Expected et change worth the cost of new AFRs in rail

[steve316]

From post before a .075 angle was going to keep compression the same. That would be part of cylinder head change; and would have very little loss in compression.

[n2omike]

Good luck trying to find someone to port an IRON head nowadays. Nobody is going to put it on their CNC machine, that's for sure. Would need a completely different program, compared an aluminum head... so you're back in the 'black magic' days of 40 years ago when everything was hand ported. IF you do find someone willing to hand port the heads, you need to make sure they can deliver on their promises. There were LOTS of guys back in the day doing a little smoothing with a sanding roll to make it shiny, and calling it a port job.

IF you can find someone to truly do those IRON heads justice, porting them could be a good option. You just have to weigh the costs vs. buying something new and re-selling your old ones.

When you do the upgrade, just make sure the valve springs match the camshaft. There's a big difference between a 0.600" and a 0.700"+ solid roller... especially if the 0.600" is old tech, and the 0.700"+ has some fast, modern lobes.

Good Luck!

[KnightEngines]

If you go with the afr's & mill them you'll be in a world of piston to valve clearance hurt if you're that tight already.
If you port the irons & cut the seats a bit lower you can mill them back to where you are now for compression & retain piston to valve clearance.
But if you are that tight with a flat cam you're gonna be in trouble with a roller.

Pity you're thousands of miles away, I'd port em for you & I have no doubt they'd murder a set of out the box afr heads.

If it were mine I'd go roller, change the pistons to suit & port the irons heads.

Ps - iron heads make more hp per cfm than alloy....

[CamKing]

Leave the iron heads on it. If you have the budget, have those heads ported.
Either way, you should switch cam, lifters, springs and pushrods
Go with a cam around 268/276 @ .050", a 110-112 LSA, and at least .700" lift

With the wider LSA,,,,wouldn't that cost midrange power? Also,,,I have .080"/.100" valve clearance ,after the fly cut with my current approx 590-.600" gross lift and the 105LSA....would the wider 110-112LSA gain me some piston clearance? The machinist who did the fly cut said I didn't have much meat left to go deeper on pockets.

No, the wide LSA would slightly lower the power below 5,000rpm, and with a 5,500rpm stall, you will never see it.
The wider LSA will increase P2V clearance, and the longer duration will decrease it. With out knowing what your valve lift is, at 10degrees from TDC, I don't know what the difference would be. I would guess that if you went to a 266/274 @.050" on a 112 LSA, you would lose about .020"-.040" P2V.

[Bill Chase]

Hvh has a cnc program for those heads, Speier does iron by hand. If you are not familiar with eithers reputation?

Good luck trying to find someone to port an IRON head nowadays. Nobody is going to put it on their CNC machine, that's for sure. Would need a completely different program, compared an aluminum head... so you're back in the 'black magic' days of 40 years ago when everything was hand ported. IF you do find someone willing to hand port the heads, you need to make sure they can deliver on their promises. There were LOTS of guys back in the day doing a little smoothing with a sanding roll to make it shiny, and calling it a port job.

IF you can find someone to truly do those IRON heads justice, porting them could be a good option. You just have to weigh the costs vs. buying something new and re-selling your old ones.

When you do the upgrade, just make sure the valve springs match the camshaft. There's a big difference between a 0.600" and a 0.700"+ solid roller... especially if the 0.600" is old tech, and the 0.700"+ has some fast, modern lobes.

Good Luck!

[n2omike]

Hvh has a cnc program for those heads, Speier does iron by hand. If you are not familiar with eithers reputation?

Most guys don't like to port iron, as it's harder on tooling and goes a lot slower than grinding through aluminum. Therefore, GOOD work will generally be more expensive. That being said, if they just need a little shaping, it might not be too bad. I've ported a lot of stock stuff that required a LOT of hogging. That stuff takes forever, and is hard on grinders/burrs.

Speier has a great reputation. If he is willing to dive into them, that's awesome.
I didn't know anyone had a CNC program for those iron heads, as it would require different program than cutting the same head in aluminum. That would be a great option.

Bill, you act like I'm bashing on here. So, no... I was not aware of the porters who still like grinding on iron, and definitely wasn't aware of any CNC programs for those heads. Of course, I'm well aware of both vendors quality reputations. I'm just NOT aware of each one's entire portfolio. Your input is always welcome, but you can add these details without taking an aggressive tone.

To the Original Poster, good luck with your project!

[CamKing]

At 225cc intake runners. The heads don't need to be made bigger, just better.
Cleaning them up, in the correct places is all they need.

[Bill Chase]

No pun intended, just pointing out that there are some reputable shops doing work on these castings, by hand, as well as cnc. Iron may be expensive to port, but if you already have it? It is certainly an option to consider.

Hvh has a cnc program for those heads, Speier does iron by hand. If you are not familiar with eithers reputation?

Most guys don't like to port iron, as it's harder on tooling and goes a lot slower than grinding through aluminum. Therefore, GOOD work will generally be more expensive. That being said, if they just need a little shaping, it might not be too bad. I've ported a lot of stock stuff that required a LOT of hogging. That stuff takes forever, and is hard on grinders/burrs.

Speier has a great reputation. If he is willing to dive into them, that's awesome.
I didn't know anyone had a CNC program for those iron heads, as it would require different program than cutting the same head in aluminum. That would be a great option.

Bill, you act like I'm bashing on here. So, no... I was not aware of the porters who still like grinding on iron, and definitely wasn't aware of any CNC programs for those heads. Of course, I'm well aware of both vendors quality reputations. I'm just NOT aware of each one's entire portfolio. Your input is always welcome, but you can add these details without taking an aggressive tone.

To the Original Poster, good luck with your project!