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J code 302 cast iron heads porting

12K views 57 replies 14 participants last post by  zhlange 
#1 ·
I bought a set of bare iron heads per title. I'm planning to port match the exhaust side. I know I need the gasket and exhaust manifolds to port match the heads. But my question is do I need to 'completely' grind the 'bump' on the first two pictures? Also, does it help to port match the intake side with the intake manifolds? I've decided not to use aluminum heads. Thank you.
 

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#2 ·
I have no hands-on porting experience, but, will add, port matching intake to heads is a "good thing" with benefits in performance.
The question is, if you're putting your own labor into porting, valve work etc., this is one thing, if you're paying for labor and experience, then, you might compare costs with researching performance gains in purchasing a well known set of aluminum heads with improved flow. Just my take on this.......
 
#5 ·
I am aware of the upsides on using an aftermarket aluminum heads. I just decided to use an iron heads. I will be doing the porting job myself. Other than that, the machine shop that did my block can do the rest for $500 to rebuild the pair. That is with new valves, hardened exhaust valve seats, hot tank, clean, resurface, and install new springs and screw in studs. I have to provide the springs and screw in studs. I paid $60 for the bare set. So, worst case scenario, I'll be around $1000 at the most (gave myself some cushion there). I think that is still a good deal.
 
#3 ·
Removing the bump is a must when the smog holes aren't drilled. The first thing to remember when porting is "air doesn't like to turn". I say that so you will spend more time on the top and sides of the port than the bottom where less is happening. Try not to "flair" the opening to gasket size near the opening just to get the job done. Real porting narrows the valve guide boss and softens the "arc" from the exhaust seat to the exhaust flange , minimizing how much the air has to turn to get out. Good porting makes more power , bad porting just makes bigger holes ( ports). You can't go wrong by removing those bumps though. Grind away.
 
#4 ·
What about on heads with the thermactor ports drilled? I have. A set, but plan on not using the thermactor ports and just capping them.

I have also heard you should keep the exhaust ports slightly smaller than the exhaust gasket, but fully open the intake side.


Here are the details on how to do it:

http://www.mustangbarn.com/PDFs/Port Matching.pdf
 
#9 ·
zhlange,

They are in the smog bumps unless they aren't drilled .
 
#15 ·
Thank you. The "bumps" on the exhaust holes aren't drilled. I tried grinding it today using a Dremel tool, ahhh I need a bigger die grinder. Should I grind "parts" of the push rod hole too? It looks like it cuts the flow too.
 
#26 ·
The link refers to a 67 engine. It was assembled with Performer RPM intake, 600 cfm Holley, C9OZ-6250-C cam (the hydraulic version of the 289HP C3OZ-C cam) and home-grown port matching. The distributor was stock, curved to BOSS 302 spec, everything else was stock. It turned 323.5 hp @ 5300 rpm.

 
#11 ·
IMHO , based on 50+ years of doing small block Fords , 20 tops. The way you gain 100 is with 1.9x1.6 valves and "fully porting" them. It's really tough to get over 210 cfm intake flow out of a 289 head. That is why many start with a 351W head and are happy wit 230-240 CFM or about the same as the '66 GT40 head was. A current aluminum aftermarket head flows that AS CAST! Grinding on the heads is something anyone can do , getting them to make more horsepower requires experience and talent. It's too bad dyno testing is so expensive. Many would be surprised at what "home porting" does or doesn't do.
 
#16 ·
Z, have you considered upgrading to the 1.84/ 1.54 351W valves ? or maybe 1.9 / 1.6 aftermarket ? LSG
I've never got to that point yet. But, in theory, how does bigger valves affect performance? Does it involve a lot of machining to fit a bigger valve (from 1.78/1.45)?
 
#13 ·
I am in the process of port matching my 1968 302 2V heads and they have the same 'bumps' in them. I ground them completely away and you have no worries about plugging smog ports or busting into the water jacket or anything, they're just solid lumps of iron with nothing but more iron behind them.

