[Stan Weiss]

Yes the pistons were designed with a wrist pin offset and placed in the direction they were to quite the engine on cold start up. In the cases I have seen reversing the pistons at build time did no damage it just made the engine a little noisier. Remember almost all after market piston have no offset.

Stan

[PAUL K]

Originally Posted by Stan Weiss

Yes the pistons were designed with a wrist pin offset and placed in the direction they were to quite the engine on cold start up. In the cases I have seen reversing the pistons at build time did no damage it just made the engine a little noisier. Remember almost all after market piston have no offset
Stan

Agree .... Only issues might be some noise and premature wear. What may cause an issue is if the rods were installed backwards along with the pistons. But if there is adequate rod side clearance that wouldn't matter either.

[Jay S]

Originally Posted by 78w72

I asked this before regarding moving pistons but must have been overlooked... wont moving pistons to different cylinders after the engine has been broken in & ran for awhile cause problems with rings sealing? Or do you keep the rings in the same cylinder swapping them to the other pistons? Never heard of swapping pistons/rings to a different cylinder after break in.

The correct way is hone the cylinders, break the glaze, install new rings. Then swap the pistons.

On a good engine that has a good ring seal you could just swap them bank too bank, and do nothing and most of the time it will be ok. Engine masters did that and had the same dyno results back to back. But on a seasoned engine, your better off deglazing and rering.

I would imagine Cliff honed his 400 SBC out and installed new rings when he swapped his pistons.

I didn’t read what is all going on I guess, sounds like there is some ghost noise that is yet to be tracked down was the reason this was apart???? Good luck

[Stan Weiss]

What I have for Pontiac in '72 is the offset of the pin is 0.063"

Stan

[400 Lemans]

Originally Posted by PAUL K

Agree .... Only issues might be some noise and premature wear. What may cause an issue is if the rods were installed backwards along with the pistons. But if there is adequate rod side clearance that wouldn't matter either.

Saw this happen in the late 70s. Had a 67 GTO that was smoking pretty bad, so i tore it down for a rebuild. I thought it was still all factory but it had obviously been into before. The rods were mixed up to the crank and were tight. They had heated up so much that the big ends and caps had turned blue. Didn't spin any bearings though, but did have a very low, dull knock to the engine.

[78w72]

Originally Posted by Jay S

The correct way is hone the cylinders, break the glaze, install new rings. Then swap the pistons.

On a good engine that has a good ring seal you could just swap them bank too bank, and do nothing and most of the time it will be ok. Engine masters did that and had the same dyno results back to back. But on a seasoned engine, your better off deglazing and rering.

I would imagine Cliff honed his 400 SBC out and installed new rings when he swapped his pistons.

I didn’t read what is all going on I guess, sounds like there is some ghost noise that is yet to be tracked down was the reason this was apart???? Good luck

Thanks for the clarification. With all the critical steps involved in a good rebuild I was surprised nobody mentioned honing & new rings, seems that would be the only way to ensure a good ring seal vs just swapping pistons & already broken in rings to another cylinder where the rings werent broken in at.

[Cliff R]

"I would imagine Cliff honed his 400 SBC out and installed new rings when he swapped his pistons."

Yes, I removed the engine, pushed all the pistons out, but at that time I did NOT know they were in the block wrong.

The pistons were "odd" as back then good options for 400SBC's weren't all that common. Pretty sure they were from HY-DUTY. They were flat tops with two valve reliefs.

The pistons were pulled because of oil consumption and the engine didn't sound right even though piston clearance was less than .002". I discovered a large "F" cast on one side of the pistons while they were out and noticed they were all in backwards. For some reason this set of pistons was NOT notched, or stamped with an "F" on top of them indicating which direction to install them. I made an assumption that they were not offset during the build as they only had two valve reliefs and not marked on top of them.....BIG mistake on my part.

When I discovered the error I had already lightly honed the block and purchased new Speed Pro moly rings for it, so I went ahead and installed them.

