[1Gary]

I certainly didn't say I didn't recognize the vett head potential. We resold the set we bought to a guy who has the OEM short block and deep dished pistons to go with the heads. While we had them,we sonic checked the runners and did in fact find all of those to be thin wall castings.You see you have to be careful about what you read vs what it really is.I am very sure about that.

Now porting.RHS during a R & D research found after all the yrs of porting they have done professionally,and their best guys,couldn't port match any better than 25% and that it was very labor intensive.Now these guys I know and they have the best of the best flow benches anyone could have. BTW-you got a flow bench at all??. You need that. They constructed the CNC programs for 5 axis porting.It produced port matches that are within 5% and cut down the labor time to 8 hrs. The shape is as important as the sizing.You really need a good understanding of air flow dynamics. But one of the things RHS said was more important than the size of the ports is the cross section of the port.They added in there are many "rated" ports out there that plainly just don't flow as advertized.I know for a fact the production Vortecs stock are about 165cc intake runners and your damm lucky if you can get them to open up to 170cc's before running into water and what's more the rough intake runners is what makes Vortec's suspend the air/fuel mixture.Smooth port them and you destroy the Vortec effect.What you can do to the production Vortecs is to clean up the exhaust port to help them out.You see there is a reason behind the 180cc and 200cc Vortecs.Here again I am very sure about this.

So unless you can match the experience level of the yrs RHS was hand porting and have a very good flow bench to check each port,you can not match their performance level of port matching 25%. You are alot less than that. If you can come up with a $250,000 CNC machine and then do a study for a number of yrs for the programing,you "might" get close to correct porting.Sorry man,but that is the plain simple truth. But these day and age,hand porting is caveman tech.

Yeah-doesn't that suck? A old guy who isn't stuck in back-in-the-day way of doing things.Die grinder madness.OMG!!

[1Gary]

To the O/P.What happened to the 400's was GM never intended them to be a performance engine.In fact during the early days of the 400's was during the early days of emissions.GM had a hell of a hard time to get the 400's to even pass those early testings.So most of the OEM steam hole heads for performance are the worst of the worst.

So I suggest you start out with a conservative approach with bolt on's first that you can reuse as more money becomes available.Work on getting a very sound foundation that doesn't have any issues like burning oil,leaks,good compression,no knocks and good oil pressure.Go out and enjoy that with the understanding of it's limits.Once you have a feel for that,then you can post what you have and where you want to go.We can help you out more at that point.Wrap your thinking about hot rodding at the best case it costs thousands and not hundreds when it is all said and done,and done the right way the first time.

[632Mantis]

2 old school rules on SBC heads:

1. A flat-top piston is better than having to run a dish piston. So pick the chamber volume that will allow you to run a flat-top. ( domed is also good for race motors on race fuel )

2. Always better to squeeze a 2.02 intake valve in there. 2.02 > 1.94

[632Mantis]

Originally Posted by 1Gary

Now porting.RHS during a R & D research found after all the yrs of porting they have done professionally,and their best guys,couldn't port match any better than 25% and that it was very labor intensive.Now these guys I know and they have the best of the best flow benches anyone could have. BTW-you got a flow bench at all??. You need that. They constructed the CNC programs for 5 axis porting.It produced port matches that are within 5% and cut down the labor time to 8 hrs. The shape is as important as the sizing.You really need a good understanding of air flow dynamics. But one of the things RHS said was more important than the size of the ports is the cross section of the port.They added in there are many "rated" ports out there that plainly just don't flow as advertized.I know for a fact the production Vortecs stock are about 165cc intake runners and your damm lucky if you can get them to open up to 170cc's before running into water and what's more the rough intake runners is what makes Vortec's suspend the air/fuel mixture.Smooth port them and you destroy the Vortec effect.What you can do to the production Vortecs is to clean up the exhaust port to help them out.You see there is a reason behind the 180cc and 200cc Vortecs.Here again I am very sure about this.