You do want to leave the exhaust ports in the head about 1/16" smaller than the openings in the manifold or headers because if the exhaust gases hit a 'step' that can be just as detrimental to flow as the lumps you just ground out.

You can do the same to the intake and intake side of the heads but with a die grinder on a bench the minimal return is probably not worth the effort.

You will see an increase in power, and most people claim they can feel it. I have yet to see myself so I cannot confirm and deny, but if you are trying to squeeze as much as you can out of stock heads without spending tons of money port matching seems to be well worth the effort. Don't expect that this process will get you a track car, but if all you are looking for is a fun driver with an original looking engine and around 300 horses then you have realistic expectations.
 
#17 ·
I don't have a lot of expectations for this route. I just enjoy doing 'something' out from stock parts. It's a good learning experience for me. Plus, my car is a daily driver and not looking for a track car.

What type of headers and intake do you use? Seems like we are in the same boat, 6 to 8 soon.
 
#22 ·
Z, if the guys cutting your seats are using a machine like we have at my work, the enlargement will take all of thirty seconds setup time. LSG
LSG,

I honestly don't know what they'll use. All I know is that they are a machine shop and a race engine shop. I can ask them if I know what I should be asking for? Name of the machine or process? Thank you
 
#30 ·
cylinderheads, more

Z, the shop I work for would cut the seats on a Sunnen VGS20. There are also some very nice machines out there from Serdi. There maybe others I don't know about. For everday street driving and fun, the iron heads, cleaned up as you're thinking, with 1.84 / 1.54 valves will be great. Yes, you need a die grinder and carbide cutters and a mandrel and some tootsie rolls to do the porting. A dremel would do it, but take you months to get it done. With a die grinder this could be ready in a couple of hours. No, it won't be 'perfect' or 'professional', but also won't cost you hundreds. You don't have to think of it as porting so much as it is just getting what the designers intended rather than what the foundry cast. For a manifold, you'll want a Weiand Street Warrior, #8124, or a Weiand Stealth #8020. The performer Edel #2121 is more expensive, and the RPM is also more expensive, and both of the Eddys have too thin of side rails on the carb pad. The Weiands don't have this problem. Need a cam ? LSG
 
#31 ·
Z, the shop I work for would cut the seats on a Sunnen VGS20. There are also some very nice machines out there from Serdi. There maybe others I don't know about. For everday street driving and fun, the iron heads, cleaned up as you're thinking, with 1.84 / 1.54 valves will be great. Yes, you need a die grinder and carbide cutters and a mandrel and some tootsie rolls to do the porting. A dremel would do it, but take you months to get it done. With a die grinder this could be ready in a couple of hours. No, it won't be 'perfect' or 'professional', but also won't cost you hundreds. You don't have to think of it as porting so much as it is just getting what the designers intended rather than what the foundry cast. For a manifold, you'll want a Weiand Street Warrior, #8124, or a Weiand Stealth #8020. The performer Edel #2121 is more expensive, and the RPM is also more expensive, and both of the Eddys have too thin of side rails on the carb pad. The Weiands don't have this problem. Need a cam ? LSG
I am shopping for a die grinder. Mandrel? I can't picture why I would need one. But then again I'm a rookie. I will ask my machine shop what they have for machines. I am leaning towards a Weiand Stealth intake. 22GT suggested this cam C9OZ-6250-C. Do you have any suggestions? I don't know if there is a significant difference between full roller and roller flat tappet when it comes to performance. Thank you.
 
#32 ·
First I want to thank you for this thread. I'm close to building my first Ford engine and my plan parallels yours in many ways.

A mandrel is the part of the die grinder that holds the bit. You will also need access to an air compressor to run your die grinder.
I ported my first set of heads a few years ago and learned a few things.
- Don't get in a hurry. It took me 14 hours with a die grinder to do what I wanted to my heads.
- Do your porting before any other machine work is performed.
- Learn about the characteristics of of your particular heads. Some of the humps and bumps are needed to help the air turn.
- Be consistent with what you remove from each port.
- Buy lots of bits. Worn out bits waste time.
- Do the work outside if possible. It's very messy.
- Ear & eye protection are needed.
 
