Car: 1967 Firebird Vert 326

Car is actually my parents. Old BMW's is my thing.

Last year (before I started learning about cars) I was driving the car on a pretty long drive home from the shore. Long story short it overheated and got all sorts of messed up. Took it to the mechanic and he said the heads were gonna need to be resurfaced and need all new gaskets. Leading up to this happening the motor was running on like half power and getting alot of smoke discharge from the breather on the valve cover. Mechanic said what was happening was the seals were all deteriorating from not being run on leaded fuel.

Car will start and hold a rough idle but pretty much no power obviously.

So where do I start. Im used to straight 6's and 80's german engineering.

Thanks guys!

-Jimmy

How many miles are on the engine?

On my first car back in high school, I thought about just pulling the heads and doing a valve job.

A very wise father of a friend, who still had his original '64 GTO and was a die-hard "car guy", cautioned me that if I just rebuilt the heads and slapped them back on a tired motor, I could actually cause more problems.

He pointed out that by rebuilding the head I would be putting my compression ratios back where they were originally. And if my piston rings were also old, the valve job would speed up their failure or perhaps start causing me to have oil control problems.

Old BMW's benefit from just head rebuilding as they are purposely constructed with loose tolerances and are made to be freshened up before the motor. That's why the old BMW staight sixes have high oil consumption and will start burning oil sooner that your typical American V8.

Or at least that's what I was told about my old 320 I had when I was overseas in Germany. I went through a quart of oil about every 500 miles.

Agreed. High mileage engines can be a crap-shoot when repairing them. You only get one "wear pattern" for the rings. The renewed heads will increase pressure, potentially altering that pattern. It will begin to smoke rather soon...

Get another mechanic. There is no relationship with seals and fuel type. STRICTLY "myth and superstition". FWIW, many "modern" techs, though fully qualified for repairing modern cars, are often in "over their head" with older cars. While one assumes the older stuff is less complex (basically true), they have a completely different "set" of strengths and weaknesses than modern engines/cars have.

If the ONLY thing "wrong" is the head gaskets, milling the heads for "flat" shouldn't create the pressure "issue" with the rings, UNLESS a significant amount has to be removed (in excess of .010").

Best of luck. If any further questions, be sure to ask!

Jim

147k Miles the motor. Everything is vins matching so kinda had to dismiss just dropping something else in there. Im obvioiosly not trying to have to rebuild the whole motor and I dont have high expectations for it. Just wanna get it running well and clean for the summer time.

Thanks so much for the help guys

Any more input?

What is the best location to buy parts online and are there any good manuals for doing this kind of work?

147k on an original motor...long past due for an entire rebuild. You may end up spending a bunch of money and end up with something not much better running than what you have now...and then have to spend more. My .02

So whats the best method of attack then?

One of those engine myths that keep on going.

About the only problem that can be introduced is debris in the bores and subsequent scoring of the walls, and that's up to the mechanic to prevent. The rings won't know the difference in pressure as they are subjected to a very wide range of pressure daily. If a slight increase in cylinder pressure could somehow damage the rings, just recurving the distributor would cause problems.

A proper leak-down test on the engine before doing any work would be a good investment so you know what needs to be addressed.

I'd do a full rebuild if it's in the budget and being numbers matching it would be worth it. A stock or mild rebuild should cost you about 3k-4k, less if you just have the machine work done and do the assembly yourself.

Do your parents want to sell the car?

Car is absolutely not for sale. Its already double in value you since we bought it.

So what the general consensus on doing the heads? Yay or nay.

Not enough info to make that decision for you.

If there's a lot of blow-by from the valve cover breather, it's possible that the rings are shot. Do a leak-down test to see if you also damaged the rings when you overheated the engine. Check the timing chain as well.

Repair as needed.

If you are seriously keeping the car, then pull the engine and do a complete rebuild. Then you know where you are at, and can do everything right the first time rather than fix a number of things as they fail. At 140k, do it right. Otherwise you will get frustrated with all the 'constant' repairs and lose interest in the call alltogether.

FWIW, it seems like you don't want our opinion to do it right, so stop asking.

Harsh, didnt know this was one of "those" forums.

Im just trying to figure out what "right" is and what im capable of doing.

