91rs5.0

will a 3.0" crank work with 6.0" rods. the original rods are 5.94"... is there anyway to make it work with 6.0" rods? or is .06 too much of a difference?

formularpm

Out of curiousity, what kind of engine are you talking about?

91rs5.0

350. the crank is out of a 4.3 caprice.

formularpm

Im assuming that the 5.94" rods are from the Caprice too? And you are planning on using 6" rods instead? Assuming the 4.3 crank has the same journal size as the rods, they should work; the piston/deck "height" is what will offset any changes in stroke or rod length. It seems to me that a 302in.^3 piston for a 6" rod would work. I would definitely mock up the assembly and check/modify the deck height though.

91rs5.0

ok. then i'll just get the 5.94 connecting rods from the caprice too. the standard 4.030 pistons will work with those rods i assume.

paul_huryk

Isn't the 4.3L a V6 motor?

formularpm

Depends what you mean by "standard" but probably not. A regular 3.48" stroke 350 piston probably will not work properly with a 3" stroke crank without taking half an inch off the deck height.

91rs5.0

no. i'm talking about the 4.3l v8 (baby lt1) out of a caprice.

91rs5.0

wow, im starting to get a headache. so the 6" rods won't work without different pistons, and the 5.94 will still need different pistons. is there manufacturer that makes these pistons for 3" stroke? thanks

mw66nova

iTrader: (13)

i believe that aftermarket companies will make pistons for the 6" rod, but your gonna have to call the piston maker of your choice to see what's available for your application.

wildman923

Call your local machine shop and have them price out the pistons. Just tell them your building a 302 thats .030 over.
BOB

Fast355

iTrader: (2)

The 5.94" rods will not need different pistons, unless the 265 v8s pistons are still attached. Any piston for a standard 5.7" rod with a 3.48" stroke will work fine. The reason is the compression height is the same on both a regular 350 piston and the baby LT1 4.3. If you take 1/2 the stroke, add the rod length the two lengths will be the same. 3.0/2= 1.5+5.94=7.44 then 3.48/2=1.74+5.7=7.44. Then you add in your compression height and how deep the piston is in the whole and they will be in the exact same place. It is the cheap way to build a 302, although I hope you have a 1 piece rear seal block. I helped build a 267 out of a 305 block , 4.3 crank and those 5.94"rods. the same way and the stock 305 piston worked just fine in this case.

SLP IROC-Z

iTrader: (1)

i take it your building a 302?

you HAVE to use the crank and rods from teh L99 engine (caprice 265 v8) with pistons for a 350 sbc w/ 5.7" rod.

heres how it works

the 350 has a 3.48 stroke, thats .24" longer at TDC then a 3.00 crank assuming both are using the same rods and pistons. so that means the piston wont hit TDC with a 3.0 crank and 5.7" rods UNLESS! and this works out perfect, you increase the rod length to 5.94", i think GM did this on purpose.

3.00" stroke
5.94" rod
350 pistons for 5.7" rod

it works out perfect. good luck with your build, i am going to be putting togther one of these in the future.

91rs5.0

yea thats what i meant by standard pistons, standard 5.7 rod pistons that originally sit in the 350.

so how did the 305 react to the decrease in stroke? was it a lot more rev friendly?

AJ_92RS

Just to warn you ahead of time, you are going to need either special light weight pistons or pay to have Malory metal added to the crank in order to balance the rotating assembly.

The 3.75" bore pistons from a 265 V8 will be considerably lighter than 4.030" standard replacement pistons. So be ready to pay for either one of those two things.

You may find the "uniqueness" quickly wears off once the $$$ runs thin.

my3rdgen

Does the 4.3 V8 (baby LT1) have a 3.00 inch stroke, or a 3.10?

91rs5.0

well, i already have the crankshaft, might as well make use of it. and the rods will cost me $10 a piece.

91rs5.0

3.00, 3.10 is 283 i think.

RB83L69

A 350 crank core will cost you about $50.

$50 = 30-50 HP

That's likely to be somewhere between $1.00 and $1.60 per HP, depending on how you build the rest of the motor. Maybe even less than $1/HP, if you build a REALLY REALLY hot one.

That's the cheapest HP money can buy, BY FAR.

The decision to use that "free" crank won't look so good when you put it together and it's gutless and your "uniqueness" gets totally smoked by people with the same money or less in their stuff, and you realize that you just spent $2000 or whatever, on building this gutless motor; and the only way to fix it is to go buy that $50 core, and THEN re-spend about half of that $2000 all over again.