#35 ·
Thank you for input. I'll remember these bullet points. What headers and intake did you match the heads with? Is your car a daily driver too?
 
#33 ·
heads, cam, more

Z, get some carbide cutters and you'll be able to do the pair of heads with just 2 or 3 cutters. You'll want the box of tootsie rolls, but you'll probably only use a half doxen or so. Be very carefull on the short radius area. you only want to smooth the finish there, don't use the cutters on that part. on the cam, the old cam is fine, but there are new ones that have more spread and slightly less duration with more lift. You might like a Comp 35-255-5 camshaft from a 351W ( 13726548 ). Your engine would be fine with a Stealth 8020, but would have slightly better low speed ( below 4K ) power with a Warrior 8124. The Warrior is less tall and the runners aren't quite as large. I have the 8020, but just because I found a nice used one. LSG
 
#34 ·
Z, get some carbide cutters and you'll be able to do the pair of heads with just 2 or 3 cutters. You'll want the box of tootsie rolls, but you'll probably only use a half doxen or so. Be very carefull on the short radius area. you only want to smooth the finish there, don't use the cutters on that part. on the cam, the old cam is fine, but there are new ones that have more spread and slightly less duration with more lift. You might like a Comp 35-255-5 camshaft from a 351W ( 13726548 ). Your engine would be fine with a Stealth 8020, but would have slightly better low speed ( below 4K ) power with a Warrior 8124. The Warrior is less tall and the runners aren't quite as large. I have the 8020, but just because I found a nice used one. LSG

My plan is to flattened the thermactor bumps first and go from there. The carbide cutters are for the thermactor bumps and the pushrod guide cliffs? I will take a look at that particular cam. I am planning on using a hydraulic roller camshaft. And for the intake, if the 8124 gives more power on the lower end that is probably for me.
 
#36 ·
The heads I ported were for a 318 with an Edelbrock 4bbl and manifolds. I found templates for cutting the ports on the internet. The car is a weekend driver and the engine has no ill manners.


In the months to come, I'll be building a 289 and I want to use the cast iron heads. I'm on a budget and need the best bang for the buck. My plan is for a stock bottom end with forged pistons, new valve train and ported/rebuilt heads. I want to avoid mods that require another mod to make work. That gets expensive. I also want to retain the stock look with a little more than stock performance.
 
#38 ·
That sounds like a good plan. My bottom end is pretty much stock too. The only "non-stock" on the bottom end are the ARP main studs and ARP rod bolts. What cam do you use?
 
#40 ·
I have a set of '70 351w heads on my 331 that are supporting 370 RWHP. When I ported them, I was very aggressive and did the following, but with a 302 head i'd be more conservative as the ports are smaller. I would open them up to a felpro 1250 intake gasket and not a1262 intake gasket. Exhaust ports a bit smaller too and i'd use a smaller gasket:

Intake:
Widened roof and raised intake port roof 1/4"...very important...straightens port out
Smoothed down pushrod hump to open up intake opening. Used self made caliper to measure how thin hump was getting and stopped when about .030 thick.
Opened up throat and bowl and remove intake valve guide hump completely. Intake guides, when installed, stick into port about 1/4 to 3/8". I got lucky here because I didnt hit water jackets
Essentially did not touch short side radius except to smooth and widen floor
Opened up intake opening to Felpro 1262 gasket dimensions. Tapered into port
Port matched intake manifold to match head intake port opening dimensions

Exhaust:
Widened roof and raised exhaust port roof 3/16 - 1/4"...very important...straightens port out
Completely removed thermactor hump.
Opened up throat and bowl. Completely removed valve guide hump. Exhaust valve guides stick into exhaust port about 1/4"...not as much as intake valve guide will get very hot sticking into port too much. Got lucky again and didn't hit water jackets.
Essentially did not touch short side radius except to smooth and widen floor
Opened up exhaust opening to dimensions of copper exhaust gaskets...1.425 x 1.375. Tapered into port
Port matched header ports to match head exhaust port dimensions.

