SMALL BLOCK HEADS

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the wall

the wall

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I shouldn't do this but I cant help myself. Someone just posted a vid on youtube explaining why small blocks are so good. Folks this is the most inaccurate vid I have seen in a long time. Small block 340 and 360 head have poor exhaust ports and good intake ports. The intake port is a large reason for 340 domination on factory street engines. Because of the poor exhaust port headers make a big difference in performance. This vid claims that the only reasons small blocks run like they do is a accident by Chrysler engineers. And only this genius figured it out and then goes on to show early 426 hemi heads and big blocks heads as prof to the reason for small block performance. NOOOOT
Small block chevys have excellent exhaust port and bad intake port. This is why the 340 beats the lt1 all day long. If it was about exhaust flow chevy would dominate the world but they don't, look back in the day of nascar when they were running. ford and mopar were the big dominators when big block power was being used chevy then had a Superior exhaust port.
Ford 351 c engine are killer on the street and the track at that time and there exhaust port sucks bad.
Here's the truth about exhaust, better exhaust on a mopar picks them up a bunch. early chevy engines like fuelie head engines the builder had be careful not to make the exhaust to effective cause the result was over scavenge causing poor fuel consumption and poor mid range response. This is why it was common practice to put a split pattern cam in a chevy with lower number on the exhaust side. it was also common to put a 1.6 rocker on the intake and a 1.5 on the exhaust to balance them out.
One more point, the struggle isn't getting exhaust out....its getting intake in. If it was the exhaust you are worried about then you put in a smaller intake valve and put in a larger exhaust valve. The intake is larger cause we live in about 14lbs of atmosphere that's all the push we have to get oxygen into the engine.(unless you use a turbo, blower or nitrous). The exhaust on the other hand has many pounds if needed to get it out and that's why using a turbo witch plugs the hell out of exhaust flow works. Remember when the piston is on it way up it can make a heck of a lot of pressure. Check it with a compression gauge you will see it.
Now 340 exhaust is bad but it is not terrible and there is a advantage to fixing the exhaust for sure. W2 heads have awesome exhaust in them and the have very good intakes so that makes it hard to compare at least factory to factory parts are concerned. And ford Cleveland exhaust ports are terrible and fixing them is a nice pick up.
340 engines advantages are big bore short stroke. long rod stroke ratio; strong factory parts and good intake ports' large diameter lifters. large diameter valve springs to name a few.
Alright long enough rant here bottom line if your using factyory parts don't give up on the exhaust it important and there is big improvement to be had. so header up it works good on LA heads, GOOD LUCK ALL
 
the wall said:
I shouldn't do this but I cant help myself. Someone just posted a vid on youtube explaining why small blocks are so good. Folks this is the most inaccurate vid I have seen in a long time. Small block 340 and 360 head have poor exhaust ports and good intake ports. The intake port is a large reason for 340 domination on factory street engines. Because of the poor exhaust port headers make a big difference in performance. This vid claims that the only reasons small blocks run like they do is a accident by Chrysler engineers. And only this genius figured it out and then goes on to show early 426 hemi heads and big blocks heads as prof to the reason for small block performance. NOOOOT
Small block chevys have excellent exhaust port and bad intake port. This is why the 340 beats the lt1 all day long. If it was about exhaust flow chevy would dominate the world but they don't, look back in the day of nascar when they were running. ford and mopar were the big dominators when big block power was being used chevy then had a Superior exhaust port.
Ford 351 c engine are killer on the street and the track at that time and there exhaust port sucks bad.
Here's the truth about exhaust, better exhaust on a mopar picks them up a bunch. early chevy engines like fuelie head engines the builder had be careful not to make the exhaust to effective cause the result was over scavenge causing poor fuel consumption and poor mid range response. This is why it was common practice to put a split pattern cam in a chevy with lower number on the exhaust side. it was also common to put a 1.6 rocker on the intake and a 1.5 on the exhaust to balance them out.
One more point, the struggle isn't getting exhaust out....its getting intake in. If it was the exhaust you are worried about then you put in a smaller intake valve and put in a larger exhaust valve. The intake is larger cause we live in about 14lbs of atmosphere that's all the push we have to get oxygen into the engine.(unless you use a turbo, blower or nitrous). The exhaust on the other hand has many pounds if needed to get it out and that's why using a turbo witch plugs the hell out of exhaust flow works. Remember when the piston is on it way up it can make a heck of a lot of pressure. Check it with a compression gauge you will see it.
Now 340 exhaust is bad but it is not terrible and there is a advantage to fixing the exhaust for sure. W2 heads have awesome exhaust in them and the have very good intakes so that makes it hard to compare at least factory to factory parts are concerned. And ford Cleveland exhaust ports are terrible and fixing them is a nice pick up.
340 engines advantages are big bore short stroke. long rod stroke ratio; strong factory parts and good intake ports' large diameter lifters. large diameter valve springs to name a few.
Alright long enough rant here bottom line if your using factyory parts don't give up on the exhaust it important and there is big improvement to be had. so header up it works good on LA heads, GOOD LUCK ALL
Click to expand...


