First, this may better fit in the General Engine section, but since all TBI 3rd Gens have 305s and this has been discussed so much in this forum over the years, I'm putting it here. I think there's more 305 discussion here than anywhere else on this site.

So Engine Power took a '90 302 SBF and an '84 305 SBC and put the same cam, intake, carb, ignition and headers on them. I was surprised to see the old boat anchor 305 make literally the same hp and torque as the 302. Now the 305 wasn't hamstrung by the swirl port heads, peanut cam and 2bbl TBI throttle body the L03 has, but still, I didn't expect the 305 to do so well.

https://www.powernationtv.com/episod...ement-showdown

Well now they've revisited the challenge, taking fan suggestions and putting iron GT40-P heads on the 302 and 059 Vortec heads on the 305. They posted flow numbers on both heads. I was surprised to see the 059 Vortec heads flowed quite a bit better than the iron GT40s. Despite that, the 302 outperformed the 305 by quite a bit. The GT40 heads had smaller combustion chambers than what they took off the 302, bumping compression from 9.02 to 9.56. Meanwhile, even though the 305 Vortec heads had the same 58 cc combustion chambers as before, they used a thick composite head gasket that dropped compression from 9.03 to 8.56.

https://www.powernationtv.com/episod...vs-305-round-2

So, I've asked them to repeat the test on the 305 with a factory-style head gasket, restoring the compression. Seems only fair.

I've also asked them to swap to a set of 906/062 Vortec heads that came on the L-31 Vortec 350s.

Awhile back, there was a big debate on here on whether 305 Vortec heads are "true" Vortec heads. They use the same intake as the 350 Vortec heads, but they don't have the heart-shaped combustion chambers of the 906/062 Vortecs and they have a different intake runner design. While the flow numbers Engine Power got from the 305 Vortecs were better than any other305 head I've ever seen, they're not nearly as good as the L31 Vortec's numbers.

It's a lot of work getting L31 Vortec heads to work on a 305. You've got to shave the hell out of them to get from a 64cc combustion chamber back to a 58cc one, and that creates a lot of valvetrain geometry issues that are way over my head, but I think the difference in power might be worth it. I'd love to see Engine Power do it and settle the debate once and for all.

https://www.facebook.com/PowerNationTV/videos/2443624432656327
What do y'all think? If you agree with me, hit them up!

 

The Mexican 062 350 heads that have been sold over the counter for the past ~20 years flow worse than the 059s do. The 350 heads will perform worse than the 305 heads on a 305. Heart shape chamber does nothing fpr a smaller bore engine either. The 305 heads burns just as quickly as the 350 head if not a little quicker. Meaning a 305 Vortec actually usually ends up running less timing than the 350 Vortec to make peak power.

The 601s they removed from the 305 should have been 53cc. Also have to wonder if they put the correct reach plug in the Vortec head.

 

Well here, 305 Vortec heads were only worth 17 hp and actually made less torque than with the 601s. I know you've been a proponent of the 305 Vortec head for many years, but I've never seen any actual data on their outperforming 350 Vortecs on any engine.

This guy flow tested GM 350 Vortecs, Mexican Vortecs and GM 305 Vortecs. While the Mexican Vortecs did underperform the GM 350 Vortecs as you said, they still outperformed the 305 Vortecs everywhere except at .600 lift. The Original 350 Vortecs crushed the 305 Vortecs.


According to Scoggin-Dickey, though they still sell Chevrolet Performance p/n 19436449. The flow numbers they list for that head match the traditional Vortec numbers (239 cfm @ .600), and they're available all over the internet for 600-650 bucks, each..

https://sdparts.com/i-24502323-chevr...5WdeHP1w6Q8W60

I'm actually pretty sure the "ebay 305 Vortec heads" Engine Power used are the Engine Quest ch305s. The flow numbers they got are nearly identical, and Engine Quest sells them on ebay for about what Engine Power said they paid for theirs..

