[Sirrotica]

As Cliff has said, the ridge is a great indicator on cylinder wear. Pontiac blocks stand up well to wear, if they were taken care of.

I have re ringed a lot of 400s 428s and 455s and run them at stock bore with the cast pistons they came with. I still own a standard bore, low mileage 428 that I ran in the 69 Grand Prix race car in my third signature pic, it has TRW forged pistons in it, still ran fine when removed from the race car after 3 seasons.

When I was racing dirt track cars we had a claimer rule on the beginner class cars of $225, meaning a competitor could buy your car if you won 3 races in a row (1975 thru 1982 time period). Obviously with the rule you didn't want to infuse a ton of money into the car, or engine, so I did a lot of engines with just a hone, new rings and bearings, good oil pump and a 068 cam and new lifters, and a fresh valve job, although if the valve seal was good, sometimes not even a valve job.

I did engines for myself, as well as people I sponsored having owned a business at the time. So I did a good deal on Pontiacs with standard bores, stock pistons, and rods. They survived very well in that environment, and as my signature pictures show, I did quite well in my racing career.

When I retired the car in the second picture the engine was sold, and went into a 68 Firebird street car. That engine had 2 full seasons of racing on it. Years later I happened to run into the guy, and he still had the car, but had taken it off the road due to rust issues. He said the engine still ran well, and was looking for another car to put it in. That answers the longevity question.

The engines I built won a lot of races over the time they were in race cars. These engines had acceptable blow by, didn't use oil, and had good power. Overheating them repeatedly though, would ruin the ring seal quickly. Maybe my experience with re ringing a standard bore Pontiac will hopefully give you some insight.

[Nobuddy]

OJ - I'm sure many will disagree with me, but from what you have described I would be tempted to just clean and reassemble the engine then see how it runs. Assuming your inspections find nothing wrong of course. Are the pistons still in the bores?

Might waste some time but it also might be just fine. Doesn't sound like you are going to pound on it or huge miles so what would be wrong about having a survivor 1968 YT engine?

Barry

[gtobird]

The pistons are all out of the engine now so I can inspect them.

One issue is that you can visibly see the coating on the cam bearings flaking off in some spots. I want to hot tank the block, so it would get new cam bearings anyway. I suppose I could just install new cam bearings myself, but I'm not up for a degrease fest anyway so it's going into the shop either way.

From all of the replies I received on this, it just goes to show that I wasn't alone in putting things together without big money in my earlier days.

I find it quite interesting to see the range of replies I received and the rationale supporting peoples comments. I'm afraid that my modest opening question led people to believe I was trying to do this with almost no budget. That's simply not true, but what I'm waking up to is that I don't need to build a big dollar engine when it will only see light use and not many miles. I can then use the money I've saved to get one of those Elon Musk brain chips.

[Scarebird]

If the rods and mains are the OEM kit and in excellent shape, why not reuse them?

Given some of the issues with replacement parts, cleaning and reusing the known fitted bearings might not be a bad idea.

[Nobuddy]

I wasn't really thinking about budget, it was just keeping known good original parts. Assuming of course that they pass inspection.

[gtobird]

One more update. I spent a good deal of today cleaning up the mess I made in my garage and putting things away. During the first part of last winter I repainted the plaster walls and updated the lighting, while adding some nostalgia artwork. It bothers me when I go from being fussy about the looks of the garage to creating a sludge fest.

Anyway, I examined the head gaskets and they look original to me so I cleaned some of the sludge off and sure enough, there was a GM logo and part number 9790910 on the gasket and on the end of the gasket VIC-2-POLD. I believe GM used more than one supplier, but kept the same part number. I'm thinking the VIC-2-POLD means it was a Victor Reinz gasket. If anyone can confirm that, I would find it interesting. Tomorrow I will hopefully have time to examine the pistons.

Also, how / where did GM mark the cams? No question, this one is worn and so are lifters. The cam timing gear looks to have been replaced with a sintered metal gear and the chain had a lot of slop in it.

OJ

[steve25]

In the second paragraph of your first post here you stated that you sent the motor in for machining, so how can you be inspecting the block and cam bearings?

I don’t get it!

[Greg Reid]

Well In fairness he did not say that he sent it in, he said that he tore it down TO send it in.

[Sirrotica]

Victor, and Mc Cord made most of the GM head gaskets from memory. I used to work for the Pontiac dealer when I had just graduated from high school/Vo tech.

I always bought my engine gaskets from The dealer because I could buy only what I needed, and it was cheaper. From formerly working there I knew the parts manager, he took good care of me. When I had my garage I always kept some gaskets in stock, because I specialized in repairing, and modifying Pontiacs.

GM marked the cams usually with single letters on the nose of the cams, older ones had numbers also. Here is a listing on Wallace racing supplying the codes:

http://wallaceracing.com/camcode1.htm

Pontiac marked the front of the cams, aftermarket usually marks the rear. I'm guessing the person assembling the retainer, and timing gears could just glance at the front of the cam while it was in the engine to confirm what cam was installed.

