305 Vortec Heads vs 350 Vortec Heads (Flow Data) 

My 059s were 224 cfm out of the box and close to 250 when ported with a 1.94/1.6 valve package. They respond well to bigger valves and a little chamber deshrouding. I did not touch the swirl ramp other than to blend it in a little more smoothly. Stock they still outflow a 2.02 camel hump.

Thank you for doing this. As an old hot rodder who still likes to build hot little 283s, you have my full attention. I have one fresh 30 over short block waiting for heads, and a second block going 40 over with a really nice rotating assy, so head choices need to be made. Having said that, I see no reason to use 305 vortec heads on a 355, the 350 vortec chamber is worth too much power to give up just for the compression gain of the 305 heads. On a 355 there are better ways to get that bit of compression ratio back with piston choice ( and I mean the right flat top brand here), head gasket choice, and a bit of block decking. For a smaller bore engine, though........you've got some good info here.

I wanted a set of the 305 Vortec heads for a little 307 I had but traded the engine before that happened. Now I want that 307 back! Lol

That's kind of crazy 305 Chevy heads with TBI style Chevy headed combustion Chambers with Vortec intake manifold bolt patterns that would be cool to see an engine build with that heads on a dyno

I have built 520 heads for a 287 with a .525 lift cam exhaust porting, minor intake porting(leave the tiny ramp alone). These heads are 165cc intake, 70cc exhaust and ours had 59 cc chambers. It made that little mouse absolutely scream, had RPM air gap, 600 cfm Holley, 1 5/8 headers and a recurved HEI. Rev’ed easily to 7200, it was absolute music!

Wow finally a video about the 305 Vortec Heads, thank you very much for this! My 92 Camaro RS 305 TBI is getting this upgrade with a pair of 059s and a Edelbrock 7516 intake and I was looking for info like this. Will keep you all posted when finished (Budget is tight nowadays).

I got a vortec 305 in my '96 and it run surprisingly well to have a 3.08 gear.

Thank you for the video! The 305 vortec combustion chamber is almost the same as the 350 vortec, it just doesn't have the point that turns it into the heart shape, and that is fine, since the 350 heart shape point actually shrouds the exhaust valve flow out of the chamber. The 305 vortec chamber is nothing like a swirlport chamber for those that only see the lack of heart shape

I purchased the CIFIC marine 059 replacement heads bare. Seems good quality.

Unless you're installing a larger cam without pulling the heads I think it's far easier to cut the tops of the guides. It only takes about 5 minutes with the proper cutter and a cordless drill, at that point you can run whatever springs and retainers you want without worrying about them hitting the seals or the tops of the guides.

Thank you it is great truly informative RU-vid Channel good things are coming your way dude

Having spent half of last night reviewing your previous videos I would be very interested in seeing what a 1.94 intake & a 1.60 exghaust on t 305 heads will show. And thank you for this. Ive had a hard time finding much info that would heĺp my problem and am danged glad I stumbled across your site. Im in CA. And t smog restrictions are a real problem. Without getting to deep, the best I think I could do ( so far..) is to use an 'aproved' RV cam to clear t test & then use 1.6 rockers for more lift. I cant even install t headers Ive bought OR dual exghaust until I can get my ass out of hear, that would be illegal in my '86 van. Thanx again.

Thank you for the data!

I'm glad you put this info out it helps my decision. i have an el camimo with a 305 in it, I think putting my 305 vortec heads would help out in the power department a little. it should gain power on the whole curve, I would think. do you think its possible that there would be a 15 horse gain? im gonna keep the stock cam in it. i would love to see what some 1.94 valves woukd do on these. a valve job, some bowl work, and maybe a little short turn work would be interesting too.

I like to see. Stock. 350 v. Up agents ported three angel 2.02 ..1.60. like 550 lift. FLAT top PISTONS. No OUTHER change. On the dino. Then in the car. I want to do that on my 4.3 but I need another set of stock heads..... And on both sets my factory valve job was junk. Like 10 those run out on the EX. LEAKED LIKE A SIVE. I WANTED TO BOLT THEM ON STOCK. SO NOW I HAVE TWO SET'S I F. WITH. DO TO THE RONA. AND GM. SHITTY WORK. THANK YOU FOR YOUR HARD WORK. PORTING CAST IRON HEADS SUCKS. NOT TO FORGET 125 THO. SEAT WITH. ON EX. JUNK.

