Im finishing up porting and polishing my stock 97 heads (561 castings) using a die grinder and the SA porting kit. I did a lot of research on here on the subject and picked up David Vizards book 'How to Build & Modify Chevy Small Block V8 heads' I finished up the basics, widened pushrod pinch, cleaned up and smoothed intake and exhaust ports, polished the combustion chambers, port matched my intake, didnt try to change the short side radius at all. I really didn't narrow the intake/exh guides much the first time, after reading more in the book I see the importance of this, I'm going to go back over them and try to narrow them as much as I can.

Have some questions:

1. In the valve bowl area, I just used sanding rolls to smooth things out, didnt attempt to take out any material with the stone at all. I understand youre not to hit the valve seat, but when you're smoothing the bowls do you not touch the base of the seats at all or do you blend the bowl into the base of the seats?

2. I want to install new Manley Race Flo 2.0 I 1.56 E valves. Do I need to unshroud the combustions chambers for these valves? So far I just cleaned up the chambers, removed as little material as possible and didnt attempt to unshroud the valves at all.

3. For the machine work for these valves, should I just have the seats cut for these valves or would I benefit much from a 3 angle valve job?
I am using the hotcam for now, depending on how well these heads flow when done I may go to a larger cam down the road. Want to have .010 milled off the heads as well and using a .026 gasket.

Appreciate any and all feedback

 

Is Vizard's book on head porting good? I have his stuff on budget small blocks and carburetion; I think he's great. Where didja buy this?

 

It's a very good book, bought it on Amazon.com for $15.

 

any help appreciated.

 

I don't know anything about porting just so you know. But in Vizards book, does it say anything about opening up the bowls to a certain percentage of the valve size? Or is it valve seat? I thought I read that somewhere. Plus opening up the bowls to a certain size is one of the first things you should do, I believe. As far as unshrouding the new valves, I don't think much material is removed although I wouldn't know how or exactly where it should be done. I believe Lloyd said that, after the chamber work on my heads, which included the same size valves as yours, so unshrouding was needed, and after the .010 milling, the chamber size was still the same cc. I can tell you this, you will have to check your pushrod lenght, as I too, went with thinner gaskets and wound up with 7.15 pushrods. Good luck.

 

I'll take a stab at a few of these being I stayed at a Holiday Inn Express last night.

1) You're using a stone? Wrong. You need to go buy cutters instead. Yes, the seat will be cut. It's the pretty area with the angles on it you need to avoid.

2) You should have done some chamber work regardless. If you're installing bigger valves it's even more necessary.

3) If you have the seats cut for the new valves, that IS a valvejob.

Stones don't work on Al, only on iron. You need some carbide cutters ($$$$) and some WD40 to lube them with. That'll keep them from getting clogged up with aluminum. Also, you should really try to work on the SSR some. There's power to be had there. Definitely narrow the valve guides too.

Ben T.

 

There really aren't any good books out there on head porting, but of what we [the public] have his is one of the better reads.

Ben T.

 

Thanks for the feed back Studytime.

Yes Im using a rotary stone along with WD40, beleive me, it removes aluminum just fine. Im just trying too see how close you port/polish the bowls up to the base of the valve seats.

I've cleaned up the combustion chamber for now, smoothed out the rough casting spots, went over it with a 120 grit flapping wheel then cross buffed them using WD40. Im mainly concerned if I need to unshroud the intake valves any and how much.

There is a difference between just having the seats cut, and a 3 angle valve job. At a minimum I will have them cut for the new valves, just wondering if a 3 angle job is necessary.

I read the short side radius really shouldnt be touched by a beginner, so I didnt attempt to reshape it at all, just cleaned up.

Z-rated, The book says an important area to open up in the intake bowl is the area between the guide and the cyl wall, along with narrowing the guides. Thats what I'm concentrating on. I do need to check the pushrod length as well, thanks for the info.

 

Gregg, maybe e-mail Lloyd or Bret, on what kind of valve job would be best. They always state there's power to be had with the proper one.

 

Don't mess with the port floor, it works pretty good stock and I know from experience that very small changes there can mess the flow up across the board. Vizard mentions widening the port walls above the hump area of the floor so there is more area for the air move through there. The valve seats are usually opened up to 85% to 90% of the valve diameter, I'd stay toward the 85% end of that for better mid-lift flow if you don't have a really big cam. Streamling the guide and guide boss agressively can give you a few cfm.

If you haven't seen any properly ported LT1 heads in person i can tell you that the roof of the port is raised until it breaks through the rocker stud hole fully. The heigh here is tapered off meets your deepened and widened bowl to give a smooth radius on the long side/top of the port. Definitely worth widening and deepening the bowl on the cylinder wall side of the bowl, there's a lot of flow there so extra volume helps.

Here's a link to some pics from Larry Meaux webpage. Some pretty nice photos of how to treat the guides and guide bosses. Also show nicely how the enlared inside diameter of the valve seat should be blended into the lower cut on the valve seats and into the bowl.


http://www.maxracesoftware.com/new_page_1.htm



Good luck, Michael

 

The link is down. Do you know the updated link?