400 Heads...newbie question

[DNFXDLI]

The 4 bbl heads are typically too large for a steet engine that is going to see most of it's life under 6000 rpm.

 

[dragogt]

Nonsense..

 

[DNFXDLI]

Nonsense..

 

[dragogt]

Thought you'd like that..

 

[DNFXDLI]

Thought you'd like that..

I would expect nothing less....

 

[LEB Ben]

Thanks Duncan...the more I read, that's the conclusion I was coming to...sad panda.

 

[dragogt]

Thanks Duncan...the more I read, that's the conclusion I was coming to...sad panda.

Nonsense..

I stand by that, I still say get a set and see what happens; I'll bet your surprised...

 

[LEB Ben]

One of my buds that I was hitting up for the 2v heads does have a set of 4v's...wants $350 for them.

There seemed to be some belief (controversial at best) that there would be some valve/piston issues if a standard set of 4v's were just bolted on...can't recall what the fix was...but not many folks seemed to be drinking that kool-aid.

 

[dragogt]

Thats a good price for a set of heads, I've heard something about that with W's because of the canted valves but not on a M block... (not to say that it cant happen)

 

[LEB Ben]

Thats a good price for a set of heads,

He's been trying to sell the whole motor for $500 for about a year now, so he said it wouldn't be right to take the same or more for the heads than he wanted for the whole engine.

 

[DNFXDLI]

The 4bbl heads will work just not as well as the ones with smaller ports and runners.

 

[dragogt]

He's been trying to sell the whole motor for $500 for about a year now, so he said it wouldn't be right to take the same or more for the heads than he wanted for the whole engine.

Come the end of the year, if he hasn't sold the heads by then I'll buy them...

 

[LEB Ben]

The 4bbl heads will work just not as well as the ones with smaller ports and runners.

Same principle as 'over carbing'...sorta???

 

[DNFXDLI]

Same principle as 'over carbing'...sorta???

In effect yes....you need to keep the air velocity up for proper atomization...but as posted by Aaron, some of the new aftermarket heads give you the best of both worlds....but it boils down to the almighty dollar as well.

 

[LEB Ben]

^^^True...not looking to spend a couple grand at this point in time.

 

[dragogt]

I HEAVILY believed in velocity profiling not too long ago. I was suckered into that world hook, line, and sinker.

Ask just about anyone about this, and they bring up 2 engines. The Boss 302, and the Boss 429. Every article ever written on these engines talks about how the huge ports hurt the street manners of these engines. This is where alot of TDL people get their "proof". I wonder what a Boss 429 would do with a CI cam?

.... yup..... the old 302 Boss is always used as the proof. However, one of the things I have been able to learn/confirm/understand here now, was a little event I took part of mooons ago.

We built a little Clevor using a 289, and installed the classic LeMans cam........ saying it was a turd below 4000 RPM was an understatement. Anyway, the owner got pissed and decided to sell the car but keep the camshaft, so we went back and installed the regular 289 stock HFT cam due to a person interested in buying the car. To say that "mismatched" setup pulled like a freight train and revved like a banshee to the moon WAS an understatement..... it even killed a few bugs VW's with 88mm piston kits, cam and Weber's) on street tires in the local clandestine 1/8 track before it got sold....... something it never did before.... . Yet never understood why (just guessed) those huge Cleveland heads (not filled) would work that much better with the stock 289 HFT cam.

To this day, and noticing the actual OEM trend, I wonder what would have happened if would have really engineered the Cleveland heads........ .... perhaps we could be talking about the CLEV-x pushrod heads instead of the LS-x nowadays.

Think about this impressive performing very mild 289 Joel has described with Cleveland heads and a garbage stock 289 HFT cam. That absolute junk cam has no real lobe area or lift to take advantage of those heads. Yet, the joke of a cam cleaned up / picked up the lowend significantly while still pulling pretty well up top due to the heads. Sounds like a crude and very limited version of today's trend in everything from truck to sports car factory engines.

This is what I see. Fast forward to today. Take a modern valve train that can reliably use a modern lobe that has plenty of lobe area and lift without having to let the seat and .050 duration get out of hand. Previously necessary duration on the seat and low lift has been taken away more duration is added at higher lifts where the cylinder head is really capable of moving some air. Now the lobe area is where a good properly sized (too big by old school standards) high flowing head can make best use of it over a very broad rpm range. In other words you're now moving a ton of air without letting the bottom end become a mess because of excessive seat duration.

Guys think for a second about what is keeping air speed up in these seemingly excessively large cylinder heads these days.

................

 

[DNFXDLI]

We will just have to agree to disagree Aaron....we could both find all the information that we want to back up our points of view.

 

[dragogt]

No worries..

 

[mrxlh]

Ben, I would just do a really good job match porting a set of stockers with full radius valve jobs. Short runner intake if you want topend, long runner intake if you want more low end. The only compensation factor for too large of ports is increasing displacement. Your cam choice along with static compression ratio selected, intake, carb, ignition system, and exhaust will unlock a ton out of any stock head.

For anybody wanting to know anything about heads and how to make horsepower, read Jerry Branch's book. His original flow bench is what the NIST used to write and accredit all after.

 

[LEB Ben]

Dually noted...I'll have to find a copy of that.