 

I ran 059s at ~10-10.5:1 not 8.5:1. Also single pattern cam is where it is at for a 305. They lost a substantial amount of that torque because they crippled the compression ratio. I do not see anyway in the world a flat top piston, GM 0.020" thick head gasket and 53cc 601 head was only 9.00:1. They are close to a point low on their compression calculation. I also question if they put the correct reach of plug in the Vortec heads. Very common mistake and cost a bit of power.

GM does not sell a production equivalent Vortec. Those are the over the counter Mexican heads I was talking about. The 062s vs 059s I flowed did not have the Mexican 062s up in flow anywhere compared to the 059s. That being said my untouched 97 906s reached 242 cfm on the same bench.

 

As I said the 059s in that test were being crippled by the static compression being in the 8s. Look at what compression, good quench and fresh ring seal did for power with no other changes. They made 360 hp with untouched Chinese 059s and a 218/224 @ 0.050 on a 110 lsa roller cam. Now they just need some 1.94/1.60s, some bowl work, exhaust porting and more cam duration. That 305 would easily break through 400 hp with a little head work and a cam in the high 220s/low 230s @ 0.050 with 0.600" lift.

 

I thought the first two episodes of this were really interesting and offered good information, even though they totally blew it by not bothering to cc the heads they were taking off and putting on, then compounded the error by using a way too thick head gasket., causing them to give up more than a full point in compression to the 302. They thought the 601 heads they took off the 305 had 58cc chambers when in fact, they had 53cc chambers.

I just don't understand it. They have an incredibly well-equipped machine shop and Pat is a MASTER machinist. Why they wouldn't bother to cc those heads makes no sense at all to me. What bugs me even more is, once they discovered their error, I don't understand why they wouldn't have gone back and corrected it by simply decking the heads and using the correct head gaskets. Then they could have swapped to a set of 350 Vortecs and showcased the difference between the two.

Instead, they did this, which is absolutely bonkers.

Who in their right mind is going to put a thousand bucks worth of pistons into a 305?

Who is going to put a thousand bucks worth of pistons into a 305 that require custom machine work to not hit the valves?

Balance the CAST crank and rotating assembly, and not spend the money for even ARP bolts?

And then run stock cast iron heads?

Let's assume in stage 2 of this that they HADN"T screwed the compression ration up and the 305 had made the same 344hp the 302 had. They only made 359hp in this episode! All this money and work for 17hp?

I guarantee you a stock L31 long block with upgraded valve springs and the same cam, intake and carb from this 305 beats that.

The bottom line is this was a really interesting idea that they blew through poor research and lazy, sloppy execution.

There are going to be all kinds of L03 fanboys wanting to do this (stage 2, not 3) to their TBI thirdgens who will be massively disappointed if they do because all 305s are not equal. They started out with a 305 HO that had flat top pistons. An L03 made 8.5:1 brand new; Lord knows what they're making now.

 

Im not a Ford guy by any stretch but i have no doubts the Ford 302 is a much better platform than the SBC 305. 305 is absolute waste of time to build when there are 350s everywhere for the taking. Ive built a 305 and it was a complete waste of time and $ with hardly any benefit.

 

I have built a couple 305s that far outperformed these. Ford 302 is no better than a 305. Ernie Neals Super Stock 265 L99 4.3L Caprice went 10.83 in the 1/4. Rules limited to starting with a factory iron L99 4.3L V8 head casting and a 0.030" over L99 265/305 bore. He gave up 40 cid to a 305 and still ran 10.80s.

 

I have built 305s as learning experience and did pretty well in building a few for a dirt racing that can only run a 305 SBC.

You realize my 383 only has ARP bolts in the aftermarket rods and ARP studs on the heads. Main caps are still stock GM bolts. Those pistons are definitely not $1,000 worth of pistons. Also a L03 is around 9.3:1, not 8.5. I have cc'd a couple of them including a truck engine. That was not a HO engine they started with. HO would have started with more power. It was a LE9/LF3 truck/van engine. The 601s were truck heads.

I also firmly believe this engine would kick a commonly available Hecho en Mexico 062 headed 350 in the rear and leave it in its rear view mirror. My Mexican 062 headed L31 started with TBI 350 HP and TQ numbers. Those heads are JUNK.