The Combustion Chamber on the 305 Head is the biggest issue.. It's basically a old school wedge design vs a Modern Heart Shape. If everything was the same other then combustion chamber the heart shaped head will make more power.

I would like to get the part numbers for the the valve spring upgrade as well as the part numbers for the locks and retainers and I'm curious if they will be ok with a Crower 280 hydraulic flat tappet cam on a .40 over 350 please let me know what you think thanks for all your info

I snagged a L31 from late 90s yukon from LQK and plan to use the 062 vortec heads with LS lifters and ls3/6 beehives as i have many used sets laying around from build LS engines. I got the offset valve locks and such. Motor is to upgrade an 86 Vette with a locked up L98. I also have a brand new zz4 cam that I'm debating to use over a low mileage cam from a 97 LT1 from an f-car. I'm thinking more using the LT1 cam with just LS1 beehives which are good to .520 lift. Also will be keeping it TPI fuel injected. And since I'm using the tpi system (and yes lower base from a 89 L98), I know the zz4 cam will not breathe in higher rpms like it is able to if was in an LT1 or a dual plane/carb w/ headers set-up.. But I also have a set of 113 L98 heads that were 'built' from what looks like a long time ago. And since I'm not sure how long (after getting the car running again) I plan to keep it, I don't want to use the 113 heads as we all know ate getting hard to find. Especially, since I snagged them up for just $200 that came with nice cast alum tall valve covers and aftermarket parts and hardened pushrods even. I do plan to port the 062 heads regardless. I do a lot of LS heads. But never did any sbc gen.1 or 2's. So I am learning some from another guy. But I am very eager to see final numbers. As I have an ole 88 K1500 with the GM 350 h.o. crate in it and she hauls azzzzz. With the 33x12.5x15 mudrovers on her, she spanks 4.6 poopstangs all day!!! And its the 4spd with low granny too. Its been a good 15 years since I built anything non-LS and am getting very eager! Looking forward to more vortec info! Thx for making this video!

Thank you for the last post, it does answer my interest in vortex heads 4 t 305 question. Regarding trying 305 heads on a 350, or larger block, I'm more curious about what you said of a 327. What about aftermarket pistons w/305 bore and a 327 crank. Is that even possible...?

Did you ever experiment more with porting on this head? Be curious what it would be capable of. Charles Servedio has been working on a 193 casting swirl port and has gotten over 300 cfm out of it 😮

Appreciate all the info you do for us but love to see you do a set of peanut Port heads for a 454

Ever dyno 4.3l vortec heads,96-up

good vid. good to know if I ever wanted to refresh a 305 but clearly buy 350 vortecs if youre touching a 350 and don't bother with these

Try the LM7 valves. 1.9/1.55 with 8mm stems. Possibly 40°seats on the exhaust for a single pattern cam for more low speed torque. You could use stock LS guides or upgrade to bronze.

Anyone have info on these 14011034. My friend quit racing years ago and gave me these fully ported/polished 2.055 intake valves girdles and screw in studs I know his car ran in the 10s with these heads on a 406 sbc and nitrous

could you test the 350 tbi swirl port heads? curious to see the difference between 305 swirl port heads and 350 swirl port heads. im suprised removing the ramp didnt make much of a difference

Considering putting a set of 305 Vortec heads on a stock SBC 400 bottom end with stock pistons. Any advice/input on that? Quench area and head gasket selection?

I think 300 to 400 is a sweet spot for American V8s

What program do you use for the flow chart? Good info, I had a set of them years ago but never flow tested them after finding out that they were different from the 350 vortechs!

Thanks!!

darn i need to know how to that valve spring kit you talked about and showed fixs a big issue ? thanks for video

I'm curious if velocity was changed.

Hi from UK, liking the content. I'm stripping a 305 in the workshop as we speak, it's from a boat all original, but I'm sure came with mercruiser vortec heads, I'm curious about flow figures so I can pick a good head, I have a quadrijet and points ignition to put on it, all the things other people avoid, always had good results with points ignition, sorting ignition advance with springs and weights is the key!

