Great info! Thanks for posting.

thanks for keeping it interesting around here Fast68 !!

The info about the vjob with a cutter or a stone was of great help to me.Thank you.

Excellent info that backs up the videos and articles I've been studying.

That is a HUGE amount of low to mid lift flow!!
Right in the sweet spots of where the cam sees it twice each cycle with dramatic increase in avg. #'s.

How many hours does this type of quality valve job take you?
How about the time for blending after the cutting is done?
Do you use cutters or stones?
Did you do any deshrouding in the chamber after the larger valve was installed?

I agree, great info and lots to learn from those in the know who do it, test it and get results PLUS return customers..........

I was taught basic valve jobs in auto shop in high school and I always tried to learn more about them. But I always remember reading that for best performance put the seat out close to the edge of the valve head where the valve diameter is the largest. Of course not so close that it will still be fine if it sinks some in time. And to back cut the exh valves also. But I have seen that alot over the years where some do work to their cars themselfs or with friends who really are not qualified and mess the combo up more then help it. Ron

I'm not sure what I'm looking at, even blowing the pic up. Any way of marking the seat to better see what you're taking about. I really want to understand what you're showing, very interesting, thanks

Good stuff Dwayne!

Great info!!!

Often times a man's life in these parts depends upon a mear scrap of information.

I'm sure glad you were the man who went through my heads. Thanks a million for all the advice, time and guidance on my project, Dwayne!

Dwayne,how does flow characteristics of flow change when boost is added to the equation??

Thanks Dwayne.

The 45* on the original seat sits well below the transition into the chamber. The larger valve with the recut seat raises the valve up out of the "hole" which improves the low-lift flow (less obstructed path into the chamber).

Wait... Whoa... Hold on a sec. So you're saying that the cheapest valve job is not as good as the way overpriced valve job at a completing shop?!

Always a pleasure to see your work Dwayne.

I have no idea what the other shop charged..... For all I know I was less $$$.

In this particular case, it wouldn't have taken any longer, and shouldn't have cost a penny extra to cut the seats to the proper diameter, instead of cutting the seat smaller than what was done originally, and consequently sinking the valve.
In fact, it would have taken less time because the seat would have cleaned up with less actual cutting time.

A lot of times if I'm freshening a set of heads that I did originally, and the seats aren't pounded out, I'll just give them a light bump with a fine stone to refinish the sealing surface.
This is usually the best way to ensure the least amount of material is being removed from the seat.
Which way the seats get refinished(machining or grinding) is basically a judgement call made after evaluating the condition of the heads.

Here's another example or what can only be described as "poor workmanship"..... Aka, a butcher job.
This is a set of older "large oval port" BBC heads, that were last done by some large "volume rebuilder".
These are about as bad as I've seen with regards to valve seat work.
The step in the pic is .085" deep!!

I'm also including a pic of the exhaust seat recession.
I don't know how it looked before they were run, but this is what you get from HD service with old iron heads, non-hardened seats, and unleaded fuel.

On the last refresh on my 915s, yes I know get new heads, I replaced the 2.14 with 2.18s and went with new valve seats in the exhaust. We were after not only better flow but a more constant and reduced chamber volume, all work was done by a Mopar racer/head rebuilder and top notch. I'm very satisfied with the heads. 620tq /645hp e85, 500", 12.5 cr

I'm not sure how much more can be done to the head$, next time new heads and these if they're still good will go on the backup motor.

I appreciate the information in this thread, one thing I would like to add is all new heads need to be worked over, guides and seats.

Hmmm. When I built a SBC powered Mustang, maybe that is why my machinist wanted me to send him the Track 1 heads bare. Said that for him to get and install the valve gear won't be much more than buying assembled heads, and they will work better.

Heads are no different than any other part built in volume........ Some will need/should have the details looked over, and addressed if necessary.
Just like pretty much every other part of a perfermance engine build, if you're trying the get the best power/maximum durability out of the components you're going to use.

Some should really get a fair amount of attention before being put into service, others will be fine. The only way to know is to check.

Wow, that exhaust valve looks like it is about to be pulled through into the port.
Yikes.
Hope they have weak springs on that head. lol