Cyl Head/Valve Job Repair

[NC Engine Builder]

It certainly CAN be welded up and remachined to the point it would be impossible to tell. But the labor it takes to do it all properly, will likely equal a new head.

 

[Newbomb Turk]

That is the best route. It needs to be welded up. Can you apply that much heat to the head without a total rebuild?

Yes you can. If you know what you are doing. You’ll need to surface the head but that should be done anyway.

 

[92b]

Another option would be to sell the damaged head as it is. I've been looking for a damaged or used TF head to do some (practice) porting with. PM me if interested. Maybe we can work out something that works for both of us.

To me this sounds like the best option if you two can come to an agreement.

 

[mopowers]

I just swung by the machinist and got his (and another one of the old machinist that works in the shop's) opinion. They both believe it is a seat on top of a seat. They agreed that whichever shop repaired it likely didn't have a tall enough seat on hand to replace the whole original seat and bored it out for an oversized .250" tall seat. They both agreed that it would likely work as-is, but was a little wonky.

They discussed putting a top cut on the existing seat but didn't think his cutter would be able to put much of a 60* cut on it since the ID is so large.

They both thought that the chamber likely hadn't been welded on and that the exhaust seat is the original seat from trickflow. He also was looking at the valve guides and thought they all seemed to be in great shape as did the valve stems on valves that weren't replaced, though he'll do a proper mic job when they dive in.

After discussing options and looking through his seat catalog, we decided on an alternative solution. Since we have no idea of the quality of the seat install, he's going to remove the existing intake seat (top and bottom). He found a seat in his catalog that he'll install. It's got a 2.125" OD, is 7/16" tall, and has a large enough ID to open it up to the same ID as the others and match the throat in the port. He'll then do a complete valve job on both heads and cut the new seat to match. He's also going to touch up the seat surface on valves as well and deck both heads. He also said he'd polish up the chamber a bit to pretty it up and assemble the heads for the spring installed height I want. His price was very reasonable. In fact, if they look good when I pick them up, I'll probably spot him some extra cash.

It was pretty obvious to me that him and his machinist partner know what they're doing. It also gave me a chance to drop my block off for machining. I can post up a photo of the finished valve job if ya'll are interested.

 

[Newbomb Turk]

I just swung by the machinist and got his (and another one of the old machinist that works in the shop's) opinion. They both believe it is a seat on top of a seat. They agreed that whichever shop repaired it likely didn't have a tall enough seat on hand to replace the whole original seat and bored it out for an oversized .250" tall seat. They both agreed that it would likely work as-is, but was a little wonky.

They discussed putting a top cut on the existing seat but didn't think his cutter would be able to put much of a 60* cut on it since the ID is so large.

They both thought that the chamber likely hadn't been welded on and that the exhaust seat is the original seat from trickflow. He also was looking at the valve guides and thought they all seemed to be in great shape as did the valve stems on valves that weren't replaced, though he'll do a proper mic job when they dive in.

After discussing options and looking through his seat catalog, we decided on an alternative solution. Since we have no idea of the quality of the seat install, he's going to remove the existing intake seat (top and bottom). He found a seat in his catalog that he'll install. It's got a 2.125" OD, is 7/16" tall, and has a large enough ID to open it up to the same ID as the others and match the throat in the port. He'll then do a complete valve job on both heads and cut the new seat to match. He's also going to touch up the seat surface on valves as well and deck both heads. He also said he'd polish up the chamber a bit to pretty it up and assemble the heads for the spring installed height I want. His price was very reasonable. In fact, if they look good when I pick them up, I'll probably spot him some extra cash.

It was pretty obvious to me that him and his machinist partner know what they're doing. It also gave me a chance to drop my block off for machining. I can post up a photo of the finished valve job if ya'll are interested.

Your guy has his head on straight.

I’m looking at pictures on my phone so I just didn’t see the seat over a seat deal.

In fact I’ve never seen that or heard of it. How hard is it to order a seat if you don’t have one on hand. That is bullshit work and whoever did that should not only be ashamed they ought to find a new career.

Nowhere in my world is that EVER an acceptable fix. Bet your *** if it failed the ding dong that did it wouldn’t warranty it.

 

[mopowers]

Forgot to mention - I also called Trick Flow and they directed me to a shop they deal with for repairs (Total Engine Airflow). I talked to a really nice guy there who also walked me through the same repair process that I ultimately decided on. Only that would require sending them to their shop in Ohio and back. I'd much rather deal with a competent local shop, but it's good to know that option exists.

 

[Woody500]

You're right seat does look funny. I didn't notice why.
What I did see is; Yes they did weld on chamber, & anyone who has welded Aluminum would see the porosity where it is welded, caused by a dirty casting( or improper cleaning/ grinding prep), where imperfections flow to the surface & cause voids or 'airholes' in the weld.
Thetefore, I'd then wonder about coolant leaks!

 

[Woody500]

Any Trick Flow experienced weldors can tell us if their castings are ever 'Dirty or Clean to weld on.

 

[Woody500]

I realized whoever said exh seat never was removed was right, even without proof of the intake seat jury rig, as proof, the pits in the weld can many times be floated to the surface of the puddle with more heat and filler rod & then be ground to shape...So head never was heated enough to be properly welded.
Beware

 

[mopowers]

I went by the machine shop today to drop off a couple parts. He cut out the two seats pretty easily. He's just waiting on the new oversized seat. His work looked great so far.

I also confirmed that the chamber was not welded on. I think it just looks like it in photos. At some point, something bounced around the chamber (look at the closed portion of the chamber). Whoever "fixed" the seat the first time around had smoothed out the chamber while leaving some minor pinholes as to not take out too much material. I'm very confident that when I get it back from my machinist, it'll be good to go.