 

OK, so the pistons by themselves are $600, not $1,000. You still have to have the block bored for them, and you have to have the engine pre-assembled, clearances checked, pistons fly cut, re-checked, etc. That's at least another couple of hundred bucks. Then there's the balancing. By the time the average enthusiast pays to have all that done ... well over a thousand bucks.

Again, no one is going to do that with a 305 ... unless they have to.

Take a 350 ... flat top pistons, same heads, cam, intake and carb, and you will make more power. It's just that simple..

https://www.summitracing.com/parts/u...hoCJpQQAvD_BwE

Every time I say "350 Vortec", you spit out "Mexican Vortecs" and begin ranting about how they don't flow. GM Performance Parts sells genuine GM Vortec heads that flow the same 239 cfm @.500 lift 350 Vortec heads always have. I don't know where they're made and don't care. They outflow 305 Vortec heads. Always have, always will.

Jeasus, you're like a dog with a bone, except also with a SERIOUS case of OCD.

https://sdparts.com/i-24502323-chevr...+cylinder+head

They also sell new brand new L31 long blocks with those same heads.

https://www.summitracing.com/parts/nal-19432780

Up until 3 years ago, they would deliver one to your doorstep for 2 grand! Right before the price went up, my buddy bought one for his 67 C-10. He swapped the valve springs for the Comp upgraded ones, put in a .510 lift, .246 duration cam, and made 412 hp and 425 lb/ft torque.

 

I do not care what you read somewhere. The newer GM over the counter Vortecs did not flow 239 cfm nor did the ones on the crate engines. They were Hecho en Mexico GARBAGE for years and only flowed about 215 cfm @ 0.400 and dropped off to 207 cfm @ 0.450+. Well documented by myself and others including HotRod Magazine and Cutters Performance. So yes you should definitely care where your Vortec heads were cast. The Mexican heads cracked between the seats like clockwork.

I also had one of those "Goodwrench" crate engines from the 2005 time frame. It was a POS. The Mexican 062 heads cracked and it also had a crank journal out of round that knocked out a rod bearing in 40K miles. That POS is the reason I built a 383.

 

Once again you come in hot ... and wrong.

It's not a Goodwrench engine; it's a Chevrolet Performance engine. Different animal entirely.

And the engine in question's gone tens of thousands of miles, and made hundreds of passes with not a single problem.

Also, SDPC only posts flow numbers they have verified themselves. When SDPC lists the heads as having flowed 239 cfm, they flowed 239 cfm on SDPC's flow bench.

Finally, wasn't it you who used to insist 305 Vortec heads were the same as 350 Vortec heads, except sized for a 305's bore and with 58cc chambers? Seems like I remember you being just as insistent about that back in the day as you are about those "Mexican Vortecs" now.

Odd you don't bring that up anymore.

But even if you were correct on that (which you're not, Engine Quest still sells their Vortecs on ebay, and they're superior to any Vortec GM ever made, Mexican, or otherwise.. RHS also still makes their Vortecs; the old Pro Toplines ... again, fixed the cracking issues and flow even better than the original GMs.

 

As I have clearly stated in the past and did not realize at the time because the stuff was still basically new at the time, the heart shaped small chamber/smaller valve heads were L99 265 heads that I thought at the time were the 305 Vortec heads. That does not change the fact the 059/520 Vortec are the best small bore cast iron SBC head.

I am 1000% correct on the Mexican Vortecs though. Goodwrench and GMPP both use the same exact part number. Does not matter if it is a Goodwrench or a GMPP L31 based crate engine, they are the exact same shortblock and heads built in gasp Mexico at the time. Even the Industrial and Marine engines were built there. The Mexican casting and maching quality was trash compared to the OE production stuff in the US and Canada. SDPC is flat wrong if they are claiming 239 cfm of flow from any Mexican made 062. Here is an article from 2009. They discovered the same exact thing with their GMPP Mexican 062 over the counter heads. I literally bought a 2003 GMT800 Sonora 4x4 with a 5.7L/5spd dirt cheap about 6 years ago knowing it had cracked heads or blown head gaskets. I went through the bottom end, put Etec170 on it and it was a great runner.

