TOO MUCH ?

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Amata Bene

Amata Bene

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I have an early "72" 340 forged crank motor. From time of purchase it did not run right. Got into it only to find numerous issues. Thought a cam, lifters, springs, and new seals would put it back on the road long enough for me to do the build on a replacement BB. The swap will take some time. Turns out I was wrong. The block is at the machine shop, now 40 over. Because it was already at 30 and to tapered to hone straight. The crank has to be turned (tbd) and polished. Getting lined honed, new cam bearings, KB pistons & rings, and a balanced rotating assembly. Along wit ARP fasteners for the rods and studs for the mains. This was suppose to be part of the work on the BB. I wasn't intending on doing this work to the 340 YET. It was going to be done, just not first. The 340 is in a B-body car. That is why I wanted to build the 400 first. Then find a decent early 70's A body Duster, Dart, Scamp, something. < This is the prefaces.
So here is why I ask "TOO MUCH?" With the free (?) time and the heads just setting here till the machine shop wants them I decided to try my hand at porting :eek:. I have never ported a set of heads to the extent that I want these ported. (Keep this in mind if you have some early 70's 915 340/360 J heads you want to unload.) Here is what I have done. I don't know if I have hurt or helped in the production of HP. I will be going to 2.02 In and keeping the 1.60 Ex with new guides, multi angle seats, and a bowl cut that I will blend. This is the Intake, they are all verry similar. TOO MUCH?

Port 1.jpg


Port 2.jpg
 
When I said "they are all verry similar" I was speaking of the intakes. The exhaust look like this.

Porting 4 ex.jpg


Heads 29.jpg
 
Looks great!
Carry on.

Don’t get carried away grinding down the lump in the roof by the intake guide…….. particularly the two ports by the shorter head bolt.

Re-surface finish-
I don’t know what you used there, but 60g can look pretty shiny in pics.

IMG_3810.png
 
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PRH said:
Looks great!
Carry on.

Don’t get carried away grinding down the lump in the roof by the intake guide…….. particularly the two ports by the shorter head bolt.
Click to expand...


Yup. Unless you want to put a spacer in there.

That’s only for anal retentive jackasses like me.
 
One other thing……..
My preference is to not port the bowl all the way up to the seating angle of the valve job.
I like to leave a distinct line where the porting ends at the lower portion of the bottom angle of the valve job.

2BD9BDF0-7E73-4F8A-B323-8843FA566AC1.jpeg
 
PRH said:
One other thing……..
My preference is to not port the bowl all the way up to the seating angle of the valve job.
I like to leave a distinct line where the porting ends at the lower portion of the bottom angle of the valve job.

View attachment 1716381167
Click to expand...
Yeah, the fella at the machine shop said the same thing. He thinks I'll be ok after the bowl cut. "Just go easy on the blending" he said. The ex is another story, wait and see.
 
PRH said:
On the ex I do a radius off the bottom of the seat angle, although there isn’t much there to work with on a J head.
Click to expand...
Is that to get the bell shape I've seen people talking about. This much porting is all new to me. So yeah, you can teach an old dog new tricks.:lol:
 
PRH said:
On the ex I do a radius off the bottom of the seat angle, although there isn’t much there to work with on a J head.
Click to expand...
Mind you that I'm doing all this with pneumatic die grinders and several different shapes and sizes of double cut burring bits. And a butt load of HF sanding rolls.
 
It generally flows better with the radius, and you’re not trying to manage/re-atomize “wet flow”(like you are on the intake).
 
Yup.

Angles below where the valve seats for the intake……..radius on the exhaust.
 
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