TLDR:
I do have one question but this is more of a venting post. The question:
Looking at the pics below do I need to worry about the block-to-head mating surface on the block side. I am taking the head to the machine shop as the fire definitely took out some metal.

Dykem'd the block surface and slid a level back and forth. It scratched everything, including the burnt spot! Without a dial indicator, I can not detect any dip between the cylinders on the block. Should I worry or will doing the head be good enough?

Whine session!
I wanted, shopped for and bought a 300 for the legendary RELIABILITY. It is not working out. I rebuilt it this truck from the ground up.

3,600 miles since total rebuild and it just one problem after another -- mainly bad parts that I have another (whiney) thread on, The failed parts have all mostly been external bolt-on so it was not too big a deal. The headman headers were the exception! Getting those headers out and putting an '88 exhaust system in (per advice from you fine folks) was a hassle but overall it has been just external parts.

Then it started running rough and backfiring. I am like WHAT NOW? This thing won't run for a month straight! Compression test and #3 and #4 are running 30 psi! With the luck I am having many nightmarish thoughts about pulling the whole engine ran through my head but I was able to verify the rings were holding pressure. Weird to burn two valves at the same time, though. There was no oil and water mixing so I had ruled out the head gasket. But I was wrong about that eh? I am relieved that it is just the head.

I just undid all the exhaust system work I did two months ago, pulling the head today. {sigh} Are you ever ready to just give up? I am getting close!



Close up of the block side. There is a little scortching but I can not detect any metal gone.



Head -- You can feel the 'dip' where the fire passed through!



On the upside, the bores look GREAT! One bright point is I was correct that the compression loss was not the rings! That's something. A little something!

 

Cast iron usually does not eat away like aluminum. Unless you run it a very long time. What is the back story on this engine and cylinder head? Is it a rebuilt engine you bought? Or a rebuilt head? Or this engine had this problem when you bought it or the truck?

It doesn't sound like you ran it very long at all after the gasket blew. With the dip in the head in that area, it looks to me like that dip was there when you put it together, and it did not compress the gasket properly. That is why I am asking about the history of this. It looks like this cylinder head was run a long time with a bad gasket before you got it.

P.S. The block and head are cast iron. So you would think they would wear together. Another reason it seems to me this cylinder head is not original to this block.

 

Sorry to hear about your problems and this one

It would have been nice to see the block picture without the gasket in place to get a better picture of the area but you said it checks good so go with it.

Did you rebuild the motor or a shop?
Why do you think the gasket blew, bad gasket, bolts not TQ right or ?

I think I would run a bottoming tap down all the head bolt holes and look into getting new head bolt or maybe studs / nut but that would be over kill.
Dave ----

 

Since you both asked the same question let me answer you both in one place. A year and a half ago all the machine shops were backlogged. My engine had been at a machine shop for 6 months and they said it would be another 6 months before it would be done.

I got peeved and took my engine back from them. Apparently, 300's are not stock items anymore (or at least then!) Jeggs and Summit list them but when you go to order the delivery date is months away. I finally found one on the shelf at https://titanengines.com/

Long block. Here it fresh out of the packing tub thing.

I checked the head and rocker arm torque before I put the valve cover on.

It fired up and ran great until it suddenly did not! I had EXCELLENT compressions at my 500-mile check




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Well it's pretty and it smelled so good! It smelled like oil and testosterone!

 

That is sooo good to know!

Yes. Long block from rebuilder! See other post!

No, less than 5 miles and two sessions at idle tinkering with things before I did the compression check.

Verrrrry interesting! Very! What you said about wearing together and being the engine is a long block rebuilder I bet X head got bolted onto Y block!

 

i will work on that tomorrow

See other post!

I dunno! I was gonna ask you guys that!

FWIW The head came off *very* easily - it just popped right off -- and 75% of the head gasket came off clean. I have never seen that before but every head I have ever pulled had at least 100,000 miles on it! So I don't know if those things were just because of the low mileage or indicative of a bad build??? Heck, now that I think about it, the intake/exhaust gasket I put on in November left much more MUCH more residue than the head gasket.

Also, In my life time (not a pro just fixing my own stuff) I have never had a head gasket burn out between cylinders before. For me it has always been about milky oil/overheating. I even had one that would blow coolant and steam out the gap between the head and block (that will wake you up!) but I have never seen this burning before. So this is new to me.

 

No need to get a picture without the gasket unless you want for your records.

There could be so many reasons why the gasket let go, head was warped when installed, not TQ in right order, holes in the block would not let the bolts tighten (bottom out), bad gasket, just to name a few off the top of my head.
Send the head out to have it milled flat.
Like I said run a bottoming tap down all the bolt holes and then blow them out with air.
I would also look into new head bolts just to be safe, could them be stretching?
Get a good name head gasket like Fel-Pro.

