I want to port my L98 heads. What work should I do? As of now I'm afraid to do anything but blend the intake bowls for fear of hindering performance. To what extent have you guys done and what kind of results did you get? My mods are in my signature. If I do port the heads it will be at the same time I install the cam. Thanks.

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1986 CAMARO Z28 -> 151,000 original miles, 43,000 on 89' vette 350 block, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys, T5 with 3.35 1st gear and 0 miles, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, Spohn LCA's, Spohn adjustable panhard rod, Subframes connectors, polyurethane swaybar bushings/endlinks, 2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp. ET 13.22@ 106.4MPH 3300lbs less driver and speakers Next mods-> Homemade ram air, B&M shifter, Extreme Energy 230/236 cam.

 

I'm not a head guru but I'll take a crack at this.

First thing I'd do is get the exhaust side fully ported out. Some may disagree but that's what I'd do first. Stock heads ALWAYS have a weaker exhaust than intake- much weaker. I'm not going to give exact recommendations becuase there are a zillion ways to do this. Some shops like to put in a larger 1.6 exhaust valve, some stick with the 1.5. Their exect techniques and port shapes are their own traded secrest but I can say that the vast majority of the magic happens just below the head of the valve, around the seat and around the valve guide. The "short turn radius" is an area of concern to take it from a tight 45* angle just below the valve head to a nice smooth radius shape.

Intake would be a strong concentration on the area just below the intake valve head, around the seat and the valve guide again. The short turn raduis should again be made into just that- a RADIUS, not a sharp angle like it usually is stock. You're not looking to remove a buch of material or radially alter the port shape. Just can't do that with stock heads. Again, the exact specs and shapes are closely guarded trade secrets. A 3-angle or raduisued valve seat is also a common practice. Don't forget about those vlaves, either! Using a set of high quality performance valves can help flow, too- Manley makes a nice set of stainless vaves with swirl-polished head sna undercut stems that will bosst performance (and last forever) for not a lot of money.

The chambers thenselves could also stand a little attention. Some shops like to remove a little material around the intake valve to help unshroud it and improve intake flow. Also, any sharp edges should be smoothed out so as not the give detonation a place to start. Also, many shops will screw in a set of appropriate plugs to make sure sharp threads don't protrude into the chamber or the plug isn't sunk into the plug hole, reducing it's ignition effectiveness.

CHoose a GOOD reputable shop would be the best advice. If you're doing it yourself then get a set of junkyard heads to prcatice on- you'll ruin the first few you lay the grinder to, unless you're prodigy or something.


[This message has been edited by Damon (edited January 16, 2001).]

 

Damon,

For not being a head "guru", you've covered the basics pretty well.

Another little trick to get a little more around the valves is to put a slight radius on the FRONT face of the intake valve margin. Just break the sharp edges a little to smooth the intake flow. On high HP engines, builders I talked with say that alone can be worth 5 HP. A street engine probably won't see that much gain, but even 1 HP is worth the effort as long as the valves are already removed. They've said that similar treatment of exhaust valves doesn't hurt, but has yielded no advantage on the dyno.

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Later,
Vader
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"I cannot take this any more... Saying everything I've said before..."
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KaleCo Auto Parts

[This message has been edited by Vader (edited January 16, 2001).]

 

I had Scoggin-Dickey port my heads and install Manley Race Flo valves for 800 bucks. Their work is very professional and speedy. I feel I got my moneys worth. The only thing I wish Scoggin-Dickey would have done is open up the pushrod pinch a little more. Oh well, the intake bowl work, gasket matching and exhaust side are awesome.

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84 Camaro ZZ4 with HOT cam. 1.88 60' (12.98 @ 105MPH E.T.)
Other Mods: You name it and I have probably changed it.

2001 Dodge Ram Quad Cab 5.9L 4*2

ASE Certified Auto Tech
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JDM,

Instead of a thousand words, this might help a little to explain what we've been saying:



One of the benefits in installing larger valves is the ability to easily enlarge the valve bowl area, directly above the back face of the valve. You should also reduce the large "bulb" of material on the short side radius (side of the valve bowl closest to the port) as much as possible to improve port size and direct air flow straight to the back of the valve.

