valve flowed with just a very small blending of the machining cuts that were left over from the valve job. I am not too concerned with all out flow numbers, in fact I am more interested in these questions:

Where do they flow what they flow? ie valve lifts
What does the port flow backwards esp at low lifts?
What does the port sound like?
Does the flow stall/backup? If so-How badly?

4" Bore fixture @ 28" water

.1 56.5 + 8.3
.2 101.1 + 14.2
.3 145 + 14.8
.4 173.5 + 8.2
.5 177.8 + 2.5
.6 180.2 No data from the previous test

Oddly the port didn't stall at the .430-.450 mark like I expected. Usually when you stick a big valve in a small port it wants to stall but as you can see the gains were diminishing quickly above the .450" lift range.(most 360 heads do) J.Rob

p.s. In this photo you can just make out the 5/16 cast guide I pressed in.

 

[RAMM]

Being the type of guy that cannot leave well enough alone I decide to do a quick and I mean quick pocket port and a very little bit of guide profiling. This is still with the untouched port opening. Remember these heads are being designed for part throttle economy/driveability while supporting approx 1 hp per cube and 1.12 lbs/cube (347 hp 390 ft/lbs) on 87 octane. I am not after all out flow--I am after efficiency which means port velocity (but not too much velocity). Here is what they flowed after about 20 mins of cutting with just a carbide. I leave everything as cut usually.

basic bowl/guide reducing-profiling

.1 57.3
.2 103.5
.3 149.5
.4 186 .42" 190 cfm was recorded
.5 187
.6 188.5

As you can see the port now has a slight stall, more than likely because I have inconsistencies in air speeds within the port. A noteworthy point was how the port sounded at the .400-.420" lift mark--it was smooth and quiet. As the valve was opened further it became louder but not turbulent with none of the undulations associated with a port that backs up real bad. I think at this point I might as well stop or I'll get greedy chasing that sweet sound and turn these into heads that are more race than street. J.Rob

 

[RAMM]

Ok so I wonder if the pushrod pinch can be altered quickly and easily to unlock some easy smooth airflow. After a couple of measurements I calculate that it should support 210-216 cfm give or take a few based on it's area. The pushrod hump itself is quite abrupt and I don't like how the port walls get closer together as they approach the roof which is already fighting for real estate with the valve cover bolt boss. I decided to use a straight wall carbide and knock the valve cover boss out and just ease the pushrod bulge back a bit while also squaring it up. Here are the results and I think I will leave them like this to be honest. I'm quite impressed with the flow stability of these little suckers. I believe they will get the job done and I don't have more than a few dollars into them other than the guides and valve seals. Here is what playing with the pinch did. J.Rob

.1 58.2
.2 106.2
.3 153.4
.4 186.5
.5 187.2
.6 190

 

[YY1]

Nicely worded. Even I can understand what you are doing!!

 

[CUDACOX]

Hey, I would like to know more of your build. I'm seriously considering rebuilding my #'s matching 318.Hoping to get as much H.P. and Torque as possible. Please share or P.M. me with your build. Thanks, Craig

 

[csx452]

Looking forward to hearing more. Good luck with your build. Looks great so far.

 

[1wild&crazyguy]

As ive been telling people..the 302 is the same port as any other 318 head....and also that even opening the window up to a 360 gasket only really yields a couple few cfm untill you get into 210+cfm range.
its again nice to see the superflow tell the same story my TP bench does.

Good job, keep it up cause yeah there are many who build these lil guys up.:supz:

Ill also have more to come in the '318 head porting for the average joe' where so far stock valved they go around 195/177cfm....though i wish i had all the tolling you have so i can play more with valve sizing.lol

 

[toolmanmike]

Nice work and an interesting read. I was stupid and sold a set of 302's. Now I wish I had them back. I'm looking for another pair. tmm

 

[Dartboy52]

Nice work, can't wait to see more

 

[Valvebounce]

nice work, can't wait to see more

x2!

