Damaged Aluminum Head & Cylinder

Howdy!

I just bought what I thought to be the find of the decade: CI Aluminum head and a built 250. I bought it off Facebook marketplace from a guy for $400. It basically came with everything but a carb: adjustable rockers, dual valve springs, ds II (just the distributor), upgraded cam (have to see what it is), new pistons, I think he said it was bored out a little, engine mounts, dual outlet CI header, modified oil pan for higher capacity, etc...

Here is the problem: the #6 piston cracked. No damage to cylinder wall, but damage to aluminum head (picture below).

Question: is this salvageable? Home fix or machine shop fix?





Thanks in advance!
-Shawn

Hi, it looks like the ring land broke and the Piston hammered it onto the head. One of the causes of broken ring lands is detonation. So maybe they have a high compression ratio, or too much ignition timing.
I think you need to inspect all the pistons, and check the pistons for an oversize stamp.
I think any performance cylinder head guy could check out the head for cracks, and if the head is not hurt, mill, grind, and polish the combustion chamber back to life. He may want to match all the chambers.
If the compression ratio is too high you might want to remove material from all the chambers so you don't need racing fuel just to go for a drive.
Good luck

You will need to have the head Zglowed to see if it's cracked most times these heads can be repaired by Heliarc (welding) after that it will need some machine shop work a surface cut and valve job. On the block if there's no damage you could replace the Piston or Pistons that would also require a little shop work pressing them off and on the rods. After that you can install the Pistons back into the block at home. Consider getting better Pistons since if one broke maybe the quality might need to be upgraded. I would say you got a really good deal if you don't mind investing in the repairs, but if you don't want to take it on let me know. Best of luck

B RON CO":179yuvf8 said:

Hi, it looks like the ring land broke and the Piston hammered it onto the head. One of the causes of broken ring lands is detonation. So maybe they have a high compression ratio, or too much ignition timing.
I think you need to inspect all the pistons, and check the pistons for an oversize stamp.
I think any performance cylinder head guy could check out the head for cracks, and if the head is not hurt, mill, grind, and polish the combustion chamber back to life. He may want to match all the chambers.
If the compression ratio is too high you might want to remove material from all the chambers so you don't need racing fuel just to go for a drive.
Good luck

Click to expand...

Well, the guy I bought it from told me that his brother-in-law had it built and that he had a pcv the went from the valve cover to the #6 runner on the intake manifold. Would this cause the detonation and destruction?

bubba22349":179yuvf8 said:

You will need to have the head Zglowed to see if it's cracked most times these heads can be repaired by Heliarc (welding) after that it will need some machine shop work a surface cut and valve job. On the block if there's no damage you could replace the Piston or Pistons that would also require a little shop work pressing them off and on the rods. After that you can install the Pistons back into the block at home. Consider getting better Pistons since if one broke maybe the quality might need to be upgraded. I would say you got a really good deal if you don't mind investing in the repairs, but if you don't want to take it on let me know. Best of luck

Click to expand...

Thanks Bubba! I think I’ll hold onto it and get it fixed up. When I get a chance, I’m going to pull the piston to see if it’s labeled with a manufacturer. Are you recommending a valve job on all cylinders or just the damaged?

i agree with the others, have the head checked over for cracking. if there is no cracking, then the head can be refurbished to run again.

i agree with the detonation issue though, perhaps there was a vacuum leak that caused that cylinder to be excessively lean, and the detonation busted up the ring and piston.

another issue to consider is the possibility of FOD damage. perhaps a washer or small screw fell down into the cylinder and caused the damage. i am betting a small screw got beat to death and you might find teh remains in the debris.

To answer your question I need to know what use your planing for the head and short block mild build or full on performance build. Basically there's the first class spare no expense repairs or for a moderate or low budget repair, all of them can work, but results can very.

