[Murf]

Yeah but make sure your idiot light works! That drum work on Ram Jam’s version of Black Betty sounds a lot like bottom end troubles! Don’t ask. ��

[Kenth]

Originally Posted by steve25

Something related to piston noise is being overlooked here I think.

Prior to the the first 400 motor in 67 Pontiac pistons where fully round and in my mind other the the issue of having the rods facing the wrong way on the crank if you had a piston in a motor the wrong way I don’t think you would hear much added noise when cold.

Now let’s look at the 350s, 400s, 428s and the 455s with there inventive usage of a Cam ground piston.

Now if you reversed these pistons, yes to me you would be in for a good amount of cold slap noise, and along with the noise comes ware.

Just some food for thought here.

This is from the 1966 Tempest Shop Manual:

[steve25]

Yes, and thanks for the shop info.

Yes I know the early Pistons where also made with the thrust offset.

[Cliff R]

"I'd agree with Cliff that the pistons had a trough, so thinking they were not off-set. Also seem to remember Pontiac had complaints about piston slap when cold on the SD Birds?"

I have some orginal SD pistons around here someplace hanging on a set of Crower rods but not sure where I stuffed them? They came out of an ill-fated 455 that we lost at the top end of the track at 6400rpm's when the lifter bores caved in. A good lesson is getting a bit too "aggressive" (276/284@ .050" and .750" lift) with a solid roller camshaft in a full race application.....and yes, we have a lifter bore brace in that engine, it just made more of a mess to chean up when we took it apart for inspection.

If I run into them (I'm in the middle of a big shop clean up since retiring) i'll make it a point to check them for pin offset and kindly ask the Moderators to make a "stickie" out of it.........Cliff Out....

[mgarblik]

SD-455 pistons do not use an offset pin. Yes, they have a single complete cut for valve clearance. The rods do have a proper facing ID mark on them . I am refurbishing a stock engine right now. The cold noise maker were the clunky, heavy TRW forgings, the large piston to wall clearance specified, .006"-.0068" factory spec., and the high growth 2618 alloy used to forge them. Personally, I love the sound. Like a well tuned diesel until they warm to operating temperature. No doubt there is an SD-455 under the hood when one starts up cold.

[mgarblik]

Originally Posted by mgarblik

SD-455 pistons do not use an offset pin. Yes, they have a single complete cut for valve clearance. The rods do have a proper facing ID mark on them . I am refurbishing a stock engine right now. The cold noise maker were the clunky, heavy TRW forgings, the large piston to wall clearance specified, .006"-.0068" factory spec., and the high growth 2618 alloy used to forge them. Personally, I love the sound. Like a well tuned diesel until they warm to operating temperature. No doubt there is an SD-455 under the hood when one starts up cold.

SD=Rod and piston pics: Couldn't get them posted fast enough. Sorry for the double post.

[rick38]

I am building a another 455 for my 66 gto 4 speed 3.31 gear car .


I have a 455 .030 over with flat top speed pro pistons and a melling 041 copy cam I have a set of mild ported 6x-8 with heat risers blocked

the heads are about 101 cc now. My plan was to mill about .040 to get about 95 cc What do you folks think ?

Any input would be appreciated Rick

[Jay S]

Originally Posted by mgarblik

SD-455 pistons do not use an offset pin. Yes, they have a single complete cut for valve clearance. The rods do have a proper facing ID mark on them I am refurbishing a stock engine right now. The cold noise maker were the clunky, heavy TRW forgings, the large piston to wall clearance specified, .006"-.0068" factory spec., and the high growth 2618 alloy used to forge them. Personally, I love the sound. Like a well tuned diesel until they warm to operating temperature. No doubt there is an SD-455 under the hood when one starts up cold.

Maybe you could check and see if the SD pistons have the holes drilled thru the oil ring instead of the long slots like the other OEM pistons? I could show some pictures if you don’t follow what I mean. If the SD pistons were designed by TRW and run that much piston too wall clearance I bet they are the VMS-75 alloy, which is closer to a 4032, but the design of the skirt expand’s a bunch and needs a lot of piston to wall clearance. If they had that skirt design with the small holes under the oil ring, they will have quite a bit of piston slap cold no matter what the offset is from that .006-.007” piston to wall needed for the extra skirt expansion.

