Hey everybody,
I am thinking about porting out my 416's and I was curious about sometthing. I figure that it is a pretty good idea to get a good valve job done after I port them but is it totally necessary? I imagine that metal shavings will be going everywhere but, would a good cleaning do the trick. I almost hate to even take a chance with it, but I would like to get out of spending the extra $$ on getting machine work done.
Also how important is it to do the bowl work? If it wouldn't make that much of a difference, I'd rather not mess around with the bowls. Plus there is less of a chance of messing up the valve seats.(I'm still thinking about the possibility of skipping on the valve work)
Thanks!

 

get the seats and valves machined AFTER you port and polish, plus you'll have the heads aprt anyway and you can put them back together so you ought to save some jack on that part of the shop work.

 

Thanks for the reply. I planned on getting the valve job done after I did the porting. The only thing that kinda sparked my curiosity was some threads I've read. I've noticed that some guys get new after market heads and talk about porting them before installing them. I just couldn't see myself spending the money for new heads and having to send them to get machined before putting them on the car. So thats where I wondered if everyone was getting valve jobs or just cleaning them after their work...so I just thought I'd ask.

 

well if you're real damn careful you won't have to get the seats resurfaced, but i always end up messing a few up, usually with the collet on my grinder and not the cutter.

 

Yep. It's really hard to not hit the seat. I would always recomend getting machine work done on any new head unless it comes ported and polished. You can clean up the casting flash and roughness, plus port matching always helps. It also helps increase engine life, because you might find some thing wrong with the head. New heads are pretty good though. Errors are much less common. Sometimes all of the sand doesn't get out of the casting either. Racing and cars in general are just big money pits. There's no way around it.

 

I didn't send my new, ported heads to a shop, but the valves and seats did have to be lapped in even though I didn't nick any of them during the porting.

A suggestion: I'm assuming you're building a performance 305. Consider putting in 1.94" intake valves while you're at it. Also check the guides carefully for wear. With that, I'm actually suggesting two trips to the machine shop: 1) have the guides checked and replaced if necessary, and have them "rough in" the 1.94" seats. Then, after you take them home and do the porting, 2) take them back to the machine shop for the 3-angle valve job.

 

What kind of prices would I be looking at for the 1.94s? I've thought about doing that kind of thing but I have to keep stopping myself. See, my budget is limited by one thing...my wife. Problem is that I already have an 84 chevy pickup that is fully restored. Its got a 502 crate in it and allot of dollars too. So if I really want to drive something with neck snapping power, I just fire it up. The camaro is my everyday driver(gotta be behind the wheel of a bowtie) so I try to limit what I do with it...but on the same note I can't stand the whole peanut deal. So cam, heads, and porting the intake is the project I'm putting together.

 

As for what to do when porting, there's a good tech article on this site (in the "Tech Articles" section, on the first page), on basic how-to things.

I'm about to start porting my 416's, too.
Porting the bowl is probably one of the most important parts of porting. For our mild 305's, we're not going to have to make the runners monstrous, so it's a matter of making sure the head doesn't impede the flow of air that the runners can supply. In other words, I'm not going to make my heads try to flow 240cfm @ .600" by hogging out the runners.

Once you get the heads off the car, you will immediately notice that there are a few areas that can be fixed in the pocket. Like the big ridges on the short side radius, right by the valve. Or the end of the valve guide.
Some guys like to grind down the valve guide until it's flush with the runner. On our heads, we'd probably have to grind 3/4" of guide off to do this. Sounds like a bad idea to me. I'm just going to smooth the bottom of the guides, so that there are no ridges, and air can move uninterrupted into the chamber.

If I get my heads done before you do, or you get your heads done before me, maybe we can compare notes through PM's, or whatever.

 

I have ported and ploished like 4 sets of heads and never have had a problem not hitting the seats. just take your time. also when you do it don't "polish" the intake side. you want to increase the size of the ports but still have a little turbulance to mix the air/fuel better. so increase the size but don't necessarly "polish" em. I have my exhause ports polished though. I spent about 15 on each port with about 600 grit finger sanding

 

Thanks for all of the input...I'm going to order the porting kit today. NTChrist, I'll post after I get going on these things!
I can't seem to find the Tech Article on this though...I guess that what happens after being up all night.

 

Here's a link which was posted on the TPI forum by one of the moderators a while back.

http://www.sa-motorsports.com/diyport.htm

Not for 305 heads specifically, but I figure the theory is the same for any heads you wish to port.

Good luck! and keep us posted on the project!

