PRH
Well-Known Member
What was the valve diameter, throat diameter, bowl diameter when you were at this stage?
Picture of 340/360 head porting....Mistakes?
- Thread starter Cudafever
- Start date
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Oogliboogli
PRH
Well-Known Member
More armchair quarterbacking.......
Imo...... you haven’t taken enough off that lump in the roof next to the guide boss, in the head bolt area.
That material needs to be completely removed for the “high effort” type jobs.
Along with more material removed behind the guide, making for more of a “boat tail” type shape.
Imo...... you haven’t taken enough off that lump in the roof next to the guide boss, in the head bolt area.
That material needs to be completely removed for the “high effort” type jobs.
Along with more material removed behind the guide, making for more of a “boat tail” type shape.
yellow rose
Overnight Sensation
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Oogliboogli
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Oogliboogli
I'd remove that roof kink. I would more 90-degree off That straight side short turn and I would leave that whole straight wall in rough finish from the carbide bit. And then run sandpaper over the entire dogleg wall.
I would also put an angle right at the peak of where the push rod pops out into the port window. That's after I grind it to be about .060 thin. Assuming the shirt side is laid back only a hair... I would work the approaching ramp down flatter across wall to wall... meaning mostly the straight side. Leave a lik lip on the top of the turn.
I would also put an angle right at the peak of where the push rod pops out into the port window. That's after I grind it to be about .060 thin. Assuming the shirt side is laid back only a hair... I would work the approaching ramp down flatter across wall to wall... meaning mostly the straight side. Leave a lik lip on the top of the turn.
PRH
Well-Known Member
Oh, for sure it’s way more work than I’d take on.
But it looks like that’s a “test head”, so it’s not so bad only doing one port to test the theories.
With “normal” porting...... no holes, no sleeves, no extraordinairy measures........ an X head can get into the 270’s @.550 and not have the numbers get too terrible at the top end of the flow curve.
They do seem to be pretty fussy about the shape of the valve in the .400-.550 lift area....... but once they fall over, the shape of the valve hardly makes any difference.
I’m more conservative at the short turn on the 915 and later heads....... as I prefer not finding water there.
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yellow rose
Overnight Sensation
PRH
Well-Known Member
I was messing with a junk 596 head as a test piece several years ago.
Filled the PR hole, 2.08 valve, really whittled the guide down, layed the ST waaaaay back.
Worked awesome.
Low 280’s, rock solid past .700 lift.
Then I was reworking some used previously ported J’s...... that had a pretty steep ST and were done at about 250@.450-.500 lift.
Started rolling the ST back....... busted through before I was even close to what I’d done on the 596.
So, I tried the intake port next to the one that was flowing 280...... broke thru very easily...... hardly layed back much at all.
Obviously some serious core shift....... which allowed that one port to be reworked in that area without breaking through....... but not at all representative of what you can normally get away with.
Filled the PR hole, 2.08 valve, really whittled the guide down, layed the ST waaaaay back.
Worked awesome.
Low 280’s, rock solid past .700 lift.
Then I was reworking some used previously ported J’s...... that had a pretty steep ST and were done at about 250@.450-.500 lift.
Started rolling the ST back....... busted through before I was even close to what I’d done on the 596.
So, I tried the intake port next to the one that was flowing 280...... broke thru very easily...... hardly layed back much at all.
Obviously some serious core shift....... which allowed that one port to be reworked in that area without breaking through....... but not at all representative of what you can normally get away with.
PRH
Well-Known Member
How much porting you “need” depends on the goals, and also what you can live with in terms of how rowdy the motor is.
The heads really don’t need to be anything too special if you’re trying to make, say.......... 475-525hp on a 408-416 stroker.
Get them into the 250cfm range, and not fall off a cliff at .550-.600 lift......and as long as the planned package can work with a pretty healthy cam........ it’s no problem.
It’s the smaller hyd or hyd roller cam, not much stall/gear, OD, power brakes, a/c type builds that are harder to make that kind of power..... without resorting to “better” heads.
The heads really don’t need to be anything too special if you’re trying to make, say.......... 475-525hp on a 408-416 stroker.
Get them into the 250cfm range, and not fall off a cliff at .550-.600 lift......and as long as the planned package can work with a pretty healthy cam........ it’s no problem.
It’s the smaller hyd or hyd roller cam, not much stall/gear, OD, power brakes, a/c type builds that are harder to make that kind of power..... without resorting to “better” heads.
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Oogliboogli
Hard seat all the intakes , cheap if you can do it youself. Port to the seat id, not too wide up in the bowl, just deepen it there. 265-275 from a 915 J.
PRH
Well-Known Member
Must be cudafever is out in the shop making chips 
I have know idea why i didn't get a notification that some one had posted up on my thread.
Not Ignoring you all. just stumble on it. and i'm glad.
Ok first Yes this is a test head.
PRH i will dig up my notebook and see if i can match a pic to my notes so i can answer you questions.
But to start with.
Here is the history of this particular head and how it got to this state.
Started out on my first 340. 360 head 974 w/188. Dropped a intake valve and destroyed my cyl block.
New motor, same head with one hardened intake seat and 8 exh hardened seats. bowl blend to hardened seat on one intake and exh. made plastic templates so i could make all the rest of the bowls the same. This was the first time with a die grinder and a cyl head.
