292 y-block pistons: a strange idea

Hi,
Im putting together a 292, and I came across a possible other choice for replacement pistons for 292's and 312's. A cheap choice with some benefits.
My engine was already a 0.060" over 292 (3.810), but i needed a larger piston to take care of the rebore.
SO it turns out that 1982~1985 buick 3.0 v6 pistons (silvolite 1734, clevite TC2225) come in 3.800, 3.820, 3.830, 3.840, and 3.860. They are a flat top piston, and use the same set of piston rings as the y blocks. (sealed power E369K) The best part is that they have a higher compression height than the original y block piston ( 1.808 vs. 1.760).
In my case, then, it looks like the piston will go from being -0.040" in the hole (below deck) to being 0.008" above deck. So, no need to deck the block. this takes care ( hopefully) of the low compression caused by modern composition head gaskets ( which are much thicker than the original.) with some 68cc ECZ-C cylinder heads, im looking at a honest 9.5:1. it also ends up being a 302 ford (basically).
there is a catch.. the original rods have bronze bushings, while the buick pistons use a pressed pin. Even more luckily, tho... sealed power makes a wrist pin in the 0.975" size that is the same length as the buick piston. this means that the pistons and the rods merely need to be honed ( the rod about 0.001", the piston 0.035") and everything goes to gether wonderfully.
the super best part: pistons are $10 each on ebay, and the wrist pins are $6 each.
So the recipe as it is: 302 CI, isky E-4, 9.5:1 CR, 1.54 rockers, ECZ-C heads milled 0.024" with 1.92" intakes, a set of headers, and a unspecified intake system... hopefully it will all work out. and all for less than $1500!(without intake or headers)
I still have to check valve piston interference, but with the E-4, i shouldnt have a problem...well see.

Anyway, comments , questions, contradictions?
john

 

Many Y blocks, in my experience anyway, have decks that are out of true both with each other and with the crank centerline...requiring material removal. You may be able to mill the piston tops accordingly to get things where you want them.

 

Man, I hope that works out for you! It sounds like it would work - and the way you explained it all really makes sense. You've definitely done some research.

Please keep us updated and let us know if all those parts end up working together!

Malcolm

 

You oughtta tell that info to "Y" block guru- John Mummert.

Pretty interesting.

Oldmics

 

How can you have the piston above the deck on a Y-block? There is a portion of the head chamber that is flat to the head. Better hope your gasket doesn't compress too much, and you get no stretch at high RPM.

 

Damn near all modern replacement gaskets i see are like .045 or so if this is the case and you are proud .008" sounds like perfect quench to me .

 

Have you ever looked at how close a Windsor or Clevland head gasket comes to a Y block bolt pattern and bore centers. I bet it's real close. Would a Y block still be a Y block without the wierd intake ports?

 

Check out these pics.... shown is a Argentina made 292 Fase II
the block looks to be unchanged from the typical 292/312 engines
But it has a set of Argentina ONLY cylinder heads...very similar to 289/302/351W heads!!

 

theres no reason you can't just mill .008 off the top of the pistons is there?, i have a set of G heads i wonder what my compression ratio would end up being? i think i'll price a set of pistons myself today. thanks for doing my homework for me..lol

 

Wow. I like the Argintine heads. I looked at Windson/Cleveland gaskets on a Y block head and the bolt holes lined up except for two. Bore spacing was good. Never looked at water holes. Thought about it but couldn't think of a good reason to do the deed.

 

i like it. is the buick piston availible in forged i wonder? y block pistons are fucken expensive!

 

I've heard the thought of these buick pistons somewhere before. So, if they fit ok why not. But, as was mentioned earlier the point of machining a yblock is to get the decks good and square, not necessarily to lower the deck height.
I personally would not spend any money on the c heads, there are better options there.
Sounds like you're doing some good work! Keep thinking! and let us know.
A good source for this project would be Mummert or Ted Eaton in Lorena, TX.

 

so i just got a price on the clevite pistons, there $29 each, how much are y-block pistons?

 

Do an Ebay search on the Clevite #. There's a place with all sizes for $59 a set (you'll need two sets ).

 

Yeah, this is your intro post?!? Damn! Welcome to the HAMB! Thats what we like to see around here.

 

yeah, just doing my part with the research. and im super-cheap.
I just weighed the buick pistons and new wristpins : 715 grams. maybe subtract a couple grams for the broze bushing that was removed, so call it 713 grams.
I think i still have 1 old 292 piston left, ill have to go weigh that next.
We going to put the same piston/conrod in all 8 holes, and well see how much the block is warped. hopefully they will be within a 0.001" or two each time.

By the way, if anyone wants a set of 6x 3.80 buick pistons, or 4x 3.82 pistons, let me know. I need a 2 pcs 1.54 rocker arms, still.

as for the C heads vs. the G heads, they look like they have the same combustion chamber and exhaust port. Im not sure the intake port is too different, Ive never seen dimensions on any of them ( 1.8"x 1.4", etc)
be interesting to know that though. if anyone has a "G" head, could they measure it? When the guy put in the 1.92's, he bored out a nice chunk of meat... so maybe they will be ok. Im not trying too hard anyway.

JOhn

 

I applaud your work, and wish you success!