1.94/1.6 valves installed and intake valve unshrouded on chamber wall side. Also cylinder matched chambers (put head on bare block, turn over block and look into cylinder. Scribe edges of head where chamber is mismatched to cylinder wall, remove head and grind to scribe marks...usually no more than 1/16" of mismatch)
 
#41 ·
Thank you for all the details. But are these instructions all for a 302 block?
 
#44 ·
Finally worked on the heads today. I was successful on shaving the Thermactor bumps on all ports of the first head. I think I killed my Dremel tool. I haven't done the valve guide "bumps" yet. I don't know if I should just stop on the Thermactor bumps. The bronze guides are still on the valve guides. I don't know if I should take off the guides first if I decide to continue with the valve guides. Also, I don't know what to do with the exhaust opening in relations to the gasket. Should I leave some gap between the gasket opening and the exhaust ports?
 

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#45 ·
Sorry, I take pictures too. The sunset was amazing today.
 

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#47 · (Edited)
I think you should take that angular curve out of your exhaust port so it is a rounded symetrical rectangular shape. When exhaust valve pocket grinding, be careful on the side walls down near the guide boss. They are thin. My previous early 70's stock 302 heads that I also home ported ran low 13's at the drags. I was under stalled with that set up so there was more in it that I never saw. I had a basic upgrade on it which included Performer rpm cam and intake and a 650 holley carb, 4.10 gears.

I used a cylindrical rock to grind down my guide bosses from the combustion chamber side and then from the exhaust port entry. These are aftermarket iron heads so you won't necessarily be able to open them up this much but you can see how much of the valve guide boss was taken down.




This is work in progress but it shows where I am trying to go. I couldn't find a finished photo anywhere.



These heads were completely ported or sometimes called stage 3 which included intake and exhaust valve pockets, runners, guide bosses and deshrouding the valves in the combustion chambers. I also had the face into the valve seats cut just a bit, a 5 angle job and a back cut on the valves. These flow 236 cfms intake and 178 exhaust now and I'm done. Sick and tired of grinding these things.
 
#49 ·
"
I think you should take that angular curve out of your exhaust port so it is a rounded symetrical rectangular shape. When exhaust valve pocket grinding, be careful on the side walls down near the guide boss. They are thin.

I used a cylindrical rock to grind down my guide bosses from the combustion chamber side and then from the exhaust port entry. These are aftermarket iron heads so you won't necessarily be able to open them up this much but you can see how much of the valve guide boss was taken down."

So I don't completely blend the valve guide bosses with the roof like what the instructions from Glazier Nolan links stated? My heads needs to be machined after this so the valve guides bushing are still in. It might need to be replaced I don't know yet so should I still just follow what you've just mentioned regarding the valve guides? I'll try to even out the exhaust ports. My gasket is Fel Pro MS90000 and will be using a hipo exhaust manifolds. Is it ok to shave some of the gasket if needed? Thank you.
 
#48 ·
"I'd raise the exhaust roof to match, but leave the floor gap alone.[/QUOTE]""

This is where I get confused from the Glazier Nolan instructions. It states leave at least 1/16" gap.

"Larger valves are comparable in price to stock replacements. If you're already cutting new hardened seats it isn't going to cost anymore to be bigger...Same with grinding the intake seats larger.[/QUOTE]"

I will be using 1.84/1.54 valves.
 
#55 ·
This is where I get confused from the Glazier Nolan instructions. It states leave at least 1/16" gap.
Well, you have slightly more than 1/16", except on the RH side in the photo, where there is none. The lower right corner could be opened up a little more, to match the shape of the other three corners. The exhaust manifold should be larger, exactly matching the hole in the gasket.
 