Just a side note, and I really don’t care one way or the other if someone wants to make a different case for piston offset, but it seems like I have been the only one so far that has built some Pontiacs with the stock type pistons in backward. I have not done a Pontiac with reverse hanging pistons for years. But with their long factory pistons skirts, tall decks, and good rod to stroke ratios, the cold piston slap noise was less than what I hear today with newer LS engines. Some have mentioned some problems with SBC’s and reverse pistons, and that could very well be. I know a lot of people that did that in the circle track world, and on stroker SBC to get more rod to block clearance's on some SBC’s. I think the SBC 400 and even a SBC 350 can do some funky stuff with the pistons reverse hung, the 400 only had a 5.565” long rod, with a 3.75” crank, in a short 9.123” block. The strokers or SBC with a 6” rod did better, but the 400 with the 5.656” rod almost pulls the piston pin out of the bottom of the cylinder, and does not take much to unseal the rings or make noise. Joe Sherman use to claim 15 to 30 HP from reversing pistons on some SBC’s. Engine master’s could find any difference on one of their tests. Smokey Yunick supposedly had some equation that maximized what he thought should be the best piston offset for making power at certain RPMs. Kind of what I remember is he was not on board with the keeping the same offset or no offset, he seemed to think it should vary. He claimed that most the nascar teams were running there pistons in backwards in that era were offset was run in factory backed cars. I have no idea what Pontiac or any of the teams did. Tom Hoover, a Chrysler backed drag racer, whom was also was an Engineer for Chrysler ran the piston is backwards, and did some seminars back in the day for direct connection where he talked about piston offset. He more or less said the reverse offset gained some low end torque and added some extra ring wear. Most of the time is does very little and just adds some noise in cold start ups. Like mentioned, nothing a good stereo can’t cure. Lol

[Jay S]

Originally Posted by rick38

I am building a another 455 for my 66 gto 4 speed 3.31 gear car .


I have a 455 .030 over with flat top speed pro pistons and a melling 041 copy cam I have a set of mild ported 6x-8 with heat risers blocked

the heads are about 101 cc now. My plan was to mill about .040 to get about 95 cc What do you folks think ?

Any input would be appreciated Rick

Start your own thread if you want something answered, or it will be lost in this long thread that is going in circles.

[mgarblik]

The TRW SD pistons have drilled oil drain holes, not the typical open long slot like most cast pistons and some 4032 alloy forged ones. I don't have them handy right now but possibly 3-4 holes on each side about 5/32" each. Not sure about that.

[Jay S]

Originally Posted by mgarblik

The TRW SD pistons have drilled oil drain holes, not the typical open long slot like most cast pistons and some 4032 alloy forged ones. I don't have them handy right now but possibly 3-4 holes on each side about 5/32" each. Not sure about that.

That would explain why the SD455 needed so much piston to skirt clearance. That skirt design expands a bunch.

[Tom Vaught]

Surprised mgarblik that the connecting rod you show did not have a letter code on the rod beam of the rod. Example "A" rods, "E" Rods, "L" Rods, "M" Rods, etc.

Must have been very early rods by the "Forging House" on the Lake Michigan side of the state. I have personally owned rods with all of the letters above as well as Ra-V rods.

Tom V.

[Tom Vaught]

Surprised mgarblik that the connecting rod you show did not have a letter code on the rod beam of the rod. Example "A" rods, "E" Rods, "L" Rods, "M" Rods, etc.

Must have been very early rods by the "Forging House" on the Lake Michigan side of the state. I have personally owned rods with all of the letters above as well as Ra-V rods.

Tom V.

[mgarblik]

It is a very early production engine. The rods are all "A" series. The "A" is pretty faint on the beam. The heads have no casting number and no date codes. Only the complete part number. The above pic with the piston and rod in it shows the "A". Hard to see.

[Dragncar]

Originally Posted by rick38

I am building a another 455 for my 66 gto 4 speed 3.31 gear car .


I have a 455 .030 over with flat top speed pro pistons and a melling 041 copy cam I have a set of mild ported 6x-8 with heat risers blocked

the heads are about 101 cc now. My plan was to mill about .040 to get about 95 cc What do you folks think ?

Any input would be appreciated Rick

You will be fine. But there is a bunch of other stuff to talk about.
Start another thread and we can talk about your build in more detail.

[Dragncar]

Originally Posted by mgarblik

SD-455 pistons do not use an offset pin. Yes, they have a single complete cut for valve clearance. The rods do have a proper facing ID mark on them . I am refurbishing a stock engine right now. The cold noise maker were the clunky, heavy TRW forgings, the large piston to wall clearance specified, .006"-.0068" factory spec., and the high growth 2618 alloy used to forge them. Personally, I love the sound. Like a well tuned diesel until they warm to operating temperature. No doubt there is an SD-455 under the hood when one starts up cold.

My 461 has .006 piston to wall and I can not hear any noticeable piston noise when cold, but maybe I am missing something. You have fired up more of these engines than me. Butler Ross pistons, filled block.
Does sound great though.