With the pistons back in the right direction the engine took on a whole new character and NO MORE NOISE. It also quit using oil completely and I don't remember ever adding to it between changes for the next 90,000 miles. Back then that vehicle (1979 K-5 Blazer) was my main ride, and we drove it all over on vacations, trips to the beach, out to Colorado on Elk hunting trips, trailering my cars to the track, etc, etc. It got a LOT of hard miles put on it and never grumbled once after grumbling continuously for the first 10,000 miles with the pistons in it with the offset the wrong direction.

Folks this is FIRST hand experience, and a costly one. Pistons are fine offset in the right direction, or using them without offset, but rest assured they do NOT like to be installed backwards in the block, at least if you plan on putting more than a few hundred miles on it int he next ten years, or all your miles are 1/4 mile at a time.......FWIW.......

[TRADERMIKE 2012]

Originally Posted by PAUL K

Agree .... The only issues might be some noise and premature wear. What may cause an issue is if the rods were installed backwards along with the pistons. But if there is adequate rod side clearance that wouldn't matter either.

That is good to know! I am looking through my photos @ the bottom end, that are in my archives, to inspect the orientation of these Pontiac Rods in relationship to the Crank in this Engine. If I can't find the past photos, then I will pull the Oil Pan and look, 3 steps forward and 2 steps back, as usual.

[TRADERMIKE 2012]

Originally Posted by 400 Lemans

Saw this happen in the late 70s. Had a 67 GTO that was smoking pretty bad, so i tore it down for a rebuild. I thought it was still all factory but it had obviously been into before. The rods were mixed up to the crank and were tight. They had heated up so much that the big ends and caps had turned blue. Didn't spin any bearings though, but did have a very low, dull knock to the engine.

I posted the schematic in this thread of the lower bottom Crank/Piston Journals, are the #'s in spec?

[TRADERMIKE 2012]

Originally Posted by Stan Weiss

What I have for Pontiac in '72 is the offset of the pin is 0.063"

Stan

My Engine is 1967 Pontiac 428 ci HO.

[TRADERMIKE 2012]

Originally Posted by Stan Weiss

Yes, the pistons were designed with a wrist pin offset and placed in the direction they were to quit the engine on cold start up. In the cases I have seen reversing the pistons at build time did no damage, it just made the engine run a little noisier. Remember almost all aftermarket pistons have no offset. Stan

Mikes reply:
That is good to know also, thank you folks for all this spectacular input, makes for a more thorough investigation/decision on my part, there is no right or wrong way, there is only my way, at the end.

P.S. The best thing to do is knuckle down and pull the Pistons, hone each Cylinder, then install new Bearings and Rings and never look back. Still on the Fence. I can tell you this, we are performing the Pontiac mod., as we speak, the holes in the Block are Taped and we are going out to find the 1/4" Brass/copper Plugs to fill them now.

[TRADERMIKE 2012]

Originally Posted by TRADERMIKE 2012

Mikes reply:
That is good to know also, thank you folks for all this spectacular input, makes for a more thorough investigation/decision on my part, there is no right or wrong way, there is only my way, at the end.

P.S. The best thing to do is knuckle down and pull the Pistons, hone each Cylinder, then install new Bearings and Rings and never look back. Still on the Fence. I can tell you this, we are performing the Pontiac mod., as we speak, the holes in the Block are Taped and we are going out to find the 1/4" Brass/copper Plugs to fill them now.

Mikes Reply:

It turns out that the Block cooling holes were different sizes, so we opted to drill all three, in each Head, to the largest size 3/8" and then taped them /threaded. We found Ace was going out of business in Pompano Beach Fla., they had the 3/8" plugs in Stainless-steel, we used lock-tite to seal the threads and sent them lower than the Block. We elected to use good metal drills that I had used on the I-beam Boat trailer turned into a flatbed trailer. Ranging in 3 different sizes small, medium and say 1/4" ones, then we turned to my (round black) full kit, for metal only, for the final 3/8" cut.

We then moved on to the 421 ci mod. , that is drilling the holes that are in the gasket on the 421 but not used on the 428, except in this instance. These holes are between the center exhaust Valves, my machinist that is remanufacturing the heads concurs that these holes do in fact meet in the Heads water jacket, but he did not drill them for me , so I will drill them myself.