 

Has that exhuast side polished kept clean? I'm just wondering, because it seems like it would get soot on it and then not work any more. Just wondering.

 

Yes you need to work on the bowls to get a worth while
result. Plan on haveing to get a valve job, you're gonna hit a seat.
You should up grade to 1.94 intake valves to get a good result.
Consider having the heads machined for positive seals.
A competent machine shop can do this for a reasonable price
including supplying the new valves.
Get an estimate.

 

It does get carbon on it like anything else in an engine. I will say though that it was a thin layer you could wipe off with your finger, and I cant say that for other unported heads I've seen and touched. If polishing does anything, I dont know but I did it anyway.

 

When I got my 416's, they hadn't been polished on the exhaust side, but they had been used.
They were caked with carbon deposits. The rough casting seemed to catch it all.
If polishing it will limit the carbon to just a thin film, then I'll be happy.

 

I just ordered my SA porting kit yesterday. (I had to get it from Winnipeg because no one in Calgary carries it. That is ridiculous for a city of almost a million!)

Anyway, I'm hoping it is here by Friday, as I'm eager to get at this

Why don't we all post pictures of our progress so we can get expert advice from the guys like Vader and F-Bird'88?

 

Has anyone tried to protect the seats? I bought a pair of heads that are rebuilt already and I'm not going to have the seats worked again if I can help it. I was thinking of melting down a wheel weight and hammering out a strip and protecting the seats with that. At least a thick buildup of masking tape would be better than trying to not hit them with the collet, because it's a tight fit as you try to get the drum angled around the short side radius.

 

I'm in the same boat. My heads have been rebuilt recently, and I'm damned if I'm going to spend much money on heads for a 305.

 

like I said before if you take your time and don't me a moron...... you won't hit the seats. I have done it to like 4 sets of heads, and everyone was fine afterwards. I don"t meant to insult people but just take your time and dont" get super close to the seats if you can"t have them repaired (or don't wanna pay to) it will still help out even if you don't go to the seat edge.

Josh

 

i don't see how you could not hit a seat, especially with the collet if you're working thru the chamber side of the head. when the file graps you'll touch the seat.

 

Your 305 heads, if done properly, will serve EXCELLENTLY on any small block Chevy!

F-Bird'*88 has had his personally prepped 305 heads working on a 400!!!

You can get them done to the point that they truly are at 95% of a set of Vortec heads. So if you do them right, you can keep them for many small blocks in the future

 

Okay, I decided to go with the 1.94 intakes valves but I've come up with a couple questions. I guess I'm looking for reassurance before I spend the loot on these things. Plus, this is gong to be the only time these heads are coming off!

1. Since I'm going with larger intakes, should I go with larger exhausts too?

2. The guy at the machine shop was worried about the valves being too large for the 305. He said he was concerned about the 1.94's hitting the bores but depending on what cam I use, I might be allright. I was planning on using the summit cam .420/.442 lift. This is where I look to you guys for help.

Thanks!

 

The 1.5" exhaust valves are fine.

1.94" intakes won't hit anything in a 305, especially with that lift. But, make sure they aren't excessively shrouded in the chamber per the instructions with the SA kit.

BTW, the SA instructions use a 305 head for the purpose of illustration...

 

Got my SA kit today. Now I just need an electric die grinder.

 

This is what I did to help protect the seats when I did my P&P work. Get some of that Aluminum duct tape. Lay a strip down on a work table. Use a razor knife to cut it into 1/2" x 1/2" squares. The place the squares on the seats, overlaping them just a little. When your finished, carefully remove the tape. Use some solvent to clean up any residue left. This will not guarentee that you still won't mess up a seat. But it will offer some protection.

 

Any particular reason you're going electric? Other than not having a big enough air compressor, that is?

Those poster-size instructions are nice, huh?

 

Yeah, no compressor and die grinders want LOTS of air

I also have the pdf from SA with fairly large photos and instructions from F-Bird'88, so I'm hoping for a good solid 35 hp increase from the heads alone. We'll see ...

 

1) As five7kid said, 1.5" exhaust valves will be okay.

2) There is no way that 1.94"s could ever hit the bore, unless you have like a 1.500" lift cam. A guy on the TBI board (NJSpeeder) uses the Edelbrock heads on his stock-bore 305 with no problems. These particular Edelbrock heads have 2.02" intake valves, with 1.60" exhaust valves. He has not reported any valve problems.
The common belief is that under 0.450" inch valve lift, even 2.02" valves won't contact the cylinder bores.