The SBC intake port is better than the SBM port. The difference is the valve angle. Port for port the SBM is weak there too.
 
yellow rose said:
The SBC intake port is better than the SBM port. The difference is the valve angle. Port for port the SBM is weak there too.
Click to expand...
sorry your wrong do your
yellow rose said:
The SBC intake port is better than the SBM port. The difference is the valve angle. Port for port the SBM is weak there too.
Click to expand...
I guess its were you get your info from my head testing shows 212-220 on mopar J casting intake and on fuelie 292 heads i get 190-206 averages ill believe my stuff thank you
 
the wall said:
sorry your wrong do your

I guess its were you get your info from my head testing shows 212-220 on mopar J casting intake and on fuelie 292 heads i get 190-206 averages ill believe my stuff thank you
Click to expand...


You’re not listening. I said “port for port”. Take the valve angle out of it, and the SBC PORT is better. The 18 degree valve angle is what makes the weaker SBM port make more power.

You can’t just look at one aspect of any head and claim one is better than the other without looking at valve angle, port angle, cross section, chamber shape, plug location, pushrod pinch etc. It all adds up.

Again, port for port, the SBC port is better.

I watched that video. There was much that UT nailed. He has figured out that building big inch small blocks with OE architecture is a bad thing. Something I’ve known for decades, and have written many times here.

That’s the biggest take away from that video.

His flame test is iffy at best. It takes about 15 minutes on a flow bench using various pressure drops to see the issues with the SBM exhaust ports.
 
yellow rose said:
You’re not listening. I said “port for port”. Take the valve angle out of it, and the SBC PORT is better. The 18 degree valve angle is what makes the weaker SBM port make more power.

You can’t just look at one aspect of any head and claim one is better than the other without looking at valve angle, port angle, cross section, chamber shape, plug location, pushrod pinch etc. It all adds up.
Click to expand...

the biggest advantage as far as flow goes on 18 degree is un shrouding valves. Its also easier to achieve more compression without a dome. that being said un shrouding a chevy head if you could to the max will not let it flow sbm numbers. that is taking in consideration port angle, cross section, chamber shape,plug location pinch etc... what does this have to do with the exhaust anyway your the one not listening when the primary subject is about how well sbm exhaust works
 
Now I’m curious- where is the link to the video you are referring too?
 
So, what I did not get out of your speech in the original post is where all the energy is going? I just watched Uncle Tony and his explanations of the reason (planned or un-planned) why small block heads are actually really good heads. Nothing about intake or nothing about flow numbers - but in typical UTG he explains in a basic for the masses. Something I totally appreciate.