Re: "I still have to check valve piston interference, but with the E-4, i shouldnt have a problem"

You're referring to the cam being mild?
That might work but I wouldn't count on it.
1. you're moving the dome wayyy up (perhaps 1/3 of the distance to the valve during overlap?)
2. the Buick valves are probably not in the same position laterally across the chamber, so your Y valves won't center in the reliefs
3. the Buick valves are probably not at the same angle either
#2 & 3 may need only minor Dremel work.

However: for this to be financially practical, every dimension and every machining operation must be correct, or you have 8 door stops. Not unknown for the last machinist (who quoted you $100, and done in 1 week) now takes 6 months and hands you a bill for $300 - and did it wrong.
The carpenter's rule: measure twice, cut once.

 

i'll measure my g heads on friday

 

another update: buick pistons & wrist pins :713 g ( 3.820")
original Y block pistons and wrist pins: 767g (3.810")

looks like its time for an engine balancing.

 

Got everything back from the machine shop.. looks like everythings OK, at least with the original cam mockup ... havent got the E-4 yet.
its important to note: neither the old nor the new pistons have valve reliefs, and both were flattops.

Panic: to address your concerns; yes, the flat top ( no reliefs) is 0.048" higher, but the head gasket thickness is 0.035" thicker than original, too. (new felpro composite vs. old tin version) I essentially have 0.035" quench. this is a little thinner than i wanted, as I heard that 0.040" is optimal. I dont think it matters so much after a while. The original quench was approx 0.050".

john

 

The costs for using these pistons:
pistons : $10/each on ebay $80
pins: $6/each from machine shop, may be cheaper on internet $48
press out bronze bushings, hone rod and piston for new pin $40
press wristpins into rods: $40
total: $168.

Thats $50 cheaper than the speedway pistons, ( the cheapest I saw other wise) and the Buick piston deck height, weight, and available sizes are all better.

john

 

I'll just add...
I'm an old Buick 350 guy myself. Forged pistons for the 350 were dis-continued a few years ago. Sadly, this happened just as the re-birth of the "performance" buick 350 was taking place.

There was a lot of chit-chat about piston options a couple years ago on the V8Buick board. The 3.8 and 3.0 V6, along with the 340 and 350 buick engines all use the 3.800 inch bore piston, but all of them are slightly different as far as deck height and valve relief/piston top design.

All of the research has been done in this area, and if your serious, it would be well worth your time to go to the V8Buick site, click on the small block forum, and ask/search there.

I dont want to say it as gospel, but I do remember some talk about the 3.0 piston being a true flat-top with a thick dome that could be shaved and/or relieved without too much trouble... I also seem to remember something about it being available in a forged version.

The Buick guys are currently putting SBC rods into their engines... Any chance of a good [and cheap] rod upgrade for the 292 since your already mixing and matching parts??????

 

Yeah, the block would still be "Y'd" ..

 

So, this is a Y-block then?

 

Yep, although it's an FE looks like a Y to me. Gives the 427's a place for cross bolted mains, don't ya think ?

 

hows this project going?

 

goin good! the pistons are right at zero deck, so maybe I measured all the crud built up on the old pistons to get my original 0.040 in the hole. I think they must have been 0.045~0.048 in the hole originally. Im at zero deck now.
with 0.024 shaved 69cc ECZ-C heads that puts me at 9.1 CR. Lower than i was hoping for, but still not too bad. Im in colorado, so i need all the compression I can get, due to the altitude.

for the con rod question, the only thing I saw that would work would be a Carillo K1 LSX rod from the GM Gen III motors. (6.450" long with a 2.100" journal)
With a 3.30" crank turned down to 2.100" journals, you get a 3.41" stroke. ( with 0.020" oversize SBC 2.1" conrod bearings, its 2.080") bore it to 3.86" and you get a 319 CI.
The buick piston would be proud about 0.038" and its a true flat top, but that gives you some meat to mill... to create a mini dome. If you didnt mill anything, you would have line-to-line interference with the head and a stratospheric 11.22:1 CR!!!!
If you mill a quench ring and create a mini dome out of the buick , you could be in the 9.5:1~10.5:1 CR range, which would still be pretty good.
lots of money with the crank/piston machining and the fancy rods, but the pistons and the rods would be super light! Those K1 rods only measure 620 grams, while normal 292 rods are 680gr. that plus the piston savings and youre saving 100grams + per hole!!! That thing would be a rev meister! This is with garden variety 292 stuff, except for the carillo rods.

wotta crazy idea!
maybe next time
john

 

little bit more accurate cr calc: it would be 10.2:1 CR if you milled off 0.038" to create a zero deck situation. If you left a mini-dome shape the cr would be higher.

The buick rods work with chevy stuff because the chevy journals are smaller and they have the same length as the buick rods.. 6.000"
Y blocks are messed up with their 6.324" length. nothing really works except for LS1 stroker rods. those carillo LS1 6.450" rods are $500 a set.....
sombody go build a high compression 319 y-block!

except for the rods and the machining it would be cheap!

john

 

May I offer something to this informative debate???

Late Chev 292 6 cylinder rods, also have a 2.100" journal size

They are 6.760" long, and have a Pin size of 0.927" and weigh 670 gms

If you were to find a piston from say a Holden V6 which has a real short compression height, you may find yourself with an even lighter combination, and for possibly even less money, seeing as though the Australian dollar is so weak against the greenback.

 

With a 6.76" rod, I found a piston with a 1.446 compression height, out of a gen 2 3800 v6 buick..this would make everything work OK... the problem is that it has a huge dish in it.. approx 25 cc. That would ruin the compression!
o well, ill keep looking.