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Author
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Topic: Had my Boss 302 heads on a flowbench...
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Rustang
Gearhead Posts: 733
From: Clarion PA
Registered: Nov 2000
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posted 07-22-2001 05:21 PM
   
I took my intake manifold to a local head porter this week to have it straightened out. (I butchered it when I ported it!) I left one of my heads there for him to match to the intake. Anyhow, he stuck the head on the Superflow and got the following:Intake, starting at .100 lift to .700:
70, 147, 213, 265, 300, 310, 321 
Exhaust at the same lift points:
54, 95, 136, 171, 195, 200, 200
I was very surprised on the intake numbers! Especially since they have the Roush spacers in them. I guess I just got lucky since I ported them myself. The guy that checked them was suprised too. He double checked everything and reran the test and came up with the same numbers. So now I know that I have enough cylinder head (there's still some left in the exhaust though) and I'm going to concentrate on other areas.
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Mpcoluv
Gearhead Posts: 1278
From: Charlotte NC usa
Registered: Apr 2001
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posted 07-22-2001 08:10 PM
Those numbers look great.
Did you notice any improvement in low end due to the Roush inserts?
Can you post any photos of the heads?
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kid vishus
Gearhead Posts: 6098
From: middle of NC
Registered: Oct 2000
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posted 07-22-2001 08:39 PM
Those numbers look good. 
And you are right, there is more to be had in the exhaust ports. My 4v C heads went 228 cfm at .700 lift on the exhuast with my home port job. Your intake numbers are better than mine in the upper lift range, those Roush plates must help.
Here's mine just for comparison sakeintake .100 to .700
74,155,228,275,281,290,305 exhaust .100 to .700
50,93,141,177,201,216,228
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Rustang
Gearhead Posts: 733
From: Clarion PA
Registered: Nov 2000
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posted 07-22-2001 09:18 PM
Actually, Kid, I read one of your posts from the Cleveland archives and ported the exhausts based on what you described! I've completed these mods on one head (NOT the one at the porters. All it had done was bowl work, trimmed valve guide, and good valve job)
Anyhow, I raised the port not quite 1/8", straightened out around the head bolt, removed the small emmissions hump, and did a little clean up around the upper left header bolt. I then polished it up a little. Your 228 CFM is impressive. One other thing that I hope helps out low lift is I smoothed the transition of both valves in the combustion chamber. Those big machined recesses in the chambers looked like they'd be terrible for flow in the seat to chamber transition( I think the chambers were machined this way from the factory).
I'd like to reflow them now, but times a waistin' .... GOTTA GO!!!!!
Oh, and MP, I'll try to get some pictures up in the next couple of days.------------------
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Rustang
Gearhead Posts: 733
From: Clarion PA
Registered: Nov 2000
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posted 07-22-2001 09:25 PM
Kid, I just thought of something. How 'bout I trade you my intake port for your exhaust port?  ------------------
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 07-22-2001 09:42 PM
Great numbers on you intake flow!!
The exhaust side of the Cleveland style head is very restrictive.. They were designed strictly for a turndown ehaust manifold to allow for tight engine bay clearances..
You must work on getting more action at the roof of the exhaust port by smoothing out any obstructons and bumps and widening it as much as headers will allow, and smoothing down the short turn radius.. Also use headers that follow the roof of the port as long as possible.. The lower 1/3 of the exhaust port is useless at high rpms.. It's been a few years since I played with a Cleveland but I remember that they are totally different than any other animal.. If only FORD had spent a couple more years on it?? [This message has been edited by bluestreek (edited 07-22-2001).]
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kid vishus
Gearhead Posts: 6098
From: middle of NC
Registered: Oct 2000
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posted 07-22-2001 09:48 PM
WOW
With just bowl work and trimming the guide boss down some and knocking the bump down in the roof, my exhaust only went 185 cfm at .700 lift. I picked the rest up with the port work later.
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 07-22-2001 09:54 PM
Kid,
Looking at your exhaust numbers, I'd say you did your homework..
