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Old 08-05-2012, 07:29 PM
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Ok. Thanks for the advice!! Hopefully won't have shroud issues. Planning to just smooth out the combustion chambers, ports and bowl area. Don't want to remove much material if I can help it.

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Old 08-07-2012, 07:24 AM
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Unless the video IS by someone notable, I would put much more "salt" in Mr. Vizard's book. Misconception is among the most common areas of ruining heads when trying to "port". A "litttle" IS better unless you're shooting for super-high revs and don't care about low-end.

Also be careful comparing heads using runner volumes. Not all ports are "equal", even when they're the same "size". Extensive use of "inside" and "outside" calipers (dividers) is necessary. Cross-section MUST be maintained up to the "venturi". Use a smaller OD valve as a "gage" for the bowl/throat work.

Although the video is not using Chevy heads, Pete McCarthy has an excellent video porting Pontiac heads. The majority of the fundementals are the same. THAT video might offer some insight giving you an advantage. For those not familiar with Pete and his work, he's one of the guys responsible for the "Angeles-McCarthy" '68 Firebird C/SSA that has been a class and race winner at NHRA events over the last 15 years, sporting a 400 Pontiac and running in the low 9s with a Q-Jet. He knows what he's doing... Pete's getting on" these days, but his books and videos are stilling selling well.

Jim
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Old 08-07-2012, 06:59 PM
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Mr. P Body.... thats what im talkin bout.
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Old 08-07-2012, 10:55 PM
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Thanks for the good info Jim. I think I will read David Vizards book as well before I even touch a head.
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Old 08-08-2012, 08:50 PM
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My new heads arrived today. I see what you were saying about blending the intake port roof Italian, deffinatly a pretty big ridge there.
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Old 08-09-2012, 12:24 AM
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Originally Posted by prostcelica View Post
Anybody have any Idea what Kind of valve job come stock on the E-streets. I dont see any info on there site. Cant I just disseble the heads, do the porting, reassemble and them put them back in service??. I want to avoid a machine shop if I can.
You have to take a look what kind of valve job they have, the e-streets i have seen had horrible valve job in them and valve springs are crap on those heads, i hope you have a better heads/quality
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Old 08-09-2012, 07:22 AM
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To add to what Timo says, we too, have seen pretty shoddy seat grinds coming out of most aftermarket head suppliers. There's nearly ALWAYS improvements to be made.

We also advise our customers, if supplying heads for us to build, buy them "bare". The hardware various aftermarket companies use, including Edelbrock, "meet" minimum requirements. They don't "exceed" them, and in a performance build, EVERYTHING shoulld exceed requirements for durability.

Jim
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Old 08-09-2012, 12:16 PM
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Thanks guys. These heads have a 3 angle valve job but not sure on the quality of the vavle job as heads are still assembled. What am I looking for in a bad valve job?? Is it something that can be corrected when I port and polish ??
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Old 08-09-2012, 02:39 PM
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Originally Posted by prostcelica View Post
Thanks guys. These heads have a 3 angle valve job but not sure on the quality of the vavle job as heads are still assembled. What am I looking for in a bad valve job?? Is it something that can be corrected when I port and polish ??
Without the proper valve grinding equipment, about all you can do at home is lap valves IF you know how to do that. If they're new, I'd leave them alone in the valve and seat areas.
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Old 08-09-2012, 06:54 PM
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Traditionally, the term "three angle valve job" refers to three separate angles on the seat. Most already know this, but I'm going through the "exercise" for those that may not be clear. The "top" angle is 30 deg. The "seat" is 45 and the "throat", 60. As a youngster in machine shops, that's the way we were taught. The primary purpose of the distinct angles is to insure the seat angle is concentric and of equal width all the way "around". The intake seat isn't as crucial regarding the width of the seat for longevity. The exhaust is very important, as that's how the heat dissapates from the valve. Heat is like electricity. It follows the path of least resistance. A "thnner" portion will transfer heat in a more concentrated manner, "burning" either the seat or the valve.

Today, we use a little different rationale on the angles. The seat angle of a typical small block will always be 45 deg. But by changing the top and throat, we can improve flow. A 15-17 deg. top and 70 deg throat will significantly increase flow "across the lift range". To the tune of 5-7 CFM. The intake is more "reactive". A top of 10, blended to a 30, a seat of 45, .060" wide and a 70 deg throat will improve mid- and high-lift flow. A wider seat and "more" 30 will improve low-lift flow. For a lower revving street engine, low-lift flow is important for torque production.

All that said, the "provided" valve seats will seal the cylinders and allow the engine to run properly. They are, by no means, "optimum". Some of the Dart and Brodix stuff I've seen delivered "ready to run" had really nice radius seats.

That brings us to modern "high performance" or "competition" valve grinds. Most shops today use stones only for "stock" valve jobs or "truing" the seat angles after the cutters do their "stuff". We have carbide cutters in various "profiles" for different applications, operating in a heavy machine. Very accurate. A true radius (exhaust) will obviously flow much better than anything with abrupt changes. Many builders use a full radius cutter on small blocks for drags. We use one that has a 15 degree "top" angle included in the profile for accurately limiting the OD. We also have a method of creating a "venturi" seat. Pontiacs REALLY "like" that one...

One last thing. Most engine families have cylinder heads based on different principles and applications. No two respond the same to the same seat profiles. Even some within the same family will respond differently to similar modifications. There are NO "absolutes".

This is strictly about the seats. There are some things that can be done with the valves, as well. That's a "story" for another day.

FWIW

Jim
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  #26 (permalink)  
Old 08-09-2012, 08:12 PM
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That's very good information Jim for everyone, regardless of their expertise!
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Old 08-13-2012, 10:11 AM
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Originally Posted by 1971BB427 View Post
That's very good information Jim for everyone, regardless of their expertise!
x2
and to celica, buy that David Vizard`s book or books
I have a several of his books and they are good and informative with good pictures in them

take a look here:
Amazon.com: David Vizard: Books
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Old 08-13-2012, 05:29 PM
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Thanks Timofinn. Im deffinatly going to buy Vizards porting book.
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Old 08-15-2012, 04:24 PM
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The how to Port and Flow Test heads is about a waste of $. It's full of graphs and pictures of aftermarket heads that have been done and CNC'd. Plus a bunch of overly technical stuff that won't apply to most hot rodders, like wet flow analysis. It doesn't show how to do anything. Vizard's book on budget sbc is good tho.
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Old 08-15-2012, 07:23 PM
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Yes sir another tip for you...change out the studs they are junk.... i ran the estreets on my camaro last year and bent a few of them, caused rocker arm binding and wiped out my cam.
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