He is a MoPar guy for sure and comes off as a regular guy with some skills. But you went in depth- really in-depth. I’m sure if you connected with him on here (he is on here) you could debate deeper than what he is showing here. Honestly I’m glad you are proving a point- I’m just not sure that point is needing to be proved. I am not as versed in head flow numbers as you are so I am not picking a fight. My end question is do you think the Mopar small block head is junk or really good? I’m a tad confused.
Syleng1
 
the wall said:
the biggest advantage as far as flow goes on 18 degree is un shrouding valves. Its also easier to achieve more compression without a dome. that being said un shrouding a chevy head if you could to the max will not let it flow sbm numbers. that is taking in consideration port angle, cross section, chamber shape,plug location pinch etc... what does this have to do with the exhaust anyway your the one not listening when the primary subject is about how well sbm exhaust works
Click to expand...


Go back and read your first post. YOU brought up the intake port ****.

If you don’t think valve and port angle don’t affect performance other than unshrouding valves you’d be mistaken.
 
Syleng1 said:
So, what I did not get out of your speech in the original post is where all the energy is going? I just watched Uncle Tony and his explanations of the reason (planned or un-planned) why small block heads are actually really good heads. Nothing about intake or nothing about flow numbers - but in typical UTG he explains in a basic for the masses. Something I totally appreciate.

He is a MoPar guy for sure and comes off as a regular guy with some skills. But you went in depth- really in-depth. I’m sure if you connected with him on here (he is on here) you could debate deeper than what he is showing here. Honestly I’m glad you are proving a point- I’m just not sure that point is needing to be proved. I am not as versed in head flow numbers as you are so I am not picking a fight. My end question is do you think the Mopar small block head is junk or really good? I’m a tad confused.
Syleng1
Click to expand...
this post is not about intake its about exhaust. the intake is more important then the exhaust is for performance.(within reason). thats why i bring it up if it was just exhaust and that was it then leave a 2 barrel on your 318 and your good to go. flow numbers are a response to someone in my opinion is trying to get a gotcha moment. the energy is that the exhaust is not the reason for sbm being such a great engine. this is misleading and when you dont go into detail on certain subjects it leave people making mistake on there build or reasoning on other subjects incorrectly. this does not help. i dont mind basic explanations but this one is ridicules if you care about whats really going on in your engine. If your stuck with a certain size engine then all the things around it become very important like heads. if you dont have a good intake port you are going nowhere period. What if you were a young person starting out in the hobby and you saw this vid, might you get the idea that you need to look at exhaust flow number to decide what platform to start with. there are so many reasons why a 340-360 are the killer that they are. crappy exhaust doesn't help but the intake is what make a engine a legend. thats why hemis run like they do. his claim is the exhaust is awesome for a strange reason. This is why i want to clarify. You said "I’m just not sure that point is needing to be proved". this is why i started my thread with, I shouldn't do this but i cant help myself. but i think the deeper you dive and more versed you get, the better you are at your craft and its for those reason i really strive for whats really going on.
as far as mopar heads, there awesome. 272 318 heads out perform considering there valve and port volume on intake and exhaust. but thats not racing. 340 360 heads are good heads, thats the heads used in NHRA G/stock running 340 heads up against 396 chevys. last time i looked 340 had the record. thats some good heads to make that happen. if you tickle a 340 port with a die grinder they respond. Im not the best porting guy in the world but with a 2.02 valve ive gotten 273 CFM numbers. best ive gotten from a 2.02 fuelie head was 252 and mopar w2s ive gotten 308. the chevy bowtie heads best i could do was 271 with a 2.02 valve thats a ton of work to get there but it can be done. after market heads are the way to go these days for many reasons but money and flow are the main reason. if your going to go stock mopars are some of the best. but it helps to know what your working with to get the bang for the buck out of the pieces you decide to use. good luck be safe.
 
I think.... (oooo boy) that the video was his amazement of the exhaust port which many porters here seem to like a lot. Some claim best in the biz. IDK much about the “Other Guys” ports since that is a case of IDGAF. The intake port is indeed hampered by the pushrod pinch. Not so much with the other manufacturers. That is also why the W series heads do so well. A seriously reduced pushrod pinch.

