In my experience people have been advised to NOT do any porting of the Vortec heads, as they are a bit tricky to get right. I think polishing the exhaust port should be alright, though

Whats so tricky? They did them in this article. Btw this is the porting method I am using now.

Porting Vortec Heads- Car Craft Magazine

in that article it looks like they're just doing a bit of bowl work and a valve job, not a full on port job.
As they mention in there, (and what sitting bull is saying), is that vortecs are great as cast, and so you only need to do a little bit of cleanup, (which is what they're doing in that article), in order to get good flow. You don't need to drastically reshape the ports, like you would on an older style of head.
If you do try to reshape the ports, you lose the port velocity that GM put so much time of engineering into, to perfect. So you lose power.

They pretty much did all they could to the bowls with a 1.94 1.5 valve port without ruining the port. Pretty much all you could do with a stock port anyhow. They also took quite a bit off the pushrod pinch which is pretty much the same as a stock head which yet again is all that can be done. The only thing I see they didnt touch was the short turn radius which they mentioned is already perfect. I dont know what else you expected since they got very close to the flow limit of the 1.94 valve which Im sure wouldnt take much more. Unless your putting in larger valves I doubt you will see much more. The heads put up some pretty good numbers so I dont see a problem. Thats the whole beauty of vortec heads minimal effort with plenty of gain.

oh i'm not arguing that they're good heads, that's for sure! I don't want to clutter up this thread with hearsay, or arguing, so i'll leave it at this post:

I apologize, I didn't read the article carefully...
.
.
now I have. I didn't notice where they mention the pushrod pinch? EDIT: now I did... They also didn't touch the area near the head bolt hole. It's "basically" just bowl work. And a tad of chamber work, in that they blended the spark plug boss. No work between intake port-> spark plug.

I attached the flow chart, for if/when that site goes down. You'll notice their results are pretty text book of "ported" vortecs. Mediocre, if any gains on the intake eh? But ASTRONOMICAL gains on the exhaust! 60CFM!!! That's why "they" say to only port the exhaust. The intake is barely worth the time invested for the amount of CFM gains there, and, what if you did screw something up? You'd lose flow, or port velocity. I'm just saying it's not worth the risk for a measly 6-10CFM, compared to the 416/601 heads this thread is based on, where 30+ CFM is not unheard of.

That kind of intake/exhaust port flow (on the vortecs), makes me think a single pattern cam would work best there... But hey, that's another thread topic there
434HP with lunati 230/235 hydraulic flat tappet performer RPM air gap, and *stock* vortecs. 464HP with the ported. Yowza.

Im in now way was trying to take away from the thread but just pointing out that porting vortecs are no harder than any other head. Possibly less work since less material will be needed to be removed. I have read through this thread and agree what has been done to the 416/601 heads is definately worth merit. Any DIY porting is definately worth merit.

I didn't mean to stir the pot here guys, and I am sorry if I did...
I was asking the question regarding the 305cid vortec, which from my understanding a quite different from the 350 - L31 (#062 or #906) castings... I have a set of the latter 305cid so called 'vortec' and this is what I wanted to do some work on this winter, and as such was wondering if besides the larger intake valve and gasket matching, would the p&p as outlined in this thread be applicable to those heads...
TIA
-Andrew

If you have a Vortec head you should ONLY do to it what the real pros say is OK. This thread is NOT about Vortec heads but polishing the exhaust ports will be perfectly fine to do.

Hey, didn't I just say that somewhere

I just noticed that this thread has been accessed more than 24,000 times

I am profoundly humbled that this has been able to help so many folks with their heads. Thanks everyone

w00t shiny paper weights!

So I flow-tested the latest set of 416 heads today. 218@28" at .400" lift.
233@28" at .550" lift. That's without filling in the rocker stud void in the roof of the port with epoxy. Previous testing showed an additional 6-8 cfm @ high lift by filling in this void.
Good little street/bracket brat head.