You are correct. "Port profile" is very important, which is why aftermarket race heads have very different castings over stock heads. "Port location" and "profile" along with larger valves are why aftermarket race heads make more power. Also the valve pocket areas play a role.
In every serious race head you will ever see, the port locations are raised.
Some of them are radically relocated.
You will never achieve this with stock heads.
Intake runners should always be rough. Minimizes seperation.
Chamber and exhaust side can be polished smooth if desired. Usually doesn't result in any power gains, but can help minimize carbon deposits.

[F-BIRD'88]

Originally Posted by 632Mantis

2 old school rules on SBC heads:

1. A flat-top piston is better than having to run a dish piston. So pick the chamber volume that will allow you to run a flat-top. ( domed is also good for race motors on race fuel )

2. Always better to squeeze a 2.02 intake valve in there. 2.02 > 1.94

Both these are false.

[smith9300]

Hey guys sorry for not sayin anything but I just picked up a set of vortec heads and it is an all stock 400

[SSedan64]

Here's a build CHP did a while back, SBC400 w/Vortec Heads, The Impersonator 428HP/525TQ.
Chevrolet 406 Big Block - Chevy High Performance

[1Gary]

Originally Posted by SSedan64

Here's a build CHP did a while back, SBC400 w/Vortec Heads, The Impersonator 428HP/525TQ.
Chevrolet 406 Big Block - Chevy High Performance

Read between the lines in the ref.Probe pistons??Prepackaged "deals" always has to cheap out somewhere in order to meet a low retail price.The pistons are in this case low dollar.Then the heads/cam combo peaking at 5,000 is the other case where a 400's potential isn't truly capitalized.A good self respecting 400 should be able to do much better than 1.28hp/c.i.

Cam it right and put on decent aftermarket heads or even Bowtie Vortec's.Do it once right to avoid the do-over-costs.$6,000 grand??. Then rave about it??. Where does it say anything about torque plates for a finish hone??. That is critical for 400's.I don't mind the scat rods,but the Scat crank I am not a fan of. Where does it say anything about screw in rocker studs??. Did I miss that??. I did see the promotion in the first paragraph of what 4 or 5 different products.I think you guys get my point.And that is why forums like this one is around.

There isn't one fan magazine that has spine to give a bad review of parts suppliers that buy ad space.Not one.Reading trade publications gets you closer to the truth.

[cobalt327]

The operative word on the build up was TORQUE.

A SBC 400 cammed to make 525 lb-ft of torque at 3,500 RPM ain't gonna have astronomical HP figures. Heads are fine w/pressed studs at those RPM levels and spring pressure required for a relatively mild 0.480" lift cam.

[1Gary]

Cobalt-you pick up on only one thing I up objected to amongst numerous common sense issues.

[cobalt327]

Nothing particularly wrong w/Scat- preferred over Eagle.

Forged Probe pistons aren't considered to be lower shelf.

[1Gary]

Cobalt-suffice to say your faith in the mickey mouse articles is amazing.LOL

[cobalt327]

The article isn't what I'm talking about.

BTW, you seem to quote from the Engine Builders mag fairly often. Many of the articles there contain quotes directly from the manufacture reps. Not exactly unbiased.

[1Gary]

Originally Posted by cobalt327

BTW, you seem to quote from the Engine Builders mag fairly often. Many of the articles there contain quotes directly from the manufacture reps. Not exactly unbiased.

Yes I do.Your right.I recommend people read that on line.The significant difference is it is a trades publication slanted towards people in the high performance business.You get to see a behind the scenes outlook.

[cobalt327]

Just got off the phone w/Frank @ Coast High Performance. They torque plate hone ALL the engines they sell. Not just the high end builds.

Nothing like actually verifying things (what a concept!) instead of aSSuming.

Now, I'm not defending the car rags. Almost all of them pander to their advertisers- including Engine Builder. Circle track is one of the better mags for tech info, the rest generally suck.

What I am saying is it is up to the reader to verify things for themselves. Due diligence should be the rule not the exception.