Head before would rev 6000 rpm after porting would rev to 7200 RPM same compression same cam same everything. head was the only thing different. Was a dog at the track and ran a full sec SLOWER! Acted like a 2 stroke and had no power until 4000 rpm and then just took off. And it wouldn't pass emission either.
Pulled them and put a stock set of X head on it and was happy. had bottom end shift a 5800 rpm.
So after i builts my first real(????) porting bench. i when a searching for these head.
When i first get these number for you. you have to understand, that this bench was to small and after 300 lift i had to drop from 28" down to 10 and do the math from there to represent 28"
I was vary good at making turbulence in these ports and at 10" it was hiding a lot of it.
Not Ignoring you all. just stumble on it. and i'm glad.
Ok first Yes this is a test head.
PRH i will dig up my notebook and see if i can match a pic to my notes so i can answer you questions.
But to start with.
Here is the history of this particular head and how it got to this state.
Started out on my first 340. 360 head 974 w/188. Dropped a intake valve and destroyed my cyl block.
New motor, same head with one hardened intake seat and 8 exh hardened seats. bowl blend to hardened seat on one intake and exh. made plastic templates so i could make all the rest of the bowls the same. This was the first time with a die grinder and a cyl head.
Head before would rev 6000 rpm after porting would rev to 7200 RPM same compression same cam same everything. head was the only thing different. Was a dog at the track and ran a full sec SLOWER! Acted like a 2 stroke and had no power until 4000 rpm and then just took off. And it wouldn't pass emission either.
Pulled them and put a stock set of X head on it and was happy. had bottom end shift a 5800 rpm.
So after i builts my first real(????) porting bench. i when a searching for these head.
When i first get these number for you. you have to understand, that this bench was to small and after 300 lift i had to drop from 28" down to 10 and do the math from there to represent 28"
I was vary good at making turbulence in these ports and at 10" it was hiding a lot of it.
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Oogliboogli
I wonder what that bowl looked like, a dunce cap, or maybe a bucket.
Any pics?
I don't know but i can tell you it was less them before i put the 2.02 Valve in(eats up way to much csa at the ssr.)
it sure look cool but was a total failure
Unfortunately i didn't do a good job marking my pic's to the time in my notes.
I can tell you that it is port #7(the port i got the best flow out of) and at this stage it has a 2.02 cut into it and with a 30 top cut and a 60/75 bowl cut. think the bowl was at around 1.67 at that point.
That port, i ended up porting out to 200 CC port with 2.19 bowl. Flowed 273@.500 and 270@600(after figuring out the chambler problems)
I then when back and started filling in the dead spots. and the ones that were not, i sanded back out.
In the end i had 175 CC port with a average csa at the throat at 1.71
Ended up at 271@.500 and 265@.600
I will try and get some current picture of my #7 port this weekend so you can see were i ended up and what you think can be improved one.
As far as the flow with a stock 2.02 valve. I have a bone stock never touch, carbon on the tulip valve and all. That i flow tested........... But can't find that data. I think it was like 199 cfm...
These heads with the 1.88 flowed 204@.500 and 203@.600
I only have a hand full of pic's left. I had a bunch of them i uploaded to photo buck, back in the day, that are useless to me now!
PRH
Well-Known Member
2.19” diameter bowl in a stock SB head?
512Stroker
We are all here because we are not all there.
I dont have a horse in this race, but I am curious if any of you porting Guru's have looked into or wish to comment on acid porting iron heads?
PRH
Well-Known Member
1.71” “bowl” diameter or “throat” diameter?
Or both?
That’s only 84.6% of a 2.02 valve.
Seems pretty small for a “high effort” type job.
The pic I was referring to about the bowl diameter “looked” like the bowl was still pretty small compared to how much was taken out of other areas of the port.
I will give you accurate answer this weekend.
Got a severe cold that turned into bronchitis. kinda avoiding my cold asz garage. It 1 degrees above 0 right now.
I will take pics of the port(#7) from several angles as well as get the calipers back out and measure the bowls as well.
Got a severe cold that turned into bronchitis. kinda avoiding my cold asz garage. It 1 degrees above 0 right now.
I will take pics of the port(#7) from several angles as well as get the calipers back out and measure the bowls as well.
One of the reason i was trying to keep the bowl less than 90% was because i had a small .474/280 MP Hyd cam at the time....
Even though i new these heads would never go back on anything,........ when i started poking holes in the SSR.
Actually my mind set change many time, with what i should do with these heads.
When i started on these heads, i only had air and a die grinder at work..........and a flow bench at home. So like i said i chased my tail a lot with a HMMmmm if i raise it here, bend it over here, grind this off here, and smooth it up over there............
The old saying make one change at at time.............i was making 20 and then testing it on my flow bench.
...
Even though i new these heads would never go back on anything,........ when i started poking holes in the SSR.
Actually my mind set change many time, with what i should do with these heads.
When i started on these heads, i only had air and a die grinder at work..........and a flow bench at home. So like i said i chased my tail a lot with a HMMmmm if i raise it here, bend it over here, grind this off here, and smooth it up over there............
The old saying make one change at at time.............i was making 20 and then testing it on my flow bench.
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