318 build

[273]

This may very well be the time that you are wrong. The op hasn't really said anything about how the car will be used.

Your right he hasn't, most won't.

The cam choices that he originally listed are mild at best.

You still can make hp with good heads and a mild ish cams look at factory LS and Gen 3 Hemi's.

Bigger valve's and ports are better for higher rpm's,

Ya like 5000-5500+ rpms on a 318.

making power

Yes probably from 3000 rpms and up maybe even lower.

and I agree but with his cam choices the bigger valve's and ports will hurt low rpm velocity which affects throttle response and low to midrange torque.

Possibly but to make 30-50 hp more is probably worth it even "IF" you give up some throttle response, AJ probably wouldn't

From what little information that the OP provided he would probably be better off with cleaning up the bowl area and a good competition valve job. As you should know, bigger valve's and ports move the power band up as they improve flow and high rpm breathing.

They also increase mid rpms to like 3000-5000 rpms where the OP gonna spend most full throttle time.

Is it a good swap depends on the OP, personally I'd rather be able make 300+ hp.

Heads dictate the possible power the rest decides how much of that potential you'll get, better heads better potential.

 

[PRH]

Pay attention people…….
DTM is teaching a clinic right now……it’s just not on anything car related.

 

[Dan the man]

Horseshit Dan. If you think a 2.02 valve kills velocity in a port that’s already too small and fast you will never get it.

I never mentioned 2.02 valve's you did. FYI 360 heads come with 1.880" intake valve's. You guys like to put words in my mouth and claim that I said things that I didn't say.

 

[Dan the man]

Pay attention people…….
DTM is teaching a clinic right now……it’s just not on anything car related.

That's because you're not paying attention.

 

[273]

He may have to be told as it's appent to me that he doesn't understand

You think rusty and other that taught you doesn't understand.

that bigger valve's and ports affect port velocity plain and simple and that the bigger valve's and ports move the powerband up. Am I wrong that those same bigger valve's and ports hurt port velocity which hurts both throttle response and low to midrange torque,

Possibly? were not talking crazy big ports and super low velocities on a super small engine revving ridiculously low rpms.

There's gonna be compromises, dudes building a low cr performance engine there compromise number 1, is the gains worth the possible losses is generally the question the OP needs to answer.

Can I ask you a question what is the ideal port cc, velocity fps and cfm for a streetable 318 with a peak hp around 5250 rpm, and what's closer stock 318 head or 360 head ?

is this correct or not.

Shouldn't you know before making the argument ?

 

[273]

That's because you're not paying attention.

Now your going after a professional lol

 

[Dan the man]

You think rusty and other that taught you doesn't understand.

Possibly? were not talking crazy big ports and super low velocities on a super small engine revving ridiculously low rpms.

There's gonna be compromises, dudes building a low cr performance engine there compromise number 1, is the gains worth the possible losses is generally the question the OP needs to answer.

Can I ask you a question what is the ideal port cc, velocity fps and cfm for a streetable 318 with a peak hp around 5250 rpm, and what's closer stock 318 head or 360 head ?


Shouldn't you know before making the argument ?

I already know

 

[Newbomb Turk]

I never mentioned 2.02 valve's you did. FYI 360 heads come with 1.880" intake valve's. You guys like to put words in my mouth and claim that I said things that I didn't say.

Pay attention Dan. I’m pointing out that even a 2.02 valve is too small.

You just don’t get it Dan.

You read magazines and believe those morons. That’s on YOU for not testing what you read.

People get sick of going back and correcting your bullshit multiple times.

If you want me to believe your velocity crapola, go build something with shot heads on it and then replace the heads with bigger heads and prove your theory.

Otherwise you are just aping error.

 

[273]

I already know

How do you know there's gonna be loss of low end torque and or throttle response ?
Beyond internet theory, dyno evidence even butt dyno evidence ?

How do you know the J head velocities aren't enough for the OP engine ? Based on what ?

 

[rumblefish360]

Ok so I'm build a 318 stock bore flat top pistons new bottom end either a 454 lift cam or a 480 lift summit grind 4 speed is putting 360 J heads on it going to help it or hurt it

1970 and pretty close to zero deck

The it from a “Been there and done it” guy (myself) for the last 40 years, OK?

