[TRADERMIKE 2012]

Originally Posted by 78w72

Rhoads lifters won't solve the noise that you think was caused by adding 4" dryer duct to the exhaust pipes... whatever caused that noise, it was completely unrelated to the lifters.

The #2 piston being installed in a different direction was not because of weight/balancing... it was most likely not done on purpose or for a "racing" reason, chances are whoever installed them just overlooked it. There is no reason or benefit to install 1 piston opposite of the others.

Still the best kept secret is why the racers put the Pistons in reverse in the first place, no one knows so far?

What do you think about the 87 actual degrees of overlap in the "041" grind vs. the former cam specs overlap only being 60 degrees? Added to any other factors that I have described in this thread, what made the strange noise? I also found two Exhaust Valves sunk into the Heads that are getting new Hardened Exhaust Seats and all the Valve guides had to be remanufactured, using a tool that leaves oil collection/grabber grooves in the Heads valve guide area.

The Head mechanic is milling down the Intake Valve seal Boss area, just like the exhaust seals were already milled for the blue double band valve seals, instead of using the former valve umbrella seals. By the way the umbrella seals were lifted off the boss seats and were moving with the valve stem up and down, adding to air or exhaust loss or reverb, could that have contributed to the noise problem, now that we observed this anomaly? I may be grasping for straws but I don't want to get this motor done and still have some unknown noise show its teeth.

The Head mechanic is not using umbrella seals, this time, on the eight Intake Valves lower boss seals area, instead he is milling the lower boss to fit a blue seal, with two metal bands, that will hold all 16 valve guide seals over the boss, never lifting off, ever. The man is meticulous. Also, I asked why he is not using valve guide inserts made of steel or copper or brass and he showed me the tool to bore in different size oil circular rings, for lack of better terms, into the existing valve guide's inner wall. He claims his way is the better way, can anyone dispute or elaborate on that please?

[Jay S]

It was a good catch by Kenneth to see it had one piston turned opposite the others. Pretty obvious mistake made by someone. Hopefully you get all the issues with the engine sorted out. That probably wasn’t not causing any problems as long as the connecting rod was oriented right, but it needs to be fixed while you have it apart. Make them all the same, either stock, or reversed.

Having the pistons reverse hung puts less force on the trust wall of the cylinder and piston skirt. It is really not much of a secret speed modification, and most of the time does not do anything. Put all the pistons back stock, or leave them backwards, but get them all the same.

Sounds like the machinist is Knurling the guides. It tightens the guide up. It is not close to as good as bronze guides, but is cheap to do when the guides are a little loose.

Changing to Rhoad’s lifter would mean breaking in another set of lifter on already used cam, which seems unnecessary since you have already run it. You probably wouldn’t like the noise Rhaod’s lifters make anyway. Advance the cam to 109, fix the other engine issues and get it back together.

The cams overlap creating a ghosts noise is very very unlikely.

[TRADERMIKE 2012]

Originally Posted by Jay S

It was a good catch by Kenneth to see it had one piston turned opposite the others. Pretty obvious mistake made by someone. Hopefully you get all the issues with the engine sorted out. That probably wasn’t causing any problems as long as the connecting rod was oriented right, but it needs to be fixed while you have it apart. Make them all the same, either stock, or reversed.

Having the pistons reverse hanging puts less force on the trust wall of the cylinder and piston skirt. It is really not much of a secret speed modification, and most of the time it does not do anything. Put all the pistons back stock, or leave them backwards, but get them all the same.

Sounds like the machinist is Knurling the guides. It tightens the guide up. It is not close to as good as bronze guides, but is cheap to do when the guides are a little loose.

Changing to Rhoad’s lifter would mean breaking in another set of lifters on an already used cam, which seems unnecessary since you have already run it. You probably wouldn’t like the noise Rhoad's lifters make anyway. Advance the cam to 109, fix the other engine issues and get it back together.

The cams overlap creating a ghost's noise is very unlikely.

Having the pistons reverse hanging puts less force on the trust wall of the cylinder and piston skirt. It is really not much of a secret speed modification, and most of the time it does not do anything. Put all the pistons back stock, or leave them backwards, but get them all the same.

You said: Having the pistons reverse hung puts less force on the trust wall of the cylinder and piston skirt. It is really not much of a secret speed modification, and most of the time it does not do anything. Put all the pistons back stock, or leave them backwards, but get them all the same.


Mikes reply: I am under the impression that the load on the original factory orientated Piston, with the offset pin that takes the thrust off the outside Piston wall and puts it up toward the inside wall, was genius and a credit to the engineers at Pontiac.

So, if one turns just the Piston 180 degrees on the same Rod factory orientation, defeating the purpose at the very least and causing more undue friction and more wear back onto the Piston outside wall. What was gained in the mind of the racers that performed this trick? What is gained and how do they get a couple of tenths gained in a quarter mile race? Some say it helped on some motors and some say not on others. Unless Blueprinting and Balancing is performed at the same time and who's to say that is the reason for the better performance. Testing on the same Engine both ways is the only way to tell, perhaps they thought of that? Makes me wonder...

[PAUL K]

The factory offset the wrist pin to make the engine run more quiet, it prevents noise from piston slap. Power can be found by installing the pistons so the offset is on the opposite side, now the piston will make more noise but will descend down the bore easier. If you install a piston with positive offset, bring it to TDC and push down on the piston top the crank will spin counterclockwise. If you do the same with a piston that has negative offset the crank will turn clockwise. If you do the same with a piston that has no offset the crank won't turn at all. Not sure how to rate this as to "how big" of a speed secret it is. I guess it's like most secrets. Once you know a secret they are either too good to keep, or not worth keeping.... I'm guessing most folks reading this thread weren't aware of why the factory pistons are offset or if they had any offset at all. But at the end of the day, as mentioned previously the most likely reason one piston was installed opposite of the other seven is human error.