Think "big picture" instead of "cheapest I can get by with".

91rs5.0

since when are 302s "gutless"? yea i know i can get a 350 crank cheap, but I want to try this out. I already have an lt1 thats goin into my car this month. and if thats still "gutless", it will be a 396 by this summer .

RB83L69

I know what they're like, because I've had a 302 before. Probably before you were a gleam in your mama's eye; maybe even before she was a gleam in your grandma's eye. Built it just about like somebody with this "rev it to the moon" bit would do it; HUGE solid cam, big heads, 4-speed, the whole schmear. Yeah it screamed.... once I got it past 35 mh in 1st gear. Problem is, it took about 12 seconds to get to 35 mph. I got my a$$ handed to me by B210s and CVCCs and Pintos at stop lights.

Some things are so obvious they're easy to overlook. Which in this case is, more inches = more power if all else is equal. You can outsmart yourself all the way around this one, but in the end, it'll still be true.

All I'm trying to do, is to save you from turning your wallet upside-down over a bonfire.

ede

not sure but isn't the big end of the 4.3 rods, or the 5.94" rods differant size than all the other SBCs, 400 excluded?

91rs5.0

chill... i don't want your history lesson. thanks for trying to save me money. when i need help with that i'll call geico.

RB83L69

And here I thought you wanted to hear some reality; instead, all you want is for some other inexperienced impressionable youngster to come along and help you ooooh and aaaaah over your idea. You're the type that's easily distracted by shiny things I guess. But that's OK, you can spend your money any way you like, it's none of my business. Heaven forbid that you should take advantage of someone else's knowledge they acquired the hard way, and would prefer to make all the mistakes yourself rather than listen to someone that's already made a few of them share how to avoid them. Not that there's anything wrong with that; doesn't affect me one way or the other; after all it's your money; it's just ..... well, stupid.

I hope you like tail lights, because you're going to be seeing alot of them soon. With an empty wallet. You won't even be able to buy a look at the front of another car in your rear-view mirror.

91rs5.0

with an lt1 i doubt i'll be seeing many tail lights. the 302 is just so i'll have something to put in the car when i decide to build up the lt1. but i agree with you, the bigger motor will make more power, all other things being equal.

Red Devil

The 302 isn't anything special, and by todays standards, rather worthless- but that's history you don't want to hear.

A stock (apparently) LT1 sin't all that special either, don't bother cleaning your rear view mirror.

If you are as thick with regard to suspension advice as you are with motor advice, it won't matter what you have in the engine bay, you won't be going anywhere quickly.

91rs5.0

I don't know you, and you don't know me, yet your first reply is an insult. I already don't like your smell.

stock lt1 will run low 13s in a 3000 pound f-body rather easily that may not be track respectable, but its street respectable.

Red Devil

You didn't know RB either but had no problem acting like an *** to him.

Last I checked thirdgens didn't weigh ≤3000lbs.... unless your s/n was ODB.

Stock LT1s run low 13's? Define -low- 13's.
Didn't the '95 'vette with an LT1 pull something along the lines of 13.7?
With a curb weight of over 3300 lbs.?
The LT4’s on the other hand dipped into the 12’s
Is that your idea of a 3300 lb. ‘f-body’ in the low 13's??

And it all depends on -whose- street. Particularly since that oh-so-mighty LT1 was replaced with more powerful engines. A 13 second car was respectable around here back in 1991… but wait… that would be history to you huh?

91rs5.0

if rb took that offensively, sorry, i didn't mean any offense by it.
my car weighs 3029 pounds. and I will do more weight reduction on it after I put the lt1 in, but it doesn't matter because I won't be keeping the lt1 stock.

five7kid

iTrader: (14)

For the sake of the technical content within this thread, I took the liberty to edit out the non-technical, rules-violating comments.

For the sake of your TGO status, I'd suggest you all keep it technical and not attempt to stroke your cyber-egos.

AJ_92RS

Or in this case, de-stroke them.

What would be cool would be to put this aftermentioned 302 into a Vega/Monza or the like. THAT would make for a fun car. Put a fart can and bookshelf on it and fool all the Jap Happies into thinking you've got an "old POS 4 cyl." domestic econobox.

But unless you can get an f-body well into the sub 3,000 lb. range I wouldn't bother. You don't really think that GM built the 302 for the Z28 because they wanted to, do you?