How about some low lift numbers or exhaust numbers…? Probably more important to most people that would consider using a set of these heads anyway

Flow testing takes time and costs money. I get them done quickly (flow at max lift) at minimal cost. By now I know what they are going to flow anyways. Didn't even bother flowing the exhaust. It will be plenty.
The idea of doing these heads is to keep the cost down. otherwise you might as well just buy aftermarket heads.
I do these for about half the cost of new heads.
These heads have the power potential of over 400BHP.
Don't worry, the low/mid lift numbers will be good. Much better than stock. Thats the whole point.
I'd rather spend the money on other good parts and details to make real usable power combination than drewl over a bunch of numbers.

I was looking for a picture and couldnt find one anymore. Are those the holes in the middle exhaust ports? EXACTLY What kid of ab epoxy would work?

Also, on shaving the 601 head, how much can you take off? I was thinking .050? I would like to be about 13-1 with 4 valve relief flattops, steel head gasket.

Is this thread still used????I'll find out i guess

A lot of what are considered easy going/bigger improvements, the vortec casting got from the factory.

Ive got the 14102187 heads. Are they those TBI heads youre talking about in the first post?
Does anybody have the original cfm data on those heads?
tnx for a very inspiering thread

Those're TBI heads and there are a few posts with flow numbers and ported flow numbers you've just gotta search for either 187 flow, tbi head flow, or swirl port flow; all of those searches should get you what you need.

im hogging down the swirl!

I just bought the S/A deluxe kit and hope to do this to the heads on my univ 350, but I'm doing it on a tight budget. Other than getting valves backcut and messing something up, would they need any machine shop work?

You don't need to do that. Maximum airflow occurs at, or near, maximum valve lift, and when that happens the biggest offender to airflow is the end of the ramp.

Grind the end of the ramp away so it can't be seen from the intake runner port. Round any sharp edges on the ramps. Round the edges of the valve guide boss, and do the rest of the stuff you would do on any porting job (i.e. read this thread, follow the steps).

be careful with porting those 187s i found those harder to do then my current 601s. they have a lot of flaws you have to work out especially on the intake side. and working in the intake port between the seat is really hard with the ramp and such which makes you more likely to hit the seats so be prepared for a valve job. BTW i wish i didnt mess my 187s up when i vacuumed the shaving out from porting on the intake side it very interesting watching it ALL swirl up and out from the ramp.

thankyou sitting bull for all your dedication and work that helps us all. the pictures and walk through is great. ive read it maybe 10 times all the way through now and decided to use the same 601s to port. only difference is im keeping the 1.84 valve size.

Okey I guessed that it was the way to go, but feels good somone confirmed it. It´s really hard not to ruin the valveseats, I really messed up on one of them so i might have to change to 1.94 valves

Hey, you are welcome

Haven't looked at this thread for a couple of years now ... and it is still helping folks out. Over 50,000 views now -- that is great

Just a little advice Don't make the cylinder head ports bigger then the headers or intake ports. Also dont polish too much (like a glass finish) because you will loose air flow. If anyone is wanting to make a home made flow bench google home made flow benches. You can put one together with a shop vac and about $150.00 US dollars. I worked on flow benches for 3 months at a college for high performance engine building. Follow what these guys are saying and you will see a nice change in how much air your engine can take in. Remember more air, plus more fuel, plus more spark = more power. Thanks guys for helping out everyone else with your pictures and examples.

This is a great post. Im planning on porting and polishing a set of 305 donor heads from an 83 chevy half ton. Theyre 601s. Im wondering if anyone has an idea on how much they flow using the 1.84,1.5 stock valves. there isnt much capitol here for expensive machine work albeit I might have to spend some for the larger intakes. I read one article that said anything over 194cfms was a waste unless you were going witha really big cam. I have no intertion of doing that. I have a 78 chevy c20 with a 350 and I plan on putting the 700r4 behind the new motor for the overdrive. Id like to get as much torque and hp as I can while maintaining some kind of milage. I dont know what kind of pistons are in the motor perhaps someone could tell me a good way to get some kind of idea of what kind of compression I might get with this combination. I really dont want to go over approxamately 9.5 to 1 because I want to use the low grade pump gas. I have a new distributor Ill have to fill ya in on the particulars later. Its supposed to be able to go to 8500 rpms with an adjustable advance curve. Got it for some money owed. Has a better than stock (higher voltage) coil. New lucky for me. What I hope to acomplish is more mid range power and torque. I think the truck has an RV cam in it. I was pullin a 6000 pound load and it fell on its nose and liked to get hot on the hills. Presently has a th400 behind it. should be lots of fun installing th r4. I have no idea the rpms the thing wil turn with the r4. Dont do lots of pulling with it but would like a good acceleration when I open the back barrels. Has a stock rebuilt Qjet. Thanks

