i have a couple questions for u not really on the labor side of the work but the end product. how much hp do u predict this will add? and also how much do u guys think this would cost to have done by a pro? i am thinking of having the enigne rebuilt(over 100,000 and i think some of them were hard miles) and i would put a mild cam in and was wondering about having head work done. thanks

 

Thanks RB83L69

I really appreciate your input, especially about the combustion chambers. I've done about as much pocket porting and port matching and port polishing as I'm gonna do. I'm getting kid of burnt out from this

I did a boat load of work on them tonight and just need to do some touch ups and polishing tomorrow.

From what I can see, the gasket matching business is grossly overrated, just like you said.

And the bowls on the heads are nearly flat at the bottom transition from bowl to floor/roof, as the case may be. Hard to make a radius blend job out of nothing

 

Well, the guys who really know their stuff, like F-Bird'88, Vader, RB83L69 and so forth, figure somewhere between a 10 and 15% hp increase. This will extrapolate linearly with any increase in the size of the small block they are bolted to, so the work should be the last set of heads you'll need to do in a long time

I would guess you would be looking at a minimum of 10 hours by a pro who knows his business, probably at around $40/hr.

Like I said, that is a guess. (I'm no pro so it is taking me a LOT longer.)

If the shortblock is still good (rings and bearings) then I'd go for the head job. five7kid (who is a fixture on the Carb board) did the same with his 305 and it really hauls now. Go talk to him about it.

 

Here is another shot of my grinding tonight.

 

And another. The ridges under the valve seat are gone now and did that ever take a lot of grinding

I hope I didn't overdo any of it but there was a LOT of iron hanging around there!

As you can see, I need to do some polishing work to make this more presentable

 

Finally, a shot of the second head's exhaust ports. They need a wee bit of polishing, too.

 

Just curious on how you come up with this? I am soon going to be porting a set of stock heads (got them used, but rebuilt for ~$100 ). I've read a book that was writen by David Vizard (I'm sure you know who he is) and he states, IIRC, that messing with the short side radius, especially on the exhaust, can hinder flow since the air flowing past it can literally crash into the high side (AKA long side) and disrupt the velocity which it's gained.

Now I'm definetely no expert, but this would seem to make sense. Most of the air that's going to be flowing thru the ports will want to stay on the high side due to it's own intention of going 'straight' (AKA inertia). I'm not saying that you shouldn't touch the short side radius, but perhaps smoothing it while removing as little material as possible is the best route (for the air anyway ).

Not trying to flame. Just a bit of info that Mr. Vizard says is a common misconception. Please discuss you opinion (or better yet 'your statement'), not defend it.

AJ

 

I hope you're not done yet cause I take a lot more metal out
of mine. I really open up the path beside the guide, on the common wall and roof to flow more. And thin a streamline the guide boss. When I'm done there is no more as cast metal in the port. Then I run the stones through it to clean and smooth my cutter work.
Then I use the 40 grit rolls, then polish the hell out of the exhaust ports. Like I said I take 10cc's of metal out of each port.
If you're interested in CCing the ports and chambers, I found an
economical way to do it at home. I use an old cd rom to
cover the top of the chamber or ports. I use a little Vasoline
to seal up the CD to the deck and a little to seal up the valve seats and a little on the valve stems. If the chamber leaks water during measureing you'll get an error. You have to cap the chamber with something because if you just fill it to the top
the water's surface tension would allow you to put in a lot more water than "full" over the deck before it would spill over.
You can get a long graduated glass tube with base from a Pharmacy that holds 100ml and a brown plastic medicine bottle that holds 250ml and an inciline needle that holds 1cc.
1ml = 1cc The 1cc needle is real handy for pouring the last little bit to fill the chamber through the hole in the CDrom. You can remove the metal needle part and dispose of it as a safety measure. Go in to the pharmacist's counter and ask for them.
They may have them in stock or can get them real easy.
Tell them what you want them for and there won't be a problem.

 

 

Are you referring to the intake, exhaust or both?

 

Both .... I have a friend who has Fibermyalsia and some days
she really suffers. Take your time on this It takes me a couple of weeks (on and off) to do this. If your hands are buzzing take a day or two off.
Where work gloves too, it helps . 3 hrs at one session is plenty even for a semi- healthy old guy like me.
The guide bosses are still to tall and too fat.

