Hot Rod Forum banner
1 - 17 of 17 Posts

·
©®™
Joined
·
1,306 Posts
Discussion Starter · #1 ·
Last year I bought a '69 GTO. It came with an extra set of heads that were original to the car. The seller had changed out the heads after the having a valve seat drop out of it. Evidently A prior owner to him had had hardened valve seats installed and the machine shop must not have done a good job.
I don't need or want to keep these heads and would like to sell them as-is if I could but don't know how much value they would have with the work they need.
They are 62 castings and are correct for the '69 400 Pontiac engines with 350HP and 366HP Ram Air III but not the rare Ram Air IV. Also correct on some '68 GTOs but the date code corresponds to my '69 car. They are fairly desirable heads for swaps though because they came with large valves and screw-in studs.

Here's a few photos of them:







I presume welding would need to be done on the boogered chamber. I also presume that since one hardened valve seat dropped out, all should be removed and replaced by a machinist that knows how to do it without risk of them dropping out.
So my questions are:
How bad is this? Can a machine shop deal with this OK? What about as-is value?

Any advice will be appreciated.
 

·
More for Less Racer
Joined
·
20,950 Posts
Cost more than they are worth to try to fix all that IMO, and you'll still be able to see dents in the chamber.

Welding is out, old cast iron doesn't do well and most of the time cracks.

So there is no fixing the dents in the chamber other than grinding them out.....you'd have to do all the chambers in both heads the same to make them match shape and volume wise. Then machine the deck to remove the dents in that suface, and to try to reduce the chamber volume back down close to original spec.

Has that head even been magnaflux checked for cracks since the incident??.....They may be junk for that reason already.

You might sell the good one to someone else trying to make a pair, looking for one to replace their busted one.
 

·
Hates: Liver. Loves: Diesel
Joined
·
6,318 Posts
Magnaflux them. If they're good, take a piece of emory cloth to get rid of the high spots (they get hot and can cause detonation). Do a good valve job and bolt them on.

I've run heads with far worse damage than that. Unless you're going for something really special, it's a chunk of cast iron. Don't stress.
 

·
Registered
Joined
·
15,340 Posts
Probably a wipe out. The seat area looks like it’s out of enough material to remachine, though I recommend getting a shop’s machinist’s eye ball opinion as pictures aren’t really good enough for a truly solid evaluation.

Welding cast iron is tricky and is power factors more difficult with complicated castings like engine blocks and head’s where there are realtivly thin multiple internal cross-sections that make uniform heating and stress relieving next to impossible so the possibility of cooling crack formation is extremely high. If you want to find a shop willing to take welding repair on and will eat their costs in time and material if it fails I say let them try it. The highest rate of survival comes with heating the entire head in an industrial oven very high temperatures then welding followed by a slow cooling which may involve dinking the material with a punch shaped hammer to stretch the weld area as it cools. Additionally cast iron is a tricky material that actually goes through crystal lattice form changes with temperature changes so the end strength is greatly affected by the heat applied and the cool down process. Probably at best with the highest applied repair technology by a well experienced cast iron welder is probably not better than 50 percent, this in-spite of the miracles you see on YouTube videos. So like I said if you can find a shop willing to try and only charges you if they are successful I say give it a try. If you give it a go by yourself with something like Muggy Weld at worst the head is still wreckage and your out the costs of their kit so it’s not going to bankrupt you.

Losing pressed in seats is not unknown especially if the engine is run hard. It is after all nothing but a press fit subject to extreme heat! What could possibly go wrong?

Bogie
 

·
©®™
Joined
·
1,306 Posts
Discussion Starter · #5 ·
Thanks guys! Sounds like I should put them in the scrap pile. I'm not willing to put any money in them and I don't even want the hassle of shipping them and the chances of finding someone within driving distance sounds pretty remote.

A little more to the story here.
The replacement set of heads that the seller of the car acquired were a virgin set of identical 62 castings that were date coded to the car correctly too. He had his machine shop go through them and install new valves and springs. He also gave me a new in box set of rockers with them. I had my machine shop thoroughly check the previous work before assembling the engine for me. They ended up saying the work was fine but didn't like the retainers or studs so they put new sets of what they preferred on. No hardened valve seats which is pretty much the accepted thing to do with Pontiac heads from what I've heard and read.

Here's a video of the dyno at the machine shop last month.


It made quite a bit more power than I expected and you can hear that in my response.

617127
 

Attachments

·
More for Less Racer
Joined
·
20,950 Posts
Comes down to three things....

Is the head free of cracks(been magnafluxed) right now??

Is there enough material left to cut for a new bigger seat ring od and depth??

Can you live with the dents in the chamber??

if it isn't cracked, a new seat is viable, and you can live with the dents....then it just comes down to cost. The rest can be fixed.
 

·
©®™
Joined
·
1,306 Posts
Discussion Starter · #9 ·
Thanks Eric. I appreciate your help. Of course from my prospective, it's not about my level of living with it since I want to sell if they have value or junk if they don't. So I have to ask myself how a buyer would feel about those questions. If I were in a buyer's shoes, I wouldn't be interested. I'd look for a virgin set (like the seller of my car did) or opt for aluminum aftermarket.

