when my car comes off the road for the winter i plan on pulling the heads and working them over. i have some pics of my practice head and would really appreciate it if you guys could look them over and tell me what you think.
i havn't touched the chamber or the exhaust port yet.

 

Looks ok but... those heads need to be put back to the bottom of the lake.

 

Lol I guess it's a good thing that's a practice head, it looks like hell. But you seem like you are doing alright. The valve guides particularly look good. A few things to remember:

-You do NOT want a mirror finish on the intake port. You need it to be somewhat rough so that the fuel and air can stay suspended in the open areas and not stick to the sides.

-Whatever you do, do NOT knick up those valve seats. Short side radiusing is important, but make sure you steer clear here. Wrap some duct tape around the chuck of your tool just to ensure you dont hit it.

-Get that exhaust port extra sheeny

 

looking down the valve hole, you shouldn't have an edge. ie, you should be able to run your fingernail from the valve seat, down into the port, without catching your nail. See red arrow

Also, make sure your short side radius is nice and rounded.

Which castings are you going to port as your finished product? Depending on that, if you enlarge the valve size, scallop out the teal area here.

If you can, try and do an "airfoil" shape to the valve guide. See the purple arrows. The valve guide should look like it's "pointing" towards the port. Look at AFR's website, they have a nice little picture of it there, that's pretty closer to perfection on their site, shoot for that.

The blue lines are good, you enlarged that area there as much as you dare eh? You want to keep the left side (furthest from the exhaust valve), larger than the blue line on the right (closer to exhaust side). That's port bias. Just for kicks, run your carbide cutter all the way through there. Cut into the water jacket. Just so you have an idea how thick the material is there.

On your final one, i'd also use sanding rolls in the combustion chamber. Get it shiny like chrome in there.

oh yea, your port roof (IIRC) see's more flow then the port floor. You see the "dimples" on the port roof there? Make 'em gone. Raise the roof as far as you can.
Also in the port view you've got there, the right wall is curved there eh? That's the "pushrod pinch". Try and straighten that wall back as far as you can. One good way to do this, is to use a 1/4"-3/8" steel ball. Place it on the outside of the casting there, like where the pushrod would be, then use your caliper and measure from the ball, to the inside of the wall. Then subtract the ball size
Remember, if you punch through the wall there, you can epoxy it back up. Again, another place to go ahead and destroy the old "practice" heads, just for learning sake.

Seems like you're doing the right thing though.

 

Thanks!
most of this was done with a cone shaped stone. my good heads are a bit older 305 heads than my 416 practice head, so i expect the castings to be a bit thinner, they also have 1.94 valves so i will definatly need to do some unshrouding. i did straighten the pushrod pinch a little bit. should i streamline the exhaust valve guide similar to the intake ones?

the silver line in those pictures is the opening in a 4" bore headgasket.

Edit: i read just about all of the head porting threads at least a couple times.

 

don't use A HEADGASKET!!!
The holes there are like 4.166", and are oversized!
bolt the head onto the block, and stick your hand up the bore from the underside, and scribe the head that way. Also, label the head R and L then...

stone?!?! Get yourself a carbide cutter, you'll never be able to remove enough material with a stone.
older 305 heads? uh oh, what casting #? The "older" ones tend to be flat out garbage.
Yes, do the same to the exhaust valve guide as you did to the intake, also, you can shorten it a bit. Remember airfoil!

Straighten the pushrod pinch, and the cylinder head bolt hole "bulge", a fair bit.

 

i don't think the pistons are coming out, so that makes it kinda hard to stick my hand up the bore.

they can't be too bad, i ran a 14.4@95 2.2 60' w/ this combo:
327", '70's 305 heads cut for 1.94 valves, non-rpm performer manifold, holley 4160 600cfm, comp Xe268(.477/.480 224/230) hedman shorties, test pipe, 2.5" dynomax catback, TH350, stock stall, 3.73 posi, street tires

if they really are that bad i might just get a set of vortecs and a new manifold.

the flame shaped carbide right?

i think that i'm gonna pull it this winter and put in a 350 shotblock thats been sitting in my garage.

 

flame works ok. You can't cut with the tip very well though. i like the cylinderical one, with a ball end.
that works best for most places. the valve guide is the only place that needs the flame tip. flame tip then is ok for a short one, when you buy a long cutter, get a cylinderical one with a ball end.

 

do you think i will go through a couple of those or will one of each finish the job?

how much power are you making with your setup?

 

one of each should work, if you're careful. They don't really wear out like a stone will, but if you catch it on something and it bounces around, you can bend the shaft, and it'll be useless. You can cut it shorter and use it that way after.

