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1970 442 Piston question V or U notch tech questions
Referring to a 1970 442 and W30
Which pistons were the high compression pistons?
The V Notched or the U notched?
Out of curiosity does Anyone have the size of the recess (how deep)(how far across) .
Did both the 1970 442 and W30 get the same pistons?
Did the 442 and w30 have their pistons sized to the block? A or B cylinder with A or B piston? Then have the letter size stamped on the block next to the corresponding piston and also in the piston?
Referring to a 1970 442 and W30
Which pistons were the high compression pistons? The V Notched or the U notched? To late to go out in the garage to check. Someone or the CSM will clear it up in the morning.
Out of curiosity does Anyone have the size of the recess (how deep)(how far across) . 5/32" deep pops into my mind, but I could be wrong.
Did both the 1970 442 and W30 get the same pistons? Yes. It was the "Select fit" (for more clearance) on the W-30's.
Did the 442 and w30 have their pistons sized to the block? A or B cylinder with A or B piston? Then have the letter size stamped on the block next to the corresponding piston and also in the piston?
Ok so if the pistons were the same.
what gave the W30 higher compression?
Was that just the lower volume of the heads?
I know it's not much of a difference but it still has me
scratching my head wondering the magic.
Ok so if the pistons were the same.
what gave the W30 higher compression?
Was that just the lower volume of the heads?
I know it's not much of a difference but it still has me
scratching my head wondering the magic.
I don't know where that document came from, but it apparently isn't a factory document. This page is from the 1970 Powertrain booklet, which shows that both the W-30s and the base 442 motors were rated at 10.50:1, where all others were rated at 10.25:1. Of course, we know that's not really true, since the allegedly 10.50:1 455 in the 442 used the same pistons and heads as the 10.25:1 455 in the Delta. I chalk up the quarter point difference to the Olds marketing department, just like the AT W-30 with the 285/287 cam allegedly made the same HP as the MT version with the 328/328 cam.
I don't know where that document came from, but it apparently isn't a factory document. This page is from the 1970 Powertrain booklet, which shows that both the W-30s and the base 442 motors were rated at 10.50:1, where all others were rated at 10.25:1. Of course, we know that's not really true, since the allegedly 10.50:1 455 in the 442 used the same pistons and heads as the 10.25:1 455 in the Delta. I chalk up the quarter point difference to the Olds marketing department, just like the AT W-30 with the 285/287 cam allegedly made the same HP as the MT version with the 328/328 cam.
I have several books that say W30 was 10.50:1 and everything else 10.25:1.
Which is funny that you said Olds marketing probably changed it. Which I wouldn't doubt.
The higher compression and little more HP would help the buyer justify the cost of the W30 option.
I've been looking over the specs of the 442 and W30
mainly the 4spd bare bones 442 vs 4spd W30.
Like the E and F heads cc, flow rates and valve size they are iidentical to each other.
Piston's are the same only real thing i really see is difference in the cam and timing curve of the distributor.
Like the E and F heads cc, flow rates and valve size they are iidentical to each other.
Piston's are the same only real thing i really see is difference in the cam and timing curve of the distributor.
We've had this discussion before. The AT W30 motor and the run-of-the-mill 442 AT motor used the same short block - same block, crank, pistons, rods, cam, etc. The E heads vs F heads were effectively the same (same valve size, same chamber size within manufacturing tolerances. The carb jetting was the same. The only difference was the mechanical advance curve in the distributor.
So basically the 1970 W30 was a marketing performance hoax to sell cars? In contrast the other GM big guns like the Stage 1, LS6 and Ram Air IV were substantially better engines than the next lower tier engines. I love the looks of the 1970 W30 cars and own one but I'm a little disappointed it specs out the same as the base 442.
I have several books that say W30 was 10.50:1 and everything else 10.25:1. Which is funny that you said Olds marketing probably changed it. Which I wouldn't doubt. The higher compression and little more HP would help the buyer justify the cost of the W30 option.
I've been looking over the specs of the 442 and W30 mainly the 4spd bare bones 442 vs 4spd W30.
Like the E and F heads cc, flow rates and valve size they are identical to each other. Piston's are the same only real thing i really see is difference in the cam and timing curve of the distributor.
"Several books" could be wrong, especially if they used someone else's numbers. Joe P is pretty good at factory documentation. You wouldn't notice a 1/4 point compression ratio difference if you drove off the new car lot. The W-30 option consisted of several things in a package....most noticeable were stripes and W-30 emblems, and the RED front wheel wells.
"Back in the day", who the heck "justified" the price difference between a "Plain Jane 442" and the W-30 option ? Certainly not me, I wanted it and I ordered it.
What sources are you using to compare engine/powertrain specs ?
"Back in the day", who the heck "justified" the price difference between a "Plain Jane 442" and the W-30 option ? Certainly not me, I wanted it and I ordered it.
What sources are you using to compare engine/powertrain specs ?
No you definitely wouldn't notice the 1/4 point in compression. Some of this talk is with friends who are trying to squeeze out ever inch of HP.
Some of the info was factory like the chassis manual and or published stuff. .
I forget where exacty I found the cc volume numbers.
(Might have been here.) Those also were all pretty much the same. But that could easily change just by shaving the heads .010 same with compression.
I know an engine builder friends who have flow bench tested the heads. The numbers were nearly identical between the E and F heads.
So basically the 1970 W30 was a marketing performance hoax to sell cars? In contrast the other GM big guns like the Stage 1, LS6 and Ram Air IV were substantially better engines than the next lower tier engines. I love the looks of the 1970 W30 cars and own one but I'm a little disappointed it specs out the same as the base 442.
How did you make that leap?