I only posted again here because johnsongrass appears to have different opinion but he doesn't give any details on why. But really even at $200 which is his suggested starting price, it's not worth shipping them since the shipping would be so expensive. And, I really don't want to go through that trouble. But, it might be worth it to put some ads on CL. I'm in San Angelo, TX and I think there's a slim chance someone would be interested in them here. San Antonio, Austin and Dallas are all about the same distance at 200 miles. If I put them on CL in those cities, I'd probably post them for $100 to account for the distance for anyone to have to drive. That might be worth it to someone just for the one head without the damage. It's not really about the money, I just hate to junk stuff that someone might like to have.
 

·
Registered
Joined
·
15,340 Posts
A long, long time ago we had someone on this form that said welding cast iron was no big deal. When we pressed him for what he knew that the rest of us didn’t about welding cast iron it came put is successful experience was welding a broken spoke on a cast iron gear of a farm implement.

I would suggest that it’s not the same structural complexity of something like a cylinder head. Plus we were never able to find out if this was really weld where both the parent and the filler material are melted together as one piece of material or whether it was braze which is really a solder technique where the parent material is not melted only the filler rod which is wicked into the parent material by capillary action. These can make a pretty sturdy bonded joint but in your case brazing rod is not sufficiently strong enough to be built up then machined to provide the strength to support a press fit seat for the valve, especially an exhaust.

Its not that welding cast iron in a situation like yours cannot be done, but the process is complex and not often successful.

This is a huge advantage of aluminum heads as aluminum castings can be successfully repaired by welding without all the process requirements of cast iron. So can cast steel be welded. The problem with cast iron is the high percentage of dissolved carbon and the shape that carbon takes. Ordinary cast iron the carbon is in flakes it makes for a brittle material that has natural cleavage lines that follow the carbon. When you get to nodular iron where either by heat treatment or chemical intervention that causes the carbon to form roundish nodules instead of flakes the success of welding repair is improved. And this goes on into malleable forms of cast iron. While there are some blocks cast from this stuff for extreme performance engines, it is not found in production blocks and head’s; though nodular iron crank shafts are common as are center sections of some differentials, and sometimes other highly loaded parts especially on large trucks, construction and farm equipment. Just not on Pontiac cylinder head’s, rods yes, they call it Arma Steel but by the definition of percent of carbon to ferritic material even that is technically an iron not a steel.

Bogie
 

·
Hates: Liver. Loves: Diesel
Joined
·
6,318 Posts
Comes down to three things....

Is the head free of cracks(been magnafluxed) right now??

Is there enough material left to cut for a new bigger seat ring od and depth??

Can you live with the dents in the chamber??

if it isn't cracked, a new seat is viable, and you can live with the dents....then it just comes down to cost. The rest can be fixed.
I agree with this. If you were building a really hot street/strip motor and living on the edge of detonation tolerances, and maxing BMEP, I'd skip them. The head on my current 3.0L I/O lost a valve seat. Maybe it was a chunk of valve. I forget. I drove the boat 3 miles home on 3 cylinders. I pulled the head, a shop used a 2" pneumatic angle grinder with some 80 grit to knock down the high points, cut new seats, two valves in that cyilnder, and I bolted it back on. That was 3 years and probably a hundred hours of ski time ago.
 

·
Registered
Joined
·
4,273 Posts
Throw them in the parts washer. Make some headers that make 4 legs. Have the valves pointed up.
Bit of clear spray paint and a piece of glass cut and grinded smooth.

You have a "hot rod" end table.
 

·
Race it, Don't rice it!
Joined
·
8,828 Posts
Fixing that head isn't too bad.
First is a pressure check to make sure they aren't broken somewhere, then a spring pass to the clean up the seat pocket OR most likely, they will need cut to a new seat size. No need to change the valve size, just a slightly bigger OD seat and blend out the worst of the damage by hand. Might even pin the seats if the fit is loose or higher heat is expected. Fix the guides, cut the new seats, fix the valves or most likely replace them, mill the head to clean up the deck surface and vacuum test and a mybe even a pressure test again and send it. It may not be perfect but it'll run just fine. Now the biggest problem is the cost. My shop gets about $1000-$1200 and this head, unless sentimental, isn't worth the cost.
 

·
©®™
Joined
·
1,306 Posts
Discussion Starter · #16 · (Edited)
I'll give it a try but I'm not that hopeful. But if I end up putting them with my other scrap metal, at least I know I'll have tried.
I'll put them on CL in Dallas, Austin and San Antonio but I'll list them at $100 to account for the distance.
 

·
Registered
Joined
·
4,283 Posts
I sent a rare SD Pontiac head to Indy Cylinder head for them to weld a blown out seat. They said it would be no problem. It lasted about 3-400 miles before it failed. They charged me $700 for 1 seat. In the mid 1990's. Never again.
 
1 - 17 of 17 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top