I'm pretty out to lunch on the tune right now, so it bogs a bit. I'll get it dyno'd sooner or later.

 

You are doing great with the porting. Just remember not to get too carried away with porting 1 bowl/runner, because you're going to have to do it the same to them all.

I wouldnt use the old 70's 305 head if i were you. Not trying to be a jerk, but you could be easily be in the mid 13's with just about any other "decent" stock head with all the mods you have.

check out this place for carbie burs.. i've used them twice now and they have awesome service and you cannot beat their prices. Carbide Burs, Cutting Tools, Endmills, and Accessories

the image is the bur Sonix is talking about i think; they are probably the best all around bur for the job(3/8" radiused cylinder, 1/4" inch shank). I like using stones too though for doing "touch-ups", they work great for that since they dont remove metal so fast.

Just a tip; if your using a carbide cutter for the first time, no doubt use it on your practice head/anchor because they cut very fast compared to a stone.

 

no offense taken, i asked the machine shop to find me some 416's and this is what he gave me, i was mad. i just found out that i have a set of 416's off of an lg4 that i can use. should i have 1.94 valves put in or stick with the 1.84.

i spent about 15-20 min on the bowl and the pushrod pinch with the stone.

i have a pretty good feeling that these heads, my manifold, and my cam are going to find their way onto a 350 this winter, any guess on times or power?

should i get the double cut or single cut carbides, theres no difference in price?

one of these
and
one of these

Thanks!

 

Get double-cut. They cut really well.

I would get a 2 1/2" (or is it 3?) and a 6", the longer shank makes working in the runners and deep in the bowls much easier, but they can be a bit harder to control so you can use the shorter one where its easier to get to. If you want to go cheap just get the 6", but if you can swing it id get both.

get SC-3L6 DBL, and SC-3 DBL

 

my grinder(die grinder, not a dremel) only takes 1/8" and 1/4" shanks. SC-3 dbl is a 3/8, should i just get the 1/4 version? what about a flame shaped one?

 

The head of the bur is 3/8" not the shank. It's 1/4 inch shank, so you'll be ok.

 

should i have 1.94" valves put in or stick with the 1.84"?

 

If you can at all swing the extra cost, i'd go for the 1.94" valves.
I paid $80 to have the seats cut, then used my valves that I stole from the 993 practice heads I had lying around. I backcut them by hand with a drill press and a file. (you can use a hand drill and a bench grinder, or any combo of things like that..)

 

any more info on the back cutting,like how much to take out or how far up the stem. i think i could use a lathe, my grandpa has one .

 

lathe? awesome!
do a search on my name, and "back cutting" or something. I showed a few pics of what I did with a drill press and a file and dremel and sandpaper.
Google it too.
You want to clean the whole thing up, back cut intake/exhaust (remember exhaust valves are harder than sin, they will ruin a file...), then do a front radius on the exhaust valve, and a front chamfer on the intake. Check my thread, in case I got that bass-ackwards there.

 

i never said i actually knew how to use a lathe, but my grandpa has been looking for a project to teach me on. i'll go check out your thread now.

do you think unshrouding the valves like this would help?(this is a pic from the guy that got 270ish cfm out of a set of 083's)

 

Show me a link to a thread or more info on that guy.
That's some freaky impressive results.
Those look amazing.

And yes unshroud the valves.

 

here you go
the links to the first parts are in his post.

look at the edge of the chambers toward the head bolt hole at the top, that is where i was talking about unshrouding the valves. the reason i ask about that is i have never heard of doing that except for from this guy.

 

ooh, I see.
Usually you unshroud towards the spark plug, so below.
But hey, I can't argue with the guy who got 270cfm now can I?

Thanks for the link.
oh, I think I read this before, IIRC I couldn't find any pictures though...?
ah, that was some other guys picture. Unfortunately the guy who got the 270cfm managed to tell a lot of hard #'s which were impressive, but gave 0 pictures. Left me infuriated.

 

it is annoying that he didn't leave any pics.
i don't think i am going to unshroud there, just in the normal way.

i was reading some of those other porting threads, a lot of them refer to the valve throat/choke is this the little ridge right under the seat?

my carbides are on the way, i got a short flame one and a long cylindrical ball one.

 

yes, the little ridge.
good choice on carbides.

 

just so i'm sure,
i want the thoat to be about 90% the size of the valve, even if i have to gring that ridge completely away

here is where i ground the ridge down, it is exactally 90% the size of a 1.84" valve


here is a stock port with the ridge for comarison.


here is a valve i modified with the drill/die grinder method



i also opened the pushrod pinch up a lot, i didn't do near the floor because i was using a large stone. i did just pick a random amount to raise the roof because i don't have a large enough intake gasket, what size intake gasket should i open it up to? a 1204?


is it bad that i hit the valve cover bolt hole?


it really does take a long time to cut with a stone, i hope that you are right about the carbides cutting faster.

