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Engine building

7

77jimmyhighsierra

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I am getting ready to build my engine, it's a 350 with a 4-bolt main, and was wondering if it is worth buying a new crank or should I have my stock crank machined. What are the limitations of the stock crank? I will be keeping this carburated and I plan to make this my daily driver and would like it to have more power than it did when stock, but I'm not looking for anything extreme. Any advice on this is greatly appreciated.
 
I had a scatt 9000 cast crank in my 406. I have heard that they are not all they are cracked up to be. Mine had a thrust bearing failure and also cracked. I also think the engine was put together with the wrong bearings for that crank and my power level is estimated 400 hp/525 tq and it was used for towing.

I have a name brand forged crank now, but it went to a crank grinding place to be trued up and then re heat treated. They are not perfect out of the factory. My engine was blueprinted and balanced. The stroke on each piston is not the same, where it is common for it to be off a little on a crank that hasn't been precision turned. It probably won't make much difference on a low power engine, but if you get enough parts that are off just a little, it can add up on how well an engine runs and the longevity.

I was told that the scatt 9000 was good up to about 500hp. Cast is said to give a little and be less prone to cracking, where forged can not flex and will crack more easily. I don't have any first hand experience with the different parts and failures other than what I have run in my engines. It seems that there are always pros and cons to each choice.

It seems that matching all the correct parts and getting them fit up right is at least as important as the quality and expense of the parts.

If you have a decent crank, it might be worth it to have a good grind job. Either way, be sure to use a good bearing and one that matches the profile of the crank. I was told that stock cranks are a different shape, in the radius of the corners of the crank, than the aftermarket units. My engine beat the crap out of it's self due to the crank moving front to back. It ruined the trans as well. It looked like the TC beat up the input on the pump and it sent metal through the trans.

I used a GM crate tbi 350 for my 88 K5. I wanted more power, but the TBI can be a pain for upgrades. So far, the crate engine runs great. My pickup has the 406 and is a daily driver. It is carbed and isn't restricted to power increase like the tbi engines. I have to pass smog, so my options were limited on increasing the power on the 88. The pickup is a 79 and gets smogged to.

How much power are you looking for?
 
I stick w' the stock crank IF you have a competent machinist avail...a cast crank, magged and cleaned up and straight will live up to 6K rpm occasional use...for towing or offroading, it will be fine in the 400hp and under range.
 
I have a stock crank in my small block and its in the 450 hp range. I hit 6500 rpm every time I drive it. And when I am muddin I have hit 7200 rpm lots of time. I did have a good machine grind it. And balanced properly.
 
Stock crank good. As long as they have good reputation and know about a out of round snout and how to compensate accordingly.
 
A stock chevy cast crank will take a ton of abuse, this one is a true factory crank https://www.youtube.com/watch?v=zRaptw7fswY that's my red chevy making a run at 1:30, after that it was only a testing run, its not in order. Its a 400 SBC rebuilt years ago, and then had dart heads added, big single plane, holly 750, and then 150 shot of nitrous. I would put more thought into a 383 stroker kit if your budget allows. Check northernautoparts.com a full 350 kit with crank is about 500, a 383 kit with crank, about 650, a 350 kit without crank is 200, plus probably 100 to turn your crankshaft.
 
Thanks for the advice guys. I will go ahead and use my stock crank, now I just need to find a good machine shop in the area. Should I also use my stock pistons, or are there others that you would recommend? I was planning to get a set of vortec heads for it as well. Not sure about the cam either. This is all new to me. I would like to keep my budget under 2 grand.
 
Chevy911 said:
A stock chevy cast crank will take a ton of abuse, this one is a true factory crank https://www.youtube.com/watch?v=zRaptw7fswY that's my red chevy making a run at 1:30, after that it was only a testing run, its not in order. Its a 400 SBC rebuilt years ago, and then had dart heads added, big single plane, holly 750, and then 150 shot of nitrous. I would put more thought into a 383 stroker kit if your budget allows. Check northernautoparts.com a full 350 kit with crank is about 500, a 383 kit with crank, about 650, a 350 kit without crank is 200, plus probably 100 to turn your crankshaft.
Click to expand...

Thats an impressive truck you have!
 
Chevy911 said:
A stock chevy cast crank will take a ton of abuse, this one is a true factory crank https://www.youtube.com/watch?v=zRaptw7fswY that's my red chevy making a run at 1:30, after that it was only a testing run, its not in order. Its a 400 SBC rebuilt years ago, and then had dart heads added, big single plane, holly 750, and then 150 shot of nitrous. I would put more thought into a 383 stroker kit if your budget allows. Check northernautoparts.com a full 350 kit with crank is about 500, a 383 kit with crank, about 650, a 350 kit without crank is 200, plus probably 100 to turn your crankshaft.
Click to expand...

It won't let me watch the video..... said that its been blocked for copyright crap
 
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