390 w/open chamber heads

[Treblig]

64 STR8 Dart,

You know after seeing the pics you posted I remembered gasket matching the Performer intake (last year) to the 302 castings I currently have on my 318. I used felpro gaskets but don't recall which specific gasket I used. But I do remember that the intake ports were very close to the 302 casting ports. I also know that the 302 is considered a 318 head while the 596 (which I plan to use on the 390) is a 360 head. I also own a copy of "How To Hot Rod Small Block Mopar Engines". In this book it shows a marked difference between the 318 port shape and volume and the 360 port shape and volume. I'm not a Mopar expert but if the Performer matches the 302 casting so well....there's now way it will fit as well on the 596 casting. I haven't checked but now that I've thought about it "I will check!!!" If someone had said it that way (where were you RRR!!!) I would have listened more closely.
So I'll try and go out tomorrow and physically compare the ports of the 318 to the 360 relative to the Performer. Sorry guys, I just hadn't thought about it that way. You guys are beating me over the head about the RPM and I hadn't considered the fact that the Performer matched the 302 casting almost perfectly (very little clean up). Not realizing that I'm putting the Performer on 360 heads!!!!

TXSTANG84,
Squaring the deck (if it's way off) is always a good idea, I don't think anybody will argue with that. Zero decking is another story, especially when you consider my goals. I might have a different opinion after I check the block. I definitely see where you're coming from.



I thought I was done here but evidently I'm still learning!!!!!!! Keep kicking me...eventually you'll knock some sense into me!!LOL

Treblig in tex

 

[frosty_the_punk]

I recommend decking the block the minimum amount to obtain equal deck height and an ideal cylinder head mating surface for any rebuild, if your build requires a zero deck...so be it.

Personally I shy away from zero decking due to my indecisive nature, I try to reserve the option of change my mind at a later date and once you remove material from the block it's gone forever.

I'm far more likely to try to choose pistons, heads and even head gaskets that will give me my desired compression ratio with only removing the minimum amount of material from the block.

This is a lot more work, and truth be told...sometimes more expensive.

for example, my 30 thou oversize 318 has a +.007 deck height (this is still enough for a good quench) and dome top pistons. 66.5 cc heads and compression ratio is in the mid tens. The block is still as close to standard deck height as it can possibly be having only been surface ground for the mimimum amount for blueprinting.

 

[64 SRT8 Dart]

Hi Treblig,

with the Performer, you could open up the ports to the 360 size. With the 390, you're looking for a torque monster right? If I'm thinking correctly, you could open up the ports on that Performer an inch or so into it and I think you'd have excellent port velocity starting right at the plenum! That, my friend, would create gobs of torque....someone correct me if I'm wrong? Also, might consider adding a 1" spacer or so to add some plenum volume....again, someone correct me if I'm wrong.

What carb size were you running again?

 

[frosty_the_punk]

I agree, if you have access to a die grinder and all the safety gear you are better off to match-port the performer manifold about 1-1/4" deep into the runners.

Don't make the manifold ports bigger than the cylinder head ports or you'll just make everything worse than when you started.

Keep in mind though porting IS time consuming, even on aluminium. Expect to spend about an hour on each port to do it properly.

 

[Treblig]

To all: if my block is out of square more .003" I get it squared.

68STR8Dart, you said, "with the Performer, you could open up the ports to the 360 size. With the 390, you're looking for a torque monster right? If I'm thinking correctly, you could open up the ports on that Performer an inch or so into it and I think you'd have excellent port velocity starting right at the plenum! That, my friend, would create gobs of torque."

You know I thought about that also after I went to bed last night, but then I thought of something else. I'm not a flow expert, although I've done a lot of reading, but if you port the Performer back 1 1/4" or whatever distance you would create higher velocity in the intake but then when the air hits the opened-up area it will dramatically slow down because the air will be going from one diameter (intake port) to a larger diameter (head port). I know form experience that velocity and speed drop when you transition from a smaller diameter to a larger diameter. the same thing happens to water in a water line and gas in a gas line. I would need someone else's opinion on this but I'm pretty sure I am correct. Whenever you have a sudden drop in flow it is not good in a street machine???? Some one correct me if I'm going in the wrong direction???

I'm running a 600 edelbrock (probably not big enough for the 390) but I should get really good throttle response. Since I'm not going to any high RPMs it should work initially. If I'm not happy with it I can easily change it out later.
I have all the porting tools I need (die grinder, carbide burs, sanding rolls, etc) I'm a machinist and have ported heads before so it should pose no problem.