BTW as you found out not all blown head gaskets make milkshakes or overheat.
That only happens if the gasket blows from the piston to a cooling passage.
Yours was piston to piston.
Keep us posted and good luck
Dave ----

 

I do not think there are many reasons in this case. I think the cylinder head came from a used engine that had a blown gasket, and the dip in the head was just missed during inspection and rebuilding. If you wanted to be a detective, you could probably search how to date the castings on the head and the block, and you may find they are well separated as to build dates.

This could be a warranty issue probably if you wanted to pursue it. Do you still have your original engine and cylinder head? You may talk to the machine shop and see what they think. Surfacing the head to get the dip out may take out too much metal. I would seek their advice.

 

The only thing I can see being a issue taking too much off the head is lifter preload as the valve train is not adjustable.
I cant see a valve to piston being a problem as the cam gear can get wiped out and the pistons dont hit the valves.
Maybe compression raised .01 % oh wow! And I cant see the chamber flame front changing that much to cause problems either.

And if that was missed on the head in the rebuild what else could have been missed?
Dave ----

 

I am feeling better now about not having to pull the engine to deck the block! You folks may have another opinion and I am here for them!

I can get a .001 feeler under there, maybe a 1/4 of the way between the cylinders but it will not go all the way through.
I can get a .002 feeler just under the edge near the lip of the cylinder. Of course, it wont go through all the way either.
A .003 feeler will not go under at all. I read elsewhere that .003 is the limit.

It's like the fire rounded the edges of the cylinders. Sorry for the shadows!




It's 150 miles to the big city. (I overdid the small town retirement bit! lol!) Long Machine Shop in San Antonio has a 4.7 rating on Google and he said if I get it to him tomorrow, he will turn it in a week! I am leaving in the morning!

When I was a kid in the 70's I "helped" my Dad rebuild a Ford Falcon engine. You know, I failed to hold the flashlight properly! He taught me way back then how important it was to get the head bolt holes really good and clean! Odd how that memory stands out huh? That and hand lapping valves are the two things I remember from that! Wierd huh?

To the point though, I really liked your idea of converting to studs! I found this. To my understanding, ARP is top-notch and for $90 they better be!

ARP Head Studs with Hex Nuts Ford 240-300 Inline 6 Part Number: 070-152-4001

Glad to hear you approve! I got a Fel-Pro for the intake/exhaust gasket back in November and it seemed like the good stuff to me! So Fel-prod was the plan

 

No. The original head was cracked (so said the machine shop that I took the engine back from). Then I sent the original engine with the head back to Titan for the $600 core charge. They did NOT deduct from the $600 for the cracked head so to this day I do not know if the machine shop lied about the head OR Titan just did not look that hard on the core return. Of course, not looking that hard could explain *this* issue as well huh? lol!


Heading off to the machine shop in the morning! If he says it is out of limits, I will have a dozen questions about replacements, but I won't take up your time unless he rejects it though!

EDIT: I just did the same thing on the head with the level and feeler gauge I did above on the block.

I can get a .003 feeler gauge to go all the way through "the dip".
I can get a .004 feeler gauge partway through,
A .005 feeler gauge won't go under the edge at all.

 

I hate to say this but you are only checking what 6" with that straight edge.
You want to go across the block side to side and fully front to rear down each side / center and corner to corner.

I would take a long hand sanding board with say 320 or 400 grit paper and hit the top of the block.
It would show any low / high spots. Thing is I have all that for doing body work so easy for me to do.

I would go with the rebuilder did not mill or check the head that well, used a cheap head gasket and may not have cleaned the bolt holes all add up to a blown head gasket.
That is my story and I am sticking to it.
Dave ----

 

Hey all, update if you care.

I just got home with a freshly rebuilt head. All he reused were the exhaust valves and valve springs

He said the Intake valves were pitted and installed new ones. He swears they are best quality and he uses nothing from China!

I asked if he thought they just bolted a used "as was" head on. He said it looked like they had rebuilt it, but with poor workmanship and using very cheap parts. Valve guides were out of limits, valves were not fully seated and he said the oil seals were iffy. On that note, he pointed out that the oil seals he used were top of the line and should not give me any issues. They sure LOOK nice!


Those oil seals LOOK good!

Formerly damaged area

There is something about clean smooth metal that just moves me!

 

Hopefully the rest of the "rebuilt" engine will hold up.

 

^ What he said ^
If the head was that bad what would the bottom end be like?
As much as it pains me I would add a oil pressure gauge with the trucks gauge so you can keep and eye on it.

Make sure you run a bottoming tap down each head bolt hole and blow them out before putting the head on.
Dave ----