[SRR]

Originally Posted by Sirrotica

That statement makes me laugh, I've been turning wrenches most of my adult life for a profession. I've changed a lot more SBC headgaskets that were blown than Pontiac. Only one Pontiac gasket in all that time and dozens of SBC gaskets that were blown.

As I said the engineering has to be correct for the 4 bolt per cylinder to work efficiently, Pontiac engineers got it right from the first design and even though bean counters and fuel mileage requirements lead to cheapening of the castings, the engineers seemed to have left enough heft to keep the head gaskets intact.

The worst GM division for blown headgaskets by far is Buick, in everything they made and designed, V8s and V6s had headgasket problems for many years. Working in a buick dealership it wasn't unheard of to have both of my bays with headgasket jobs...……………….....

Buick also used 4 bolts per cylinder, and they didn't get it right, not even close.

Olds used 4 bolts per cylinder and as far as gasoline engines they got it right, when the designed their diesel based on the same architecture it was flawed, however doubling the compression ration from 10.5 to 22 to one probably had something to do with that. Even though the increased the bolt size they still wanted to leak. I changed a few 5.7 diesel gaskets back in the day.

From your screen name I'd hazard a guess you're a chevy guy, lots of misinformation that circulates about why some feel chevy has a superior engine over other brands. Most of this circulates around the fact that GM made millions of them and they are dirt cheap to buy new and used parts for them. Superior engineering or manufacturing isn't the main reason for their popularity. Without the aftermarket the chevy would be severely handicapped if owners relied strictly on GM factory parts, as Pontiac enthusiasts did for so many years.

If chevy quit producing their own division engines in 1978, or 1981, (depending who you ask) as Pontiac did, I doubt there would be the following that Pontiac has sustained over roughly 40 years.

Which Buick engines? I've had numerous GM engines and never lost a head gasket. I think a factor not mentioned here is neglect and the engine being over heated to the point that the head gasket gives up the ghost. Most of the knuckle dragging public will just keep adding water or pouring in stop leak plugging up the coolant passages. Most of the problems with the later SBC engines were thin castings that would crack between the valve seat before the head gasket would give out. I remember a few years ago going into a machine shop and seeing 6 sets of SBC heads on the counter...all cracked between the valve seats. Yikes.

The prior owner of my Buick 455 used studded head bolts...maybe your right.

[Sirrotica]

Originally Posted by SRR

Which Buick engines? I've had numerous GM engines and never lost a head gasket. I think a factor not mentioned here is neglect and the engine being over heated to the point that the head gasket gives up the ghost. Most of the knuckle dragging public will just keep adding water or pouring in stop leak plugging up the coolant passages. Most of the problems with the later SBC engines were thin castings that would crack between the valve seat before the head gasket would give out. I remember a few years ago going into a machine shop and seeing 6 sets of SBC heads on the counter...all cracked between the valve seats. Yikes.

350 V8
455 V8
3.8 V6
4.1 V6

I worked in a buick dealership from 1982-1985. We were constantly doing head gaskets for customer pay work, as well as warranty work.

Coolant leaking into the cylinders and burning out the exhaust. Coolant leaking externally from head gaskets running down the block. Oil seepage between the head and block. Bowed deck surfaces on the blocks between cylinders leaking compression between cylinders.

The 4.1 V6 had 6 head gasket revisions while I was working there, many times we replaced head gaskets 3-4 times on the same car before the customer either got rid of it, or the warranty expired.

Buick had a real problem from 1970-76 on their V8s, and later on the same problems existed on the V6s until at least the mid 80s. If you overheated a V8 Buick you probably doubled the possibility of a blown head gasket, running one hot (stuck thermostat) was almost a guarantee of a failed head gasket.

Unrelated to the head gasket problem we had a few V6s that had porous castings that leaked coolant, and oil behind the flywheel too. That was GMs worst time that I know of for crappy castings and soft iron from trying to save a couple dollars cutting alloys out of the base cast iron to save money and causing premature wear problems of the cylinder walls.

I had a friend that used to do valve jobs in the evenings for extra money at his house, He bought a pickup truck load of late 70s SBC cylinder heads from a wrecking yard thinking he would get some un-cracked heads to replace the cracked ones he was running into. Out of the whole load of heads, he only got 3 heads out of the whole pile. I would guess 50-60 heads with 3 un-cracked in the valve seat area. 6% good 94% cracked...….LOL.

[Schurkey]

Originally Posted by Sirrotica

I had a friend that used to do valve jobs in the evenings for extra money at his house, He bought a pickup truck load of late 70s SBC cylinder heads from a wrecking yard thinking he would get some un-cracked heads to replace the cracked ones he was running into. Out of the whole load of heads, he only got 3 heads out of the whole pile. I would guess 50-60 heads with 3 un-cracked in the valve seat area. 6% good 94% cracked...….LOL.

Sounds to me like the salvage yard cleared-out their scrap pile. I'm having trouble accepting that that high of a percentage of heads that were "supposed" to be good--or even a random sample of good/bad--would be defective.

I think they knew the heads were bad, and they dumped them on him.

[pastry_chef]

Originally Posted by Schurkey

I think they knew the heads were bad, and they dumped them on him.

Bingo! LOL but people can believe what they want.
Harvesting heads from the yards.. takes me back 25 years

Mark Jones frequently refurbishes and ports castings from the 70s, he builds hundreds of engines. https://www.youtube.com/user/VORTECPRO/videos

[Sirrotica]

Originally Posted by Schurkey

Sounds to me like the salvage yard cleared-out their scrap pile. I'm having trouble accepting that that high of a percentage of heads that were "supposed" to be good--or even a random sample of good/bad--would be defective.

I think they knew the heads were bad, and they dumped them on him.

The deal was, he kept what was good, and returned the rest, no one thought that there would only be only 3 good heads in that batch. I'm friends with both the owner of the yard, and the guy looking for cores. Just a lot of wasted effort for only 3 good core heads. GM put out a lot of crap during that time and lost their market share because of their greed.

Neither party knew what was good, or bad, until it was all over with, and neither party was trying to misrepresent the goods. I know the guy that was looking for good cores wouldn't have even started the project if he had any idea there would only be 3 usable heads out of the bunch, he was pissed he only got 3 cores for all that work.

Of course not every batch of 100 heads were defective to that ratio, or else no one would have bought their cars. (I never implied that in the post either..) There were 2 bad casting numbers that people steered clear of that were later identified, at that time no one yet knew what the ones to be avoided were.

This was right at the beginning of the bad heads, bad cams, SBC debacle. In 1978 I had a 305 1977 chevy Caprice with 17,000 miles with bad guides come in my garage for a ticking noise. At that time if you got 65,000 miles from the late chevy 305, you were blessed. The money making 305 tune-up was common in the late 70s early 80s. It consisted of new cam, lifters, timing chain and gears, pull the heads, and repair the guides and valves that were bad, and a valve job. If the heads were cracked, then new, or good used, needed to be procured. I did dozens of them myself. GM pushed a bunch of loyal customers to other brands during those years, that never returned.