 

[Hysteric]

Mine flow 228 at 520 lift with a Milodon street valve 3/8th 1.88. I didnt really take out alot of metal just a clean up in the bowls and a little on the ssr

I filled the pushrod pinch with brass stock and redrilled it to clear the pushrod. Total port volume ended up around 140+ cc.

Should know how much it makes in a couple of months.

Hysteric

 

[RAMM]

Mine flow 228 at 520 lift with a Milodon street valve 3/8th 1.88. I didnt really take out alot of metal just a clean up in the bowls and a little on the ssr

I filled the pushrod pinch with brass stock and redrilled it to clear the pushrod. Total port volume ended up around 140+ cc.

Should know how much it makes in a couple of months.

Hysteric

I was and still am seriously tempted to machine up 8 aluminum tubes and press them in the pushrod holes and go after the flow--but I need to keep my eye on the prize, and that is, street driveability, fuel economy, part throttle "tip in" and budget budget budget, with output tertiary.

If I were to get power hungry I would be using some EQ Magnums in the first place.

If I had to assign numbers to these goals it would be these-based on 347 cubic inches of old school LA Mopar.

347 hp @ 5800-5900 rpm
390 lbs @ 4400-4500 rpm (with a strong flat curve starting at 2000 rpm-I will dyno test that low as I know my 902 will do it on this little guy)

20 mpg with a AX-15 5spd Dakota tranny and a 2.76 rear

I'll ask you guys-Should I port these heads further?

Maybe I should start another thread covering the 347 build itself? J.Rob

 

[Badart]

Maybe I should start another thread covering the 347 build itself? J.Rob

Please do, I have everything to build one myself except for the MP 3.58 crank. Are you turning one down or buying the MP?

 

[66dartman]

Nice work, nice photos! How about the exhaust side? There is a bump in there, how much to remove safely? Keep up the good work!

 

[RAMM]

Please do, I have everything to build one myself except for the MP 3.58 crank. Are you turning one down or buying the MP?

I will probably turn a 360 crank down myself considering I have a few and a crank grinder. Although SCAT makes one that will drop right in AND it would be new--but that would not be very budget oriented would it? J.Rob

 

[RAMM]

Nice work, nice photos! How about the exhaust side? There is a bump in there, how much to remove safely? Keep up the good work!

I won't be removing any of the bump but I will polish the port up a bit. I'll flow it just to provide exhaust numbers for you guys, but I am not a real big believer that a flowbench can tell us anything useful when dealing with the exhaust. J.Rob

 

[Badart]

I will probably turn a 360 crank down myself considering I have a few and a crank grinder. Although SCAT makes one that will drop right in AND it would be new--but that would not be very budget oriented would it? J.Rob

Just labor intensive. Just kidding. Love the budget builds. Keep it up.

 

[moper]

I won't be removing any of the bump but I will polish the port up a bit. I'll flow it just to provide exhaust numbers for you guys, but I am not a real big believer that a flowbench can tell us anything useful when dealing with the exhaust. J.Rob

I agree.
And I'd say continue, but maybe not this head/engine. There are certainly a lot of grass roots guys who want that info, and it's not glamorous enough for the magazines.

 

[SirDan]

I'll ask you guys-Should I port these heads further?

Maybe I should start another thread covering the 347 build itself? J.Rob

Like you said before "keep your eyes on the prize". I think your current porting is good enough for what your looking to do.

I think you should start an engine build thread or a members restoration thread. I like what you are trying to do and your attention to details.

 

[CUDACOX]

Like you said before "keep your eyes on the prize". I think your current porting is good enough for what your looking to do.

I think you should start an engine build thread or a members restoration thread. I like what you are trying to do and your attention to details.

X2!! Give it!:director:

 

[flyfish]

I must say, when I first looked at this thread I thought to myself "Ugh!!...I hate 302 heads" because I like heads that flow well and make big power....but you got me thinking....I think I might have to tare into the 318 in my d150 truck to tinker a bit.

BTW, I like the pics and detailed explanation of the work. This thread is definitely what I would call "value added". Please continue.