#50 ·
When it comes to deshrouding, will you loss a little bit of compression since the combustion chambers can potentially get larger?
 
#51 ·
I'm no grinding or cam design expert, so, if you consider how cam events affect dynamic CR, it would be minimal, if, at all. Certainly not a concern based on your eventual HP gain(s). Bowl blending is more of an efficiency in airflo not CR loss.

When it comes to measuring "static" CR, chamber size (valves inserted), piston +/- (relative to block deck), gasket thickness, piston dish/pop-up/valve reliefs etc. would be the determining factors....
 
#54 ·
I finished the other head today. I've decided to stop and leave the valve guides alone. I'm content with what I'm seeing after shaving off the thermactor bumps. Thank you for all the advice posted. They were all spot on.
 
#56 ·
When I placed the gasket (before porting) one side of each ports are already right under the gasket. I really didn't touch anything on the side walls. I might have to 'trim' some sides of the gasket so it won't block the exhaust ports.
 
#57 · (Edited)
You will loose as much as a couple of cc's depending on how much de-shrouding you do and you only want to do the minimum required obviously. I had my heads angle milled down to 50 cc's though. When I cc'd my combustion chambers after assembly, they were right at 52 now. I can live with it. Again, this is within the angle mill margin for my aftermarket iron heads. I am not sure what that margin is for stock heads and if you do decide to have them milled, make sure you get somebody that knows exactly how to do this. The shop that did mine also had to re-angle the faces of the head bolt bosses on the heads and they also had to re-angle the intake port face on the heads. If done properly, it is false that you will open up an intake leak by angle milling.

I also agree on working the roof of the runner to the extent that it is symetrical with the other 3 sides of the entry(intake) or exit(exhaust) to the port. It also increases the overall cc's the port can hold which will help but theres no need to go overboard with this part. You just want to cut the facing and then blend/smooth it back into the runner(sandpaper rolls) but I would not exceed the gaskets port sizes. That is your port face sizing template. You must make sure that the gasket is positioned on the head properly to mark the material you are going to take out. Its a bit harder to place the intake than the exhaust gasket. That blue that you will see on photos of head port work is called blue dykem which you can find online. It is good stuff to use when you start taking grinders to heads but you can also use laundry or magic marker.

It did used to be sort of a rule to knock down the exhaust guide boss completely and especially on turbo heads. However, that idea has changed in recent years. I studied dozens and dozens of cnc head photos and they show the blended boss which does not hurt air flow. It actually helps because you do not want any blunt surfaces inside the valve pockets. Blending and contouring the bosses into the pocket floors allows the flow to curve into the runner or out of the runner instead of having to make an abrupt turn. Keeping the coutoured boss also continues to give reinforcement to the valve guide as well as the valve pocket so you win every which way.

Shaving a bit off gaskets is not a problem as long as they still match up with your intake and exhaust manifolds. If they don't, you will need to match the intake and exhaust manifold ports to the gaskets which match your heads. The intake ports, in particular, will have more material taken off 3 sides than the 4th or short radius side. On the exhaust, they are more generally opened the same on all 4 sides. Also, the push rod bump in the intake runner can be smoothed a little but do not knock it all the way down or you will have a hole. If you custom match your intakes, you will need to mark your heads as right and left to keep the runners lined up properly.

It will vary how the bosses are blended depending on where they are located in the pockets but here is a general idea(not my heads obviously). This photo also shows the deshrouding work in the chambers;


Gee I hope I didn't forget anything and also keep in mind that I am not a head porting expert. I've just done a few and learned some things by doing my own porting work on a few sets of heads. Studying factory CNC head photos will show you a lot and videos of professional head porters because they are the real experts.
 
#58 ·
You've given me more that I can comprehend. Thank you for the info. That is a good looking heads. I will ask the machine shop regarding milling the heads. I really want to keep the combustion chambers relatively close to stock.
 
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