SPEEDROCKET

Does anybody know the rod specs for a 350? Can't find them anywhere. Looking for rod length, crank pin, wrist pin, and BE width measurements.

Thanks

InfoJunkie

length center to center.................6.733"
dia con rod bore...........................2.2495"-2.250"
dia pin bore............................ .9789"-.9795"
brg clearance(vertical)............. .0004"-.0033"
side clrnce big end.................. .002"-.013"
hope that helps

Run to Rund

Specs are in the factory chassis service manual.
The data in the post above were probably taken from the 1970 manual, including the errors in it
rod length, center to center is 5.998" to 6.002"
bearing clearance .0005" to .0026"

SPEEDROCKET

Does anybody know, since it's quite hard to find rods for the 350(found a few for the 455) if I were to buy some rods at that legnth and bearing clearance what else I'd have to take into consideration in addtion to that, would be using them with speed pro flat top pistions and for now #7A heads(1/4" A).

Rickman48

I'm sure someone on here has a set of used or reconditioned rods for sale - have you looked in the 'for sale' section??
What happened to your old set?

cutlassefi

You should be able to find some fairly easily if you don't have yours.
Or you can always buy some aftermarket SBC rods, have your crank ground to fit and get a .060 over 350/400 SBC piston. Bunch of options, like this,

http://www.summitracing.com/parts/STL-H860CP60/

By the time you recon your stock rods with the cost of new bolts if you go that way, you can buy a better aftermarket piece.

SPEEDROCKET

I still have my old set, but am thinking of going lighter with the rods, I have cast rods right now and it just seems way to bulky when the pistons barely weight anything.

SPEEDROCKET

That kind of what I'm thinking, exactly what you said about cost of reconditioning the old rods and price of new rods. Although I'm hoping to keep these pistions they are forged aluminum and in excellent condition.

joe_padavano

Note that ALL small block Olds gas engine rods from 1964-1990 will interchange, though 403s used beefier (and thus heavier) rods than other SBOs.

SPEEDROCKET

Seriously? I'll never claim to know much but that I did not know. They just felt so damn heavy I assumed they were cast.

cutlassefi

Stock rods and pistons in a 350 are heavy anyway. If you use the piston I mentioned along with a Scat 6.200 rod you'll lose over 250 grams of weight per rod journal(x4). 454 grams is a pound. That's a bunch.

InfoJunkie

Thats exactly where its from. It's a case of eyes to fingers rather than eyes to brain to fingers.
I'll have to get rid of that book now.

SPEEDROCKET

If I do use the 6.200 rod... is that piston designed to ensure valve clearance up top? Also if I lighten up the rotating assembly does that make it safer to run a little more rpms safely with the stock crank and the bottom end of the 350?

Run to Rund

To add to Joe's post, the diesel 350 rods are beefier and have floating pins with bushed small ends. Stock rods are fine. The place to save weight is in the pistons and pins which are quite heavy by today's standards. If you bush stock rods down to .927" (SBC size) and deck the block 0.050" you can use 350 + .060" (if you don't need to bore the block, just hone it) high perf. ("race") pistons and pins and save 1/2 pound per cylinder.

SPEEDROCKET

The block is ready, its .30 over right now. I have to send the crank in to the shop to get polished, I don't quite know if it needs ground or not. But before I send it in, I want to have the pistons and rods ready, along with harmonic balancer and flywheel so they can balanced it before I get it back. Is floating pins better than pressed?

cutlassefi

Why spend the money to have the stock rods bushed blah blah blah. You're still using 40 year old stuff.

IMO I'd bore it to use a 4.125 SBC piston, grind the crank accordingly and be done. Lots of parts availablilty, much lighter and stronger than stock and will most certainly rev better. I've done it, ran sweet.

JMO.

SPEEDROCKET

What bore would I have to do to get to 4.125? What's .30 put me up to in inches?

InfoJunkie

Block,crank and heads are still 40 years old.
Pistons should be bought before the block is bored so they can be fitted for proper side clearance. Your kinda stuck now with Olds pistons and rods unless you want to bore the block again. The idea is collect all the parts first then proceed.
Stock 4.057 +.030= 4.087 you have another .038 to go

captjim

Excuse me but you did say you were using speed pro flat tops, right? barely weigh anything? Those things are friggin tanks by today's performance standards. They are strong and reliable, though. I have them in my current 355, IIRC the bob-weight with stock rods was 2220, yikes! For a small engine, that is HEAVY.

At this point your best bet is just to use the stock rods and the pistons that you have. Plenty of guys have gone quick enough safely with that combination of parts, just build it a tad loose, balance it, and you'll be fine to 6,000 rpm and 450 HP. Like Junkie stated, best to research and collect parts first. So, unless you want to start over.....

SPEEDROCKET

I would like to use them if I can, if not, I may just sell them off and start over not sure yet. There are 100 different ways to go here and I'm trying to hash it all out by bouncing ideas off you guys. The pistons that I have though are forged aluminum, and what I have to compare them with(havent' put them on a scale or anything) but they don't seem much different in weight then a 4.6 ford piston. The whole issue I'm having here is that the engine is apart and I'm trying to do it all right the first time and not do anything that makes me want to tear it back apart again to change something (the reason I'm where I'm at now, becuase it just didn't seem like it ran right)

In the end though I could just use what I have I just hope it feels like I hope it will on the *** dyno, lol. Just trying to cross my T's and dot my I's here. Thanks for the input.

What do you mean by building it a tad loose? where would be the important areas to be loose in?

SPEEDROCKET

True and good point everything is at least 40, lol, thanks for the measurments.

captjim

By loose I mean the main and rod bearing clearances, rods at .0025 and mains at .0030

As always, it comes down to goals, budget, and what you plan on doing with the car.

SPEEDROCKET

Well I want something I can drive daily if I choose to, or go play occasionally at the track, not something I do to often though. Budget is kind of up in the air at the time, because I don't have a car to put it in yet whereas last time I did, so I took shortcuts and cheap ways out to get the car back on the road. I want to have the motor and tranny completely ready for the next car I buy so I don't fall into those habits again. The reason I stated all that is because I can take my time and build the motor right this time putting money into it as it comes. Hope you understand what I'm trying to say with that, lol.

I mean if I can capitalize completly off of the rods and pistons I have I'm willing to run with them. I was just worried about weight and strength of the rods. Also kind of wondering if that minor weight reduction(2lbs or so) from the rods would take a little stress off of the crank and lower end of the engine and caps. Making an engine that I shouldn't have to tear apart again as long as I own it. As you can tell I'm not an expert here, but know enough to break something, ha, and have, twice!

cutlassefi

x2 what CaptJim said. If you do everything right, check the rods, resize if needed, balance it and make sure clearances are correct you should be fine. Then you can devote your time and money to the heads.

When you cut corners, that's when you get into trouble.

Run to Rund

Cutlassefi, please let me know when you find an off the shelf 4.125" SBC piston with close to 1.61" compression height.

cutlassefi

Don't need to, Scat 6.200 rod+1.425 Comp Distance piston, half of a 3.400 stroke (gotta grind the crank anyway to fit the rod, 1.700)=9.325. I believe that's right about the avg deck height of a SBO. The piston number I gave was a 4.060 with a 1.425 comp distance. Or you can bore it to 4.125 and use a 400/5.7 rod SBC piston with that same rod. Any other questions?