Thread: ----l67 vs l32/l26 rods/pistons

I cant seem to find the answer of the differences?

Did the l32s have coated pistons? L26 have forged rods? I am thinking of swapping but would like to know the difference.

L32, L67, L36, L26 is normally the order people go by.

As in L26 have the weakest rods.

I would be interested in some specific specs for pistons/rods

The only answer I have found is


Stronger powdered metal sinter forged connecting rods are used in 2004+ supercharged, and 2005+ naturally aspirated engines, instead of the cast iron style from Series II engines.

Do they share the same rod or is the l32 thicker? Now I just need to find the piston info.

Originally Posted by PWNED

I cant seem to find the answer of the differences?

Did the l32s have coated pistons? L26 have forged rods? I am thinking of swapping but would like to know the difference.

L67's up to 02 didnt have coatings,
the 03/04 L67's (steel pan even though it has the SIII sandcast front cover, it has cast rods) did have coated piston skirts and the crown anodized iirc)
all 04+ L32's have the coated pistons, which arent very great, most of the skirt coating is gone by 75k
the 04+ have "near net weight powdered metal "forged" rods
but they are not forged, they switched to this production metheod because of the multiple cost savings that it led to.

NNW PM rods dont have the weight variance that cast do, save time/material for balancing.
PM rods are brittle so they can machine the big end bore and bolt holes then crack the cap off (no more machining 2 separate components to mate then final machine big end)
the fractured cap also means the cap is self aligning, this is a good thing but the material being brittle to accomplish this kills my joy...

the bean counters are the assholes you can thank for that, though they were smart...instead of major overhaul of their diecasting machines they reworked the molds so that the front covers can be sand cast...saved $ there, only drawback is the rougher oil passages, that can be fixed

Originally Posted by PWNED

I would be interested in some specific specs for pistons/rods

the SC L67/32 have .1" shorter rods than the NA L36/26. SC pistons have a thicker crown and deeper dish, via the ring lands moving down .1"

Originally Posted by PWNED

The only answer I have found is


Stronger powdered metal sinter forged connecting rods are used in 2004+ supercharged, and 2005+ naturally aspirated engines, instead of the cast iron style from Series II engines.

Do they share the same rod or is the l32 thicker? Now I just need to find the piston info.

L32 is thicker and shorter than the L26, both suck, i still shoot for the 03/04 L67/32's that are newer but still have the stronger cast rods. ive seen those rods bend pretty damn good...those PM rods, shatter and leave a helluva mess

btw "forged" in their terminology is that the powdered metal is pressed/forged into shape then the pressing is heated to fuse the metal particles.

it is not a forging in the conventional sense where a hot ingot is hot forged into the shape of a rod over multiple dies thereby giving the steel a grain structure that improves the metals strength...that is a true rod forging

good info there. it's nice to see someone actually understand.

L67 block all day.

id rather have a 94/95 talldeck SI with the smaller SII crank, je forged SII l67 pistons, rebushed forged chrysler 440 rods, symetrical port SII heads

but thats a whole can of worms im still working through with the custom SII phased SI cam and need to fab an intake
someday though ill probably get it up and running with SI asymetrical port heads/intake

1.9 rod/stroke ratio would dramitically reduce the piston thrust of the short deck/high angularity of the SII

i love em all though...vintage engineering thats withstood the test of time

regards, James

yeah, i know. you're a mad scientist with all of your projects, but that's what makes them fun to follow along with.

because i'm not as far along as you would be with knowing how all the parts would intertwine, i'll stick with an L67 block, haha.

Originally Posted by Turbocharged400sbc

L67's up to 02 didnt have coatings,
the 03/04 L67's (steel pan even though it has the SIII sandcast front cover, it has cast rods) did have coated piston skirts and the crown anodized iirc)
all 04+ L32's have the coated pistons, which arent very great, most of the skirt coating is gone by 75k
the 04+ have "near net weight powdered metal "forged" rods
but they are not forged, they switched to this production metheod because of the multiple cost savings that it led to.