For the first class as new repair the head would to be checked for cracks then need some welding to restore it back to excellent condition again. and the heat from welding will cause it to move requiring that the head gets a compleat fresh valve job and resurfacing. Usally this isn't all that costly on a lightly damaged head but you need to find a good Heliarc welder you can take it to. After that the machining of surface and a valve job (ask for a three angle with back cutting) these can be handled at any good auto machine shop. Then you also need to replace the pistion having the machine shop press the pistion pin out and press the new pistions with pins back on with a matching one and weight matched should be that hard. Or replace the set with a full matching set good quality. Full set of Rings or find one ring set if just replacing the one piston, full set of gaskets and you can handle the reassembly or let the shop do it for you.

However if you maybe don't want to go to that kind of expense and time to repair by welding the head to match the other combustion chambers that is ok too I understand having to have a tight budget, and it will still run like that. In that case since all this is relatively light damage and it's located all inside the combustion chamber area not affecting the head gasket sealing surface. Also if it's not cracked (it probably isn't doesn't look like a very hard hit), you could lightly dress up the rough spots with Dremel or a sanding block inside the chamber or even choose to leave it as is. Assuming this lower budget plan then all you need to do is check the deck surface with a straight edge to see if it's still flat. Then poor some fuel or paint thiner into the chamber and see if anything leaks past the valves into the ports if it doesn't you are good to go without need of a fresh valve job.

So it all depends on your goals, expectations for the engine and then the budget amount to work with. I have seen and worked on much worse before with requests that only the absolute minimum amount of parts are used just to repair and put it back in service in that case the head is left alone if it's still flat and valves still seal might be that all you need to get it running is the one piston, one cylinder ring set, and some gaskets. At this point you won't even know if you will need a piston until you pull out the number 6 Rod to see the amount of damage. Best of luck

i will say this, the beauty of aluminum used in cylinder heads and blocks is that they can be fairly easily repaired, assuming you can weld aluminum. i have seen top fuel blocks made from aluminum that had a rod thrown through the side, and the low buck teams would weld the block pieces back together and go racing again.

Hi, so you know it is not a good idea to run a PCV valve off off one intake runner on any engine, your damaged cylinder does not look to have been running lean. One other thing I would check out is if the spark plug has the correct reach. The plug looks to be recessed a little. Maybe that is the way it is supposed to be, I really don't know about that.
On Bubbas point about leaving some of the scars, I would be concerned that a jagged edge could become a hot spot, and that could lead to detonation, so I think all the damage needs to be smoothed over. Perhaps unshrouding the spark plug area would be a good thing.
Personally, if it were my engine, I would probably change all the pistons, rings and bearings.
Good luck

bubba22349":3kitenra said:

So it all depends on your goals, expectations for the engine and then the budget amount to work with. I have seen and worked on much worse before with requests that only the absolute minimum amount of parts are used just to repair and put it back in service in that case the head is left alone if it's still flat and valves still seal might be that all you need to get it running is the one piston, one cylinder ring set, and some gaskets. At this point you won't even know if you will need a piston until you pull out the number 6 Rod to see the amount of damage. Best of luck

Click to expand...

Bubba, this is a perfect response to my question. Thank you for all of the info. My goals for the car are to have peppier street performance, and nothing in the realm of top performance or drag racing... If I were to clean up and smooth the damaged combustion chamber, what is the side effect of having a different chamber size than the other 5? I have to find a hoist so I can put the engine on a stand and start taking it apart to see the damage to #6...

B RON CO":3kitenra said:

Hi, so you know it is not a good idea to run a PCV valve off off one intake runner on any engine, your damaged cylinder does not look to have been running lean. One other thing I would check out is if the spark plug has the correct reach. The plug looks to be recessed a little. Maybe that is the way it is supposed to be, I really don't know about that.
On Bubbas point about leaving some of the scars, I would be concerned that a jagged edge could become a hot spot, and that could lead to detonation, so I think all the damage needs to be smoothed over. Perhaps unshrouding the spark plug area would be a good thing.
Personally, if it were my engine, I would probably change all the pistons, rings and bearings.
Good luck

Click to expand...