Enlarge the port openings to match the intake gasket patterns. Reduce the diameter of the valve stem guide boss in the valve bowl area as much as possible without reducing the length of the guide. The guide boss alone can significantly impede flow. Make the transition from the tall rectangular port opening to the flatter oval valve bowl area as smooth as possible and try to maintain the same cross-sectional area (free area) through the entire passage.

Once you're satisfied with the results, make paper or card stock templates that fit the passages, then repeat the process seven more times for the remaining ports.

Treat the exhaust ports in a similar fashion, and polish the exhaust ports as much as practical to prevent carbon accumulation and keep as much heat in the exhaust gasses as possible.

Polish the combustion chambers as well, then clean and reassemble the heads.

Piece of cake....

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Later,
Vader
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"I cannot take this any more... Saying everything I've said before..."
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[This message has been edited by Vader (edited January 16, 2001).]

 

Thanks guys. VADER, what did you mean by the intake valve margin???

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1986 CAMARO Z28 -> 151,000 original miles, 43,000 on 89' vette 350 block, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys, T5 with 3.35 1st gear and 0 miles, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, Spohn LCA's, Spohn adjustable panhard rod, Subframes connectors, polyurethane swaybar bushings/endlinks, 2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp. ET 13.22@ 106.4MPH 3300lbs less driver and speakers Next mods-> Homemade ram air, B&M shifter, Extreme Energy 230/236 cam.

 

JDM,

The margin of a valve is the parallel area between the face of the valve and the angle ground to match the seat.

The far left diagram is a standard valve, with a single angle, standard margin and face. There is a sharp angle (corner) where the margin meets the face of the valve.

The second (middle) diagram shows the same valve with a multi-angle grind and standard margin. The three angles of the valve grind allow for improved air flow around the edge of the valve while still providing for good sealing.

The right diagram shows a standard single angle grind with a radiused margin. The radiused margin/face allows for improved flow around the valve edges.

Combine a multi-angle valve seat grind with a radiused margin, and flow around the edges of the valve is improved to maximum.



Builders I have spoken with say even a single valve grind with a radiused margin will improve peak power more than a three-angle valve grind alone. Coupled with the multi-angle grind, flow is improved even further and peak power gains can be from 8-10 HP. All this from a little detail like how the valves are finished.

Please, don't tell all your Ford-driving buddies about this, because it seems to respond well in the Cleveland engines as well. The new "Erector set/Tinker Toy" (Romeo) engines don't seem to respond to much of anything, so it really doesn't matter for them.

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Later,
Vader
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"I cannot take this any more... Saying everything I've said before..."
Adobe Acrobat Reader 4.0
KaleCo Auto Parts

[This message has been edited by Vader (edited January 17, 2001).]

 

Wow, I can do that at home with a die grinder?

A few more questions:

1. Can I get a valve job done on the ones in my engine right now?

2. Does the procedure in quesition one require me to also have the heads machined?

3. How much does it cost to get the valves grinded? If the heads need to be done also, how much will they cost?

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1986 CAMARO Z28 -> 151,000 original miles, 43,000 on 89' vette 350 block, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys, T5 with 3.35 1st gear and 0 miles, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, Spohn LCA's, Spohn adjustable panhard rod, Subframes connectors, polyurethane swaybar bushings/endlinks, 2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp. ET 13.22@ 106.4MPH 3300lbs less driver and speakers Next mods-> Homemade ram air, B&M shifter, Extreme Energy 230/236 cam.