 

are the s/r tourqer heads the same as l98's or lb9's but there ported?

if there not the same then what kinda of gain would i be looking at if i ported my heads (full port) not just pocketing siamesed the stock base, used slp siamesed runners and fully siamesed them and ported the plenum with an air foil lol (gotta have the extra 30 cfm)..and an AFPR...if theres a difference between the s/r's and the stock heads how much more of a gain would i see versus the stock fully ported 305 heads to the s/r's........i know the s/r's are stock replacment but im sure theres another difference...let me know guys..i wanna dip into the mid/hi 13's for the price of a porting set lol ohh and the runners

what about doin this on a desktop dyno if n e one has one
thanks guys
"crazy"

 

Here are the tips from F-Bird'88--I'm sure he won't mind

Porting 305 Heads

I ported the hell out of a pair of 305 "416" castings. I installed 1.94 and 1.60" valves and got them flow tested. The intakes came up to 225cfm@.450" (185 cfm stock). The exhausts came up to 140cfm@.500" (110 to 120 cfm stock). I took out about 10cc's of metal out of each port. I unshrouded the combustion chamber for the new valves too. After having the heads planned, combustion chambers were 60cc's. On the intake port, enlarge the bowl under the valve. Shorten, thin and streamline the valve guide boss. The long side port wall (common wall) needs to be straightened as much as you dare. Especially right near the guide. Raise the port roof a good 1/8"+ from intake flange to the bowl. The short side in the bowl needs to be radiused and blended into the floor. Widen the floor there and blend into the walls. Don't lower the floor, just clean it up. Gasket match the intake flange to what ever gasket your using. The port wall at the push rod can be enlarged. Don't highly polish the intake port. Just blend your stone and cutter work with 40 and 60 grit rolls. The exhaust bowl can be enlarged and blended into the runner. Blend radius the short side under the valve. Shorten, trim and streamline the guideboss. Clean up and enlarge the rest of the port, consentrate on the roof and walls. Do not enlarge it bigger than your header gasket. Polish the exhaust port and combustion chamber. If you spray water with the garden hose in the port you can see where the airflow is concentrated. Those are the areas to work. These heads would rival a set of unworked Vortec L31 heads. WD-40 really helps keep the dust down while grinding.

 

thank you for more details on how to do this...i will probly end up printing this out so when i go to port my heads ill have all in info i need right in front of me....now with that ll said n done...i know im lookin at 10 hours or so of work but how much power will i make for this effort (it will be my first so ill go a little conservative)
but with fully ported lb9 heads and a siamesed stock manifold and fully siamesed slp runners and a stock ported plenum...

i was just thinking when gasket matching the manifold to the heads....do i do the manifold first with siamesing and not make the runners n e bigger (is it possible to make the stock manifold bigger) then gasket match that to the heads...but how much do i know to take off of the manifold...

i want to use the stock parts untill i get some $$$ to invest in good aftermarket pieces....i want to port the heads as much as possible as well as the stock intake manifold but i want it to be matched as close as possible....ill just siamese the stock runners untill i get $$ for the siamesed slp the do a full siameseing on them and the stock plenum i want to work over......
i would really prefer that if someone wants to go over detailed instructions to e-mail me..akers_13@hotmail.com....
thank you guys

 

You don't really need to enlarge the port opening or manifold
port opening much. Just square it up so the walls and roof and floor line up. Use a stock gasket or felpro 1205 tops
as a guide. If you hog it out you'll just create a bulge in the flow path. (slows volosity) This is not a restriction. If you are going to enlarge any , raise the roof of the port.

 

Most of the folks who have done this have said it took them a good 25 hours the first time they did it. So 10 is probably optimistic

The SA guys dynoed their heads after doing everything they suggest in their instructions. They gained 19 or 20 hp. But by enlarging the intake valve from 1.82 to 1.94 Desktop Dyno 2000 says it provides another 10 hp, higher up in the rpm band.

I think by really following F-Bird'88's instructions we ought to be able to get a nice solid 35 hp total from these heads on our tiny little 305s.

When we can afford a 350 or 400 they will scale up nicely

 

I also think we ought to compile our efforts here and when we are all done we should make it into a Tech Article so everyone on our beloved thirgen.org site can benefit from it

Just think how much a good set of heads are--and how much money we can save everyone, just as long as they are willing to put some elbow grease into their stock heads.

And this is a REAL help for those of us working with the 305

Then the same heads can be used over and over again on bigger V8s.

On a 350 it should provide 15% more hp, which works out to an additional 5.25 hp, or 40 hp total.

