weakest points of a 350?

[brett_s]

Hi,

I've been following all the recent posts in regards to the buick 350, and have found it incredibly interesting. My question is, what are the hp/rpm range where certain parts will fail (approximately)?
Assuming you had enough head flow, and a good intake (hopefully someday), at what point do parts of the rotating assemebly become the limiting factors? What can be done to remedy the limitation? Same thing with the valve train. Also, are there better years for certain items such as connecting rods or crankshafts? What about oiling system problems, does the 350 have the same issues as the big block?

What rpm/hp levels do the following items become questionable?
Block?
Connecting Rods?
Crank?
Valvetrain?
Bearings?
Oilling system?
Etc.

Thanks in advance for the education. Someday in the near future, I'd like to be able to get a nice 70-72 gs350, and would greatly appreciate the education on the motor. Hopefully someone out there with enough experience would be able to shine a light on this for me.

Thanks,
Brett

[Sean Buick 76]

Quote from Bill Mah regarding the stock rods:

"We had mine hummin' at the 700hp mark before we decided to have the billet rods made. That was also in excess of 7k rpm.
The late model rods seem to handle the pounding well."


Quote from Darryl Roederer, A.K.A. "Professor Buick"

"Jim- The rods WILL be the limiting factor, and will fail somewhere around 575-600 HP in the 6500 RPM range..... WATCH OUT!!!

I'm assuming your running "late" style cap screw rods in this engine? Side beams polished? Balancing pads "shaved" to reduce weight??? Mine were completely polished on all surfaces, sonic treated, and hard chromed... and 600 HP was "THE LIMIT"! Tho I was running heavier 10:1 "street" slugs and nitrous. With the "light weights" your using, you may have bought a little insurance."

Another from Darryl Roederer:

"Bud's engine made 580 HP at 6000 RPM [rev-limited] and was clearly capable of over 600 with more revs.
It used 10.5:1 forged slugs, MILDLY ported heads, small tube headers, that intake, Holly 900 cfm 3V carb, and a hot ignition.... And a HUGE cam.

Everything else inside the engine was pretty much built up from stock parts!

I do remember that engine had MEGGA torque in the 4000 rpm range, pulled like a hot big block, and it kept it's power right up to the 6000 limit.

With the tunnel ram, my engine[s] made 540 on motor alone at 6500 with a smaller cam and the same mild heads. We tried to feed 200 hp worth of nitrous into it, but expirenced that gut-wrenching rod failure at about 6200 revs..... TWICE. That's right, I built two motors,,,, and blew both of them up on the dyno."

[Sean Buick 76]

Unlike the 455 Buick the 350 Buick have a Y block design which is stronger by design.

We haven't really hit the limit for the blocks yet. Bill M got a block to hold together at over 1000 hp for a bunch of runs...

The only blocks that have been lost have been from another part breaking and causing a chain reaction ending in a broken block.

The valvetrain is good on these motors just make sure you use good springs when you upgrade the cam. The roller rockers are good but not nessisary for most builds (there is a seperate thread on this).

[gsjohnny]

Hi,

I've been following all the recent posts in regards to the buick 350, and have found it incredibly interesting. My question is, what are the hp/rpm range where certain parts will fail (approximately)?
Assuming you had enough head flow, and a good intake (hopefully someday), at what point do parts of the rotating assemebly become the limiting factors? What can be done to remedy the limitation? Same thing with the valve train. Also, are there better years for certain items such as connecting rods or crankshafts? What about oiling system problems, does the 350 have the same issues as the big block?

What rpm/hp levels do the following items become questionable?
Block?
Connecting Rods?
Crank?
Valvetrain?
Bearings?
Oilling system?
Etc.

Thanks in advance for the education. Someday in the near future, I'd like to be able to get a nice 70-72 gs350, and would greatly appreciate the education on the motor. Hopefully someone out there with enough experience would be able to shine a light on this for me.

Thanks,
Brett


only problem i know of is 'dont hit the wall'...........:LAUGH:

brett, i would answer the questions, but apparently you have read it all the threads. thats great. get a 350 and join in the fun.:TU:

[Sean Buick 76]

Childs & Albert have made 8 rods

Eagle has made 1 custom crank

[brett_s]

Thanks for the reply guys. From what you have said, the weakest point is the rods, somewhere in the 6500 rpm range and 550-600 hp when properly worked with cleanup and good rod bolts (similar to a big block which I know more about). You also refer to using later "capscrew" rods. Again, since I don't know much about the sbb, I need to plead ignorance here. What years/models used the capscrew rods? What's the limitation of the non-capscrew rods? What's the limitation of the stock capscrew rods? Are these cast or forged rods?

Apparently, the block is a non issue and the stock crank is fairly stout. Valvetrain is fairly decent. What about the oiling system (again, i'm more familar with the big block buick and all the things required to keep that together)? What about cam bearing issues like the bbb? Are you guys using special cam, rod and main bearings, or running stock type?

If I wanted to build a very strong street/strip motor, somwhere in the 450-460hp range, what would it to make it live a long life?

Sorry to keep pestering you all, but I'm fairly intriqued buy this motor?

Thanks,
Brett

[Sean Buick 76]

I'm not sure what year the capscrew rods came out, they are just a stronger setup than the older ones. I'll take a picture and post it.

If you want 450 hp you'd have no problem with a properly built stock bottom end. Head porting, large cam, you'd be there without any aftermarket parts other than headers and intake. The TA intake seems to be the best but could use a little porting.

[BignastyGS]

I'm not sure what year the capscrew rods came out, they are just a stronger setup than the older ones. I'll take a picture and post it.

If you want 450 hp you'd have no problem with a properly built stock bottom end. Head porting, large cam, you'd be there without any aftermarket parts other than headers and intake. The TA intake seems to be the best but could use a little porting.

73 and up are generally cap screw rods. I have 3 pistons/rods that I took out of a motor I trashed that I can make a deal on if someone needs them. They are OEM,but not harmed as far as I can tell...

[sbbracer]

The rod swith over was in 73. I have found 73 with both types of rods on them. The cap screw rod will be fine in all street combo,s up to 550 hp - 6000 rpm. You may also want to add baffles in the pan to stop oil from leaving the sump aon hard acceleration. This is key for drag racing.
Dan

[Sean Buick 76]

Good tip on the oil pan baffles.

[regal1973]

The weakest point I’ve personally encounted was the plastic rocker positioners two snapped while the car was on the dyno which bent 2 push rods & the dyno had to be aborted. Been to shy to take the car for another dyno run.

[BillMah52]

The weakest point I’ve personally encounted was the plastic rocker positioners two snapped while the car was on the dyno which bent 2 push rods & the dyno had to be aborted. Been to shy to take the car for another dyno run.

Good point to bring up! If you stay with the stock rocker setup it would be a wise move to install all new nylon buttons on the rocker shafts. They get brittle over time and the occassional change isn't too tough or expensive.
Much easier than having to change pushrods!!!