 

1. You can get a valve job done on any heads you want to.

2. A valve job is machine work. They chuck the heads up in a mill with a table that tilts; line it up to the valve guide; and run a stone (or 3 stones in succession for the factory-style 3-angle job) into the valve seat. They put the valves in something that looks like a lathe except with a drill chuck, and another motor holding a stone that can be moved around at an angle to the axis of the one holding the valve (or vice-versa), and spin both the valve and the stone. It is basically pointless to reface the seats without also doing the valves, or vice-versa. The point is to get new, unblemished surfaces on both parts, to ensure a perfect seal.

3. It's skilled labor, requiring expensive specialized machine tools. The price may appear as a flat rate but is based on an hhourly charge. Typical prices for a quality racing valve job NOI are in the $75-90 per head range. Don't buy your machine work from the low bidder, buy it from the guy that builds the motors in the race cars that win at your local circle track.

After this is all done, all the valves and all the seats are interchangeable. Any valve could go into any position. Then each valve is slid into a guide, and lapped to match that seat as closely as possible with fine lapping compound. After that is done the valves are uniquely fitted to that one place in the head and can't be swapped around.

I would not recommend trying what Vader is suggesting (part of standard racing grade valve work, blank stares at the corner parts store) with a die grinder.

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"So many Mustangs, so little time..."

[This message has been edited by RB83L69 (edited January 19, 2001).]

 

One of my valves need to be replaced because the tip is rounded off. Is this going to pose a seating problem?

So I can get a 3-angle valve job for about 175 bucks? Can I use the existing valves? This will give me about 10 hp right?

How does this sound for a mild port job?

1. Pocket port 1/2" into the port throat, including smoothing the short turn radius.

2. Narrowing the valve guide.

3. Enlarging the port entry, and smoothing all surfaces.

Will this all combined with a valve job give me 15hp? Thanks.

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1986 CAMARO Z28 -> 151,000 original miles, 43,000 on 89' vette 350 block, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys, T5 with 3.35 1st gear and 0 miles, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, Spohn LCA's, Spohn adjustable panhard rod, Subframes connectors, polyurethane swaybar bushings/endlinks, 2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp. ET 13.22@ 106.4MPH 3300lbs less driver and speakers Next mods-> Homemade ram air, B&M shifter, Extreme Energy 230/236 cam.

 

No, replacing one valve will pose no problem. It would be a good idea to find and fix whatever rounded it off, if you haven't already. Suspects would include a wallowed-out guide slot and of course a wasted rocker arm. However, new valve = valve job, period. IMHO that decision has already made itself for you. $175 is about right. You can re-use the existing valves, if (big if) they are in re-useable condition. This would include things like that they are not bent, their stem not so worn in the guide that the guide seals won't seal, not warped face, not already ground so many times that they will become knife-edged from doing it once more, etc. Only inspection after tear-down will tell for sure. There's like zero point in wasting effort on trying to hot-rod a defective motor anyway, so now would be the time to get any problems straightened out.

IMHO your port description is appropriate for a DIY job. It may be good for alot more than 15 HP (and I do mean maybe ALOT if the castings are poor) or maybe less, depending on the particular castings you have and what condition they are in. It's safe to say that you will maximize their HP capacity, whatever that is.

A couple of further pieces of advice on porting: make the guide have a shape more like an airfoil than a circular thing. That is, take material off the sides and not so much off the approach side especially. Leave the intake port surface rough, that is, don't polish it. Do polish the exhaust side. Break over the edges of the combustion chamber where the surface mill machine work meets the cast-in chamber; a sharp edge there will promote detonation. Make all 8 of everything as nearly identical as possible. Check how the spark plugs fit; be careful that you don't have a situation where the sharp outer edge protrudes into the chaber, this also will create detonation. The the "squish" area on the spark plug side is extremely important. If it becomes too shallow from surface milling, grind it back in. Make absolutely certain that these are as much identical as possible among all cylinders; again, this is part of your detonation protection.

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"So many Mustangs, so little time..."


[This message has been edited by RB83L69 (edited January 19, 2001).]

 

Any of you that are thinking about radiusing the valve margin...