I will be plugging the hole in the #6 runner and finding a different spot for the PCV. Is a PCV needed? I have seen setups without them, but not sure of the alternative... I found a thread in which Mike posted the recommended spark plugs. I will make sure I run the correct set. I will change out all pistons if I cannot find a matching replacement for what's in there now. Yes, I have read about the hot spots in the handbook, and definitely will smooth out the damage. Thanks for your input.

rbohm":1dmfi3ei said:

i will say this, the beauty of aluminum used in cylinder heads and blocks is that they can be fairly easily repaired, assuming you can weld aluminum. i have seen top fuel blocks made from aluminum that had a rod thrown through the side, and the low buck teams would weld the block pieces back together and go racing again.

Click to expand...

Great to know they are resilient, and fixable.

There is a chance that the rod is bent,better check that...I know if it was a 200 rod, it would be bent, but the 250 rods are stronger.

drag-200stang":1ytqodjz said:

There is a chance that the rod is bent,better check that...I know if it was a 200 rod, it would be bent, but the 250 rods are stronger.

Click to expand...

Just to clarify, you are talking about the piston rod right? Thanks!

I'm still trying to navigate and understand the internals of the engine. I'm starting to get a decent grasp on how it all works, but it's slow... Just gotta keep reading. I've re-read Lavron's 250 build thread a few times which has really helped me understand some of the measurements and what not especially for the 250.

65_Stang_170":1heb5w7y said:

bubba22349":1heb5w7y said:

So it all depends on your goals, expectations for the engine and then the budget amount to work with. I have seen and worked on much worse before with requests that only the absolute minimum amount of parts are used just to repair and put it back in service in that case the head is left alone if it's still flat and valves still seal might be that all you need to get it running is the one piston, one cylinder ring set, and some gaskets. At this point you won't even know if you will need a piston until you pull out the number 6 Rod to see the amount of damage. Best of luck

Click to expand...

Bubba, this is a perfect response to my question. Thank you for all of the info. My goals for the car are to have peppier street performance, and nothing in the realm of top performance or drag racing... If I were to clean up and smooth the damaged combustion chamber, what is the side effect of having a different chamber size than the other 5? I have to find a hoist so I can put the engine on a stand and start taking it apart to see the damage to #6....

Click to expand...

These fine Aluminun heads are an excellent design that took many hours of development work to achieve and is the very best cylinder head for any type of a Hi Performance build up of one of our Ford small block sixes. The cylinder head design is the key to making power in any engine combo. Together with the extra torque of a 250 short block it will for sure meet all of your stated goals and then some. Compared to the stock 170 it's a going to be a huge difference in power and drivability.

Now as for the side effects of having a different chamber size (CC's) that's larger because of the extra metal removed this for sure results in somewhat less power being made in that one cylinder compared to other 5. If the difference were significant, (I don't see evidence of that right now but only measuring the CC volumes will tell you that). In a worse case senareo were the cranking compression is down more than 10 % to 15 % from the other cylinders there would be some ruffness or an imbalance in running especially at idle and under a load. The missing material in key areas of that chamber and its finale chamber shape being different from the others will also have an affect in the flow in that chamber compared to the others and probably how the flame front traveles in that cylinder also, again the net effect would be some loss in power. The question is how much is it going to be, and you won't know this until it's reassembled. So in that case you wouldn't want to remove any more material in that chamber or change its shape if you can help it. Hope that answers your questions, best of luck.

65_Stang_170":1mip0qhg said:

B RON CO":1mip0qhg said:

Hi, it looks like the ring land broke and the Piston hammered it onto the head. One of the causes of broken ring lands is detonation. So maybe they have a high compression ratio, or too much ignition timing.
I think you need to inspect all the pistons, and check the pistons for an oversize stamp.
I think any performance cylinder head guy could check out the head for cracks, and if the head is not hurt, mill, grind, and polish the combustion chamber back to life. He may want to match all the chambers.
If the compression ratio is too high you might want to remove material from all the chambers so you don't need racing fuel just to go for a drive.
Good luck

Click to expand...

