Keith

First, lets get out of the way that I am cheap.

OK, now onto the question. Please correct me if I have anything wrong.

LSx deck Height = 9.24"
5.3, 5.7, 6.0L con rod length is 6.098"
5.3, 5.7, 6.0L stroke is 3.622"

(3.622"/2) = 1.811"
1.811" + 6.098" = 7.909"
9.24" - 7.909" = 1.331" pin height

I get a 1.331" piston pin height doing all the math.

A 4.8L con rod is 6.298"
4.8L stroke is 3.268"

(3.268"/2) = 1.634"
1.634" + 6.298" = 7.932"
9.24" - 7.932" = 1.308" pin height

1.331" - 1.308" = .023" difference

Could I run a 6.0L block and pistons with my 4.8L crank and rods?
I come up with this combination sticking .023" out of the hole. Is that too much? Could I mill the pistons down a bit? This combo wil probably go in my truck after the warranty runs out. That way I can get the block, season it with a lot of heat cycles and run it for some miles, while I save up for a 408 rotating kit.

Am I crazy?

Thanks.

Keith

bueller?

bueller?

bueller?

vanillagorilla

iTrader: (1)

He's too busy driving an antique Ferrari.

Anyway, let me get this straight. You want to take a 6.0L block, and 6.0L pistons and stick your 4.8 crank and rods in it? I agree with your math, and that the pistons would be .023" out of the hole, but IMO that's way too much! Plus, depending on what 6.0L pistons you get, you might not be able to mill anything off of them. I think an LQ4 piston is dished a little. Plus 6.0L have bigger combustion chambers in thier heads, so with the 4.8L small cc size and being .023" out, I think you would have some crazy compression ratio.

Displacement would only be 328.5cid, which is a tad bigger than a 5.3. With the amount of work, cost (machining), you would be more in it than if you bought a stock 6.0L. I know what its like to be on a budget, but if I were you, I'd run the **** out of the 4.8, and when funds are better, apply all your knowledge and experience to the 408.

So yes you ARE crazy!

Nice times too, I feel your pain.

silent1

iTrader: (3)

Yes you can run the 4.8 rods and crank but, .023" is waaaaaaay too much! You'd need to run a head gasket in the .070" compressed thickness range. Even then you'd run the risk of compression rings popping out of the cylinders.

Deckhand

iTrader: (1)

or couldnt you just use the shorter connecting rod off the 6.0L , and just use the 4.8 crank?

ktmrider

There have been quite a few folks mulling this question recently. They are looking to make short-stroke motors that will rev to the moon, similar to the Z28 302 CID motors GM produced for the Trans Am series. It also puts the CID very close to the "old" 327 size, important to some for nostalgia reasons.
Richard/SS did quite a bit of conversion calcuations. You can do it with specific mods but in the end cost was a driving factor. Not worth the price of admission for a one-off engine.

Andy1

Fandango,

From a previous thread that I started, the pin hieght difference is only .003 -.004". To correct your specs, the 4.8 rod is 6.278", a difference of exactly .020".....which is where your error is. On paper, the combination will work. The whole advantage with your proposed swapping of parts, is that you get a short stroke 5.3 (4.00" x 3.278" b/s) with a superb rod ratio. If you retain your 4.8 heads, the comperssion ratio even works out well at I believe 9.66:1.

The price of admission would be to take your 4.8 rotating assembly and heads, get a 6.0 block and pistons, and you're good to go. Basically, a piston and block swap. Now whether this motor would be best suited for a truck application is another issue. However, chevy did put this old style 327 with this b/s combination (4.00x3.25) in many many trucks. Either way, the 327 is arguably the best motor Chevy ever built.

Andy

Keith

edit - missed Andy1's post.

Hmm, this almost sounds too good to be true, it might just work out.
somehow I forgot your post.
Thanks for the corrections.

Andy1

Since I'm close to making a decision to build the short stroke 328, I wish that someone would offer a performance 6.0 hypereutectic cast piston. Only one's offered are not performance versions, but OEM replacements (not heat treated). I recently called United Engine and Machine, manufactrer's of KB and Silvolite (and maybe others'). They advised me they have no plan, at this time, to manufacture a performance hypeutectic piston for the 4.8, 5.3, 6.0. When I asked about piston slap, they simply said Chevy designed the piston skirts too short. FWIW.

Andy

Keith

I understand your want for a quality 6.0 piston, but would the stock piston work for now?

I guess it's either forged aftermarkets or stock ones.

I wonder if any other piston has the same or near the same pin height as the 6.0 ones? Like maybe out of a dodge? ford? Might be a cheap alternative, if there is omething available like that.