Yes the floor on both the intake and exhaust port has no arch
compared to a Vortec or a dart head. The intake can be epoxied up but the exhaust has to be welded. This is beyond our little
budget port job. But you can still radius and smooth the sharpe
ridge left by the factory bowl cutter. The exhaust port needs to have two deep flow paths cut around the guide boss. and the guide, shortened and trimmed to allow the flow around it.
What size are the intake valve seats now? That would be the widest dimention of the 45 deg seat.
I'm wondering if they are 1.72" instead of 1.84" in the stock 416 castings.

 

Heres a pic. The shiny area is where fuel is cleaning the chamber, and for the most part its sticking to it there. Not really a good thing.

 

AJ:

On the exhaust short side, there is almost always a funky step and a sharp edge left from the casting and seat machining processes. Getting rid of it (i.e. smoothing it out) seems to help most stock heads greatly. One should not remove any more material than necessary, just do away with that sharp transition there, which produces turbulence at the point of highest flow velocity in the whole head. Alot of the porting process is just that; getting smooth laminar flow by eliminating turbulence at sharp corners, abrupt transitions, etc.

I guess it's a matter of interpretation... there's a big difference between "smoothing" and "hogging"... the latter is almost never the right thing to do. Mr. Vizard's remarks I believe are aimed at people who might think that the purpose of porting is to make the ports as large as possible, which is definitely a mistake.

 

Madmax- Would you say that you could expect most other SBC's to have a atomization problem there, too? I think I'll rough mine up a little extra, just in case.

Sitting Bull- Thanks for starting this mother of a thread up, it came just in time to help me with my heads.

 

Was thinking about what you said abut it being 2 tubes
meeting at a right angle instead of two tubes with a nice elbow.
On studying the pics more it seems that the long side of the intake port, between the guide and sparkplug side of the seat
does not have a nice radius and the port does not have good port bias. (offset towards the common wall to induce swirl
like other chev heads.) The area between the guide and
valve seat closest to the spark plug should be not so dug out
there. Unless i'm seeing things, these castings are different from the 416's. What size are the valve seats?

 

Probably so. Theres not very much difference in port shape, valve size, combustion chamber shape I think to make any significant difference where that happens.

 

The valves are 1.5 and 1.84. At least those are the size of the valves that I'm using to protect the chambers and they seem to fit right down into the seat snugly, and aren't sitting above the chamber floor.

The guides are a real pain to try and do. The cutter just tends to gouge them on the right side and chatter like crazy on the left. So I just gently rubbed it over the top to get the casting finish off.

And there is almost NO short side radius on the exhaust side! It just exits stage left!!!

I also outsmarted myself on the chambers and without thinking went and opened up the area around the exhaust valve, within 5/8 of the plug, too. Don't ask how, I already feel too stupid

Do you think that is going to hurt things?

 

OK, thanks madmax!!!

I'll make sure I rough that area up a bit when I go through the chamber work

What kind of heads are those?

 

You are welcome NT!

I was kind of hoping that SOMEONE would do a thread like this during the spring/summer season. It's just about the only time we Canadians can do this work, unless we have a heated garage. (And it sure leaves you covered with dirt. I'm going to have to spray the floor with water and try shoot all that metal powder down to the street.)

Plus, we just have to take advantage of our experts' advice and experience with this porting business, and document it for everyone with a Tech Article and photos.

Why aren't you posting some pics of your heads?

 

L98 aluminum

 

Did you polish the chambers on those L98 when you had them off? Do you think that was the problem, too highly polished?

Or did you just sort of grind off the factory finish?

 

You're right. It's amazing the amount of info we can get from these guys if we just READ.

I could take a few pics of my heads (they're back from being cleaned and inspected now), but they're just sitting on my bedroom floor.
I'm currently working on polishing a set of 16" Firebird rims for the car. I figure I should learn the intracacies of using the Dremel to polish, on the rims, and use that ability on the heads, once perfected.
I'm happy just watching the head work happen now.

Yeah, it's nice to be in the 'States for a little while to enjoy the summers (although I am moving back to mother Canada in a few months). I could do without the 100+ degree F temps, tho...

 

I have a question about that. Is the 10ccs coming from the port, the bowl or both combined?

I have removed a lot of metal, especially in the bowls. Just getting the lips under the valve seats removed and the edges smoothed has required quite a bit of grinding. I don't know if 10ccs are gone but it is a not inconsiderable amount.

