Hi,

I was wondering if anyone can tell me a reliable way of telling how much a head mating surface has been machined from stock condition.

Also did the valve seats originally come from the factory with a single angle valve seat only ? Is it recommended to go with the more up to date 3 angle valve seat commonly in use today or stick with the factory single angle ?

Thanks,
Mark.

 

The heads have a rectangular tab at their front which is supposed to be 1.00 inches thick stock. Mic that with paint and rust removed, for approximate mill work done. CCing the chambers also could give some related info. General rule of thumb is 1 cc reduction for each .006 milled. In the case of '58-'59 113 heads, the ratio is supposed to be 1 cc loss for each .0055 milled. Sunken valves will throw things off a little, with higher chamber volumes than would be expected.
Good question on the seat and valve angles, and look forward to some responses on that one. They did come from the factory with single angle cut. The multi cut should help in high rpms, but what about its use in normal driving? Help or hindrance?

 

Everyone has opinions on this engine building stuff, which is why disagreements get started on such issues and why they often become so heated. It is difficult for people who build a few engines to obtain the sort of knowledge that is developed by experienced builders, and by experienced builders, I mean people who not only assemble the engines, but also do the machine work and testing of the engines. For instance, I've built somewhere between 50 and 60 engines, but this didn't entail testing port configurations on flow benches or operating many of the machine tools (I surfaced heads on a Storm-Vulcan block decking machine, but didn't operate the boring bar or the crank machine). So, most folks have to take someone else's word for things. Many of these magazine writers have no more personal knowledge than we do, and rely on what the information they gather for whatever articles they write. Then, we read whatever their editors don't clip out of what they write. Personally, I put a lot of weight on what David Vizard says in his books, "How to Build Horsepower" volumes 1 & 2. Many people talk engines like Aristotle: "Of course, heavy objects fall faster than light ones -- it is so common sense that we don't need to verify it!" Vizard talks engines like Galileo: "I'm going to test even the things that seem obvious and then work up a theory to explain it." Vizard spends a lot of time on the flow bench and the dyno, and then builds his engines to fit his theories.

Anyway, Some factory engines in the old days came with 30* seats on the intakes to increase low-lift flow. Remember that low-lift flow is especially important with mildly cammed engines that are street driven. The 30* issue seems to indicate to me that a good valve job will increase low-speed power.

Here is a summary of what Vizard says in "How to Build Horsepower Vol. 1," pp 27-34 regarding street-type performance techniques:

1. Don't make the port bigger in cross sectional area, to keep velocity up

2. Don't smooth the port -- leave the finish rough, as cast

3. "...a top quality 3-angle valve job will make a significant improvement in port flow at all engines speeds. For most V8s, seat widths of 0.065-inch for the intake and 0.070- to 0.075-inch for the exhaust -- both at 45 degrees -- offer optimum flow, sealing, and excellent thermal transfer to keep the valve heads cool. ... Finally, flow can often be further improved by adding a 30-degree backcut to the underside of the intake valve."

Vizard then goes on to talk about removing obstructions in the ports without increasing the overall port cross-sectional area, and how flow gains are then verified by the flow bench. He says that the guide restriction is one place to attack, and that the lip between the machined areas of the seat and the rough cast wall of the port bowl is another important area to attack. He says:

"Careful work in the bowl and seat areas will, relative to teh time invested, produce the greatest improvement in port flow."

He then mentions that exhaust work should parallel the intake work.

Y Block Magazine, a few years ago, had 2 great articles by John Mummert about Y Block head work. I feel that these articles are superior to the more usually referred to articles of Doc Frohmader that appeared in Street Rodder Magazine after Mummert's Y Block articles. Frohmader may have seen more than most of us, but he is still not a "hands-on" engine builder: He was taking his own machinist's word for what was best and what wasn't, and I don't personally feel that that guy's "seat of the pants" guesses that he applied to Frohmader's set of Y Block heads are going to trump all the hours that Mummert has put in with a grinder and on a flow bench, working with many different kinds of Y Block heads.

But then again, everyone is spending their own money to build their motors, so it is really everyone's choice as to what to do, right?

 

Thanks for the info and your time guys, I'm a recent Y-Block convert, having bought myself a short wheel base '64 F100 a month or so ago. Wasn't sure about keeping the Y in the engine bay but upon looking under the hood and hearing the clatter of tappets and all the good info on this site and others I was converted.
Thanks again,
Mark.

 

Happy to hear that you've "seen the light".