318 head porting for the average joe

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Valvebounce said:
Hey @MOPAROFFICIAL
Any progress with the above picture? I'm quite sure I'm not the only one who's curious to see what kind of numbers the larger valve produces?
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The port in the pic shown flows almost 20 cfm better up to .400 lift. Within 4cfm of its peak by .400 lift as well.
The .1oo lift is 60 cfm... as opposed to 45 or 48cfm as cast @1.78
There's plenty to be done in that it's a ledge at the ssr still. Thats with an old dirty wire wheeled stock 1.88 valve I had handy.
I'm editing , probably tomorrow.
 
Excellent work so far MO!

Great to see guys 'like you' taking the time and trouble to help the 318 crowds lol...

The turbulence after .400 in the YT #3 vid was quite a shocker with such small SSR work?

Have you done Episode 4 as I can't find it LOL...

My early 318/273 closed chamber heads, have the 1.88's already fitted but I don't have access to a bench.
I'm hoping this wasn't a big step backwards as the exhaust seat work cost £400 already DOH...

302 1.88 intake.jpg
 
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Obviously any port is a balanced 'flow path' from carb to valve.
All Mopar heads have a pinch point for the pushrods etc.

So any port must transfer a rectangular orifice to a circular one.
CSA should remain somewhat constant throughout the flow path.

When doing modern heads with 4 valve set-ups, we tended to go for a slight 'funnel effect'.
Much easier with a straight port with an approx 45 degree angle around the valve stem.

Most 'old iron' heads are more like a 75 degree turn from manifold face to valve stem at 15 degrees?
The biggest restriction being the valve guide boss and here is where the 'action happens'.

We just need to know what is 'OK' and what is TOO much?
I have done many hours on 'J heads' and like the early 318 'closed chamber' head even more!

Good luck to all 318/273 head porters, as the Big-Block 'era' is over (for me anyways) lol.

LESS IS MORE...

J head work.jpg


J head ports.jpg
 
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MOPAROFFICIAL said:
Crap lower lift, a hair better than 1.78 and no deshroud, 52 or something at .100 lift for instance.

View attachment 1715945697
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Let me throw this in..
Years ago when I was doing a 318 block , stretched to 4.04 bore std 340 kb243's I worked some 273 head with a 1.88/1.50 valve combo. This is a pick of one of the ports 'chamber side' sitting on the 4.040 bore I was scribing the far side for deshrouding. The major detail her is i did not deshroud the lower ssr side of the chamber... instead I played the boundary game and only put a slight angle on it. .so there was no smooth ramp.. it was a gap and 30 degree lip. Also the valve job 'shop did it' has a ledge around it... bad. The port in this pic from 10 yrs ago flowed around 223-227cfm.. BUT the ledge around the valve and the lower chamber shrouding around the ssr ' I believe'...killed the low lift. .300 was only 160's iirr. I'll have to look at my log book.
I wasnt happy or where I wanted with them. In the end it got a .473 lift solid and ran great, just could have been better! Take away... a lip or ledge around the valve is never good unless something else is messed up.

20220623_073302.jpg
 
Here are my average Joe intake ports:

20220718200354-b96024c4-me.jpg


20220718200414-fabc6544-me.jpg


Heads had 1.88/1.60 valve installed years ago, so trying to make the best of what I have.

Seems like not a lot of focus on the exhaust side here, but just to be clear, can I take out the speed humps in the roof of the exhaust ports (sorry for the upside down pic).

20220718200333-e84a64ae-me.jpg
 
This is just my opinion and other will have there's.
Don't touch the floor(looks like it has been clean up a little already).

Don't take the bump out as it may help reversion if you do.
there are Many reason why exhaust ports are not focused on much........
Here is the simple answer: You can make or brake the performance of a port job much faster and easier on the intake side then you can the exh.
 
HardVG said:
Here are my average Joe intake ports:

View attachment 1715957469

View attachment 1715957470

Heads had 1.88/1.60 valve installed years ago, so trying to make the best of what I have.

Seems like not a lot of focus on the exhaust side here, but just to be clear, can I take out the speed humps in the roof of the exhaust ports (sorry for the upside down pic).

View attachment 1715957471
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Page 2, 3
Posts # 41,56.
Show the 'all out' on the exhaust.
If you blend the bump... do not lay the ssr back, go mostly straight up off the 60, and just lip the top of the ssr. You dont want the roof and floor to separate/ loose velocity. Total shape of the runner is important for both top and bottom to follow the same angles n shape .
 
