[badazz81z28]

I have lots and lots of books on the subject but they all have choppy black and white pictures and they are hard to see!. Does anyone have any pics of ported 049 or 781 BBC heads so I can reall se whats going on? I would be so greatful. Thanks

[NXS]

Although not BBC these are what I make vortecs look like. The goal is a straight down drop on the valve {approx 1/2" minimum}.

[badazz81z28]

I have been reading a book called How to Hot Rod block chevys and it mentions to make sure theres lip or a radius in the bowl, do you know what that means? or Is that just out dated information? Thanks so much for the picture!!!!

[NXS]

Not, sure but i bet it's that 1/2" inch drop i mentioned. If not the air hits the valve at an angle and scoots across it, compiling all the air in one part rather than evenly around the valve. Maybe a BB person can tell you.

[Bumpstick]

As with any BBC head (oval or rectangle port) basicly just smoothing out the passages will do what you want... The runners are so large to begin with that a little smoothing and blending are all thats even needed... For the street gasket matching is about all thats needed... All out race is different...

[badazz81z28]

This is what Im starting with. I couldnt imagine the rules change for a BBC or SBC heads but I would appreciate a BBC guys opinion. Thanks

[firestone]

This is small block stuff, but there are some good pictures here.

http://www.chevyhiperformance.com/te...518/index.html

Adam

[baddbob]

Have the valve sizes been increased to 2.19/1.88's? That would be my first step then just some blending into the bowl and knock off those rocker stud bulges that protrude into the roof of the ports. Bob

[badazz81z28]

So I should get the valve job done first? I was planning on it after just incase I hit a seat while porting.

[k-star]

what CI engine are they going on???

Race only????, Street/race????

Cam??

Target hp and rpm range????


Keith

[baddbob]

I'd polish the combustion chambers, knock down the bulges in the port runners and any casting flash, then have the larger valves installed and make sure the shop uses a bowl hog to enlarge the bowl below the seat, Then when you get them back just blend the bowl into the cut made by the bowl hog and you'll be good to go. With a BB head I've been told it is best to keep the bowl diameter just below the seat at 89% of the intake valve diameter. This would be a 1.95 diameter bowl just below the seat.

[badazz81z28]

Originally Posted by k-star

what CI engine are they going on???

Race only????, Street/race????

Cam??

Target hp and rpm range????


Keith

Street driven vehicle, 4.250 stroke X 4.280 bore
I want as much power as I can get keeping the torque below 600ftlbs so I dont blow my TKO

[k-star]

Ok, what you need to do is open the heads up for 2.19" in and 1.88 ex valves.... On the intake side cut the 45 seat to fit the valves, then cut the angle under the seat to 55 degrees untill you get a ring about .150" wide then just port up to that angle.... in the bowl area only and lean towards the intake mounting side with your grinding....,,, Do-not bowl hog them out...... Do the 45's in the exhaust and then the standard 60 deg, Again stop with a ring about .100 wide and port up to there....... Make the exhaust ports nice and smooth as you can, let the intakes rough.... there is no need to do anything else to theses heads. you can match intake and exhaust gaskets but it does nothing to help flow,,,,,It don't hurt but why waste you time.....

A 049 or 781 in this set up can support 600hp with a good victor jr style intake and the correct header.....IMO these heads are better then any aftermarket head of the same size and flow numbers...... remember there is much more to a head working correct then big flow numbers.....

Keith

[ratlover]

Here's what I did. I am not an expert, but I did research the subject as thoroughly as possible. I spent a lot of time on the exhaust "short side radius" Turn the head up like pic 1 and really smooth out the curve around the corner. Polish to a high gloss.
Pic 2 is what I did inside the valve bowl sorry about the quality.
this is a 781 head.
I believe the bowl work and port match is all you have to worry about with the intake port.