318 head flow

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skrews

skrews

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What kind of flow numbers have you seen from untouched 318 castings? Particularly 675 castings. What flow bench and test depression did you use?
Started in on a set of 675 heads with no intent to flow them when done. Now the wheels are turning and I'm kind of curious as I'm actually putting some effort in them, and didn't do a before test. 1.94/1.6 valves, gasket matched to 340/360 port size, bowl work, short side rework, removing most of the guide boss. Shooting for 210 cfm range with high velocity.
 
I think there is an article in the small block pages that details a home pocket port and floor hump push back that gives before and after flow figures on a set of 675 heads.
 
That would be where I found the 175 number. Not to come off like a dique, but that number was generated with a DIY bench so I take that with a grain of salt. Hoping someone here has tested with a SuperFlo bench at 28" or can link to an article/thread where a SuperFlo bench was used.
 
skrews said:
My interwebs research has found claims ranging from 135 to 175. :wtf:
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skrews said:
That would be where I found the 175 number. Not to come off like a dique, but that number was generated with a DIY bench so I take that with a grain of salt. Hoping someone here has tested with a SuperFlo bench at 28" or can link to an article/thread where a SuperFlo bench was used.
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Sounds like you arent well informed.
That flowbench has been run next to a superflow 600, was 2 cfm difference, less and showed the same turbulence in that particular head. Name brands dont mean ****, join a forum if you havent and see what people buy and put together that works way better. It's very interesting. Depending on the thread , time of day, some ones mood swing..."its all a grain of salt" anyways and the drag strip will tell you what you really got, right...
Anyways..175 ish That's what they flow like it or not, give or take...
Btw, 127-135cfm is a stock slant flow number, that stan Weiss site is somewhat of a joke with anyone able to submit and publish their magical numbers no matter how ridiculous they seem....for instance bjr is listed.
200-205cfm with a stock 1.78 valve and 220cfm with a 1.88 is what I did with the 318 heads, given the 1.88 wasnt a full effort but actually a target. I will say this.. a 318 with a nice lil street cam and those 1.78 205 cfm heads really pulled hard...I'd stick to the small valve and porting.jmo I'd save the 1.94 for a set of 574,915,308 heads
 
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MOPAROFFICIAL said:
Sounds like you arent well informed.
That flowbench has been run next to a superflow 600, was 2 cfm difference, less and showed the same turbulence in that particular head. Name brands dont mean ****, join a forum if you havent and see what people buy and put together that works way better. Depending on the thread , time of day, some ones mood swing..."its all a grain of salt" anyways and the drag strip will tell you what you really got.
175 ish
That's what they flow like it or not.
Btw, 135 is a stock slant flow number, that stan Weiss site is somewhat of a joke with anyone able to submit and publish their magical numbers no matter how ridiculous they seem....for instance bjr is listed.
200-205cfm with a stock 1.78 valve and 220cfm with a 1.88 is what I did with the 318 heads, given the 1.88 wasnt a full effort but a actually a target.
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Do enough work with flow benches and you will see that different brands and even models from the same company don't agree. They are like home made yard sticks. SuperFlo will tell you that. I'm sure your bench gives you repeatable results, but I guarantee it won't match up to the SF1020 bench I use.
And if you want to talk time slips showing how much I know.

3300#
365 ci
596 heads ported by me
.528 cam
pump gas
0526180803.jpg
 
Never had a bench flow, so my only "before and after" has been what the E.T. slip has dropped with home porting.

I'm interested in what your doing...… :)
 
PRH said:
Just flow it then.......... leaves no doubt as to what it flows.
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Already to far into the port work. I might go see if I can dig up another head to get some numbers. Just figured I'd save myself the trouble if someone had tested one of these turds on an SF bench.
 
skrews said:
Do enough work with flow benches and you will see that different brands and even models from the same company don't agree. They are like home made yard sticks. SuperFlo will tell you that. I'm sure your bench gives you repeatable results, but I guarantee it won't match up to the SF1020 bench I use.
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This is all very interesting, though it makes me want to ask the question ( hypothetical )........would a SF1020 in Key West Florida yield the same results as your bench in Washington, state?? Does the software have auto correction factors for elevation, relative humidity, temperature, barometric pressure, to some given SAE standard, or do you just see raw data and then make the long hand corrections?

I ask/say this as I beleave that in the long run flow bench numbers are just food for thought, I do not hold them to be absolutes, reguardless of who's/kind of bench, they are all just "yardstick measures". I came to this conclusion over 30 years ago after studying Fluid Dynamics in collage ( B+/A- don't remember for sure).

Port your heads, do what you think is best, don't pucker your azz over what another bench says; who cares!! Your time slip showing your ported iron heads is impressive, car is well sorted.
 
skrews said:
Already to far into the port work. I might go see if I can dig up another head to get some numbers. Just figured I'd save myself the trouble if someone had tested one of these turds on an SF bench.
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If you trust the bench, and you’re looking for 210 out of the finished product........ just have that tested.
If you’re at 210....... you’re done.

It doesn’t really matter what it started out at, if that bench is your yardstick, and 210 is the intended goal.

Someone brought me some ported 452 BB heads to look over, and he had a flow sheet from the place that did them.
I pulled some valves, looked at the head, looked at the flow sheet....... and was quite sure the numbers were going to be slightly higher on my bench than what was on the sheet.
And they were.

I know what kind of number that level of porting on those heads will yield on my bench...... which is my yardstick.

The caveat there is......... I had a 1 in 8 chance I was testing the same cylinder.
 
Yes, it is much more important to actually race our engines in a complete car than race a flowbench against another flowbench or a dyno against another dyno. It's so much more fulfilling and satisfying! The actual "true flow" of a flowbench isn't nearly as important as it being able to meter air accurately enough to show a flow improvement when modifications are made...
 
It's just a number from a machine operated by a human in different areas of the country. Just a number. The OP was looking for someone that flowed stock 318 heads as a baseline for his home ported heads. If he isn't going to flow his heads before and after this conversation is a moot point.
 
A few shots of the dumpster fire 318's 675 heads. Valve guide eliminated for .5" bronze, and seat cut for 1.94 intake valve .

0201191729a.jpg


0201191729.jpg


0202191528a.jpg
 
fishmens67 said:
:thumbsup:
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Nothing better than budget building and doing as much as possible as you can. How people like Vic Edelbrock, Mickey Thompson, Smokey Yunick, Don Garlits, (heck, everyone really, the list is endless!) brought this hobby to life and built empires.
 
Of course, the real test would be how well they compared on the dyno against some 360 heads that had a basic bowl blend done, and milled to equalize the cr between the two.

Be interesting if you’re keeping track of your time how long they’re going to take.
Maybe you could time yourself on a couple of ports.

Are the heads going to be run on a 318?
 
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PRH said:
Of course, the real test would be how well they compared on the dyno against some 360 heads that had a basic bowl blend done, and milled to equalize the cr between the two.

Be interesting if you’re keeping track of your time how long they’re going to take.
Maybe you could time yourself on a couple of ports.
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^^^ Agree completely. This project is a fools errand. So far I have about 10 hours in these things. The ports have been deep gasket matched to 340/360 size and the guide bosses have been ground out. Thats a lot of metal LOL. Only reason I'm doing them is because I already had the heads, valves, guides, locks/retainers. These are destined to go on a cast piston 318 thats literally being put together with a bunch of shop sweepings and scraps. The only new parts going in it are the rings, gaskets, and the bronze guides. Everything else is used.
 
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