[Stan Weiss]

Originally Posted by PAUL K

The factory offset the wrist pin to make the engine run more quiet, it prevents noise from piston slap. Power can be found by installing the pistons so the offset is on the opposite side, now the piston will make more noise but will descend down the bore easier. If you install a piston with positive offset, bring it to TDC and push down on the piston top the crank will spin counterclockwise. If you do the same with a piston that has negative offset the crank will turn clockwise. If you do the same with a piston that has no offset the crank won't turn at all. Not sure how to rate this as to "how big" of a speed secret it is. I guess it's like most secrets. Once you know a secret they are either too good to keep, or not worth keeping.... I'm guessing most folks reading this thread weren't aware of why the factory pistons are offset or if they had any offset at all. But at the end of the day, as mentioned previously the most likely reason one piston was installed opposite of the other seven is human error.

When there is no pin offset the piston and the rod journal are ATDC together. Depending on the direction of the pin offset the piston will either be before or after its TDC when the rod journal is ATDC.

Stan

[PAUL K]

Originally Posted by Stan Weiss

When there is no pin offset the piston and the rod journal are ATDC together. Depending on the direction of the pin offset the piston will either be before or after its TDC when the rod journal is ATDC.

Stan

Hi Stan, that's probably a better way of saying it, technically

[78w72]

Originally Posted by TRADERMIKE 2012

Still the best kept secret is why the racers put the Pistons in reverse in the first place, no one knows so far?

What do you think about the 87 actual degrees of overlap in the "041" grind vs. the former cam specs overlap only being 60 degrees? Added to any other factors that I have described in this thread, what made the strange noise? I also found two Exhaust Valves sunk into the Heads that are getting new Hardened Exhaust Seats and all the Valve guides had to be remanufactured, using a tool that leaves oil collection/grabber grooves in the Heads valve guide area.

The Head mechanic is milling down the Intake Valve seal Boss area, just like the exhaust seals were already milled for the blue double band valve seals, instead of using the former valve umbrella seals. By the way the umbrella seals were lifted off the boss seats and were moving with the valve stem up and down, adding to air or exhaust loss or reverb, could that have contributed to the noise problem, now that we observed this anomaly? I may be grasping for straws but I don't want to get this motor done and still have some unknown noise show its teeth.

The Head mechanic is not using umbrella seals, this time, on the eight Intake Valves lower boss seals area, instead he is milling the lower boss to fit a blue seal, with two metal bands, that will hold all 16 valve guide seals over the boss, never lifting off, ever. The man is meticulous. Also, I asked why he is not using valve guide inserts made of steel or copper or brass and he showed me the tool to bore in different size oil circular rings, for lack of better terms, into the existing valve guide's inner wall. He claims his way is the better way, can anyone dispute or elaborate on that please?

Just trying to get you off the rhoads lifters fixing or changing the sound you heard thing. The lifters didnt cause the sound nor will new lifters fix the sound.

I got nothin on the overlap difference of the cams, the cam expert members have commented on that, I would listen to what they are saying & get the cam set right with the degree wheel & move on.

Got nothin on the noise issue either, but I said earlier on in this thread the noise wasnt caused by 4" dryer duct on the exhaust, there is not enough back pressure to cause anything you are grasping at like valve seals or exhaust seat issues. Whatever the cause, the reman'd heads will address everything related to "reverb" since you will have fresh heads & no holes in your crossover block off.

Fix #2 piston or leave them all as is if you dont want to touch the bottom end & keep your fingers crossed, or put the pistons back to stock positions & check the rod orientation & bearings.

[TRADERMIKE 2012]

Originally Posted by 78w72

Just trying to get you off the Rhoads lifters fixing or changing the sound you heard thing. The lifters didn't cause the sound nor will new lifters fix the sound.

I got nothing on the overlap difference of the cams, the cam expert members have commented on that, I would listen to what they are saying & get the cam set right with the degree wheel & move on.

Got nothing on the noise issue either, but I said earlier on in this thread the noise wasn't caused by 4" dryer duct on the exhaust, there is not enough back pressure to cause anything you are grasping at like valve seals or exhaust seat issues. Whatever the cause, the remanufactured heads will address everything related to "reverb" since you will have fresh heads & no holes in your crossover block off.

Fix #2 piston or leave them all as is if you don't want to touch the bottom end & keep your fingers crossed, or put the pistons back to stock positions & check the rod orientation & bearings.

Mikes reply: Forget the Rhoads Lifters for now, put Humpty Dumpty back together again properly degreed this time and get on breaking in the Trans. that I rebuilt, well put, that is the way for me to go. I am trying to educate myself with the degree wheel as we speak. The Heads are still in the mechanics' hands for now.

[Jay S]

Read Paul’s comment and picture how that wrong piston is operating relative to the other 7. It is pushing down on the crank crank at top dead center a couple degrees different than the other 7 pistons. That is throwing off the balance of the engine some because the mass of the piston has a different dwell at top dead center than the other 7. There would be no way I can think of that any engine could be balanced properly like that.

In addition to the balance, running the piston offset backwards from stock, it also changes the timing the engine wants also by a few degrees. I want to say it takes less timing by a couple degrees.

It can (and did) run like that, but it is certainly not right.