Valves that have a small margin left from repeated valve jobs need to be replaced. The reason is because the narrow edge of the valve gets very hot, and the thinner it is, the more likely it is to warp and not seal anymore. Undercut stems, tuliped valves, and radiused or the three angle valve faces are one of those racing things that add power but may not be practical on a car intended to drive for a long time on the street. Its something to consider with how crazy you want to get and how much you want to possibly sacrifice on your engines' life span. If it were my choice (and it was) I wouldnt do the 3 angled face, but the radius if done right is ok.

 

Max,

Good call. I did the same on my last LT1 and new Manley Race-Flos. Standard 45°/46° single valve grind and radiused margins.

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Later,
Vader
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"I'm gonna talk about some freaky sheet now..."
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I'm still a little fuzzy after all the BS about pipes and rocks and steel beams they crammed into my head last semester, but its slowly coming back... I worked in a machine shop for about 6 years so I used to do this sorta stuff but my memory is kinda like on hold or something, maybe I need a new battery LOL!

 

And yet more questions....

What is this "squirsh" area you are refering to and what has to be done to it after milling?

So I should probably skip the multi-angle valve job and just do the radius surface myself? Can this be done with a die grinder or does it have to be done by a machine shop? Can you run me through the whole procedure?

RB83L69, I was refering to machine work done to the valves, not the heads.


Here's a little info on the heads: they are L89 cast iron center bolt heads. They have 40,000 miles on them, they are in almost new shape. I have a very solid motor. The valve tip was a result of a bent pushrod. I replaced the pushrod and rocker. The person who built my engine did not use self aligning rockers. (DUMB@SS)

Have any of you ported a set of these heads? How well did they respond? what work did you do, and what cam was used? What have you heard about these heads and response to porting them?

Thanks a bunch, you guys are great help, glad I don't own a mustang. - Jesse

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1986 CAMARO Z28 -> 151,000 original miles, 43,000 on 89' vette 350 block, L89 cast iron heads, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys

T5 with 3.35 1st gear and 0 miles, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, Spohn LCA's, Spohn adjustable panhard rod, Subframes connectors, polyurethane swaybar bushings/endlinks

2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp.

ET 13.22@ 106.4MPH 3300lbs less driver and speakers Next mods-> Homemade ram air, B&M shifter, Extreme Energy 230/236 cam.




[This message has been edited by JDMZ28 (edited January 19, 2001).]

 

I'll se if I can come up with a picture.

Older small block heads had a chamber that looked basically like a bathtub. In 69, they added a little feature, off to the side of the chamber under the spark plug, that looks like a little ramp sort of shape. It was designed to create a massive "squirt" of gases out of that side of the cylinder, across the top of the piston, right under the plug. The purpose was to introduce turbulence inside the cylinder at the moment of max compression, to aid flame travel. It really works. It's one of the reasons that cars suddenly didn't have to have 101 octane gas any more but could run OK with the pitiful 97 octane stuff that we were being forced to accept, by helping prevent spark knock.

You could maybe radius the valves in a drill with sandpaper. It would be very difficult if not impossible to avoid damaging the seat surface of the valve though. In fact, that's one of the facts of life about porting heads: you almost always will touch the seat accidentally, and just one touch means the head has to go to the shop. If I were you I'd plan on it. Get them milled if you want to increase the CR; then port them and work up the chambers; then send them out for a valve job. That's the order these things need to be done in to get a truy premium set of heads; all the porting in the world isn't going to do a bit of good if the valves leak.

I've never ported a set of those particular heads, lots of others. I'll let others who have worked with that particualr casting speak to their results. My experience is with many other castings, but fluid flow is fuid flow... some things apply to them all. I'm only telling you things that apply generally to all heads.

You really shouldn't be so concerned about getting a valve job. It's just money; I know don't want to spend any more than you have to, but on the other hand, there are some things that just have to be done. You wouldn't try to re-use gaskets, valves are about the same way, a "soft" sealing part. If you disturb them, renew them.

you're close to the 12s...keep your eye on the prize.

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"So many Mustangs, so little time..."
ICON Motorsports