On a 383 we get around 7 hp to up us to 42 hp.

On a 400 it works out to almost 9 more ponies or 44 hp.

... does it get any better than that???

 

Here's a little trick you can employ to really kick up low
and mid lift flow on the intake port. (where it really counts on
a mild street hop-up.) Only open up the valve bowls
to just below the stock 1.84" valve seat in the head.
Have your machinist grind a 30 deg seat on the new 1.94" valve and intake valve seat. (The stock angle is 45 deg) Followed by a 45 and 60 deg under the
seat. He'll have lots of room to establish a new 30deg seat.
This will have a simular effect as if the valve was being opened
a lot quicker within the same seat duration.
Old Pontiac motors use this to good results.
Do this on the intakes only. 1.6 rockers on the intake
side help too. This may require elongating the pushrod slot in the head. (Louis Tool)

Now I'm giving away all my secrets......

 

20 horse for 20 hours of labor i can justify that lol...ok so the intake manifold doesnt need to be enlarged just "massaged" but siamesed what an inch and a half maybe a little more...
so i may be off but tell me if im close..
230 stock hp and 300 ft lbs......
so theres 20 hp to gain from the heads 10 more for bigger valves probly 10 more for a 3 angle valve job
siamesein the base siamesing the runners and porting the plenum will bring the peak higher and probly add maybe 30 horse and an AFPR brings another 20
so 20 hours of work for 300+ horse and im guessing another 50 ft lbs
hell thats a runnin' 305
add a 125 nitrous kit
and youll be spankin ls1's and be eatin there breakfast to while slappin there sister around lmao
so does my "guestimate" sound close?
forget dippin ill be well into the 13's
YEAH!!!!!!!!

 

My machinist said the 3 angle valve jobs were old school and that he does a radius valve job. He showed me a set of heads that he just got finished with and they have a smooth radius from the chamber to inside the pocket.

 

So are Pontiac motors, till ya get your doors blown off by one.
Gotta watch those 60's GTO's.....

This is a budget build up not a pro-mod. A radius seat has a very small contact area. Won't last long on the street.
And costs a fortune. #3 angles 30/45/60 will flow just as good
on this head.

 

Russel,

Will your suggested valve angles last as long as a "normal" valve job? I just can't stand the thought of having to redo the valves every couple of years. I would love to see 150,000 miles of trouble free street driving.

Also, are stock valves good enough or do we NEED to go stainless steel?

 

so with a good porting job on the heads. a 3 angle valve job a good siamesing on the manifold, fully siamesed runners and a ported plenum how much a of a PEAK hp will i gain i know ill gain a helluva lot from 4,500 to 5,500...how much of a gain will i see up top??

and also how much torque will i gain
thank you guys

i dont mean to "hijack" n e ones post..i would just like as much info as possible before i tackle this, and to know how much power i will be gaining....thanks guys!!!!

 

I tried this yesterday when I did my heads and it worked fine. I never got near the seats with the bit or sanding drum, but the collet did bump every now and then. The tape was sufficient to protect the seats. Now I'm ready to bolt these puppies on.

 

Any potential shortening of the valvejob life would be far outweighed by the benefit in low/mid lift flow.
Just don't use any race tricks like extreemly narrow seat widths. Not nessessary. You'll be old and gray before
they'll need to be redone.

Any valve that meets or exceeds the quality of the factory
valve is more than enough for our purposes.

 

Steve,

Can you post some pics of your work for us to see? We'd appreciate seeing how your heads came out.

 

Excellent! This will save us all a few more bucks not having to go stainless steel

 

i may be able to get my hands on iron l98's...how much more power would i be able to get if i ported them and had them milled down to 54cc (to bump up compression) over 56cc ported 305 heads??..if ported 305's are able to get 95% of vortecs i can only imagine how much ported l98's will rock. the l98's had 1.94 intakes and 1.60 exhaust correct?? could i stuff a 2.02 in there?? ill still have a siamesed manifold siamesed runners and a siamesed plenum...
and prolby a cam dowm the road a little....
plz respond guys i wanna start this as soon as possible
thanks guys!!
"crazy"

 

The iron L-98 heads look to have about the same potential.
I would pass on 2.02's for a 305. 1.94 is good enough.

 

does that mean a little less or a little more =)...i think it would be less work for the l98's because they already have the 1.94/1.60 so just go with the stock valves and do a 3 angle.....youd think that with bigger heads theyed be able to port out bigger....n e ways thank alot!!