NNW PM rods dont have the weight variance that cast do, save time/material for balancing.
PM rods are brittle so they can machine the big end bore and bolt holes then crack the cap off (no more machining 2 separate components to mate then final machine big end)
the fractured cap also means the cap is self aligning, this is a good thing but the material being brittle to accomplish this kills my joy...

the bean counters are the assholes you can thank for that, though they were smart...instead of major overhaul of their diecasting machines they reworked the molds so that the front covers can be sand cast...saved $ there, only drawback is the rougher oil passages, that can be fixed


the SC L67/32 have .1" shorter rods than the NA L36/26. SC pistons have a thicker crown and deeper dish, via the ring lands moving down .1"



L32 is thicker and shorter than the L26, both suck, i still shoot for the 03/04 L67/32's that are newer but still have the stronger cast rods. ive seen those rods bend pretty damn good...those PM rods, shatter and leave a helluva mess

btw "forged" in their terminology is that the powdered metal is pressed/forged into shape then the pressing is heated to fuse the metal particles.

it is not a forging in the conventional sense where a hot ingot is hot forged into the shape of a rod over multiple dies thereby giving the steel a grain structure that improves the metals strength...that is a true rod forging

Do the pre 04/03 l67 have cast rods? What is the SIII front cover you speak of? Sounds like the L67 before 2002 is the best engine for durability.

all L67's from 96.5 to 03.5/04 had cast rods, there are some gray area's though as the parts bins ran empty and the new cheaper parts were slipped into the production line.

ive pulled a april of 04 compG L32 and it was a steel pan/cast rod L67/32 with the SII sand cast front cover. ive also seen a late 04 COMPG with an aluminum pan....

if the donor motor is pulled from a GP, check for the steel or alum pan.

so far all the steel pan motors have been cast rods, the alum pans the PM....if anyone has found otherwise let me know but so far its been holding true...

the SIII front cover is mechanically identical to the SII the molds were reworked for sand casting instead of the more expensive rework to continue die casting them.... they have a rough sand like texture and dont have the indent on the oil filter neck boss like the die cast "smooth" covers do.

03/04 L67 are fine to include in your search...even if it has the SIII front cover

Originally Posted by Turbocharged400sbc

all L67's from 96.5 to 03.5/04 had cast rods, there are some gray area's though as the parts bins ran empty and the new cheaper parts were slipped into the production line.

ive pulled a april of 04 compG L32 and it was a steel pan/cast rod L67/32 with the SII sand cast front cover. ive also seen a late 04 COMPG with an aluminum pan....

if the donor motor is pulled from a GP, check for the steel or alum pan.

so far all the steel pan motors have been cast rods, the alum pans the PM....if anyone has found otherwise let me know but so far its been holding true...

the SIII front cover is mechanically identical to the SII the molds were reworked for sand casting instead of the more expensive rework to continue die casting them.... they have a rough sand like texture and dont have the indent on the oil filter neck boss like the die cast "smooth" covers do.

03/04 L67 are fine to include in your search...even if it has the SIII front cover

Awesome! I really appreciate your info! A lot! What does SIII stand for?

Series III (its what gm put on the 04+ engine covers...even though the block is still cast with Series II)

SII Front Cover




SII Oil passage....(ewwww)




SIII Front Cover




SIII Oil passage, a lot cleaner

Wow I should have realized you were talking about series 2 or 3 my bad. Thank you for the pictures. Wow what were they thinking.

the SII die cast covers have thin flashing from the molding process, this is knocked out (sometimes quite poorly)
the die cast covers have nice smooth passages with only a few trouble spots.

the SII have rough passages everywhere but no real impediments to oil flow.

that said, as long as both oil pump recesses are in good shape between a diecast and sandcast cover...ill chose the die cast as overall the passages are much nicer and its short work to address the shortcomings...the sand cast covers end up taking alot more time to bring em into good shape

My 01 L67 bottom end with 117,000 miles is doing just dandy.