Chevy 350 Vortec

[muscle]

Been a while since my last post on here but Ive had a hella 2 months with engines breaking.

Some of you guys may remember my 400 sm blk that I built up a while back.

Anyways the air cleaner came loose and the 1/4-20 flat nut holding it on fell into the intake and landed on top of #5 piston between it and the deck.


Say bye bye to the 400

Then a few weeks ago, my '97 chevy work truck broke a crank in the 350 vortec motor. I needed the truck badly so I ordered a new GM crate engine.

It dawned on me that I could possibly build the vortec up for the replacement motor for the Jimmy. So I cracked open the oil pan this evening to have a look and the crank is cracked right through the 5-6 piston journal. (the piston rod was holding it together and why it would still run)

But the engine is a 2-bolt main and I wanted to build up something with at least 400 HP.

Asssuming that the vortec block is good which i have no reason to believe otherwise...

My question is - should i look for a standard 350 4-bolt main block to build up or can I build this 2-bolt vortec up to 400 HP? What would you guys do?

 

[slyguy_22]

the 2 bolt should hold up fine. for added security i you can get splayed main caps, which im sure you already know about. my 400 sbc is bored .30 and its is only a 2bolt and its fine. do you still have the 400 sbc? reason i ask is cause i have the 89 tbi setup on top of mine and im not really happy with it. i was curious if the vortec setup (heads and intake) would bolt to the 400?

 

[76zimmer]

I'd say go with it, The 2 bolt will hold up fine if you keep it below 6000. Use studs for extra insurance on the mains, and ARP rod bolts.
Sorry bout the carnage (twice, watch out they say it comes in 3's)

Good luck.

 

[sled_dog]

vortec roller block is a good base for a build. don't worry about the 2 bolt thing. if you are REALLY worried about it, go splayed like was already mentioned. Will be stronger than factory 4 bolt. Get the block magnafluxed first though. I went through a 4 bolt roller 350 block during my 383 build. It was cracked around the first cam bearing in the timing cover area. Seen pictures of the newer style engines with the entire lifter are cracked up.

They are not AS strong as the older 350s but, if its not cracked, go with it, great build base. Especially for the factor of using the proven reliable factory roller lifter setup. Just get some new lifters(mileage and grenaded engine make me say don't reuse them), and a decent roller cam and you should have a sweet engine when all is said and done.

Sure there is no core charge with the engine you ordered?

 

[1fastchevy]

Also the 1 piece main seals and oilpan and intake and valve covers all seal better, Dave plus+ hate when that damn nut falls off that was a nice small block

 

[dyeager535]

Sleeve that bad boy!

 

[muscle]

Sleeve that bad boy!

I would be concerned with having a sleeve on an already very warm running engine.

vortec roller block is a good base for a build. don't worry about the 2 bolt thing. if you are REALLY worried about it, go splayed like was already mentioned. Will be stronger than factory 4 bolt. Get the block magnafluxed first though. I went through a 4 bolt roller 350 block during my 383 build. It was cracked around the first cam bearing in the timing cover area. Seen pictures of the newer style engines with the entire lifter are cracked up.

Ive had the 400 (RIP) up to 5500 at times so splayed maincaps may be a good idea for this vortec. My next question is can I use the 400 crank in the vortec and build a 383 with it or will i need a differant crank?

I havent tore into a vortec before so Im not knowledgeable as to what can or cannot be swapped in.

Magnafluxing the vortec will be a no brainer . I doubt that the broken crank went any further. the rod caps on #6 is holding the crank together and the engine would run. Nothing grenaded, but yea, I would mag the block.

For now I would use a good intake with my 750cfm holley but would like to eventually go to TBI.

$100 core charge on this engine which is no big deal but thats why Im here to find out if I want to keep it.

 

[dyeager535]

Sleeving would likely make the heat problem a bit less. Net change would be slight if you only sleeved the one cylinder (have to bore out to what the others are) but it's gotta be thick enough to maintain integrity, so likely thicker than the walls the block already has.