Well, the guy I bought it from told me that his brother-in-law had it built and that he had a pcv the went from the valve cover to the #6 runner on the intake manifold. Would this cause the detonation and destruction?

bubba22349":1mip0qhg said:

You will need to have the head Zglowed to see if it's cracked most times these heads can be repaired by Heliarc (welding) after that it will need some machine shop work a surface cut and valve job. On the block if there's no damage you could replace the Piston or Pistons that would also require a little shop work pressing them off and on the rods. After that you can install the Pistons back into the block at home. Consider getting better Pistons since if one broke maybe the quality might need to be upgraded. I would say you got a really good deal if you don't mind investing in the repairs, but if you don't want to take it on let me know. Best of luck

Click to expand...

Thanks Bubba! I think I’ll hold onto it and get it fixed up. When I get a chance, I’m going to pull the piston to see if it’s labeled with a manufacturer. Are you recommending a valve job on all cylinders or just the damaged?

Click to expand...

Hooking the pcv valve to an intake runner would lean the mixture to that cylinder & cause detonation.
Always hook the pcv at the carb. flange area.

wsa111":1u6h62o3 said:

Hooking the pcv valve to an intake runner would lean the mixture to that cylinder & cause detonation.
Always hook the pcv at the carb. flange area.

Click to expand...

"...he had a pcv the went from the valve cover to the #6 runner on the intake manifold. Would this cause the detonation and destruction?..."

the VI alu head can have a "closed pcv system" just like the standard heads did in their later yrs.
As Bill sez the pcv valve on back VC 'hole' w/tube to flange nipple; frnt (so as to B easiest to top off the crankase) VC 'hole' hose to the AC housing. Looking around I do not see a pic to post. Only some weber carbs can not live w/this set up. I like it as I can not use a cat (my lead gas) and wish to do my best for the enviornment. The run frm headers to turminus is so short (in frnt of rear pass tire) I'm not sure I could get one in. All ways lookin for more info tho...
:arrow:

bubba22349":20gqz0hq said:

The question is how much is it going to be, and you won't know this until it's reassembled. So in that case you wouldn't want to remove any more material in that chamber or change its shape if you can help it. Hope that answers your questions, best of luck.

Click to expand...

Bubba, you have me feeling optimistic about a possible home fix, but only time will tell. If I don't feel confident in my results, I'll swing it over to a machine shop to clean up.

wsa111":20gqz0hq said:

Hooking the pcv valve to an intake runner would lean the mixture to that cylinder & cause detonation.
Always hook the pcv at the carb. flange area.

Click to expand...

Bill, I plan on plugging the hole on the intake runner and moving the pcv hookup to under the carb (whenever I figure out what carb I'm going to use...). Thank you.

Ok, I took a hack at cleaning it up. Do I need to take it all the way down so that it is completely smooth? Or does it look pretty good as is?



Thanks!
-Shawn

65_Stang_170":gm2op433 said:

Ok, I took a hack at cleaning it up. Do I need to take it all the way down so that it is completely smooth? Or does it look pretty good as is?



Thanks!
-Shawn

Click to expand...

that looks pretty good. you might round off the edges on the deeper gouges that likely wont machine out to prevent sharp edges causing detonation. otherwise i think you are good to go.

run it!

65_Stang_170":213q83fd said:

drag-200stang":213q83fd said:

There is a chance that the rod is bent,better check that...I know if it was a 200 rod, it would be bent, but the 250 rods are stronger.

Click to expand...

Just to clarify, you are talking about the piston rod right? Thanks!

I'm still trying to navigate and understand the internals of the engine. I'm starting to get a decent grasp on how it all works, but it's slow... Just gotta keep reading. I've re-read Lavron's 250 build thread a few times which has really helped me understand some of the measurements and what not especially for the 250.

Click to expand...

Yes, the one that smashed the broken piston parts into the head.
It would also be a good thing to check the push rods too.