Going from 23 degree to Brodix 18x; anybody ?

[Walter R. Malik]

I have a customer who wants to go from 23 degree Pontiac 867 heads to the Brodix 18x heads when refreshing his asphalt, oval track, late model engine, These heads are supposed to use all 23 degree valve train parts and headers.

Has anyone performed this particular type of change ?
What are the pitfalls and what can be an expected result...?

[Frankshaft]

They are alright. They make a hair more than an equivalent 23 degree head that you could make that big, with that big intake valve. Problem still is the pushrod pinch for a port that large, and that large a valve. It can be only so big. The other negative is the big chamber for an 18 degree head. Making it kinda pointless. Its a nice head otherwise. I did a 434 years ago with some, made a bit over 700hp on race gas. But a "normal" 18 degree head will make over 800 on the same combo. I think the raised port helps a little, that's why it makes slightly more power than an equivalent 23 degree head. I have also reworked them, with welding and working the pinch, and using a heavily offset intake rocker, but that defeats the purpose of the head. If you had them, then its worth modifying. To buy new, I would use a real 18 degree head, and buy the proper rockers and offset lifters. That's my advice.

[Walter R. Malik]

They are alright. They make a hair more than an equivalent 23 degree head that you could make that big, with that big intake valve. Problem still is the pushrod pinch for a port that large, and that large a valve. It can be only so big. The other negative is the big chamber for an 18 degree head. Making it kinda pointless. Its a nice head otherwise. I did a 434 years ago with some, made a bit over 700hp on race gas. But a "normal" 18 degree head will make over 800 on the same combo. I think the raised port helps a little, that's why it makes slightly more power than an equivalent 23 degree head. I have also reworked them, with welding and working the pinch, and using a heavily offset intake rocker, but that defeats the purpose of the head. If you had them, then its worth modifying. To buy new, I would use a real 18 degree head, and buy the proper rockers and offset lifters. That's my advice.

His 867 heads have the pushrod pinch opened to need these .250" offset, stud type intake rockers being used.
I am the third party here, simply the engine builder getting paid to do this transformation but, his mind is made-up.
These heads will be bought and used so, I am trying to learn the best way to go with this process ahead of actually getting into it.

[swampbuggy]

Walter, i have a brand new set of 18° C heads I want to sell. Mark H.

[Walter R. Malik]

Walter, i have a brand new set of 18° C heads I want to sell. Mark H.

!8C heads are almost completely different than 18X heads...

[user-30257]

Posts like this prove how many people left on speedtalk are actual engine builders. Great to see all the comments.

Yes im back from speedtalk jail.

I wouldn't waste my time putting those heads on. Those 867 heads when done right require at minimum .350 offset intake rocker.

Those fake 18 degree heads have the same potential as the heads you have. I would advice going to a true 18 degree deal if you want any significant gain. Frankfoot said it best.

[turbo2256b]

The shop i worked for designed the 18x chevy heads ports and their porting programs for Brodix. Shop is in Westland Mi.

[user-30257]

The shop i worked for designed the 18x chevy heads ports and their porting programs for Brodix. Shop is in Westland Mi.

Cool story

[swampbuggy]

So are my 18 deg. C heads the real deal ??????? Mark H.

[Walter R. Malik]

So are my 18 deg. C heads the real deal ??????? Mark H.

According to Brodix ... the 18C's are supposed to be their version of the High-Port, Chevrolet 18 degree heads with special valve spacing.
A head having Chevrolet 18 degree intake port location and exhaust ports, (drilled and tapped for a "spread port" 23 degree bolt pattern if desired), small combustion chambers, 5 degree intake face requiring .750" offset intake rocker arms.

[swampbuggy]

Yes Walter, the (C) head is sometimes called 18 Deg. CLONE. It is very close if not exactly the same as the GM 18 Deg. head. This is (factual) information. The heads i have which are (18 deg. C) have a Brodix CNC program and only require a .550" offset intake rocker with a .150" or .180" offset lifter, depending on how fat the pushrod is. The 18 deg. (C) head that requires a .750" offset has a part number beginning with WP. The W represents Wilton, Walbon, or something that begins with W. This WP program has more peak flow at a sacrifice of mid flow. Mark H

[Walter R. Malik]

Posts like this prove how many people left on speedtalk are actual engine builders. Great to see all the comments.

Yep ... this get more obvious every time I post a question.

[user-17438]

Posts like this prove how many people left on speedtalk are actual engine builders. Great to see all the comments.

Yep ... this get more obvious every time I post a question.

Its comical. at least you know you wont get the bad advice shoved down your throat.

[ZIGGY]

OTOH, it doesn't seem to me that he's gotten much in answer to what I understand to be his question.

I am the third party here, simply the engine builder getting paid to do this transformation but, his mind is made-up.
These heads will be bought and used so, I am trying to learn the best way to go with this process ahead of actually getting into it.

(Maybe with exception of Swampbuggy 2nd post.)

[user-30257]

OTOH, it doesn't seem to me that he's gotten much in answer to what I understand to be his question.

I am the third party here, simply the engine builder getting paid to do this transformation but, his mind is made-up.
These heads will be bought and used so, I am trying to learn the best way to go with this process ahead of actually getting into it.

What is there to say. He is getting a head that at best will pick up a few horspower compared to the867 heads..

The answer was, use some real 18 degree heads.