The Heads are not yet completed, but we keep on painting the Engine and compartment. We decided to pull the Fan shroud, so we can read the degree wheel better and paint the Radiator and forward Bulkhead area and then to the rear with a punch-out paint job. The degree wheel reads 1-1/2 degree, Advanced. I think that Butler had that added in because the Intake was 112 c/l and the Exhaust was 115 c/l thus: 115-112 = 3 divided by 2 = 1-1/2 degrees c/l built into this Melling "041" Cam, sold through Butler Performance Brothers.

So, does that mean that the Cam position is correctly orientated in this motor, with the new advanced type Timing chain and Gear? We performed the degree wheel like this , with the Heads removed we installed the dial indicator over the high portion of the Piston top. We determined the top dead center as the piston came up to its highest point. The number one Piston and the Hydraulic Lifters are on the Base circle so, the Valves are closed on the compression stroke. We have Initial TDC. Attached wire hanger and pointed it over the Degree wheel zero mark.

Turned the motor clockwise, the direction it turns in naturally, and 360 degrees later where at zero again, no slop in that direction. Now we turn CCW for 360 degrees and we end up on 1-1/2 degree advanced at the Crankshaft. Tell me if I am thinking correctly, the Cam is now advanced by 1-1/2 degrees Advanced and if I plan on adding more Advance, I could add say four degrees at the Crank and that would give me two up at the Cam plus the 1-1/2 = 3-1/2 total. So, I was told that I am at 113-1/2 C/L from the Melling factory by Butler, so, 113 -1/2 - 3-1/2 = 110. Now if I move the Timing at the Crank another two degrees advanced that would give me plus one at the Cam for (=) total of 109 that is my target advance, what do you think?

The last thing I would like to say is that what if the person that built this Motor actually Blue printed and balanced the Crank shaft and Pistons for race reasons, I know that my father raced and he said he took his Engines for blue printing and balancing on the two Corvettes with 427 ci mills. If I screw around with moving the Pistons around on the Crank, I might just be interfering with perfection? Your thought on this new reasoning please. confused....

[PAUL K]

If the pistons were installed in wrong direction intentionally it is nothing to worry about. It's not uncommon for this to be done. Most likely if the original builder wanted to install the pistons backwards he would have known to install the rods correctly.

[lust4speed]

Originally Posted by TRADERMIKE 2012

Mikes Reply:...We performed the degree wheel like this , with the Heads removed we installed the dial indicator over the high portion of the Piston top. We determined the top dead center as the piston came up to its highest point. The number one Piston and the Hydraulic Lifters are on the Base circle so, the Valves are closed on the compression stroke. We have Initial TDC. Attached wire hanger and pointed it over the Degree wheel zero mark.

Turned the motor clockwise, the direction it turns in naturally, and 360 degrees later where at zero again, no slop in that direction. Now we turn CCW for 360 degrees and we end up on 1-1/2 degree advanced at the Crankshaft....

All you confirmed is you have a respectable 1-1/2° slop in your timing chain - nothing more.

Did you arrive at TDC by taking measurements at .050" before and after TDC adjusting your wheel to arrive at true TDC? After you establish true TDC then you need to find the ICL by the same .050" before and after ICL and record the measurements. Then you can finally figure out whether your cam is advanced and by how much.

[Kenth]

Originally Posted by PAUL K

If the pistons were installed in wrong direction intentionally it is nothing to worry about. It's not uncommon for this to be done. Most likely if the original builder wanted to install the pistons backwards he would have known to install the rods correctly.

Why install #2 piston in the correct direction and the rest backwards?
This engine screems for a proper rebuild.

[TRADERMIKE 2012]

Originally Posted by lust4speed

All you confirmed is you have a respectable 1-1/2° slop in your timing chain - nothing more.

Did you arrive at TDC by taking measurements at .050" before and after TDC adjusting your wheel to arrive at true TDC? After you establish true TDC then you need to find the ICL by the same .050" before and after ICL and record the measurements. Then you can finally figure out whether your cam is advanced and by how much.

It is a good thing that the degree wheel is still attached to the Crank. I will inform my roommate, who did the test wrong, how to do it correctly, hopefully, we can get it right from your method, thank you for your support.