I need someone who has real world experience (knowledge) about air flow when it comes to changes in "vessel diameter"??? ANYONE OUT THERE>>>HINT "RRR"


treblig

 

[moper]

Everything is related off the crank center line in an engine. Square decking = good.

Just my opinion here - I disagree with the choice to not bother addressing the deck issue "because this is just a torque engine". There are two things that need to be "right" in my mind: crank centerline, and deck height. The factory machining sucked. All of it. so if technology exists to correct the result of the scuking, then I'm all for using it. The end goal is higher performance than a factory engine. Whether performance be horsepower, torque, emissions, economy, or a combination of some or all. So with that in mind - The crank centerline (or main bearing bore centerline) is one two bores that modern machining equipment uses to index itself. Every engine I do gets the mains honed and the decks square decked. Because everything is related to those being a given spec. "Zero deocking" is BS in terms of a description because it can be any height that leaves the piston flush with the deck surface. It's a minor misuse of a word but you can have a small block deck "zero decked" and that deck hieght could be 9.590, 9.600, 9.550 all depending on the accuracy of the main bearing bores, the crank, rods, and pistons used. Decking is the action of milling the gasket surfaces of the block. Depending on the block, the machinist, and the milling equipment used this could be a good or bad thing as there is no reference to setting a deck hieght or correcting any relationship of the deck to anything else. Square decking is machining the head gasket sirfaces in order to make them parallel with the crank centerline, perpendicular to the bores, and set at a known height. Because the deck surface placement and accuracy affects individual cylinder compression ratios (static and dynamic), gasket sealing, valvetrain stability, and individual pushrod lengths it IS that important to get as perfect as possible.

 

[Treblig]

Moper, No comment on air flow through a vessel when the diameter changes?? Cavitation??

Treblig

 

[frosty_the_punk]

You're over thinking this. You should only be trying to make the intake manifold port opening the same size and shape as the port opening in the cylinder head.

Think of it like this... You can port them and the vessel will expand with a smooth contour or you can leave them as cast and it will expand with a step.

 

[frosty_the_punk]

Just my opinion here - I disagree with the choice to not bother addressing the deck issue "because this is just a torque engine". There are two things that need to be "right" in my mind: crank centerline, and deck height. The factory machining sucked. All of it. so if technology exists to correct the result of the scuking, then I'm all for using it. The end goal is higher performance than a factory engine. Whether performance be horsepower, torque, emissions, economy, or a combination of some or all. So with that in mind - The crank centerline (or main bearing bore centerline) is one two bores that modern machining equipment uses to index itself. Every engine I do gets the mains honed and the decks square decked. Because everything is related to those being a given spec. "Zero deocking" is BS in terms of a description because it can be any height that leaves the piston flush with the deck surface. It's a minor misuse of a word but you can have a small block deck "zero decked" and that deck hieght could be 9.590, 9.600, 9.550 all depending on the accuracy of the main bearing bores, the crank, rods, and pistons used. Decking is the action of milling the gasket surfaces of the block. Depending on the block, the machinist, and the milling equipment used this could be a good or bad thing as there is no reference to setting a deck hieght or correcting any relationship of the deck to anything else. Square decking is machining the head gasket sirfaces in order to make them parallel with the crank centerline, perpendicular to the bores, and set at a known height. Because the deck surface placement and accuracy affects individual cylinder compression ratios (static and dynamic), gasket sealing, valvetrain stability, and individual pushrod lengths it IS that important to get as perfect as possible.

Agreed 100%

 

[moper]

Moper, No comment on air flow through a vessel when the diameter changes?? Cavitation??

Treblig

There's so much that's involved in that I'd call it a whole 'nother post and my impression is it will be highly debated.
So the short version according to me - yes - you're right in a general sense. A fluid will slow down when it transitions from a smaller to larger conduit but we're not talking a fluid in a pipe... Cavitation is irrelevant to this discussion.

 

[RustyRatRod]

Well see, I take some things for granted. Whenever I talk about decking a block, square decking goes without saying. Anything more is simply regarding how the engine itself is built. Like my 383. It's zero decked for the combination of parts layin in the spare bedroom. But, it was also square decked as well. Anything not involving squaring the decks up with the crank center line is a waste of time and money.

 

[txstang84]

moper, my apologies for improper word choice/combination. By zero decking, I mistakenly referred to decking the block to blueprint height as measured off the mains to 9.6" I understand the difference between, and humbly apologize for the lack of clarity.

Again, not poking here, and maybe I read the text incorrectly, but in post #43, you stated that you totally disagree with square decking the block, yet in your most recent reply, you say it's important to maintain proper tolerances and geometry...