If I am spending money on a head for a 4.00" or larger SBC it is certainly not going to be a Vortec or even an iron head for that matter. Even cheap aluminum heads outflow most aftermarket iron offerings and make more power.




https://www.hotrod.com/how-to/hrdp-0...ck-chevy-build

Here is another alternate source of information. Basically a carbon copy of the same data set that my Mexican 062 heads flowed and duplicated by HotRod Magazine. That is thus 3 different sets of data that align.

 

Here is what I mistakingly identified as a Vortec 305 head years ago. 50 something cc chamber, 1.84/1.50 valves. So yes a small bore Vortec heart shapped combustion chamber does exist for a SBC albeit Gen2 as it came on a 3.735" bore L99 4.3L not a 305. It was literally laying in a pile of core engines at the time. At the time I had never been into an LT1 deep enough to know the cooling differences. I saw the LT1s revised bolt angles and thought it was a Vortec. Just to give you an idea Ernie Neals Super Stock L99 Caprice ran 10.83 in the 1/4 with the 1.84/1.50 valve L99 heads on a factory compression ratio small bore L99 265. That little 265 would pull the front wheels off the ground on the launch. If you cannot make good power with what is essentially a factory stroked version of that engine aka 305 Vortec, I do not know what to tell you. The one I built made 423 hp and 418 tq with GM TBI. Engine Power needs to do a little head work and put some cam duration engine as I mentioned already and that 305 will easily crank out well over 400 hp with the 059s. They already did another 305 and a 340 build that both made a lot more power.



I will also be the first to say I have a 383 that I wish I had gone with a Dart SHP 4.125" bore block on and a 3.875" or even 3.91" stroke crank on merely because it moves around a vehicle that weighs close to what 2 factory weight 3rd gens weigh together.

 

0

Right, and I tried and tried to tell you that 305 Vortecs had d-shaped combustion chambers and were not a fast burn design, and over and over again you INSISTED I was wrong and went into great detail over the builds you'd done with those heads, and for literally YEARS, every time 305 Vortec heads came up, you would jump into the conversation INSISTING they flowed the same as 350 Vortecs, and no matter how many people tried to tell you different, you

WOULD.

NOT.

LISTEN.

and INSISTED the people disagreeing with you were WRONG.

It's not just that you wouldn't listen, though. You were so INSISTENT on your expert opinion that you wouldn't even bother to check. Time and again I would post pics, or links to ebay auctions clearly showing the d-shaped combustion chambers, or links to cylinder head flow databases clearly showing that 305 Vortec heads didn't flow anywhere near what 350 Vortec heads did, and you'd flat out dismiss me, telling me I had the wrong heads.

And now, 15 freaking years later you FINALLY admit it, but you downplay it like it's no big thing, just a little, tiny, miniscule, minor error or your part.

Have you ever thought about how much disinformation you spread with that?

And now you're like ... awww ... ha ha ha ... whoops ... my mistake.

So here's what I'm gonna tell you. When SDPC and Pace Performance says a head flows 239 cfm, I'm gonna take them at their word, and will continue to do so until PROVEN otherwise, especially when I have a friend who bought the long block in question and is making 412 hp with it.

 

ford 4.00” bore is automatically an advantage for valve size vs a sbc 305, so theoretically by air flow alone the 302 should be better in a natural aspirated deal, given similar valve angle heads. Short stroke needs a lot of rpm to get piston speed to get air flow demand tho.
Superstock engines are very impressive however, getting alot out of small valve and port sizes. From a head i seen recently, the port is basically reshapen and effectively raised up while maintaining stock volume. This allows more air speed i believe. Those guys spend a lot of money to make them work like that but certainly not something the average enthusiast would pursue in a street strip car lol

 

I like this part:

Let's just look at that, one more time...
Promptly followed by....