1.90 x 1.56 seems to work well unschroud chambers seem to work well put them on a .040 bore 283 .

I'm building a motor for my truck and picked up a pair of 059 heads from my schools shop and going on a 350 stock bore flat top pistons but in struggling with choosing a nice budget cam and lifter combo any suggestions?

I say bigger exhaust valve in 305 head 🤠 cleaner combustion chamber more explosive mo-power ! 😜😉🤠

I was really surprised by the lack of heart shaped chamber. Thanks

Can you put the 305 vortec heads on a 350 TBI engine?

Seems like a great bolt on upgrade for the dreaded TBI swirl port heads for some of us that have 305s. I’m curious on how they compare to the older 416/601 castings

Have u flowed the 305 416 heads, I want to put them on a 350?

WOW! I'm building a 305 and have a set of 416 heads and a set of 601 heads. I'm 72 years old and used to build engines 50 years ago but know nothing about vortec heads. What should I do???

Do these heads require the same machining or beehive spring upgrade that the 350 heads require to use a muscle camshaft?

are the 305 vortec heads prone to easy cracking like the 350s ? , thanks

So how would the Vortec L30 heads work on a TBI 350 vs the Stock TBI heads when going with a jegs dual plane intake and a 650 cfm AVS2 carburetor? A dyno test between these two heads would be interesting on a TBI 350 shortblock. The test would be nice even with the small factory TBI cam just to see the difference. Also, When will you test the new summit hydraulic roller cams with LS firing order for SBC? Thanks

Where they all flowed on a 4" bore, or the 305's flowed on a 3.736" like the 305 uses? I would love to see what the swirl port ramp actually does to airflow. The obvious answer is that "It causes it to swirl," but I don't think it's that simple. Normal chevy and vortec chevy heads bias the intake flow to the outside of the port (to the cylinder wall side) and generate quite a bit of swirl because of that, the swirl port ramps are on the other side and almost block the flow on that side, I'm surprised that they didn't end the ramp sooner or later, either not blocking as much flow, or forcing it all to go around the outside side. I am impressed/surprised that you showed that the ramp didn't seem to hurt flow, I'm wondering if that would still be true with 1.94 or 2.02 valves. If it was you'd get some of the "heart-shaped" chambers back if you cut them for the larger valves, kind of like cutting old 602 casting 305 heads for larger valves, where you end up with a tiny (roughly 54cc) heart-shaped chamber. I have experimented some with the swirl port heads and found that the swirl makes more power than the added flow you got from cutting the ramps down, so porting those you wanted to leave the ramps and just clean the rest up. You ended up with a low to midrange torque monster, perfect for a truck. I suspect that a set of properly worked 305 vortecs with oversize valves would be a magic combination of power and MPG for a heavier vehicle. if want to see a weird hybrid of design/thought process, check out some LT1 iron and LT1 aluminum heads. They have some qualities of traditional SBC heads, vortec heads, fastburn heads... and the iron are different than the aluminum. I'm running a set of LT1 aluminum heads on a 305 that are heavily worked (they flow almost 260 on the small 305 bore) and modified to work on the SBC with a victor jr converted to fuel injection. You'd never guess the 305 was a 305.

Hey man do you think a 1.94 valve would actually help or hurt flow on those heads? And would they beat a 305 HO head?

how fo you know if I have a mexican vortec

GM performance parts has that tbi intake for vortec heads, makes me wonder if this head and intake combo was going to go on say 95 trucks which is such an oddball truck anyway but they decided to wait a year and they had a better head for L31 350's. After all the 305 L30 head is a TBI/TPI head done correctly with the same good exhaust flow of the TBI head but better than TPI head intake flow.

so basically a "double bump" head that's not 58 years old for next to nothing?

How does it compare to the 601 and 416 305 heads? Thanks for all the good information

Hey cutter great video. I have a question for the vortec man. If I were to switch my l31 to carburetor, i understand that I would need a shift box but would the 4l60e shift manually on the column. Thanks Pat. Keep it up

I am looking for a set of vortec heads for 305 is there a certain casting numbers I’m looking for or will any of them work

I've been waiting for this, still trying to decide heads for my engine. I've heard the 059 casting is slightly better than the 520 castings, not sure if this is the case? Maybe something to look at in the future, or any 305 vortec head video would be fun in my book! Fun to see actual numbers produced vs what has been hearsay.