 

[Treblig]

Here are some heads. One is a 318 the other 360 (596 casting). I put the intake metal gasket on each and of course there is a big difference. When I installed the Performer intake on my Cuda I blended the ports with 302 casting (318) heads. I remember only having to do a little blending. As you can see the 360 head on the top of the pic has much taller ports and also a little wider. That's why so many people say to use the RPM. I don't have an RPM so I'd have to check one against the 360 head to complete my analysis. If the RPM ports are bigger and closer to the 360 ports then it would probably flow much better. NOW...I'm not saying the Performer won't work. I'm just saying that the RPM (if it has larger ports) SHOULD flow a lot better and smother with less loss of pressure as the gases transition from the intake to the head.
Fluid dynamics dictate flow and pressure when transitioning from one diameter to another. When a gas moves from one volume and pressure to a larger volume there's always a pressure drop (just like the air coming out of an air hose). High pressure in the hose then much lower pressure as it is released into the atmosphere. I may be over thinking it but it's still a fact.
Whether or not it makes a big difference...that's another question. But one thing is for sure. I can start with the Performer and always switch later, maybe I'll run across a good deal (RPM) between now and then.
DOES ANYONE HAVE OE THEY CAN CHECK FOR PORT SIZE????
Second pic is 318, lots of material to remove. 3rd pic is 360 head, much less material to remove.

Like I said I'll probably square the block if it's more than .003 out of square.

Treblig in Tex

 

[moper]

TX - No need to apologize. A writer can only control 1/2 the conversation and hope the other half gets it as intended. In regard to the post in #43 - go reread it. I think you may have misunderstood me. I intended to say I totally disagree with not square decking.

Tre - As I said - you have the right idea but there's much more involved with a running engine as compared to a pipeline transporting a liquid or a gas. The physics of hydraulic theory works with a homogeneous liquid or gas. In a gasoline engine the mixture going through the intake port is heterogeneous unless there is direct cylinder injection where the intake tract is dry. Because of that, it is not as cut and dried. You can puzzle over it all you want. In the end, should you change the intake, you will have improvement.

 

[txstang84]

Got it-duhhh me...

 

[64 SRT8 Dart]

Moper,

although he would have improvement with, let's say the RPM mentioned, wouldn't it show itself higher in the curve? Which, if he's just wanting something to about 5500, would it show up with any significance from that number down with the RPM?
Not trying to throw a wrench in anything, learning myself here, lol.

I could get a really really good deal on an M1, like $75-$100, and thought about snagging it for my 318 and upping the cam in it but I know it would kill what low end I have....especially running the small valve 2bbl heads. Maybe it's just that I really like how the M1 looks, lol

 

[txstang84]

The gains from the RPM intake would be "felt" higher in the rpm range (mostly midrange), but not by much. Frosty pointed out an intake comparison with all those intakes, but the article didn't really go into much detail about the build other than it was a 360 longblock with 10:1, a solid cam, and mildly ported Edelbrock heads. We're already making differences there because the OP will be running a 390, with ported 360 heads, and a hydraulic cam. And as much as we ALL love seeing numbers on a dyno, until it goes in the car and gets tuned, dyno numbers are just that-numbers.

The performer intake is for up to 360 cubes, mild cam (<220* @ 050), stock or lightly modified heads, ~9:1 compression, and stock to slightly modded exhaust...when you add cubes, the power band gets shifted down...much like if you slid the same cam in a 318 then in a 360 if all things else being equal, the 360 would likely peak a little lower because the stroke is longer and it eats up the duration, like was mentioned on either the 1st or 2nd page.

The RPM would still make power plenty well with even a mild 390 and would pull harder in the midrange, but, I've already stated that, and I think treblig is pretty well happy with the idea of port matching his performer--it's the OP's engine, and he can do with it as he pleases...it will indeed work, and it'll probably be plenty good enough for what he's wanting to do, and the difference between the two intakes would be about 20-30hp peak, and about the same for the torque. The torque would be different in the midrange, probably between 2500-4000, and the increased hp, depending on the cam, timing, exhaust etc, would likely be about 3500-5500.

I don't think anyone on here ever said the performer wouldn't work for his app, but more that the RPM would be better suited for the build simply due to the breathing requirements brought on by the extra cubes and by the cam he's likely to run. It's all good though, as long as he gets quality machine work done, and gets some decently matched parts, it'll run great.

...just hope he doesn't get behind the wheel and think, maybe I shoulda coulda woulda....know what I mean?