I think this is Tony’s first small block he is taking at least a little serious. His mention, IMO being correct, is how well the small block responds to basic bolt on parts.

Be the exhaust port good or bad, headers make a difference on any engine with any head over exhaust manifolds. Valve size, angle, placement, port cross sectional area, etc... play a huge part in its performance.
 
the wall said:
this post is not about intake its about exhaust. the intake is more important then the exhaust is for performance.(within reason). thats why i bring it up if it was just exhaust and that was it then leave a 2 barrel on your 318 and your good to go. flow numbers are a response to someone in my opinion is trying to get a gotcha moment. the energy is that the exhaust is not the reason for sbm being such a great engine. this is misleading and when you dont go into detail on certain subjects it leave people making mistake on there build or reasoning on other subjects incorrectly. this does not help. i dont mind basic explanations but this one is ridicules if you care about whats really going on in your engine. If your stuck with a certain size engine then all the things around it become very important like heads. if you dont have a good intake port you are going nowhere period. What if you were a young person starting out in the hobby and you saw this vid, might you get the idea that you need to look at exhaust flow number to decide what platform to start with. there are so many reasons why a 340-360 are the killer that they are. crappy exhaust doesn't help but the intake is what make a engine a legend. thats why hemis run like they do. his claim is the exhaust is awesome for a strange reason. This is why i want to clarify. You said "I’m just not sure that point is needing to be proved". this is why i started my thread with, I shouldn't do this but i cant help myself. but i think the deeper you dive and more versed you get, the better you are at your craft and its for those reason i really strive for whats really going on.
as far as mopar heads, there awesome. 272 318 heads out perform considering there valve and port volume on intake and exhaust. but thats not racing. 340 360 heads are good heads, thats the heads used in NHRA G/stock running 340 heads up against 396 chevys. last time i looked 340 had the record. thats some good heads to make that happen. if you tickle a 340 port with a die grinder they respond. Im not the best porting guy in the world but with a 2.02 valve ive gotten 273 CFM numbers. best ive gotten from a 2.02 fuelie head was 252 and mopar w2s ive gotten 308. the chevy bowtie heads best i could do was 271 with a 2.02 valve thats a ton of work to get there but it can be done. after market heads are the way to go these days for many reasons but money and flow are the main reason. if your going to go stock mopars are some of the best. but it helps to know what your working with to get the bang for the buck out of the pieces you decide to use. good luck be safe.
Click to expand...

Im fine with discussing the exhaust.

Do you agree with UT in his assessment of the exhaust port?

FWIW, I don’t. The port is garbage. If it wasn’t, Chrysler wouldn’t have upgraded it on the W2 head. Trick Flow wouldn’t have decreased the valve size (1.6 is too big if the port isn’t junk) and reshaped the port if it was as good as he thinks.

His method of showing flow with a MAP gas torch is a poor example of what actually happens when the exhaust valve opens. It can’t duplicate the pressure waves or much else.
 
and so it begins

Vge.gif
 
yellow rose said:
You’re not listening. I said “port for port”. Take the valve angle out of it, and the SBC PORT is better. The 18 degree valve angle is what makes the weaker SBM port make more power.

Why take anything out of it? When you bolt the head on and the engine runs you can't take anything out of it.

You can’t just look at one aspect of any head and claim one is better than the other without looking at valve angle, port angle, cross section, chamber shape, plug location, pushrod pinch etc. It all adds up.

Again, port for port, the SBC port is better. No it's not--the SBC has 50+ years of OEM and aftermarket development behind it. Chrysler gave it a shot and it was superior right out of the gate.

I watched that video. There was much that UT nailed. He has figured out that building big inch small blocks with OE architecture is a bad thing. Something I’ve known for decades, and have written many times here. UT couldn't nail anything in a wood shop. The only thing we agree on is strokers are not all that and a bag of chips.