 

You got way too carried away on the port roof opening.
Make your openings like this but square to the flange.
Use a felpo 1205 gasket. You'll want to epoxy up that opening a bit on the roof and start over or the intake gasket will always leak.
You need the 6" long shaft carbide cutter to allow you to raise the port roof all the way from the opening to the valve bowl area. This is your practice head right?

Hope you are just playing around and don;t plan on using that valve again. It's curbside material now. Some people should not be allowed to pick up power tools...

 

i don't have an intake gasket to match to, i will get some before i start on the good heads. the 6" carbide is on the way.

it is a practice head and valve, i don't think i am going to modify any valves, no way to be consistent, and i have no idea what i'm doing in that respect.

i think i am going to go with 1.94/1.5" valves.

right now my main concern it the valve throat, did i take too much out there?

 

once the valve seat is cut, they machinist leaves you with a ridge. I remove that ridge and blend it. I've never done the math to find out what % it was. But I'm pretty sure it's the right amount.

holy cow that's one rough valve alright. What did you use 36 grit??? Main thing is to not touch the valve seat on the valve, that surface should remain virgin. Back cut, take off the ridge on the back of the valve, smooth it out.

holy cow, you made that port round! hey, it's a practice head, that's the best way to learn. Yes, keep it square, with the same sized radius as it had originally, just raise the roof a bit. Now you know how much you can raise it
and yes, carbide (double cut right?) will go through that like butter compared to the stone.

 

i tried to make it square but the only stone i had was about 3/4" diameter.

when i punch through in a major spot it will make a great hole for the anchor rope.

like i said, i'll leave the valves to the machine shop.

when i get the carbides i'll do a port the 'right' way in the practice head, shortly after i punch through anywhere i think is thin in the one i already messed up.

90% of a 1.84" valve is 1 5/8"
90% of a 1.94" valve is a touch under 1 3/4(1.746)
90% of a 2.02" valve is 1 13/16

 

I've got one comment. 601s!!!! About 3 years ago, I ran 15.5s @ 93 in a 5,300 lbs fullsize van with stock 14022601 castings on the 305 and 3.08 gears in the rear.

Stock Flattop piston 305 shortblock (9.8:1 compression with 53cc chambers and shim gasket)
Stock 601 head casting (1.84/1.50" valves, 53 cc chambers) with specified comp 981s.
Stock GM cast iron Q-Jet manifold and non computer Q-Jet
Recurved HEI ESC distributer with 18* initial timing and 36* total @ 2,800
Stock GM 2 1/4" rear outlet "VAN" cast iron manifolds into 2 1/4" headpipes, dual 2 1/2" Catco cats, 2 1/2" duals with 2 1/2" DR Gas X-pipe
Comp Xtreme Energy 274 camshaft
Stock GM remaned 4L60 (700r4) with Corvette 2-4 servo and stock 2,000 rpm converter, 5,800 rpm 1993 LT1 Camaro Governor (Bought it from Sallee chevrolet a few years before)
GILBERT CHEVROLET - High Performance 4L60 Four-Speed Automatic Transmission
3.08 Rear gear with 200,000 mile G80 Gov-lock
P255/70/R15s
5,300 lbs empty, 5,500 with me
10 miles of Red silicon vacuum hose (don't ask, I was younger and stupider)

Here are the same 601s after some work, including 1.90" intake valves and 1.6" exhaust valves.

EDIT- the pictures show them with 2.02/1.60 valves installed. I ran them on the 305 with 1.90/1.60 valves. The first picture is the smaller valves. The bottem ones are after working with them some more and installing the 2.02/1.60s.

 

those are some really impressive times with such a heavy vehicle.

it looks like the intake valve is really being shrouded by the chamber though.

 

Those are actually 2.02 intake valves in those pictures. I have them ready to go onto a 355. They had 1.9" intake valves in them when they were on my 305. The 1.9" valve is a 1.94" PEP Pro that was cut-down. In hind-sight, a 2.00" Intake probably would have flowed better.

FWIW, here was a couple of friends and I playing around one night in an empty parking lot. That was with the stock cam (POS GM 929 cam) with TBI conversion and exhaust.

YouTube - Van Burnout

 

i see, you could still grind the chamber wall back a bit near the plug.

i don't know why but that video is strangly entertaining.

 

If you go too far in raising the port, you reduce the area available for intake-to-head gasket sealing.... nevermind that you are messing with an area that really isn't an impediment to airflow. I know it's a practice head -- but learn from the mistakes now before you port the real thing.