[gtobird]

Originally Posted by Sirrotica

Victor, and Mc Cord made most of the GM head gaskets from memory. I used to work for the Pontiac dealer when I had just graduated from high school/Vo tech.

I always bought my engine gaskets from The dealer because I could buy only what I needed, and it was cheaper. From formerly working there I knew the parts manager, he took good care of me. When I had my garage I always kept some gaskets in stock, because I specialized in repairing, and modifying Pontiacs.

GM marked the cams usually with single letters on the nose of the cams, older ones had numbers also. Here is a listing on Wallace racing supplying the codes:

http://wallaceracing.com/camcode1.htm

Pontiac marked the front of the cams, aftermarket usually marks the rear. I'm guessing the person assembling the retainer, and timing gears could just glance at the front of the cam while it was in the engine to confirm what cam was installed.

Thanks for the confirmation on the head gaskets.


The front of the cam is marked 524009. Looking at the Wallace Racing site, it seems this might be from a 64 GTO or a 421 engine and not native to this engine. I would not find that hard to believe. The cam is quite worn on the lobes and the lifters are very worn as well. Perhaps they were used when installed????? Also, some of the cam bearings have the silverish coating sort of chipped at the front and back of the bearings. I thought this was from wear, but perhaps it's from someone installing a cam and being a bit careless. Does that make sense? It's only the edges of the bearings that have this issue, so I'm thinking it's from catching the edge when installing / removing the cam. The cam timing gear was certainly replaced as it isn't original.

OJ

[Cliff R]

Keep in mind that the "norm" back in the day was to do the bare minimum required to keep the engine in operation. Not uncommon to see used parts in it, top timing gear replaced as some of the OEM's had plastic coated top gears, etc. Most folks back when I started in this hobby had to fart in their pocket to have a cent.

When something went wrong or prevented the vehicle from being used out comes the duct tape, super glue, rubber bands, bailing wire and JB Weld to hold it together so we could keep driving. Hiring machine shops to bore, deck/square, balance, install valve guides, etc was absolutely OUT of the question for most enthusiasts, unless your dad was the CEO of a big company, which didn't happen in my neck of the woods as just about everyone came from a dirt poor farm or their dad worked on an assembly line at a local factory, or self employed in some sort of construction job.

I owned a ridge reamer, hone, cam bearing install tool and a ring compressor. I did the poor mans "rebuild" on scoores of these engines. I remember going to the local junk yard and pulling heads from SBC and 440 Mopar engines just to find a set that didn't need valve guides as I couln't afford to have them installed. I used lapping compound and an old Sears Craftsman drill on the stems to grind the valves into the seat to get a decent seal.

These days we've got a little more money to work with and have learned enough hard lessons from way back then to do a little better job with these things.

As mentioned in my first post your enemy here is tapered wear in the bores, out of round, and wear in the upper ring land in the pistons. Those are the death sentence for a "re-ring" job as the pistons moving up and town 20-40 times a second just works the rings too hard to get any life out of them. If things are tight in those areas nothing at all wrong with going in with a hone to scratch things up some and stuffing some new rings on the pistons. I go just plain cast iron so they get a good bite and medium grit stones on your hone. In most cases it's seal right up and last quite a while.

For the crank just take an old boot lace and wrap it with 600 grit auto body paper and a quick polish on the journals to remove any high spots or minor scratches. Make sure the thrust is tight on assembly, and for sure pound some new cam bearings and freeze plugs in it. A new timing set is a must, Dyna Gear, Melling, Cloyes stock 3/4" wide sets all have metal gears these days and my first choice for one of these builds. They still have USA made Morse chains as well, at least the last time I looked at one which was about a year ago.

The cam and lifters will be the sore spot. So much re-boxing going on you're likely to get SE Asian junk even if it shows up in USA labeled boxes. Flip them over and "Country of Origin" listed on the bottom ranging from India, Taiwan, Mexico, China and half a dozen others just to confuse the buyer. That's be the deal breaker with your "low end" rebuild, gettign a good USA made cam and lifter set........IMHO........

[gtobird]

Yup, I grew up in a small town of 12,000 people and like 90% of the people there, I had just enough money for beer on the weekends. My wife's engagement ring came from JC Penney and it was about $125! I remember doing a rebuild on an engine for my Camaro in the 70s and I couldn't afford a piston ring expander or compressor, nor could I afford new pistons. I scrounged enough for rings and bought some used forged pistons from a guy who raced the local 1/4 mile oval. I remember installing the rings on the pistons with my bare hands and then managed to make a ring compressor from an empty can that I cut vertically with a couple of band clamps on the outside of it. It took all day to get the pistons installed because the rings kept popping out of the end of my homemade tool. When it came to installing the engine, I made a structure out of 2 x 4s and had a $12 buffalo brand come along that I got on clearance. In the end, the engine ran pretty dang good.

