J head porting

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Dartswinger70 said:
I suppose if I was racing a 340, yes it would be aluminum heads a single plane intake and a 750 Holley carb. That would be my starting "recipe"
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I would step right into a Trick Flow head.
Enough head OOTB to build a potent street strip deal.
 
Rat Bastid said:
Because I’m a nice guy, I’ll tell you EXACTLY why I said to start with the valve job.

Because thats where the most power is. Because it establishes the throat size. Because it is the biggest factor in how the rest of the port is shaped.

I’m all for working the guide but for the amount of time and effort spent the most power to be had is in the valve job. You’ll get very little in return working the guide boss (although I suggest you do do it, just not at first) compared to getting the valve job correct.
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and it's free advice:thumbsup:
 
I was contemplating alum SM's but wasnt sure about stock pulley setup with them and didnt want to deal with trying to cobble. I had the xheads already on hand freshly done, so away I grind lol. Want them done before this coming Black Friday so i know if i need to order SM's or not lol
 
I shorten the guide to the minimum I can get without creating excess guide and stem wear. While your at it put an 11/32 valve in them and with a bowl job you'll be at 250 cfm without touching the port.
 
EL5DEMON340 said:
Just getting started on a set of 1972 j's, milled the guide down .200 and about to profile the guide. was there a long thread about porting j/x heads? I can't seem to find it. anyway, can the guide tail be removed completely? This will be going on a somewhat stock appearing 6 pack, intake has been deep port matched. I know aluminum heads would be much better but the 6 pack intake don't flow all the great anyway, plus the looks on their faces when they see they got smacked by a SB with stock heads is fun.
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Keep the tail long, have some 1 pc bronze put in. Stick to a 3 angle vj, no 15 top.
Blend all around the intake valve in the chamber, a little into the chamber on straight shot, open pinch to max .050 thick or a hair less. Work the roof a ton and smooth n ramp it down keep the throat on the small side till the vj is done, make the bowl almost a bell, do not over work the straigh/common side ssr...and almost leave the dogleg side of ssr tall as you can. Work on cross section but keep rounded/bullnosed. Common wall straighten to head bolt but dont make it flat all the way into the bowl, let it still kick out..so that there IS still a bowl on that side. You want to feel sharp angles at seat but also radius that throat from them. Dont make a bucket out of it.
Only knock some of the wall to floor hump down, for area at the ssr
 
MOPAROFFICIAL said:
Keep the tail long, have some 1 pc bronze put in. Stick to a 3 angle vj, no 15 top.
Blend all around the intake valve in the chamber, a little into the chamber on straight shot, open pinch to max .050 thick or a hair less. Work the roof a ton and smooth n ramp it down keep the throat on the small side till the vj is done, make the bowl almost a bell, do not over work the straigh/common side ssr...and almost leave the dogleg side of ssr tall as you can. Work on cross section but keep rounded/bullnosed. Common wall straighten to head bolt but dont make it flat all the way into the bowl, let it still kick out..so that there IS still a bowl on that side. You want to feel sharp angles at seat but also radius that throat from them. Dont make a bucket out of it.
Only knock some of the wall to floor hump down, for area at the ssr
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Thanks for the help. I’d like to work on one port int & exh and have it flowed to see if it’s worth my time. Not sure if I should have it flowed with the stock 1.88 valve and see if I’m on the right track or have it ruff cut for 2.02 and blend it in a bit and flow it?
 
MOPAROFFICIAL said:
Keep the tail long, have some 1 pc bronze put in. Stick to a 3 angle vj, no 15 top.
Blend all around the intake valve in the chamber, a little into the chamber on straight shot, open pinch to max .050 thick or a hair less. Work the roof a ton and smooth n ramp it down keep the throat on the small side till the vj is done, make the bowl almost a bell, do not over work the straigh/common side ssr...and almost leave the dogleg side of ssr tall as you can. Work on cross section but keep rounded/bullnosed. Common wall straighten to head bolt but dont make it flat all the way into the bowl, let it still kick out..so that there IS still a bowl on that side. You want to feel sharp angles at seat but also radius that throat from them. Dont make a bucket out of it.
Only knock some of the wall to floor hump down, for area at the ssr
Click to expand...
You make it sound so easy.
 
EL5DEMON340 said:
Thanks for the help. I’d like to work on one port int & exh and have it flowed to see if it’s worth my time. Not sure if I should have it flowed with the stock 1.88 valve and see if I’m on the right track or have it ruff cut for 2.02 and blend it in a bit and flow it?
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If you're going to do it... do not use a 1.88 tulip stocker. What you will end up with are poor low mid and decent 'for the valve head diameter ' peakf flow.
I would use either an 11/32 stem , be it 1.94 or 2.02 ...or use a 2" LS valve , 4.86 long is LS stock or a long version.
Factory valves are around 4.95 or something, that's just off the top of my head to give you an idea. You can look it up online easily.
Basically you want a nice Under head that's not in the way and has a nice angle on it and the stock valves have none of that. They're also really heavy.
Just a 1.89 dropped into a worked intake port thatvwas 1.88 will show massive gain. Buy one of each... do the 1.89 LS 1st with your porting and see what you have there. Just tape the stem to make it 3/8 to fit guide and keep the tape high on the stem enough to stabilize it but not be in the bowl at max lift.
 
Well made a porting stand at least. Will start to go at these heads in a week or so.

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As usual a year later back to work !!! All guides have been cut down about .200”, the fel-pro 1008 gasket is close so not a whole lot to de-shroud mostly the slope towards the plug side . I also softened the divot around the spark plug.

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Divenut said:
Hey Mike, @EL5DEMON340 are you gonna gasket/port match the intake as well?

Be well,
Par
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Hi Pat, yes I will, but that area is usually the lowest on the list. Most of the flow gains on these heads as I understand it are guide, bowl, and chamber along with a good valve job. These are still at 1.88 so I’m going to ruff everything in then send to machine shop to cut 2.02 size, then finish bowl blend, then back to shop for finishing. I my flow a port to see where I stand
 
I’m just poking him, because it’s fun and he always seems to change the subject when I ask. They are a “bit” better than my X heads. Here is the sheet for mine. Done by Porter Racing Heads in VT.

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Nice numbers. I’d keep lifting that valve past .550 and make some nice power.
 
I’m a bit limited because I have to run a stock cover, but there is definitely gains to be made. Going to a roller and snapping the valve open to a useable lift quicker. I can get .600+ lift using the stock cover. I plan to blackmail him for cam specs at some point.
 
Limited by a stock cover and you can get .600+ is great. I wouldn’t worry about a thing. The head is giving up cfm at .650, so anything up to at least the reported best is good. IDK what the ultimate goal is but I’d say plenty of power can be made with those heads.

What’s the goal, intake/carb?
 
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The goal is to go quicker than him, 10.2’s at least that’s how quick he is right now. Stock valve cover, ported x’s, exhaust manifolds and tweaked stock 340 intake. AVS for me. He gets a thermoquad with his Duster. :(:(:(

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EL5DEMON340 said:
Hi Pat, yes I will, but that area is usually the lowest on the list. Most of the flow gains on these heads as I understand it are guide, bowl, and chamber along with a good valve job. These are still at 1.88 so I’m going to ruff everything in then send to machine shop to cut 2.02 size, then finish bowl blend, then back to shop for finishing. I my flow a port to see where I stand
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Good stuff Mike. Looking forward to seeing your handy work. The beast shoild respond nicely to the added flow!

Be well,
 Pat
 
I went from home ported 2.02 j heads to cleaned up eddy's and gained nothing. If you go aluminum get the trick flow's or have the eddy ported..
 
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