The runner CSA (cross sectional area) is fine at the head-to-intake location. The major flow restriction is in the corner (the bowl) so that's where most of the porting work gets done.

As for the 601s shown, some comments:

Look at how shrouded the intake valves are, how deep (open) the chamber volume is, and how recessed the plug is in relation to the chamber. The intake valves are probably too large in diameter in that application, i.e. a smaller valve would have flowed as much as the ones shown.

GM also went away from large open chambers because it takes too long for the plug to burn the fuel, nevermind that the emissions are worse. Fuel+air burn speed is quite slow (5 to 20 m/sec), so GM projected the plug by inserting it deeping into the chamber, shortening the time needed for the burn to reach all parts of the chamber.

The squish area is also quite small, so that got enlarged, and the heads got either port bias or swirl ramp to increase the rotation of the fuel+air mix, so it would flow past the plug --- making it all burn faster.

All those things together made the TBI heads on 262 v6 and 305/350 v8s more restistant to detonation, allowed a higher factory CR, allowed less spark advance to be used (which helps torque and power if done optimally), and reduced the emissions. That's exactly how the TBI (and TPI) heads evolved from the carb-era heads of the early/mid 1980s. The only thing the TBI/TPI heads didn't do was flow well out of the box, and that got fixed when the reverse-flow-cooled LT1 heads were issued (followed later by the L30 and L31 for conventional cooled engines).

 

well, i got my carbides and did another port on my practice head, it came out much nicer.

 

for the final time, i'd try and leave some material here.

Next time you're in a grocery store, look at the newest car craft, december, picture of an orange '60s stang on the front, page 46.
Or look at AFR or Dart's website. Little bit of material left there.

The "slots" in the intake port, lines going around concentric? That's good. AFR's CNC ported heads have that finish, I think it's meant to keep fuel in suspension and whatnot. Good good.

 

i left most of the material behind the guide there, just tried to give it an airfoil like shape. the front(towards the port) is ok though, right?

the concentric looking lines, that was an accident, thats the only way the cutter would cut there, i think i'll leave them there on the floor because that has low velociy right?

Edit: i looked at the picture on AFR's site and their heads have more material behind the guides to begin with.

 

yes, it has low velocity, and yes, leave them there.

The front of the guide looks good, yep.

 

I found that making gauges and using a sharpie really helps on replicating the ports. Make lots of marks and cut out some gauges from plastic to simplify matching the ports. Once you have one good port you like then you can just copy it over to the other ports much simpler this way. Oh and it looks great.

I did a search through the back posts and see playing cards work well. Old credit cards would work also. I found making measurements at the tightest areas will allow you to get a better feel of how much cfm the port is capable of. I am using a formula to calculate cfm from port area but its crude but it makes it better than guessing and helps match your intended application.

 

i was planning on making some templates out of card stock or something.

 

thanks to vader for these.

I didn't use templates myself, by eye was close enough for me.

 

I mainly measured just to make sure I was taking off enough without going too much. Like I said I used a formula to calculate CFM and I didnt want my efforts to be wasted by not porting enough or going to far and breaking through or making an overly zealous port. I just didnt trust eyeing it up.

 

i've been looking for those but couldn't find 'em, it'll be interesting to see how my port compares.
Thanks!

 

I wouldnt get too **** about the valve guides. Some of the best flowing aftermarket heads i've seen have basic cone shaped guides and no fancy "air foil" to spin air. I'm sure the fancy shape may help a few CFM, but dont loose any sleep over it.

Listen to sonix about removiing too much in the "scoop" area under the guide in the bowl. You need a nice ramp there and you can find your self with a nice hole there if you have bad luck. Look at the picture of my nice machined 083 heads that i screwed up. I wasnt even trying to remove anything here, just even out a small rut.. Needless to say it was no fun.

You are doing a good job though. Just remember you are not re-designing the head, you are just fixing it's flaws.

Have you done any exhaust ports yet? They are certainly the easiest by far..

Also if you plan on putting bigger valves in the heads i would have them cut for them before you start porting, it'll help reduce porting time for you.

 

it looks as if you had the guides cut down a bit, the guides in mine look kind of like that but stick up a little bit where the pressed in guides are in yours. i didn't shorten the guide at all, it's as tall as the original, it also looks as if the outer curve of your port comes closer to the guide than on the 416's.

either way, there is going to be a considerable increase in flow over the original. i am not trying to outflow a set of vortecs(it would be nice but this is my first experience in porting and i just don't see it happening, didn't FBIRD'88 get like 235 out of them?) i am more looking for results like kitch's(220ish cfm on the intake)

 

A PEANUT LATHE!!!!