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Approximate HP gains from porting heads

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28K views 124 replies 52 participants last post by  Busted Knuckles  
#1 ·
I'm looking to port some Mopar big block heads. I've never ported anything before but I have 5 sets of iron heads and I want to give it a try.
Gasket matching looks easy but I've read that the bigger gains are found by eliminating obstructions, blending the bowls and smoothing sharp edges around the valve guide bosses.
Exhaust ports are only slightly smaller than the manifold gasket from a Fel Pro gasket kit.
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The 2" TTI header gasket shows some gains to be found!

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Check out the step below the exhaust seats. It looks like when the hardened seats were installed, they didn't care to blend the sharp edge away.
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Just a few minutes with the die grinder and most of the shelf is gone:

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The guide boss edges are smoothed a bit too.
I know this may be hard to determine but is there any range of HP gains you can hope to get by some basic port work like this? You know, gasket matching, knocking down casting flash and bowl blending?
25 HP ? 30 ?
 
#3 ·
Ive done multiple sets of iron mopar heads. Currently have 906's on my junk (451 with .585 flat tappet, tm-6 intake, 11.4 compression). You will see most gains from cleaning up below the valves into the port. Working the guide does well too. Exhaust already flows well, but spending some time in there doesnt hurt. I even burned thru 2 intake runners, squeezed some JB weld in the holes and finished it up after it hardened. That was 15 years ago and Im still running the same heads. All things being equal, they can make the same power as the edelbrock aluminum heads.
 
#4 ·
I have found that porting heads to match gaskets is worthless. It's the shape of things and where to cut that makes the most gains. Start small and be conservative. Remember once it's ground out it's hard to put back to stock. I took a sock set of 236 pp BBC head where the car ran in the high 12's and put it into the high 11's just porting them with a good valve job.
 
#12 ·
Awww, come on now.
I'm not looking to set the world on fire here, just messing with a car and trying some things that I haven't done yet.
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The car was wrecked more than 25 years ago and has sat unloved since then. I'd doing a ratty budget build with some old school engine tech. Porting heads always seemed like voodoo stuff that only a few guys could do.
You guys ever watch Uncle Tony's Garage on YouTube?
 
#13 · (Edited)
I've ported a couple of 906 sets. Ear muffs, face shield and mask. I cheated and had the machine shop that put in the hardened seats cut the bowls at the same time. The guys from engine masters did one that picked up a bunch. Steve Dulcich did a before and after on his home porting job. If I remember correctly he picked up 83HP.
I can only find the one where he did a small block set. Maybe I'm confusing the episodes.
The first thing to do is put a '69 nose on it.
 
#21 ·
Ported two sets of 'turbo' SBC heads back in the day; it was filthy work but it wasn't that bad. Gave me a chance to spend some time away from my nagging old lady. I had a true professional head guy give me some pointers, then went home and spent about 40 hours per set. I don't know what they flowed before or after but with no other changes it lopped about .15 off my 660' time. Not bad for a rank ass amateur.
 
#24 ·
I applaud you for making the effort and trying something new. All head porters went thru a learning curve. I have a set of 906's fully ported by Dick Landy. Even Landy has his limits as one of the heads finally cracked in a water jacket from too thin of a wall. Called Landy to port one head, was going to cost $650. Decided to give Edelbrocks aluminum heads a try for $1,200.

Are there big gains to be seen, sure are. Mopar muscle did an article where they took a stock 440, six pack rods and pistons, mild 509 purple cam and ported 906 heads. Engine put of 560hp. I'd say that's a Huge improvement over stock 440 HP.
 
#27 ·
Yea ive seen a couple of 509 hydraulic motors crack the 10s down under with iron heads in a bodies, and the engine isnt all that different to a stock 440 in that guise. But the heads were well ported 906s.

What you just said was a combo I had many years ago on a 30 thou over 440, but with heavily ported 452s i did myself, though i never ran that at the track but it had some balls for what it was. I even got the heads milled heavily because i had litte money in them and didnt care about them... milled until the open chamber part was gone. 80 or 100 tho from memory, comp was around 12:1... had to use shorter pushrods. We used to be able to get avgas here back in the day at the pump and that is what I ran.

Kern dog sounds like you already know what to work on first bang for buck.. or effort in this case. Anything further, well as mentioned dont be afraid to attack the pushrod pinch area of the intakes and use JB weld if you break through anywhere there LOL. If the valves are stock and have a lip on them back cut them also, uncle tony has a video of how to do that yourself with a drill press. :D

More caution on going too far with the exhausts as you wont JB weld your way out of that one but have a party on the intakes going wider into the pushrod pinch area, and taller within reason since you have some sets to play with. My 2c.
 
#29 ·
Not related to iron heads, but... One time I got a sliver of valve seat BeCu in the ring of my asshole, poor aiming with the air hose when cleaning the chips off my person.

There is no hell on Earth, like Beryllium butthole hell.
 
#33 ·
willisonTfosdik said:
Somewhere around 87% throat on a mid level low rpm street engine

Remember which way the air is going

It’s not what you take out it’s what you leave in there & where you leave it.

All things that were taught to me 40 yrs ago
Click to expand...
I watched a pro do a set before I started and that is what he said. Basically don't start changing things like removing part of the floor. I didn't have much luck with those templates but I know some guys who like them. My first effort on 906s slowed the car down. I wasn't aware that a small hydraulic cam and 9:1 compression wouldn't respond well to heavily ported heads.
 
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