Yes, sleeving 8 cylinders would get pricey, but if the others can be run as they are (assuming they are in good shape) $100 would seem small change. That, replecement parts, shouldn't be that pricey should it?

I had a piece come loose in one of my engines (EGR feed tube in an Olds) luckily it was large enough to jam the valve only.

As to splayed mains, I have heard (but read little lately) that the splayed 2 bolt setups are not as great as they were once made out to be. From a post awhile back I was party to, GM certainly removed metal from underneath the mains on 2 bolt blocks (at least later,I checked my Vortec block, it too) which reduces the effectiveness of running bolts into that area. It may contribute some strength, but what will 2 bolt studs do for you, as opposed to 4 bolts?

 

[76zimmer]

So you think a 2 bolt studded main would be a better way to go than a splayed 4 bolt setup on an original 2 bolt main block?

 

[dyeager535]

I'm not saying it is, I really have no empirical data to back that up. I just remember that splayed two bolts used to be talked about as being stronger than the stock 4 bolt setups, and while you still see the splayed 2 bolt kits, they aren't talked about in magazines as much, at least from what I've seen.

And knowing that the mains (webs actually) are thinner on some of the 2 bolt blocks, it makes a lot of sense.

It's just a matter though of whether those 2 additional bolts, if into a weaker area of the block, are aiding in strength at all, not doing a thing, or actually WORSE if it weakens the block in that area. There is, somewhere, an article that discussed all the aspects of the stock 4 bolt setups. Had info all about the effectiveness of those two outer bolts. I don't remember if that was ever posted here or not. Suppose I could google and see what comes up.

Can't find much, still see reference to the splayed caps, but the caps themselves are also not stock, so who knows? I found one article (chev high performance) that says the 2 bolt main 400's are preferred because the 4 bolts are too weak around the mains. No mention of even splayed caps. CHP isn't the end all in correctness, so take their article info with caution.

I was pretty surprised the first time I heard about the splayed setups being weak, but it's been years since then, and the splayed setups SEEM to be less prevalent in the media now than at that time.

 

[76zimmer]

Good info. I'll google a little myself. Thanks Dorian.

 

[muscle]

Yeah Dorian, appreciate that.

I just got back from talking to my machinist and he feels the studded mains are the way to go. He didnt seem to concerned to do much of anything to the mains but since I am building this motor at 400HP, he feels that I would be right on the line where some extra strength wouldnt hurt.

He also made it a point to tell me the timing on such a motor without added strength to the main caps is critical. He says detonation would be the killer to the main caps.

Ill be out in the shop to do a complete tear-down of the vortec motor.

 

[dyeager535]

If you don't mind me asking, is your Vortec block setup for mechanical fuel pump, or is the mounting pad completely gone?

Mine is almost completely finished for mech. fuel pump, was surprised to see that.

 

[sled_dog]

All Vortec blocks still have the provision for mechanical pump, as far as I know of. Just not the lobe on the camshaft.

Couldn't use a 400 crank in the Vortec block. Vortec is a single piece rear main engine. Means you need a single piece rear main crank.

 

[muscle]

If you don't mind me asking, is your Vortec block setup for mechanical fuel pump, or is the mounting pad completely gone?

Mine is almost completely finished for mech. fuel pump, was surprised to see that.

yea mine has a provision for it like sled said which brings up the question of whether i have to run an electric fuel pump.

Forgot about needing a crannk for the one-piece rear seal. I was looking at a scat crank from summit. Maybe go with a rotating assy. What would you guys choose for a crank? the forged ones look to be beyond my budget so I may have to go with a cast.

 

[dyeager535]

I don't know of any particular brand to go with, scat's pretty popular, but I'm sure there are plenty of others out there that are just as good.

The provision for the fuel pump is there, but unless there was ever a blockoff plate on yours, the block isn't drilled all the way through. (or you'd have a perpetual oil leak ) Mine is surface rusty where a plate would mount, as well as "inside", so although I didn't pull the motor, I'm certain the machining for the fuel pump wasn't finished.