Wild and crazy guy says...'' go flat ''...

318 Head Porting exhaust.JPG


150 cfm's, same as a 340/360 stock port!

Coolio, with a 1.500 valve...

318 Head Porting ehaust seat.JPG


I'm gonna go with a 1.550 as I have hardened seats already fitted lol...

200cfm's in, 150 cfm's out, PERFECTO...
 
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Well if there is no danger of hitting water, then I'm all for flattening out the speed bumps.

The port opening seems quite a bit smaller than the header flange, so there will be a decent amount of anti-reverb lip there anyway.
 
The exhaust was always over-looked 'back in the day' by most engine manufacturers!

But mother Mopar 'got lucky' with their small-block heads lol...
(Even the mighty 426 hemi was a massive compromise due to engine bay restrictions).

So any gas-flow must be better in a smooth port than a lumpy one?
The gas exhausts faster than the speed of sound for a few milliseconds.

The exhaust 'port roof' must be the most influential part of any head?
Don't get me started on Big Block heads lol...
 
Obviously mother Mopar were making engines 'on a budget' for all ocassions!

Freezing temps in Canada and trips out to 'death valley' lol.
Most cars are either 'stuck in traffic' or 'rolling down the freeway'...

Only now are folks seeing the potential of a grocery getter engine 'the 318'...
All the same parts as the mighty 340 hipo, just small-port heads lol.

The old saying 'big is better' doesn't always work as anyone knows with 340 heads on a 318?
Port flow is very important and as Harry Weslake always says ''less is more'' sometimes...

If I was sitting on a tiny 'go kart' I wouldn't wanna ride this port...
Just ask Lewis Hamilton about bumping/bouncing at 200mph lol...

Just imagine air/gasses flowing over this at 1000mph...

318 Head Porting SB.JPG
 
There is always a danger of 'hitting water' in any port!

The other side of these 'bumps' is a mirror image in reverse.

Going thin in the port roof will always be a disaster in any 'iron head'.

Especially when the gasses are at 1000 degrees for hours on end, on the Freeway...

But if you are like me, its just grocery getting and once a year 'at the track' then we are less worried?
(The times they are a changing)

A 'UK pound' for a mile of travel is hard on the wallet!
My 452ci engine was worse at £20 every 'quarter mile'...(C12 race gas '£130 for 5 gallons' UK 19 litres)
 
That's Hysterical lol...

How thin is too thin?

I guess an 1/8 of an inch of iron is desirable in a 1000 degree exhaust port.
But if you want a free-flowing port then its gonna bee possibly 'half' that where the bump is loacated?

Do you feel lucky when using a heavily ported iron head.

Or is is best to leave the bumps in place and suffer a small flow loss?

I assume the small block head has a much more superior port compared to a 906 etc?
I have fitted 1.88 exhaust valves in iron heads as per David Vizard and others info.

I would have thought a 1.70 exhaust valve would be beneficial but most say 1.65 is plenty?

318 head section.jpeg
 
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When taking max HP affects(this is not, that, of cores!) you are better to go to a 1.50 exhaust valve, to make room for a much bigger intake valve.

Intake air pressure, even in a boosted situation is Way Way, harder to get on top of the piston, then the 1000+ degree and all most, mach-1 air speed being forced out the exhaust. I know i know you say, so make it bigger, to get it out. It just don't work that way. The velocity and the over lap time is what help start the intake moving sooner. You can hurt your intake flow by messing with the exhaust side.

And that is one of the reason why i say Leave the floor alone! and only clean the exhaust port.
Just one mans opinion.
 
polyjohn said:
Even cooler vale seat tool being able to cut those DEEP entry angles!
My B&D struggles to do them at that size...

View attachment 1715961212
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Yeah it is. I think it's a 70 or 75. A lot of people out there will frown upon or look down on someone using stones, but I like them. As long as they're dressed properly and you know what'd goin on they can give results equal to some of the best cutters out there. The industry used stones for a very long time.
 
RustyRatRod said:
Yeah it is. I think it's a 70 or 75. A lot of people out there will frown upon or look down on someone using stones, but I like them. As long as they're dressed properly and you know what'd goin on they can give results equal to some of the best cutters out there. The industry used stones for a very long time.
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I actually bought the light from Sears I think it was. So it's not very old , but by all the metal dust and fingerprints ..it passes as.lol
I'm in the middle of upgrading everything, tool wise. Tbc.
 
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