Look towards a piston like a KB and have the piston set at a zero deck height. For a 350 head, the letter heads have an open chamber which require milling for a reasonable compression ratio. Look for a later 360 head with a closed chamber or to a aluminum head with a closed chamber and have it bowl ported with short side radius work done for best low lift flow from the head.

You’re shooting for a 10-1 to a 10.5-1 ratio max. 11-1 with an aluminum head is fine for 93 octane. If only 91 octane is available, drop the compression ratio by a 1/2 point.

If your cylinder heads have a 1.88 intake valve, have a cam LSA of 198. If your cylinder heads have a 2.02 valve, use a 110 LSA, which most off the shelf cams are ground with.

 

[Dan the man]

Pay attention Dan. I’m pointing out that even a 2.02 valve is too small.

You just don’t get it Dan.

You read magazines and believe those morons. That’s on YOU for not testing what you read.

People get sick of going back and correcting your bullshit multiple times.

If you want me to believe your velocity crapola, go build something with shot heads on it and then replace the heads with bigger heads and prove your theory.

Otherwise you are just aping error.

How much bigger valve can you use before you have to worry about shrouding the valve by the chamber walls or the bore itself? Don't most street cars operate in the 1800-4500 rpm range for the most part? Would big valve's and ports really be necessary for a daily driver where the person is only looking for a boost in performance and not needing tons of power

 

[rumblefish360]

He may have to be told as it's appent to me that he doesn't understand that bigger valve's and ports affect port velocity plain and simple and that the bigger valve's and ports move the powerband up. Am I wrong that those same bigger valve's and ports hurt port velocity which hurts both throttle response and low to midrange torque, is this correct or not.

Like Newbomb said…

Here’s the deal, all of the engines are basically under valved. The idea of killing port velocity is a possibility if you screw things up badly enough. This would be an out of wack combo. The issue here is the target goal which is an unknown even with the approximate compression ratio and cam so a provided. Much needs to be filled in. Too many blanks.

The 318 can use a 2.02 valve and even more cylinder head port size. I wouldn’t do a lot as a smaller port will have a good velocity and pedal response and looking at what the OE poster wrote, with some assumptions, it’ll be fine.

Unless the car is going to use a 2.45 rear gear, 28”+ tires, a starter converter while expecting a stock driving experience. This combo is off.

 

[toolmanmike]

Wow, my head hurts.

From banging it against a brick wall.

 

[Newbomb Turk]

How much bigger valve can you use before you have to worry about shrouding the valve by the chamber walls or the bore itself? Don't most street cars operate in the 1800-4500 rpm range for the most part? Would big valve's and ports really be necessary for a daily driver where the person is only looking for a boost in performance and not needing tons of power

I’m done with rhetorical volleys. I’m done with theoretical discussion about air flow and air speeds. I’m done trying to convince you that your limited knowledge, understanding, education and experience is not good.

You don’t know what you don’t know. And you won’t or can’t admit you just don’t know. I’m out.

 

[66fs]

This may very well be the time that you are wrong. The op hasn't really said anything about how the car will be used. The cam choices that he originally listed are mild at best. Bigger valve's and ports are better for higher rpm's, making power and I agree but with his cam choices the bigger valve's and ports will hurt low rpm velocity which affects throttle response and low to midrange torque. From what little information that the OP provided he would probably be better off with cleaning up the bowl area and a good competition valve job. As you should know, bigger valve's and ports move the power band up as they improve flow and high rpm breathing. I also mentioned above milling the cylinder heads and having the deck milled for a zero deck height, the small block mopars that I've dealt with all had "blind " cylinder head bolt holes and when there had been almost a 1/16" removed that makes the heads bolts that much to long and could cause inaccurate torque reading of the head bolts as possible causing the block to crack between the bolt holes and the outer part of the block ( exhaust manifold side ). These are things that you yourself probably never thought about. You probably can't stand it that it's possible that I could be correct for a change.

Unfortunately you are in theoretical BS mode. Many of us, especially RRR, have actually done this most of our lives. I have actually put .040 milled J heads on a 273, so I know you can do the same on a 318, 340, or 360. That thing flew and had plenty of torque. I have only run older engines, from 1964 to 1972 with blind threaded head holes. Never even close to bottoming out. I just tried all kinds of combinations. I and others, can tell you what will work from experience. You need to do something, and stop reading and watching nonsense. I'm throwing the BS flag.