If you use it for towing and want to run 87 octane gas then 9.5:1 is too much cr. Keep the th400. What is the head casting number on your heads now?
Dished piston, flat top???.... If it gets too hot towing up hills get a better rad and a tranny cooler+ oil cooler. If it knocks get cooler non projected tip racing/marine/towing spark plugs. R45TS is too hot. The th700R4 will not save you 1 penny towing. You cannot tow a load in OD. Keep the Th-400. It is a much stronger trans for your application.
Unless you have vortec/fast burn heads, computer timing control and EFI, you want about 8.8:1 cr max (and a small cam) for a towing application using the old combustion chamber style and a carb and 87 octane.
(I would not exceed a real 9.1:1)

A water/methanol injection system will allow a higher cr than 8.8 while towing with 87 octane. If you tow a lot of miles in a year and want to run 9.5:1/9.8:1 with the old 76cc or 305 head and 87 octane, the water injection is cost effective.
You need to gather a bit of real info to see if a 305 head is your best choice.
What is the total vehicle weight? Piston type and effective dish/valve relief volume, piston to deck clearance @TDC. present cylinder head casting number. actual chamber volume.
Your truck rear gear ratio and rear tire diameter.
For HD towing you do not want to get into a situation where you have too much compression ratio for the octane you are willing to buy.
There is no free lunch.
The stock 601 head flows about 180-185cfm intake and 110 ex

I'd be thinkin 8.8-9.0 real cr. .450" short duration cam 195°-205°in -215°ex@.050" (1.6-1.5 split rocker ratio) 108-110LSA http://www.iskycams.com/timingchart....ng_chart_id=90tri Y truck headers, 2.5 dual EX dual plane manifold tuned 600holley or 4MV Qjet. dash mounted O2 sensor/AFR meter and dial adjustable electronic timing control. ported stock heads, stock valves.
2200-2500 hiway cruise rpm under tow. (60MPH)

"062" casting L-31 vortecs will allow 9.4:1 (HD towing) on 87 octane and make geat power
the "060" stock GM OEM L-31 vortec head assemblies are great proven bang for the buck towing upgrade.
The vortec heads+ vortec manifold and 9.4 cr is more cost effective than a high cr/ ported 305 head+ electronic water injection towing package, overall.

If you need to go up very steep hills/mountains then you will need more rear gear ratio (towing torque) and a resulting higher cruise rpm. Remember the typical mild built 350 makes peak torque (best pulling power) at about 3400+/-rpm.
You need the right gearing for the job.

Ill have to get you more information F-bird. That might take a while. The towing is few and far between. The primary purpose for the vehicle is for long distance travel to the mountains and camping. I have a camper on it now that weights in at approx 200lbs. Ill get the other number like the wieght of the vehicle etc and post them all at the same time. As far as I know the pistons are probabbly forged flat tops, possibly hyper. I know very little of the history of this vehicle I got it free from my son who knows only that it was supposedly overhauled before he bought it. Its a camper special. another question I have is the fit of the air conditioner comp and whether it will fit with the higher vortec heads. The comp is one of the cylinderical shaped ones that has a bracket attached to the top of the intake. Some of the other mods Ive made, factory shorty type headers from an 85-86 with the polution ports removed, added cool air duct with much larger air intake. Stock was the small like 2" tube under the hood instead of up front. Stainless dual exhaust from an 86 with stock mufflers. Local place has some performance mufflers for less than 20 bucks very nice tone and small size. Don t know the performance characteristics. Plan on a KN filter as soon as I can afford one.

How hard is it to put in heads?