 

[Treblig]

I really appreciate you guys respecting what I am trying to build. I've read other threads and sometimes other folks what the OP to build a super powerful 8 second machine even though it's not what the OP really wants. So it really helps that you guys have kept this thread on track!!
Now I guess the last question I have is. Will my exhaust system allow me to get 325/350 (hopefully more) horses. Mag Truck 2 1/4" passenger and 340 2 3/8" (I think) driver. I installed the manifolds last year so I can't remember exactly what the 340 was?? I still have (as you can see) some extra mag truck manifolds so I can measure them. 2 1/2" full exhaust pipes with crossover.

Treblig

 

[txstang84]

I've seen some conversation on this exact subject over in the exhaust tech section--search around in there for more specific info.

They'll work, and you should still reach your goal...think about it for a second. HP 383s were rated in the 60s at 335hp, 440 Magnums at 375hp through manifolds with similar attributes. Granted those were gross hp ratings, but they were also mass produced powerplants...yours should be better since the selection of parts has been more scrupulous, and machining accomplished more carefully...they'll likely fit the bill for your purposes...also, the use of a standard Performer intake, and factory style heads, if anything they'll keep your hp to around that level.

You can port match the openings on cast manifolds if needed. I've seen it done before on cars where a stock look was desired but wanted a small increase in breathing...you won't make any huge gains, but every little bit helps.

You might have to do some grinding on that driver side manifold or possibly alter your steering shaft to allow it to clear the coupler. Those threads are also on here...the grinding on the manifold part is in the exhaust section, and I want to say there are folks that have modded their steering shafts/couplers/columns to allow extra clearance--but I don't recall where I saw them.

 

[moper]

We are talking two seperate builds when we mention a 390 (4" stroke) and a 318 (3.31 stroke). It's a HUGE difference between those and the various reactions to parts choices. In terms of a 318 - the general smaller intake = lower end, larger intake = top end fits. That's because the ports in the 318/360 Performer are sized for a 318 and the Performer RPM ports are sized for a 340 or longer stroke 360. Which do you think would better feed a 390?
I think you need to realize that what you're building is changing from a 318 to a 440 and you're considering asking it to breathe through the 318 intake. How fast do you think a 440 would be with a 383 2bbl intake on it? Do you think it would only feel different at higher rpms?

Edit -
In terms of exhaust manifolds - yeah, you cang et that and more but the camshaft is critical as is the rest of the package.

 

[Treblig]

Moper,

That's why I was considering having a custom cam since I never plan to change to headers. If I tell Hughes my head CCs and flow, pistons, rods, intake, exhaust manifolds, RPM range, rear gear, tires, tranny, torque converter and carb, I should get the best cam for my build. I haven't checked on the price of the custom built cam but it can't be that much??/

Treblig

 

[txstang84]

:happy1:

I've pretty much resigned myself in the past few posts of recommending anything above and beyond what Treblig wants to use, so now this is just a matter of entertainment for me...

 

[Treblig]

Txstang84, "You might have to do some grinding on that driver side manifold or possibly alter your steering shaft to allow it to clear the coupler. Those threads are also on here...the grinding on the manifold part is in the exhaust section, and I want to say there are folks that have modded their steering shafts/couplers/columns to allow extra clearance--but I don't recall where I saw them. "

I know you've lost interest but I have already read other posts on the manifolds and I have already installed the 340 and magnum manifolds on my 318 '69 Cuda. I just wasn't sure if they would carry the 390 exhaust output. Of course I had to switch to 302 castings because the magnum manifolds have humugous (sp) ports coming out of the heads. And you are right about the horse power they can handle. I just finished reading an article running the magnum and 340 manifolds against headers. The magnum manifolds in the article were only 2" exit hole and managed to get about 350/360 Hp at 5000 RPM. My mag manifolds are a different year and they have a 2 1/4 exit with about 1 5/8 primary holes which have not yet been ported so they should handle even more HP. The 340 manifold (driver's side) put out about 375 Hp from 5000RPM to 5800RPM. So it's looking good.....back to the popcorn.

Treblig

 

[txstang84]

It's not that I've lost interest, Treblig; you're going to do what you're going to do based on what information you've gathered. I'm just waiting to see the outcome now...

 

[moper]

It's not that I've lost interest, Treblig; you're going to do what you're going to do based on what information you've gathered.

x2.

In terms of a custom cam - IMO - you can do much better than Hughes. My first choice would be Bullet Racing Cams, 2nd would be Dwayne Porter at Porter Racing Heads in VT.