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Rustang
Gearhead Posts: 733
From: Clarion PA
Registered: Nov 2000
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posted 07-22-2001 10:34 PM
Kid, am I understanding you right in your last post that you went from 185 to 228cfm with the roof work and stuff I described? If I read that right, I could possibly pick up that much over my 200cfm!?!------------------
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kid vishus
Gearhead Posts: 6098
From: middle of NC
Registered: Oct 2000
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posted 07-22-2001 10:39 PM
Yes I did. I did work on the short turn a little more the second go around. I was a little leary of grinding to much off the first time I worked on them so there was still room for improvement. I widened the port at the transition area into the bowl a bunch too.
I wouldnt be suprised if you picked up 30 cfm. It sounds like your intial port work was better than mine and that may have some to do with why I picked up that much the second time.
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 07-22-2001 11:56 PM
We used to bore Clevelands .040 over  just to get less shrouding on the valves..
Believe it or not, it helped.. Trying to keep intake velocity up and getting it through the chamber is the name of the game.. A Cleveland can easily bog itself on the intake port if you ain't careful with the chamber, exhaust port, and the duration of the intake.. That's all I'm gonna say..
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Clevo377
Gearhead Posts: 312
From: Blackburn, Victoria, Australia
Registered: Nov 2000
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posted 07-23-2001 07:24 AM
Bluestreek, by all means start a new post. I'm slap bang in the middle of porting my 4V's. I've had the lower portions of both intake and exhaust welded up, as well as the top(outside) of the exhaust. I'm interested to hear about port shape and short side radius (how much of a radius) At present I have'nt shortened the straight shot to the back of the valve, just put a nice curve from the new material to the existing short side (I hope I've explained this okay)Am a little apprehensive about the whole deal, but hey, you don't know unless you give it a go!! Paul
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jkilroy
Gearhead Posts: 1808
From: Vicksburg, MS
Registered: Dec 99
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posted 07-23-2001 08:43 AM
All I have to say is DAMN! Those are some impressive numbers, we're talking entry level big block numbers! No wonder BOSS 302's don't have any bottom end!------------------
Jay Kilroy
68' Fastback GT 390
"No such thing as a cam thats too big"
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 07-23-2001 11:42 PM
Here's my ideas on head porting:
All you need to do is try get anything out of the way that impedes a straight shot to the valves or gets in the way of the flow.. the less turn the port has to make, the better..Larger ports aren't always better if the transition is too quick into the short turn radius..Try to maintain a balanced port instead of a large port and be careful of the water jackets..A little porting in the right areas is ussually better than a lot of porting..Keeping the velocity up in your ports is very important for quick revs and good fuel mixture.. Start off small and get the feel of it, before doing any heavy grinding.. It's a long tedious job, but can yeild good results if you take yourt time..Here's some things to pay attention to other than the ports.1. Make sure transition from valve to combustion chamber is smooth without any bumps or edges in the way.(shrouding)
2. Smooth down spark plug boss in the chamber.
3. Pocket beneath the valve seat should be perfectly even with the lower angle on the valve seat.
4. NO sharp edges or bumps that arent necessary in the port, chamber, and piston dome..
4. Pay close attention to piston dome detail and try to make it smooth and "go with the flow". (often overlooked)
5. Make sure valve sits as high in the seat as possible..(very important for good low lift numbers and torque)
6. Polish the bottom side of the valve to get a good smooth flow into the chamber..
7. Port match all gaskets and maniflods to the head ports as perfectly as possible..Any transitions you have to make should be at least 1".. Here's a little drawing for Cleveland heads that I threw together very quickly, but may help you get an idea..There's no attention to detail, so don't take it too seriously.. Porting is a very personal thing, and everyone has different ideas as to what works best for them.. Have fun!! http://www.picturelist.net/Images/dbhard/cleveport.JPG [This message has been edited by bluestreek (edited 07-24-2001).]
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