Some Pro Comp "Victor" stuff.....

This is a good argument for, if you're buying heads from somewhere other than a shop known for quality cylinder head prep..... It's probably a good idea to have someone familiar with what you're building to have a look at them before bolting them on.

This set was bought from some interweb seller, and just bolted on.
There has been some porting done, so perhaps the seller made the impression they were a head shop.

They had been run before they came into my shop........ And had already had a problem.

Unfortunately, nobody picked up on this before they got bolted on......

1.88 ex/2.25 int......... Not quite enough room for that combo.
Additionally, they're the wrong length....... About .250 too long, which I'm sure contributed to the severely worn guides. A couple were bell mouthed out to about .009 clearance at the top and bottom.

Another nice touch was the valve seats weren't machined for those valve sizes.
The heads are supposed to use 2.20/1.81 valves, and the valve job is a little "small" for even those valves.
So, when you stick your 2.25/1.88 valves on those seats, the contact pattern runs right off the inner edge of the valve.
If the valves that came with the heads had narrower faces, like what some of the "better" valves have, there would have been essentially no interface of the 45deg seat angle.

The thin grey line is the lap line......

So, you have valves almost touching each other, and rocker geometry that's less than optimal because the valves are .250 too long......... The guides get worn out...... And the valves are all clipping each other. Pretty good witness marks on all the valves from this going on for a while.

Well....... That can only go on for so long before........ A valve breaks.

The owner pulls the heads and has a shop start on the repairs, but for one reason or another the progress comes to a halt, and then the heads sit for what I believe is a couple of years.

When they show up at my shop the welding is already done, but that's about it.

The first step was to replace the damaged guides.
The two from the damaged cylinder, and the intake next to it had been removed.

These heads use guides with an odd sized OD, and I think the previous shop pulled the one to see what size it was.
At this point, I hadn't really looked at the rest of the head too closely, and just took 3 larger OD guides I had here, and turned them down to fit the hole in the head.
After that was done, and they were sized, I got to the business of installing the seats.....

Actually, after the guides were in, I flat milled the head to give me a good surface to work from and get the head flat after all the welding.

Intake seat install.....

After the seats are installed, I roughed in the chamber, and roughed in the valve job.
At this point I basically just matched what the other seats had, since it was unclear how much further I would be taking this head other than finishing the repair.

Thanks for sharing

There wasn't quite enough weld near the seats on the quench side of the chamber to get it to look better.
I blended the bottom of the seat inserts into the bowls, and hit the chamber with a sanding roll, and kissed the seats with a stone.
At this point....... The repair portion of getting these heads ready to use was done.

The decision was made to go ahead and fix the other issues and make the castings usable.
This meant 13 more guides, machine the seats, flat mill the other head.

When I recut the seats, the 45 got pushed out quite a bit from how it was done originally, which required another angle be added below the bottom angle to help get a better transition into the bowl.
Even with the bowl cut, there was a pretty noticeable ridge where the casting ended and the machining started, so that was going to need to be blended in so they wouldn't lose flow from how they were before.

The other three exhaust seats on the damaged head were severely corroded.
Initially I was thinking I could just sink the valves a little and get into some new material, but after looking at them closer, and since some $$$ had been spent fixing some other issues, and the fact that the other head didn't have this problem, I just decided to replace those 3 seats.

Here's a pic of the same cylinder as the first pic with the valve seats cut and the correct 2.20/1.81 valves. Plenty of space between them.

And a pic of the damaged cylinder all done.
Not super pretty, but it should work okay.

As mentioned previously, these heads already had some port work done to them, otherwise it wouldn't have paid to fix it.
To fix the one head was about 1/2-2/3's the cost of buying a new head and porting it an amount equal to what was done already.

Finished product(not the damaged cylinder, although I think it would be pretty much the same), still std port window:

Lift---------in/ex
.100---73.1/ 56.5
.200--151.2/97.6
.300--205.7/139.5
.400--260.6/173.2
.500--302.9/205.4
.550--316.7/215.4
.600--324.2/224.9
.650--334.7/228.6
.700--342.2/235.1
.750--342.9/238.8


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WOW spending some pretty good money on these. great work !!!!