Again, the 1970 W30 with AUTOMATIC trans used the same short block as did every other 1970 442, except for the larger piston-to-wall clearance. This is why you could get power brakes and A/C with that version of the W-30.
The 1970 W30 with MANUAL trans was a whole different engine with the 328/328 cam.
No you definitely wouldn't notice the 1/4 point in compression. Some of this talk is with friends who are trying to squeeze out ever inch of HP.
Some of the info was factory like the chassis manual and or published stuff. .
I forget where exactly I found the cc volume numbers.
(Might have been here.) Those also were all pretty much the same. But that could easily change just by shaving the heads .010 same with compression.
I know an engine builder friends who have flow bench tested the heads. The numbers were nearly identical between the E and F heads.
1. How exactly are you evaluating "every inch of HP" you gain or lose ? Dyno ? Drag strip E.T. ? "Butt dyno" ?
2. Oldsmobile specs supplied to NHRA (1968 to 1970 455) were: head cc's 69.75, pistons below the deck .002", head gasket .018".
3. Some stuff that has been "published" was not correct. I can supply you with a document that can be traced back to Oldsmobile. You can also go to the GM Heritage Center and download the stuff on the 1970 442 (about 35 MB).
4. The CSM can provide some information.
5. "Shaving the heads" is a 1950's term still used today. Actually the decks and heads are milled to remove material. Milling .005" on a 455 head is equal to 1 cc. Typically, you'll need to mill a head about .050" to near the 69.75 cc volume.
6. Concerning E and F heads. "Nearly identical" is a relative term. There was a reason Oldsmobile used F heads on a W-30. On two "street driven" cars, I doubt you would see much difference between E and F heads. On a drag strip with a blueprinted engine, it would make a difference.
Don't take this post as being harsh. I am trying to be very concise and correct.
So basically the 1970 W30 was a marketing performance hoax to sell cars? In contrast the other GM big guns like the Stage 1, LS6 and Ram Air IV were substantially better engines than the next lower tier engines. I love the looks of the 1970 W30 cars and own one but I'm a little disappointed it specs out the same as the base 442.
Be proud of what you have. Have you checked to see if you have the OW transmission used in the W-30 ? On the surface, they do APPEAR to spec out identically. There are many details incorporated into a W-30 that are not visible. They were far from a HOAX. I never worried about the "other big guns". You failed to mention the 440 Chryslers. The closest competition I had locally came from 440 Magnum (Roadrunners/R/T's) and 440 "6 packs".
.........Just my two cents worth.
Be proud of what you have. Have you checked to see if you have the OW transmission used in the W-30 ? On the surface, they do APPEAR to spec out identically. There are many details incorporated into a W-30 that are not visible. They were far from a HOAX. I never worried about the "other big guns". You failed to mention the 440 Chryslers. The closest competition I had locally came from 440 Magnum (Roadrunners/R/T's) and 440 "6 packs".
.........Just my two cents worth.
I have the 4spd.
But have looked over a standard auto and the OW trans and first hand info from a trans rebuilder. There were lots of changes to those trans. The valve bodies were totally custom shift points holding the gear longer Better clutch plates I can't remember everything extra but they definitely weren't stock.
like the W30 carb vs stock carb lots of tweeks.
I'm very happy with what I got. But how my mind thinks I just can't say hey it works. So great! No I must look at every part every detail to find out how everthing ticks and moves and works with each other.
One thing I learned through this post and found out and now have turned some more gears in my head.
The w30 had more piston clearance but used the A pistons. Which makes me wonder why..... wouldn't that also lower compression. Maybe cause some piston slap..... among other performance negative effects.
I have the 4spd.
But have looked over a standard auto and the OW trans and first hand info from a trans rebuilder. There were lots of changes to those trans. The valve bodies were totally custom shift points holding the gear longer Better clutch plates I can't remember everything extra but they definitely weren't stock.
like the W30 carb vs stock carb lots of tweeks.
I'm very happy with what I got. But how my mind thinks I just can't say hey it works. So great! No I must look at every part every detail to find out how everthing ticks and moves and works with each other.
One thing I learned through this post and found out and now have turned some more gears in my head.
The w30 had more piston clearance but used the A pistons. Which makes me wonder why..... wouldn't that also lower compression. Maybe cause some piston slap..... among other performance negative effects.
1. My reply you quoted was for Dragline and I was "assuming" he was unaware of differences.
2. The OW TH400 WAS stock. It was used in the W-30 automatics. I don't understand why you are saying the "specially calibrated" (OW) stuff was not stock. They shipped thousands from the factory.
3. The W-30 carb is a stock carb. There may have been differences you can't see.
4. Tell me where you confirmed that W-30's used only "A" pistons ? You are making some false assumptions. The final clearance was determined after "bore final honing" step. Pistons were chosen that would increase piston clearance in a W-30, be it A, B, C, D or any other letter.
So basically the 1970 W30 was a marketing performance hoax to sell cars? In contrast the other GM big guns like the Stage 1, LS6 and Ram Air IV were substantially better engines than the next lower tier engines. I love the looks of the 1970 W30 cars and own one but I'm a little disappointed it specs out the same as the base 442.
Do you know what was different on a 1970 Buick Stage 1 455 and a base GS 455 engine? Guess what - the short block was the same. The heads were the exact same castings except with 2.13" intake and 1.755" exhaust. They threw in a different cam, carb and distributor. They did even less than Oldsmobile did! Doesn't that make the Buick a hoax too?
Sorry guys, didn't mean to upset the apple cart. I'm well aware of the other subtle differences in the W30 package and I love the styling. Kinda wondering why they didn't tweak all the 1970 442's as W30's since the long block was basically the same.
April 10th, 2020, 05:57 PM