I think I was wearing about a pound of metal dust last night when I hit the shower

 

Well, it is Stampede time here in Cowtown and it has been HOT

High 80s and low 90s at times. And then yesterday it rained and got a lot cooler, down into the high 60s and low 70s during the day and into the 40s at night. That's what they say about Calgary: If you don't like the weather, wait five minutes

 

sitting bull, want to arrange a cruise with me if i get my car back on the road by sunday, Nosaint and i are starting an f-body club here in town

 

Sure! I have been talking with Nosaint via email for a few months. He sent one a couple weeks back saying he was just about ready for an inaugural meeting.

 

I was talking with him on friday i think (what a memory) and i was going to get something going for last sunday but low and behold...

Im lookin at going for an hr cruise through town and then going to a bar or something for drinks and a little bull $hit and war stories about our cars.

The southcenter Parking lot ontop of Sears is always EMPTY at 6:00 pm on sundays so we could all pile in there (if we get big enough)
Then cruise up to a pub in the north.

Anyways get ahold of me anytime da_bozo@hotmail.com
or 2571029 (home phone)
Ask for Thanos.

Oh yeah, how about that porting

 

Sounds good. I live in the extreme north, up in Citadel. Ask for Todd at 247-5076. Let me know.

Now it's off to the garge for another swing at the cat.

 

Well when there is a heap in the bottom of the shower and a pile on the floor, you're done...

Seriously, yes I measured the port volumes before and after
porting and I took out 10cc's of metal out of each port.
ON these last two sets I probabily took out more. When I get 'em back I'll cc them too.

 

Russell,

Here is a pic of the valves sitting in the seats. Maybe the seats are even larger than these valves--I'm no expert at what I'm looking at.

Let me know, please.

 

Here I enlarged and manipulated the contrast so you can see what I mean when I say there is virtually no short side radius on the exhaust port.

I hope this is visible enough for you to see.

What is your opinion on what I've done?

The others look more or less the same.

 

Here is the bowl area of the intake port. As you can see, it is about as shaped as it can get. It was a weird shape to begin with. I just ground out all the high areas and blended it together.

Does it look good or have taken out too much?

 

OK, here is another shot of an exhaust short side radius. I again pumped the contrast and whatnot in order to make this visible.

Any observations?

 

And here is a view of the opposite side of the intake bowl. This is kind of grainy but it has a little more sweep to it than the other side.

 

Looks good to me. Just radius and smooth out what you have
there. You're right there is not a lot of port floor arch to work with.

Oh well these aren't and never will be fuelie heads.
It will be a nice improvement over stock which is our aim here.

You can get a 305 head gasket and trace out the edge of
the gasket bore and use that is a guide to ensure you stay inside
this circle when unshrouding the valves in the chamber.
Use the vortec's and 416's as a guide and common sense.

You don't really need to remove a lot of material from the chambers, just a little in the right areas.
Take the head out side and squirt some water through it to see the flow patterns. Your neighbours will thing you've LOST IT! but
what the (*&%$. You'll see where the water/ air wants to
go. Just give it a little help. You can cc the heads after you're done and have them milled to restore or increase the CR.

 

The big grainy pic shows the intake port problems I mentioned.
The long wall radius is too dug out as cast. If you could look at a set of 60's camel backs or dart sportsmans you would see what I mean. You'd have to fill it in with epoxy and regrind it to abetter contour. (sort of beyond our budget project here) When your machine shop hogs the bowls for the 1.94" valves there will be a new V funnel under the new seat again.
You can/ may want to touchup the bowl blend when you get 'em back. You should be able to do this with just your stone/drill
and not hit a seat because you won't have to go very deep or remove too much material. The 416's appear to have a little better contour hear (as long as you get a set without serious core shift)
but again nothing like a old hi perf 60's camel back.
If you could get an old 1.94" valve and carve out the chamber till
it just drops in with out hitting the chamber wall that would be cool. Again get a gasket and use common sense here.

 

What about 1.6" exhaust valves? Do you think it is worth it?

As I said, I don't have any valves for these heads yet at all.

 

It certainly won't hurt any If you have to buy valves anyways, they are the same price. The set I flowed with 1.6's I got 140 @28
I would of liked more, like 155 170. Like I said my next sets are 1.5 and 1.6. I don't like opinions. I like flow bench and dyno results. I'll let you know.