I'm not a rich man, but as the song goes today.......... "I have more than I could ask for". Like so many people on this forum, I had to work for it and life really is good in my retirement. How in the heck could our country have moved from a system where everyone that works hard has a shot at a good life to where we are today? But I digress......... Got to go and check out the pistons today. We'll see how this goes.

[Jay S]

I don’t have a lot to add too any of the comments. .005” bore taper is kind of my max that I will consider a rering. More than .005” across all holes or higher it needs bored. With .003” to .005” hold the RPMs to 5000, 5500 max. When he have tried too turn engines with that much bore taper past 5500, via bigger cam or better heads…we pretty much always made them slower. Under boost we pushed past that, I think the turbo compensated. NA with bore taper hurts top end power.

I have had more issues from freshly bore engines with new oversized pistons (and not bore with a tq plate) than a rering OEM seasoned engine.

On a low compression engine for a rering I will use moly rings. On high compression pump gas we prefer too use a cast type ring, like mentioned in that post Mike did in post 3. Or something that is both resilient and can take heat on the top ring, and a moly ring on the second. Best of both then. The cast hold up better with extra heat (like preignition) than the moly. We have had trouble with the moly rings loosing there tension more than cast rings. I have peeled some off the piston like a piece of wire. The moly rings on the top ring, can seem to work harden quicker if it is a high compression engine with bore taper. The bore taper is always the worst at the top of the cylinder were the top ring seats.

[gtobird]

Originally Posted by 400 Lemans

Check the original pistons very carefully for cracks in the ring lands. Almost sprung for a re-ring job cause the bores were still decent but after another careful inspection i found three cracks on no. 7 piston. So since i had to buy new pistons anyway, i went ahead with .030 overbore and forged pistons. Some of the cracks are really hard to see. I used a magnifying glass to spot. From now on i run octane booster and 93 gas.

You are all knowing. Yes, my #7 piston has a crack in a ring land too. How is it possible that we both had the crack on #7? Does that cylinder have weird thermal characteristics that would cause this or just dumb luck that it happened on that one for me. Then again, there might be cracks on other pistons too. When I found that one, I stopped looking closely at the others figuring I need to now go to plan B, whatever that turns out to be.

Today is my birthday, so I can't say this is much of a present. Then again, I haven't accidently hurt myself on this teardown, so I guess I'll have to accept that as the consolation prize.

OJ

[Greg Reid]

You guys are scaring the crap out of me. I'm beginning to think that I need to completely tear my engine back down and go through everything again.
It's like Googling your medical symptoms!

[steve25]

Due to the design of the factory Q-jet Intake number 7 can tend to run lean.

It almost needs to be fitted with one step colder plug then what the rest of the cylinders can live with.

If your not looking to make over 420 or so hp this is a good reason to run the Performer Intake over a non ported stocker since it's hasa better flow balance across all its runners

[Jay S]

Happy Birthday!

FWIW, if the bores are ok plan B can be replace the problem piston with a good one and still move forward with the rering plan. I don’t know for sure, I would have to look, but I would think I would have some STD stock 67 to 75 400 pistons squirrel’d away you could have for shipping cost. The later 71 and later low compression engines don’t usually have issues with ring lands, and may be better candidates for std replacement pistons.. I had a complete set I gave to someone that needed a set of rods. I think I have another STD set somewhere.

[gtobird]

Originally Posted by Jay S

Happy Birthday!

FWIW, if the bores are ok plan B can be replace the problem piston with a good one and still move forward with the rering plan. I don’t know for sure, I would have to look, but I would think I would have some STD stock 67 to 75 400 pistons squirrel’d away you could have for shipping cost. The later 71 and later low compression engines don’t usually have issues with ring lands, and may be better candidates for std replacement pistons.. I had a complete set I gave to someone that needed a set of rods. I think I have another STD set somewhere.

That's very kind of you. Thank you. For the time being I'm going to hold off and think this through. I had similar thoughts to your suggestion. I'm trying to remember what happened to the set of standard size pistons I had from my last engine. It's so long ago, I can't remember if I tossed them out or kept them.

[hurryinhoosier62]

I agree with Mike on plain iron rings. Moly rings require a much finer cylinder wall finish ( 15-20 RA) than iron rings do. The proper way to achieve this finish is to start with a 280 grit stone or dingleberry hone followed by a 400 grit stone /dingleberry hone then finished with a plateau brush. Assemble these cylinders with oil and you WILL induce cylinder glazing. Plain iron rings and a 280 grit hone will give you a cylinder that will seat fairly quickly, especially if you have noticeable taper in the cylinders. Come to think of it, all we had for aircraft recip engines were plain iron ( chrome cylinders) and chrome rings ( steel cylinders). We honed the cylinders to a 280 finish.