 

[toolmanmike]

If the world would just add a 4 barrel, dual exhaust and recurve the distributor and leave it at that, the world would be a better place. If you want power, build a 340, 360, or a stroker.

 

[RustyRatRod]

This may very well be the time that you are wrong. The op hasn't really said anything about how the car will be used. The cam choices that he originally listed are mild at best. Bigger valve's and ports are better for higher rpm's, making power and I agree but with his cam choices the bigger valve's and ports will hurt low rpm velocity which affects throttle response and low to midrange torque. From what little information that the OP provided he would probably be better off with cleaning up the bowl area and a good competition valve job. As you should know, bigger valve's and ports move the power band up as they improve flow and high rpm breathing. I also mentioned above milling the cylinder heads and having the deck milled for a zero deck height, the small block mopars that I've dealt with all had "blind " cylinder head bolt holes and when there had been almost a 1/16" removed that makes the heads bolts that much to long and could cause inaccurate torque reading of the head bolts as possible causing the block to crack between the bolt holes and the outer part of the block ( exhaust manifold side ). These are things that you yourself probably never thought about. You probably can't stand it that it's possible that I could be correct for a change.

I don't care if you're right or not. I'm big enough to admit if I'm wrong. Done it many times in the past and I'll do it many more. You don't even understand what I am saying you are wrong ABOUT, so just slip back into the hole you came out of. You'll never understand.

 

[rumblefish360]

How much bigger valve can you use before you have to worry about shrouding the valve by the chamber walls or the bore itself? Don't most street cars operate in the 1800-4500 rpm range for the most part? Would big valve's and ports really be necessary for a daily driver where the person is only looking for a boost in performance and not needing tons of power

It’s mostly a target dependent issue. But yes a larger valve and port size is entirely OK. Valve shrouding is less of a cylinder issue and more of the heads chamber issue. Valve shrouding s an issue overly concerned about. While good to avoid, it’s not an issue to freak out about. Worry more about the head chamber itself.

As for myself, I have found the best engine power gains occur after headers, ignition and basic bolt on with the camshaft followed by complimentary head work. As long as the cam has a reason’s compression ratio backing it up and a good flowing head, the engine responds really well.

A low rpm engine doesn’t need a bigger valve in a mostly pedestrian setting. The OP did t give any duration numbers (& @ .050 and s best) to help this project along.

If this was my engine and destine for just regular driving around town with some added performance, I’d keep the 318 heads and call it good. The cams he listed above should be fine enough for low 14 second 1/4’s and duration dependent, at least 17 mpg.

 

[273]

How much bigger valve can you use before you have to worry about shrouding the valve by the chamber walls or the bore itself?

According to Darin Morgan about .200"+ valve to wall clearance the bore doesn't shroud flow, but doesn't mean there's not a net benefit to larger valves even if there's shrounding.

360 heads can fit on a 273 bore a 318 is .285" bigger so on the intake valve side of the bore you would have .143" plus whatever clearance the 273 had, a 340 would have another 0.065"
of clearance with a 1.88" valve but basically the same with a 2.02".

Don't most street cars operate in the 1800-4500 rpm range for the most part?

Normal for part throttle driving, performance street car is a balance between many driving circumstances but if the OP decides to hurt one for the other it's up to them.
And just cause you favor decision for full throttle doesn't mean your overly gonna hurt part throttle especially on this build level of engine.

Generally larger cams are less streetable than bigger ports for X amount of hp.

Would big valve's and ports really be necessary for a daily driver where the person is only looking for a boost in performance and not needing tons of power

A V8 ain't necessary at all for daily driving. If you want to putt around town is what the /6 was designed for 170/198, even the 225 was designed as a upgrade in performance over base. And since you don't drive a /6 at full throttle all the time even they have extra power for daily driving.

 

[RustyRatRod]

A V8 ain't necessary at all for daily driving. If you want to putt around town is what the /6 was designed for 170/198, even the 225 was designed as a upgrade in performance over base. And since you don't drive a /6 at full throttle all the time even they have extra power for daily driving.

If I was any happier with mine, I'd have to clean myself up every time after I drove it.