 

OK, I'm about done after tonight's marathon session! (Just in time--I have to return the die grinder tomorrow.)

I hit all the exhaust ports and bowls with 80 grit rolls and it DID polish things up considerably!

I also enlarged what I could of the chambers but the intake valve side was right up against the gasket outline so there was no way to deshroud them

I'll post pics tomorrow.

 

Oh alright, I'll post some of them now

Here are the finished combustion chambers. I stoned them and then polished them with 80 grit rolls. I also enlarged the chambers on the spark plug side of both valves. It was a boo-boo but once you've done it to one, you gotta do it to 'em all

 

Here's another pic of them, but from a different angle. As you can see, there was no room beside the intake valves to enlarge and deshroud them.

 

Here is a finished exhaust bowl. It is MUCH shinier and consistent than it looks. Keep in mind that this is quite magnified.

Man, am I ever beat! I'm glad this is about done

 

I've been watching this with interest, guess I'll finally chime in.

The 80-grit removed casting roughness, but didn't "polish" the exhaust or chambers. Your Deluxe kit should have included some 120-grit flap wheels and medium- and fine-grade cross buffs. The cross buffs should be used with WD-40 or the like.

When you get done with them (and it doesn't take very long with the flap wheels and cross buffs), you'll have a real shine on those surfaces. But, you only want to do this on the chambers and exhaust ports - the intake port should be left at the 80-grit finish.

I like the look of those 801 chambers. Everybody says the 416's are the better heads, but I don't like that spark plug boss sticking in the chamber like it does. But, the 416's don't have the rocker stud hole protruding into the ports, either. Guess there's no free lunch, right?

(I could only take about 3 hours at a stretch doing this myself. Spent about 12 hours total on the Worlds, plus about 3 hours doing one cylinder on the "practice" head.)

 

Your heads get a thumbs up from me.
I have a few small concerns, tho. Are you getting the seats replaced? It looks as though the seats have sunk, it was especially noticable with the valves installed.
You mentioned getting bigger valves, that of course, would take care of the seat problem, as I imagine they'd install new ones.
Secondly, do you think the short side radius is too sharp? AJ_92 mentioned air from the floor "crashing" into the roof, after being shot past the bowl/chamber. Do you or anybody else think this would be a problem?

 

Tim,

You are right. I'll do those last two things before I take the grinder back.

Did you know that even the Vortec heads have those rocker stud holes in the roof of the ports?

NT,

There is nothing I can really do about the castings shortcomings, short of epoxying things up and recontouring the bowls. That is beyond my ability and, without question, budget, so I'll just have to leave them as they are and hope for the best. I can tell you though that the ports and bowls are a LOT bigger than when I started! All of that metal powder had to come from some place, and was there ever a lot of it

I think the valve seats will be OK. I'm hoping there is enough material left to accomodate the 1.94 and 1.60 valves, too

 

OK, this is the finished product!!!

Here are the "chromed" exhaust ports. (The rough areas in the background are the entrances to the exhaust crossover passages for heating the carb.) These have been hit with carbide cutters, 80 grit rolls, 120 grit flap wheels, medium grit cross buffs and a final go over with WD40 and fine grit cross buffs. It did make a difference. I did the exact same thing with the exhaust bowls and the combustion chambers.

That's the best I can do, and besides, I'm out of time

Who'd of thunk that cast iron could be so smooth or shine so much???

 

Here is a shot of the entire combustion chamber side of the head. The chambers are as polished as I could get them, too.

 

And here is a close up of the combustion chambers. Ignore the gouges in the valve guide bosses

So folks, here is living proof: If I can do this (and I'm a physical wreck), ANY of you guys or gals can also do it

What do you say???????

How many horsepower do you think I've gained for my miniscule little 305???????

 

A good 10-15 at the fly, you never know it could even be as much as 20.

When it's all said and done you've invested what a good 20 hrs now?

 

Oh, I'm hoping for more like 30 hp at least. Standard Abrasives says their kit alone added 19 hp to their 305 and they don't do anywhere as much bowl work, do a 3 angle valve job or add 1.94 intake valves. F-Bird'88, whose instructions I'm trying to follow, gets almost L31 Vortec flow numbers from his. Anyway, that's what I'm hoping for. They may be the near equals of Dart Iron Eagles, S/R Torquers or Vortecs.

Yeah, I've put in at least 20 hrs in the last week, start to finish.