Following this chat a bit from the sidelines, I see where it may have gone off the tracks - one of the biggest downsides to text conversations.

The question about selling the car, I believe, came from the point of view of your long term plans for it to gain an understanding as to how much time and money you wanted to invest.

That's when things took a turn. If so, then please do not take offense. There are many of us talking from experience about just making top end repairs to an engine and then finding out the hard way afterwards it was a bad choice.

That said, some of the advice above about a leak-down test and perhaps a compression test, would provide the info needed as to whether a head rebuild by itself is the wise choice.

I back up my comments from above with another bad choice my brother and I did on his old Mustang II 4-banger. He got a remanufactured head, we bolted it on and went for a test drive. By the time we got back from that drive, we had completely destroyed a piston rod bearing due to the increase in compression.

Another way to look at this is that by the time you have pulled the cylinder heads off of one of these cars...

you have done everything necessary to pull the engine out short of removing the radiator (already drained), unbolting the engine mounts, and either unbolting the engine from the tranny or dropping the driveshaft and unbolting the tranny linkages and mount.

And pulling or reinstalling heavy cast iron cylinder heads from a motor while leaning over a fender or radiator support is not much fun and pretty hard on one's back. Much easier to do while standing next to the motor on a stand

Hi Jimmy,

Sorry if I offended you. Everyone here knows I'm looking for a 68 to buy and that I love the color of your car.

Given what I have read; millage matching; it's a no brainer that you should rebuild the engine.

IMO

That was a tuning issue; rod bearings can handle lots of power but not much detonation.

Is it possible that the mechanic said the seats (not seals) were deteriorating? That would make a lot more sense, as leaded fuel kept the valve seats from receding. Once the seats are worn beyond a certain point, the valves can no longer seal the combustion chamber properly and the engine will start missing and losing power.

Did the mechanic do a compression test? It's not as definitive as a leak-down test but certainly will show if the seats are gone. Repairing the heads by installing hardened valve seat inserts will fix that problem, but as has been said, be aware that the engine may need more than that.

Was the engine burning oil before that?

Point being we would have most likely have found a bearing on it's last legs if we have rebuilt the entire motor all at the same time.

My point being that replacing the head didn't cause the demise of the rod bearing.

Rod bearings don't usually go suddenly without any warning, so if it wasn't noticeable before the repair, it was damaged during your short drive, which is usually the result of detonation, which is usually a tuning issue. Just saying.

He doesn't want to rebuild the engine just for the fun of it. I can't say that I blame him. If the short block is in reasonable shape, it could last many years given the average number of miles these cars get driven.

Jimmy, welcome. I just bought a 428 that runs great. I was just going to switch out heads pull oil pan and inspect. When I pulled the pan everything looked good. So I decided to pull a couple of rods to see if ok. I found some scarring on crank and over. 003 clearance. So as of right now the block is getting bored and crank is getting turned. This motor had been rebuilt at some point but not very good. I would at least freshen up the motor. If you know the history on this motor of yours you know what has been done. All the seals have to be worn out. Gaskets must be to. To me you have only one option rebuild the engine. You will be happy you did. Trust me. Joe

I forgot to mention that timing chain,cam,lifters if original to the motor has to be getting very tired or worn. Rebuilt heads on a old cam and liftets doesn't sound like a good idea. As nice as that car looks protect your investment. Or just keep it nice like your parents had it when new. But you have to decide what you want to have done. We just give advice and compliments. Don't get upset and sell it to Gus68 he'll just mess it up. Lol jk

You won't necessarily have valve recession, but you won't know until you pull the heads. I agree with the consensus to pull the engine for a few reasons. One is the ease of working on it at good angles. Next is you don't want to risk denting/scraping the body while maneuvering 60# heads around. And finally, you can get a good look at everything while the heads are off at the machine shop, and determine whether or not to do more.

If you don't know of a good machine shop that knows Pontiacs, find one now. And buy/beg/borrow that leakdown tester and an air compressor to find out what you have to work with. It can't diagnose bearing or cam issues but it will help check rings and valves.

You can expect the cam and timing chain to be ready for replacement. The timing chain may have caused the overheating issue in the first place. That is easily done with the engine out.