 

[PRH]

After removing it, did he confirm it was indeed a seat in a seat?

 

[mopowers]

After removing it, did he confirm it was indeed a seat in a seat?

More like a seat on top of a seat, but yes. It came out in two district pieces. He saved them for me to see and even noted how each cut differently.

 

[Newbomb Turk]

More like a seat on top of a seat, but yes. It came out in two district pieces. He saved them for me to see and even noted how each cut differently.

Just absolute madness. Maybe in a pinch. Maybe.

But to do that and then charge for it?
Insane.

 

[mopowers]

Just absolute madness. Maybe in a pinch. Maybe.

But to do that and then charge for it?
Insane.

Agreed. My machinist thought that it'd probably function, but figured whoever did it likely didn't have the correct oversized seat in stock. Total half-assed repair for sure, regardless of whether it'd be functional or not. I'm just glad a paid close enough attention to catch it when I was cleaning up the heads.

 

[mopowers]

I picked up the heads today. It took a while because I was also having him machine a bare small block for me as well. I took the valve out of the repaired cyl and it looks pretty good to my untrained eye (see photos below). He took out the two seats (seat-in-seat) and ordered an oversized seat so it's now one piece. He also touched up the other seats so all of them match the same cutter. It's just a basic 3-angle cut, but it will be fine for what I'm doing with it.

Along with repairing that intake seat, also surfaced the decks and installed the springs at 1.950", though I measured them at 1.940-1.967. Is that range reasonable??

 

[mopowers]

I'm trying to decide if it it's worth knocking down this ridge around all of the valves. I have a junk exhaust valve I can use as a guard, but I don't have an extra intake valve, so I'm a little nervous getting near the valve job with a burr or tootsie roll to blend that ridge. Is it even worth it??

 

[PRH]

Depending on what you’re doing with the heads, it’ll make a little difference, or it’s a waste of time.

If you don’t have experience with that exact situation(relieving/blending the chamber adjacent to the finished valve seat), my advice is to leave it.

 

[mopowers]

Depending on what you’re doing with the heads, it’ll make a little difference, or it’s a waste of time.

If you don’t have experience with that exact situation(relieving/blending the chamber adjacent to the finished valve seat), my advice is to leave it.

It's just a mild street cruiser, so I'm not looking for every ounce of power. I'll leave them alone. Thanks for the input! I appreciate it.

Would you call a 1.945-1.967" spread on installed height acceptable? I do plan on double checking the spring pressures just to make sure they're in the ballpark.

 

[PRH]

If the spread is 1.945-1.967, which one is closer to the mean?
A- Are they more like 1.955-1.960, and the one at 1.945 has no shims?
Or B- they’re closer to 1.950-1.955, and you could add a .015 shim to the one that’s 1.967 and get it to 1.952?

Fundamentally, on a 400lb/in spring, a .015” change is 6lbs.
And…….Without a decent spring tester, you don’t know if the heights are intentionally staggered to balance the forces.

 

[mopowers]

If the spread is 1.945-1.967, which one is closer to the mean?
A- Are they more like 1.955-1.960, and the one at 1.945 has no shims?
Or B- they’re closer to 1.950-1.955, and you could add a .015 shim to the one that’s 1.967 and get it to 1.952?

Fundamentally, on a 400lb/in spring, a .015” change is 6lbs.
And…….Without a decent spring tester, you don’t know if the heights are intentionally staggered to balance the forces.

Good points about the average and intentionally staggered heights to normalize pressures. I do know they didn't check pressures or anything because I didn't ask them too. I may be swapping springs anyway. I just gave him the 1.950" to set them up at.

Here's the table I made of the heights on the head I checked. I also made a mistake. The low was actually 1.940". That was certainly the outlier. I haven't checked the other head yet.

 

[PRH]

Based on the chart, I’d address that 1.940.

 

[mopowers]

Based on the chart, I’d address that 1.940.

I just went out and looked. Turns out that one does have at least one shim under the spring locator. The problem is it's got positive valve seals. I'm not sure I can remove it without damaging thst seal. I'll have to check to see if they sells singles.

Also, after remeasuring, it's right at 1.943". The shim is likely .015", which would put it at 1.958" after removing it.

 

[PRH]

If it has the steel jacketed viton seals, you can usually get them off if you’re careful and patient.
Take the little spring off the top before sliding it over the groove in the valve.

The white Teflon seals are harder to get past the groove without damage.

 

[mopowers]

If it has the steel jacketed viton seals, you can usually get them off if you’re careful and patient.
Take the little spring off the top before sliding it over the groove in the valve.

The white Teflon seals are harder to get past the groove without damage.

They have the steel jacketed viton seals like this:

After I check installed heights and spring pressure on both heads, I may just buy a new set if I end up moving around and re-shimming springs. Thanks for the tip on removing the tiny spring. I'm guessing that's to avoid nicking the seal with the lock groove on the valve stem.

 

[gzig5]

They have the steel jacketed viton seals like this:

View attachment 1716407637

After I check installed heights and spring pressure on both heads, I may just buy a new set if I end up moving around and re-shimming springs. Thanks for the tip on removing the tiny spring. I'm guessing that's to avoid nicking the seal with the lock groove on the valve stem.

I don't know how well it works, but I've seen short videos where folks use heat shrink tube on the valve to cover the lock groove when installing the seal to protect it. For removal, removing the spring should help, but I'm wondering if you could get the cut end of the shrink tube to go into the groove, it might keep the lip of the seal from rubbing the groove shoulder on the way off. Would need to be some relatively thin shrink tube.