It really depends on your level of experience. It can be back breaking work unless youre Arnold Swartznegger. The 305 heads are fairly light compared to the normal chevy heads. I rather suspect that the vortec heads are even heavier than the norm. Tools would be a consideration as well. Whether you have air tools as oposed to a ratchet. Draining the radiator removing the exhaust manifolds air conditioning etc depending on your ride. These guys may be able to tell you some shortcuts.

Almost 64,000 views ... that is indescribable!

There's a wealth of information here. I know I've read it front to back at least twice. Great write up, thanks.

would it be possible to clean this thread up or organize this into a step by step process for those for those of us who dont have time to pick apart the thread just for the pertinent info? i think it would really help the ppl who want to port there own cheap heads, maybe im stupid, but i read this thread and still have no idea how to even start other then buying a grinder and some bits is there anyone who could draw diagrams? i think step by step with pics and diagrams would be very helpful

There's a tech article linked from the thirdgen.org homepage that is step-by-step.

The Standard Abrasives do-it-yourself-porting guidelines have photos and details.

ok ill look for that thanks so much

Hi all,

Just doing my yearly check on this thread. Almost 70,000 reads!

Now if I could just get $1 for every time someone reads this, what a Camaro I would have!

Make that 70,001. It's good to see another old timer still grinding along.

There are several other threads with porting concepts, tips, and examples, but this one is the undisputed king.

I'm looking into porting a set of 601 heads for use on a '92 350 truck block. If I do, this thread will have saved me a TON of guesswork (and having to buy decent flowing heads)!

crakarjax,

I hope your 601s turned out well for you! Here it is, May 18, 2011, and my 601s are still pumping excellent quantities of air and fuel through my 305! It is great to see folks are still getting good use out of this good old thread!

And more than 76,000 people have read this thread ... I love it!

hey there i was curious about a set of untouched 416s i have laying around. I love the info on this thread. Seems you guys know alot of these and i was curious bout these. I want to put em on my 400, and alot have been telling me to get an exspensive head which i wouldnt mind but i dont have the money to do that. So im really limited. I have the money to put into a short block cam and everything but not the heads!. Heres my qeustions of 416s. Can i take the 58 cc chambers out to 65? Could i take the intake runners out to 200cc to help with better breathing? Also what does it take to put bigger valves in a head? Im a newb to all this stuff, i only get a hey go and get some $1000 afrs. Which is very pricey for me. I mean dont get me wrong id like to just bolt on some more power. Jeezus those things would make me broke. The cam i selected, is what i want the comp cams XS 274. .501/.513 lift. So could this be possible? Thanks for any info.

if you can get afrs for $1000 I'd go for it.

No, you won't get the chambers or the runners that big, that's a ton of metal to remove.

I ported my 416 heads, and the chambers ended up at 64cc's. I think that's achievable.
The runners however, is ambitious. If you can get past 180cc's, that would be quite impressive. Ported 416's are not meant to be 200cc type of heads (big cam, race only type of thing). They're more of a strong street type of car, which is the 170-185cc port range.

Your response was very helpful. I was thinking at my geuss from mid lift to .400 lift, would it be possible that at this lift, you can make em flow decent enough to maintain the cubes with 185 ccs intake ports? They dont sound bad. For street motor, i was thinking these would be idea, the cam is really street idea also. And thats outragious for the afrs. I didnt know they costed more than a grand. For that i could by worked double humps for $900 that prob work just as well. Seen a section on nasty z28. Guy had humps on his 400 pretty impressive what times he gets.. What do you think you run with your 355 with the 416s sonix?

you end up getting the seat enlarged on getting bigger valves and then you have to open up what is underneath

well if it will free up cfms, (which i doubt) but for the 400 cubic inch displacement, we will have to talk more than just 185 cc intake side, might not be well suited for a 350 at idle, but with the cam i have XS274 it will be cammed for a stump puller and can pull from 2000 on up to 6200 with the right heads and i could take advantage of tall gears (seen a post on hotrodders about the XS268 400 ci sbc dyno metered 500ft lbs @4000rpms 475 hp @ 5800 with eldebrocks pocket ported)
i was thinking this combo would work, either way what other choice do i have on limited funds? Maybe a loss on the top end unless i do 190 cfms or more.. This will be in a highly modded truck, 700r4 with 3.50s behind there, or might even keep the th400.