Which is better, the heart shape 350 chamber or 305 chamber? Or does a guy go with a 1.92 and 1.6 valve on a 305 head? Does the swirl ramp make a big diff?

Wonder how the 305s would do with the intake cut out to 1.92

My question is can you put the 350 heads on the 305? I've heard of 305 heads on a 350 for higher compression but what about the reverse?

PISS-CUTTER.. I'd like to know exactly what areas of an 062 vortec head to port to increase flow at mid and upper rpm band? As I mentioned in comments a couple months ago, I'm using an L31 longblock to replace a locked up 86 L98. I know the tpi i already a major restrictor.. Tho i have opened up what i can. Now I'm planning on using the zz4 cam with comp cam 1.5 roller rockers. But also have a factory 97 LT1 f car camshaft.. But now have my eye on Summit Racing cam SUM-8801. Thanks

i like the XE256 and XR264HR cams or a small voodoo cam. A roller cam i like the best even though the flat hyd. makes better power until the bigger roller cams take over and then the mech roller. For a great torquey 305 its not going to have top end and rpm shall be way under 6000 rpm for sure. Hypereutectic pistons. It would be great to use 6" I beams just for the fun of it. i am getting 6.160" rods made although i have to buy 100 of them. but that is through hurricane and don't think i want those anymore. I want compstar offset ground crank with small honda journals on the rods and crank. A 1.765" radius /3.53" stroke on an undecked 9.025" block with 6" rods and 1.260" hypereutectic pistons. turns a 355 into a 360 and a 305 into something else. Just better longevity and overall . puts it almost right on 1.7 rod ratio. lower friction. better for wear. Even though the best power comes with a stock stroke and 6.285" rod and a 1" piston with a rod ratio of 1.8:01. And a non turbo or really low boost because of compression and piston shortness with the ringlands squished above the pin bore for daily driving. A custom piston for sure. With even less wear and the best power in a sbc rod ratio.

My buddy has never had anything with power (every thing stock). Now he has two c20 chevys a 72 and a 77. Both have upper 100k miles. Not worn out but tired. What do you think of those vortech 305 heads on a 350? I doubt he will ever rev over 4500. I'm thinking the compression increase should give him the thrill of power without giving him more than he can handle.

Hey Pat if you were aiming to get 1horsepower per cube with a L03 305, would you go with 305 or 350 vortec heads? Other than the cam the short block won’t be touched. I wasn’t sure if the loss in compression and possible valve shrouding would make the 350’s unusable... thanks

Oops I meant 1.94

Do you know anything about the 113 aluminum sbc heads going on a .060 400 sbc an what cam to use??

What do you think of a 305 block with a Scat 3.75" crankshaft? A .030 overbore with a good set of pistons with a compression ratio between 10.5 to 11 to 1. With a decent roller cam with at least .525 lift to get you around the flow curve and out on the straight on both the intake and exhaust. With a set of your ported 520 heads, I'm thinking it would be pretty stout, you should try it.

Sorry the 461x heads are the best out there and not the x on the bottom,

To be clear, you didn't touch the SSR or back cut the valves?

Swirl port and swirl bore are two different things, i don't think we have air flowing from the port to the bore like a corkscrew, i think the design is primarily promating flow into the center of the bore which leads to more efficient burn as the mixture is filling the cylinder in a more uniform way. The mixture hitting the backside of the ski ramp is being deflicted down and is helping to turn air on the short side past the valve, there is a convergence that dumps mixture more down into the bore center instead of a non swirl port being more towards the cylinder wall in front of the exhaust valve. I think people who designed the late model cylinder heads for GM where waaay smarter than anyone ever gave them credit for.

Great info thanks! How do 416s look to you?