 

[AJ/FormS]

Ok so I'm build a 318 stock bore flat top pistons new bottom end either a 454 lift cam or a 480 lift summit grind 4 speed is putting 360 J heads on it going to help it or hurt it

Well I wasn't gonna put my 2 cents into this hodge-podge, but since it's gone off the rails anyway; here goes.
Start a new thread cuz there is almost nothing in this thread worthy of being called good advise; and nobody actually tried to answer your question, with the exception of the one guy everybody likes to pick on.
I've given my opinion on a few 318 builds, and also got bashed, so no sense in me going thru that again.
Ryan, there are quite a few smart guys on this forum, smarter and more experienced than me. But there is also a preponderance of testosterone here, and a lotta herd-mentality.
Lemmee say this, which is based on my 50 plus years of experience;
1) the smallest difference between your 318 and a 340, is the bore size.
2) the biggest difference between them is the cylinder pressure.
3) and the 340 cam was a good cam in it's day, now 50 years ago.
4) with a manual trans, your engine is as good as married to the driveshaft, which is married to the rear gears. What you do to your engine has to be married to what the wheels are doing. If you miss the mark, you will not be happy.
5) if you install the big port heads, do it for a good reason.
6) never pick the cam first, unless your pockets are deep enough to make all the changes that may be required to run that cam. and
for crying out loud, when you refer to a cam, do so by it's 050 specs and include the LSA. From those numbers, we can generate everything we need to know about how it's gonna run. I think it's not fair that I have to go looking for those specs, knowing only a lift, and none of the smart guys can give good advise until the cam specs are known.
7) as others have asked, state what you expect out of your engine. For example, saying that your car has 3.23s and you want to keep them, is gonna throw out about 80 percent of the street cams available. and for a manual-trans 318, probably more.
8) state what fuel you are willing to pay for. Each octane gas has a pressure ceiling, beyond which the engine can get into trouble real quick. You can run less pressure than that ceiling, that's ok, but not more. and each octane build then, for optimum performance, is a different build.
And until your exact Compression ratio has been calculated, and your quench has been established, nobody can give you good advice, unless they include all the requirements that apply to that advice.
For example, if your pistons are .057 in the hole and your heads have 72cc combustion chambers , there's gonna be hundreds of dollars need to be spent to run a stock 340 cam, and to not have a dog every time your rpm falls below 3000 rpm.
So you know, one guy can tell you his 284cammed 318 with 340 heads was a giant killer, because from 4500 to 6000, and it was.
And another can tell you that his 340 headed and 340cammed, 318 was a dog with 3.23s, and it was.
And I can tell you that a first gen 340 , with 318heads, a 318 cam, and 2.94s with a bit of stall was a killer combo, and it was.
9) Nobody wants to admit that every good combo is very highly tied to cylinder pressure. Two identical engines, other than one cranks 130 and the other cranks 185, these are night and day different engines. I'm not kidding. Not only is the one close to twice as powerful, absolute; but the midrange is killer fun, and from idle to 3000, you would never know that it was just the same basic engine as the 130psi example.
Pressure makes heat. Heat makes torque. Torque times rpm makes Power.
The more pressure you have, when you need it, the more fun your engine/combo will be. and when it never comes, Ryan is a sad sad guy.
10) with a manual trans, it's very easy to make a low-pressure doggy streeter, that can only be band-aided by gears and/or slipping the clutch. Don't be a statistic.
11) now;
I did not tell you what heads to run.
I did not tell you what cam to run.
I did not tell you what cylinder pressure to run.
I did not in any way answer any of your questions.
Decide for yourself what good advice is.
Now, go read what @Dan the man said.

 

[273]

 

[RustyRatRod]

You're gonna need more popcorn.

 

[mygasser]

That's because you're not paying attention.

no it's because you talk ****, still.......

 

[273]

11) now;
I did not tell you what heads to run.
I did not tell you what cam to run.
I did not tell you what cylinder pressure to run.
I did not in any way answer any of your questions.
Decide for yourself what good advice is.

Agree 100%, all we can show the options and hopefully a realistic pros and cons of each and it is up to the OP to figure out for better or worse the best way to go, since everyone is different with their level of compromises. Eg. CR is (seem) everything to you, others can live with less and be happy question is what kind of person it the OP ?

Now, go read what @Dan the man said.

I don't know about that