[mgarblik]

Originally Posted by Dragncar

My 461 has .006 piston to wall and I can not hear any noticeable piston noise when cold, but maybe I am missing something. You have fired up more of these engines than me. Butler Ross pistons, filled block.
Does sound great though.

Agree with you. I have Ross pistons in a similar build with .006" piston to wall. Very little slap cold. It's a solid flat tappet cam and valvetrain noise is mostly what you hear. A real SD-455 is much louder with that wall clearance, must have to do with the alloy used and expansion rate or the cam grind shape on the skirts. You can really hear them slapping around in there! Beautiful noise.

[Dragncar]

Originally Posted by Cliff R

"I'd agree with Cliff that the pistons had a trough, so thinking they were not off-set. Also seem to remember Pontiac had complaints about piston slap when cold on the SD Birds?"

I have some orginal SD pistons around here someplace hanging on a set of Crower rods but not sure where I stuffed them? They came out of an ill-fated 455 that we lost at the top end of the track at 6400rpm's when the lifter bores caved in. A good lesson is getting a bit too "aggressive" (276/284@ .050" and .750" lift) with a solid roller camshaft in a full race application.....and yes, we have a lifter bore brace in that engine, it just made more of a mess to chean up when we took it apart for inspection.

If I run into them (I'm in the middle of a big shop clean up since retiring) i'll make it a point to check them for pin offset and kindly ask the Moderators to make a "stickie" out of it.........Cliff Out....

If you ever run into that cam card I would be interested in the advertised duration. How aggressive was it ?
Had Tim at Bullet specially take some of the aggressiveness out of my roller cam for safety.
Might cost me 10-12 HP but its better than a mangled mess.

[Dragncar]

Originally Posted by mgarblik

Agree with you. I have Ross pistons in a similar build with .006" piston to wall. Very little slap cold. It's a solid flat tappet cam and valvetrain noise is mostly what you hear. A real SD-455 is much louder with that wall clearance, must have to do with the alloy used and expansion rate or the cam grind shape on the skirts. You can really hear them slapping around in there! Beautiful noise.

When I was assembling the engine and using a piston to square up the rings for file fit I stuck a a piston in upside down and kinda freaked out.
The clearance was HUGE. I thought the machinist made a big mistake. I forgot the tops of pistons are smaller for heat reasons, measure at the skirt.
So I grabbed a roll of masking tape and used it to square the rings up.
Not worth the risk of dropping a piston and having to deal with whatever damage happens.
I know a fella who assembles engines in a area of his shop with plywood over his cement floor. Think I will do the same with new shop.

[Cliff R]

"If you ever run into that cam card I would be interested in the advertised duration. How aggressive was it ?
Had Tim at Bullet specially take some of the aggressiveness out of my roller cam for safety.
Might cost me 10-12 HP but its better than a mangled mess."

"Sadly I lost quite a few cam cards and dyno charts when my last PC Hard Drive took a chit. I had a "mirror" drive installed in the computer and it was supposed to have everything saved on it but I'm computer "stupid" and never once performed or set the computer up to perform the needed operations to make that happen. Well, sadly you just have to pick and choose your career path and for sure electronics HATE me so I stay as far away from them as humanly possible!

The 455 we "lunched" had a long history. I got involved with it back around 1999-2000 when it was topped with stock #48 heads and Comp 292 Magnum cam. In a 3400lb car it was running 12.0's at that time. It's backed by a TH350 and 3.73 12 bolt.

Wanting more power the owner had KRE port the #48's and supply a 260/260 @ .050" flat solid cam for it. That put it solidly into the 10's, but not good enough. Next went on 330cfm Edelbrock heads and roller cam about .650" lift and not overly "aggressive" lobes. That moved it on down to really low 10's, but after a short stint still hot good enough so the last time we "freshened" up the engine it got more cam (very aggressive profile) and 13 runs in BOOM!

The writing was on the wall anyhow as the last time I was in it there was a main cap dowel in the bottom of the pan. Looking back on it and the evolution of the engine and increased power and vehicle performance we simply reached and were exceeding the capabilities of a 1974 455 block....IMHO. As with things self destruct at the top end of the track around 6400rpms difficult to isolate a single cause, or basically what came first, the chicken or the egg? I suspect lifter bore failure or a piston nudged a valve just hard enough to start that snow ball rolling.

Matters not in the end as with those things you basically lift on the intake and carb and throw the rest in the scrap pile!

It was all replaced with a KRE complete 505cid engine package with High-Port heads up near the 750hp mark. That put the car solidly into the 9's at 135-136mph where it still runs at today nearly 20 years later. That engine has only been out once for rod bearings, new valve springs, timing chain and replacing a set of cracked Scorpion roller rockers with Crower Enduro's........