I tried, even listened on some of your other video introductions and it all sounds like Pown in the shop?I don't know, maybe that's your name? No offense, that's what it sounds like with my old ears. Anyway if you can it would be very cool if you could measure the unported port volume on the 350 and 305 heads? That would be some great info to know. The lesser the port volume a head has the easier time a smaller cid engine or a longer rod ratio shorter stroke engine has drawing in air flow. Trying to decide which Vortec heads to use, 062 or 059(I have a set of each)for my sbc 400 block with a sbc 307 crank with 6.250" rods that will be a 355. On one hand, the 305 will make it easier to get the compression up. But on the other hand, the 350 heads have the better swirl promoting chambers. But maybe thats why that swirl is under the valve?(to make up for the older style chamber?) Decisions decisions. 🤔 Thanks in advance.

it would be nice those what those 305 heads would do on a 350

It would be interesting to see dyno results on a 305. 305 vortec heads vs 350 vortec heads. I wonder if the ramp is needed to preserve swirl due to the small bore or to increase velocity for low end torque and fuel economy. I can only imagine that if the 350 heads worked better on a 305 gm would have used them instead of designing a whole new head.

Do you build vortec heads and sell I want to use a 292 comp cam I can go smaller if I need to

Good stuff. Yes a 1.94 and 1.6 valve combo would be good to see on the 305 vortec. Rather than remove the ramp, is there a way to increase the swirl?

Great stuff. So the Stan Weiss flow numbers were a bit enthusiastic for the 305 Vortec heads then? But those were 059 heads so those could be the better ones? The exhaust numbers are very close to the Stan Weiss numbers, his maxed out at 163 CFM @ .500" lift. The low lift numbers were better than the 062 heads right next to the 059 listing. They maxed out at 221 CFM @ .500" lift. Got it pulled up on my confuser, it says Chevy Vortec L31 iron, its not calling out the casting number like it is for the 305 heads. Now you got me wondering if the 059 heads flow better than your 520s? If its not to much to ask, if you find a set of 059s it would be great to know if they do in fact flow gooder like the Stan Weiss website says? Thanks for your hard work making these videos.👍 Can't wait to see what bigger valves and some port work is going to do for those! Thanks. I'm looking at building a sbc 352, its a sbc 400 block with a 3.25" stroke crank. HRM did an article back in the late 90s called; "The 350 engine Chevrolet should have built." I would post a link but yt is getting weird about doing that. If you do a search you should be able to find it easy enough.

So...whether you have a 305 or 350, is there ever a reason to choose 305 Vortec heads over 350 Vortecs?

Why not use your 305 heads on a 283, 305 or 307? Prove good usable power is available from these under dog and usually dirt cheap engines.

👍

Being that you’re a Vortec head connoisseur, what is a fair price to pay for a set? Unless they have been checked, it’s a risk, so the cost has to be low.

Call me easily impressed but those numbers were better than I expected! I've got a 305 vortec motor and I'd like to build it, this is good inspiration. Question on your spring kit, how much lift does it alot for w/o machining the guides? Do you think a cam with .575 valve lift (comp's XFI 218/224) would be too much for the flow on some ported 520 heads? Following with that, in your opinion would the heads benefit from 2.02/1.60 valves (if there's even room)? This video really makes me want to build a set of iron heads & make an 11-or-so:1 engine w/a small dome piston & that camshaft... I'd love to hear your thoughts & thanks a ton for the great content!

350 tbi engines had those heads

I love this channel, but PISS-CUTTER is a really awful name!

ehhhhhhhhhhhhh stock cast iron vortec heads, theyre real weak in the knees. I only use 3 vortec heads, cast iron are Chevrolet Performance 185cc Bowtie, and aluminum AFR 190 street, and Chevrolet 210cc Fast burn. The bare casting on the 185cc Bowtie are part #19331471 $574.25 at Summit Racing and they destroy these weak in the knees truck heads so bad its not funny. Getting a set of real performance heads for just over a grand is a much better way to go. A ported set of truck heads WILL NOT out perform the Bowtie heads andI dont care if Don Garlits himself ported them.

Makes you wonder why GM even made the 305.. Literally costed the same to produce 305 and 350 but the 350 was better in every area!! Kinda seemed like a waste of time and money producing that boat anchor 305!

1st

Blah blah blah.,.. blah blah blah. You yap way too much. Get concise. You waste everyone's time.