If ya gonna chop down a guy's merit on "what you read somewhere"...then ya better not post up "what YOU read somewhere", to try to "slam dunk" your point...whatever that might actually be. It's just a pissing match of cherry picking articles (some, not even related to the content) and who read better than whom!

My advice would be to post the flow data that you observed from your flow bench.

 

You can find the flow numbers for stock 059s, Mexican 062s, Canadian 906s, and ported 059s with 1.94/1.60 valves in multiple places from years ago on this site posted by me. Literally stated the numbers for the Mexican 062s above that I recorded. The Mexican 062s and 059s were flowed on the same bench on the same day. The 059s outflowed the Mexican 062s by a small amount.

 

The CFM claim was later in like 2010. Lliterally had Mexican 062s and a set of 059s on the same bench on the same day. The 059s slightly outflowed the Mexican 062s. That is where that claim came from. I later had a set of Canadian 906s on the same bench and they flowed signifigantly better. The OE Vortecs flowed ~239 cfm at one point. My 906s flowed 242 cfm. The Mexican heads they sold for 20 years simply do not flow that. If your friends engine made 412 HP with Mexican Vortecs it would make 430+ HP with real Canadian production heads. Same cam and setup the Mexican heads are down a solid 20 hp. I saw the same kind of performance loss even on that L31 crate engine with the stock cam. You could absolutely tell it was down on power compared to the stock L31.

 

Point, completely missed. Oh well.

 

Back to the original topic, I watched the third episode in this series last night, thought it was pretty interesting. I also wonder why they didn't just chop the head and re-run the 305, but anyway, I think it would be interesting to see a compression corrected, 350 headed test run on that 305 and see how that shakes out. OP, you should do it!

 

I too wonder why they did not chop the head but I do like that the engines are on a level playing field with internal conditions specificially ring seal or lack there of no longer a factor. I can tell you exactly what it will do to use a set of factory production Canadian 350 Vortec heads. Will trade compression and torque for a little more peak hp making a typical street car slower. Exactly like the 059s did compared to the 601s to start with. Same exact thing happens putting 799/243 heads on a Gen III 4.8/5.3L too. Friend on mine did the 243 head swap with the matching NNBS shorter runner GenIV truck intake on a dished piston Gen III 5.3L and it became even more of a dog at lower engine speeds. Happens anytime you trade compression for flow on an engine and that one was compounded by a shorter runner intake. Same thing happened when Chevy High Performance did their Goodwrench 350 builds long ago. They put on ZZ4 113 heads then moved to Vortecs. The 58cc 113s made more torque and the production era 64cc 906s traded some torque for more HP. Buddy of mine has a 1998 K1500 he tows heavy trailers with. Before he bought it somebody had put 305 Vortec heads on the L31 350 in it. He built a replacement 350 engine with 350 heads. New engine has less torque under ~3,000 rpm but it makes more top-end power. At low rpm compression will always trump flow for making torque. If you can add both compression and flow like I did on say my 5.7L 1st gen Hemi by adding 2nd generation Eagle heads you can gain both. The Eagle heads flowed a lot better and had much smaller chambers to the point I stacked two MLS head gaskets together after drilling out the rivits to bring the compression down to run on pump gas as that is how it was done multiple times before when I researched it and did the same.

 

What do you all mean by chop the heads? I assume mill them.

For the last test with the new pistons in each engine the Ford had a 10.92 to 1 compression ratio, and the Chevy had a 10.91 to 1 compression ratio.

Or do you all mean earlier on in Part 1 & 2?

 

I wish this test had started with a 90 to 93 Mustang 5.0L long block engine and a 90 to 92 LB9 5.0L long block engine. So, it would have been more of an apples-to-apples test using the best 5.0L engines of that time period.

 

I would have rather seen a 5.0L Explorer vs 5.0L Vortec truck engine myself from the start as they are something more common place in the wrecking yards.

 

Yeah, that would have worked too, and they would have started off with GT40P heads and Vortec heads.

 

Great point. That would have been way more representative of each brand (more fair starting point), and also as you said, the most common JY pick these days. No one is going to the bone yard to bust their buts and then PAY for, an LG4.