That’s the biggest take away from that video.

His flame test is iffy at best. It takes about 15 minutes on a flow bench using various pressure drops to see the issues with the SBM exhaust ports.Iffy? It's downright unscientific and all for the camera. Everything he does is for the camera-that's why he releases like 2 videos a day--for the clicks.
Click to expand...

What I figured out along time ago is this: If a SBC head flows 220 cfm the cylinder may only "see" and use 199 cfm. A SBM head that flows 219 cfm will see and use 210 cfm. This is due to the valve angle 23* vs 18* . This is also why a SBC will respond to angle milling better than a SBM. It's also why a BBM responds to angle milling and a dowel shift BIGTIME. J.Rob
 
RAMM said:
What I figured out along time ago is this: If a SBC head flows 220 cfm the cylinder may only "see" and use 199 cfm. A SBM head that flows 219 cfm will see and use 210 cfm. This is due to the valve angle 23* vs 18* . This is also why a SBC will respond to angle milling better than a SBM. It's also why a BBM responds to angle milling and a dowel shift BIGTIME. J.Rob
Click to expand...


I agree. Valve angle is important. If it wasn’t, GM would still be using 23 degree valve angles on their stuff.

Certainly as you point out, the SBM head uses the air flow more efficiently.
 
@the wall . Longtime no see.
Yep mopar sb intake ***** all over a sbc intake port. And I agree on the exhaust, I had a few weeks back brought this up and used the ford as an example making 900hp with about 470 inches with those crummy exhaust ports. It's the builder that's the problem most of the time.
Btw Just bought an old kwikway stone setup off Ebay. Looking for a seat n guide machine next, got my eye on one...1700.00. Found a sunnen rod hone for 1200.

Justin.
 
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yellow rose said:
You’re not listening. I said “port for port”. Take the valve angle out of it, and the SBC PORT is better. The 18 degree valve angle is what makes the weaker SBM port make more power.

You can’t just look at one aspect of any head and claim one is better than the other without looking at valve angle, port angle, cross section, chamber shape, plug location, pushrod pinch etc. It all adds up.

Again, port for port, the SBC port is better.

I watched that video. There was much that UT nailed. He has figured out that building big inch small blocks with OE architecture is a bad thing. Something I’ve known for decades, and have written many times here.

That’s the biggest take away from that video.

His flame test is iffy at best. It takes about 15 minutes on a flow bench using various pressure drops to see the issues with the SBM exhaust ports.
Click to expand...
Look at a lq9 or any new al chevy heads.... they sure aren't short and squatty like those old lt1 pos's are they? They are tall and narrow and they made no mistake about putting the injector path in the top.
If you've had a lt1 on the bench, ported even, it won't do what the j head will in the right hands. Stock 2.02 915 heads I have right here do 228cfm max . 906 heads stock w/2.08 do the same.
 
xLURKxDOGx said:
Another Chevy troll. Have fun with this.

J.
Click to expand...
He's not a chevy troll.
Though I haven't spoke with him in years, I know him to be one of thee most DIEHARD mopar guys I've ever met, and hanging g with him helped me jump ahead a few steps past the other guys I was hanging with.
It is absolutely true the exhaust is not as important in flow numbers as is the intake.
My j head go 280's intake and only 187-190's exhaust....and that motor will rip a new asshole and into 7000 rpm.
@pittsburghracer Brought this up...that air speed in the exhaust port is far more important than the peak flow number...

If you have any experience to compare to..you'll understand it's TRUE. Enginebuilder talks about it, many have said..but its gets burried... because they wanna sell heads!
Check it out. Its beating your head against the wall chasing flow numbers and trying to stay in the generally accepted ratio..when you don't need to. It's an 'on paper vs real life' kinda thing.
60,70,80's Chevy pockets arent deep enough btw, those ports suck. We all know that.
 
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Is a Chevrolet air pump a better design than the Chrysler air pump?
 
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