[johnta1]

Here's a link to How To Degree Cam


You will need a dial indicator and the degree wheel at a minimum.
What you have done is basically finding the TDC.
Next would be finding the cam open/close specs and where they are at on the degree wheel.

[PAUL K]

Originally Posted by Kenth

Why install #2 piston in the correct direction and the rest backwards?
This engine screems for a proper rebuild.

I was not aware that #2 piston was installed differently. I joined this party late and because of that I've been hesitant to comment. I just wanted to point out its not a big deal to install the pistons in the wrong direction and if done in a correct manner it will not cause an issue.

Not to long ago I went through a recently rebuilt engine. It was built by a guy that worked as the engine assembler at one of the largest Pontiac performance shops on the planet. He installed those pistons backwards. He told the owner of the engine it was a "speed secret" they commonly used. Just about everything else on the engine was a mess but the piston installation wasn't an issue.

[TRADERMIKE 2012]

Building A Strong Street Machine:

He tested the "041" Cam with Rhoads Lifters and I am going to start researching the cost of the Rhoads lifter. Primarily because of the 87 degrees overlap in the "041" Cam, that is 27 degrees more overlap than the # 524886 Cam that came in my vehicle. Those specs are: 1956-62 3/2bbl Tri-power Rochester's, #6. Advertised Intake and Exhaust is 283/112 .407 .447 60 293/116 .407 .447

"041" Cam specs: Melling spec. 8
Intake 231 @.050", cam lift .313", V/L .470", 112C/L 1.5
Exhaust 240 " , cam lift .313" v/l .470", 115 c/l 1.5

People say not to purchase a smaller Cam, like the former one above. I have the "041" Cam installed currently. So, after speaking to people on this forum and reading the article that I am posting today, the only sensible option is to invest in the Rhoads lifters.

Should I go for the VV Lifter that is used with a Hydraulic Cam, like the one in my vehicle now and keep the 1.5 stock Rocker arms that are also
installed currently? Do you think I need their upgrade, that uses an oil groove on the inside of their quality Lifter, this is an option that they are trying to upgrade people into purchasing? I am street driving this Engine in this 1979 Pontiac TA, "not" racing. Do I really need the extra cost in buying the upgrade in my case? Why sell the unit without the inner groove if they work without this groove? Confused again.

[TRADERMIKE 2012]

Originally Posted by johnta1

Here's a link to How to Degree Cam


You will need a dial indicator and the degree wheel at a minimum.
What you have done is basically finding the TDC.
Next would be finding the cam open/close specs and where they are at on the degree wheel.

John, I bought the Degree wheel and I own the dial indicator. I sent my roommate out with the directions I found on line. He is smart and has done all the hands on this project. He came in and said that he got 1-1/2 degrees advanced. Ironically, this cam came through Butler performance with the intent that I install it straight up. We originally installed this "041" Cam with the dot up at 12 o'clock on both gears and the router pointed at the steering wheel and the piston at TDC on the Compression stroke and both valves closed. We have the Heads sent out being remanufactured at this time and the Intake is off, how hard can this be to find TDC? We are looking at it directly, the roommate installed the dial indicator over the #1 Piston and raised the Piston until it went no further and zero it out. Now we have Initial TDC, we lined up the Wire hanger to that setting. he went CW 360 degrees and came to the same place, then he went CCW 360 degrees and obtained a reading of 1-1/2. What does that # represent? One person stated that is the slop in the timing chain, I thought it might be the Advance built into the Cam by Melling at the factory. This is brand new Timing advance Gears and chain and Cam has maybe 2000 miles on it. One person said we need to find TDC at .050" each way. So, i will show my roommate his and your post tonight and see what we find out. Everything is still installed on the motor. Some were in the archives on my computer, I have TDC, ATDC, BTDC, etc... for all the events. If I can find that information then I can use it to compare my findings, as I learn how to use the degree wheel 101, like a Cam card that I never received with the Cam. The only thing I remember is that Intake is 112 c/l and the Exhaust is 115 c/l and the difference is 3 divided by 2 = 1-1/2 advance degrees that was built into the cam. So, I can install it straight -up. Once we find the actual TDC we can move on to the next step that you're talking about. After that is done, I want to advance the cam, this time safely, knowing where we are truly at.