If there is a lesson here, I think it's that if these heads had been properly prepped prior to being installed....... a good valve job, guide clearances set, had the correct size valves installed(diameter and length)....... It's very likely this never would have happened and they'd still be on the motor today.

Wow a lot of work . Good work .Thanks for sharing Dwayne

Tex

Turned out pretty decent for as bad as it
was.. good job

Doing it right the first time is always the cheapest and easiest.

the slight weld porosity shown on the head surface after milling will still allow the gasket to seal ?

All the people who look at things strictly from the "Did I get a 'deal'?" or "Did I get the best price?" perspective don't want to hear that.

Wow, good work.

I'd definitely have someone I trust look over a set of heads before bolting them on. Good work and thanks for sharing.

This is a great thread with REAL tech info. Thankyou Dwayne.

Do you heat the head at all when installing the seat or do you just add "crush"? Just curious. J.Rob

The minor welding porosity is inside of the gasket fire ring, so I don't expect any problems from it.

As for the seat install, I heat the head to 250* for about 1/2hr, and the seat rings get put in a cooler with ice.

With aluminum heads I machine the seat bore to have about .007-.008 interference fit with the insert at room temperature.

Great info. Nice save for your customer. Thanks, Dwayne.

These are some of the details that are left out of most of the "I got these heads for a $1000 what a deal" stories that people like to tell.

Thanks for sharing Dwayne, After the 1st couple of pics I didn't think there would be a happy ending

I was actually impressed that the quality of aluminum was there so that they can be welded.... unlike my W5 door stop

When Dale and I bought his AMX in 1997, it came with a set of damaged MP Stage VI heads. They've been on about five engines since, as we've traded them back and forth between friends and family. They require a trip to the machine shop every time for something. I bet we've spent over 4K on those "free" castings in the last twenty years!

Meanwhile my Edelbrock RPMs have provided excellent service since 2002 with a couple of very minor freshen-ups.

Thanks for the pics and explanation, great work as always!

Billy, I'm actually working on some stage 6's at the shop now.

It's one of those things where.......the customer already owns them.......and you can't quite get into a set of comparable new heads for what it would cost to get these into shape.

These happen to be brand new, but I've had a few sets of used ones come through the shop where there was a good argument to be made that it might have been better to cut your losses and move on.

They still trickle into the shop from time to time.

In the case of the Pro Comps....... it wasn't really any fault of the heads themselves that resulted in the dropped valve.
I'm sure if the same parts had been installed in a set of Ede Victors, the outcome would have been the same.

Nice recovery,fix work.Getting a project like that for the buyer makes for some hard choices I would think.

I was told that if there ever was ceramic sealer used in the coolent that the head could not be welded on,any comment on that?

That's good stuff Dwayne.

Is this one of those times where you look at that thing, then stare at the owner giving him the "Dude! Seriously???" look? Or does "Well, here come's the rent!" pop into your mind and off you go into the shop ready to make some chips!

I've had them a lot worse....... This wasn't really that bad of a job.

It's just a lot of little things that take time, and that adds up.......but no one part of it was really hard to do, or all that time consuming.

The first thought I had wasn't that it as going to be hard to finish, it was actually whether or not it was going to be cost effective to do it.
As I mentioned previously, had there not been porting done, it wouldn't have been.

Kind of feel sorry for the guy who owns those heads. I've been there before. Have to decide if you keep throwing money into the bottomless pit or stop at some point.

I gave him an estimate on the repair...... He thought about it, and said "yes". There was no pressure........ He could have said no.

I don't know that I'd call it a "bottomless pit".
They're done, and should work better than they ever did.

The guides are nice and straight, correct clearance, better valve job, correct size valves, reblended bowls/seats, more flow than before...... And the valves won't be running into each other.

If the head hadn't already been welded when I got it, that could have been the tipping point that pushed the cost into the "just get a new head" territory, but it was already done.

Of course, if it was an actual Victor head, there would have been no question it would be cost effective to fix it, since the cost of a Victor head casting is about double.

Real happy with your work Dwayne 👍🏻