I bought a 90 RS with a 350 TBI said to be truck engine.The guy said it lost oil presure and would not start back up.Took the engine out and droped the pan.Removed spark plugs for easy hand turning.There was trash on the no. 8 spark plug and oil around the head gasket in that area.The oil was thin burnt smelling and smelled of gas.In the bottom of the pan looked like some gasket chunks.no large metal pieces.on top of the oil pump arm was some sludge with fine metal flakes.very fine.When I rotate the engine buy hand it turns freely but has a clack sound only in the no. 8 cylnder area up high . like a valve or somthing. For the fun of it I'm going to take it apart.How can I tell if it's a 4 bolt main or a 2? Can I put a tpi set up on this thing or is it more trouble than its worth?I'll get back in a few days with more info on what shape the crank,cam and cylinder walls are in.Thanks for your input.

 

Only way to tell how many bolts the mains are is to look. They stopped putting 4 bolts into the regular vanilla 350 trucks around that time. You usually had to gt a 2500 or 3500 to get the 4 bolt 350s.

 

I agree with Infernal on the 2 or 4 bolt question. 4 bolt blocks were a lot more common in the trucks, but it's a crapshoot as to whether yours is or not. Best way to find out is simply removing the oil pan and taking a look. You can easily bolt up a TPI unit to that motor, however the TBI heads flow like crap, so it'd run better if you got a set of the 083 casting heads that came on the TPI 350's. Another downside to the truck blocks is most of them came with flat tappet cams instead of the hydraulic roller cams. Some were machined to accept the factory roller valvetrain, others weren't, so that's another crapshoot with a truck 350. Even though the TBI 305 motors that came in the cars are pretty anemic powerwise, at least they all had the factory roller cam.

 

What do I look for?What has 2 or 4? Is a Stock 89 iroc with a 350 TPI a 2 or 4 bolt?What advantage dose the 4 bolt have over the 2? I heard my brother and his friends talk about them back in the 70's and the were all excited about 4 bolt engines

 

It's just an extra bolt on the main caps. the 3 middle caps have an extra outer bolt. Not as strong as an aftermarket splayed 4-bolt, prone to cracks. If you're making enough power that 2-bolt blocks are a problem you need splayed four-bolts IMO.

But as iwth most of these things, people get all hung up on these old school ways of thinking and 4-bolt was one of those big buzz words.

2-bolt


Factory 4-bolt


Splayed 4-bolt - made from a 2-bolt block


Best thing to do with a 4-bolt non-roller block is to hock it some old school dude for money and get a roller block with the proceeds.

 

thats good!Now that did help answer my big question.Are or 3rd gen. 350's 2 or 4. i'm not taking it apart to find out.Just curious.Thanks again

 

Generally only Corvettes and trucks got 4-bolt mains. I know any factory 3rd gen motor should have 2-bolt mains.

 

Sounds like you just need it honed out and possibly bored out and a new set of rings slapped in there, especially since you're hearing a slapping sound in the No. 8 cylinder. You can put any type of fuel/intake system you want on your engine, but the easiest thing to do would be to just keep the TBI and have your engine rebuilt, but it depends on what all you want to do with it.

What's interesting is that my engine builder advised me to just pay to have him stud my 2-bolt block, and it's going to be above 500 flywheel hp.

I guess he knows what he's talking about since he's been building engines for 30 years.

Even with his advice, I like the idea of a 4 bolt splayed setup, just for peace of mind that the main caps won't crack as easily.

 

with metal sparklie's he probably needs a magnaflux, all new bearings including cam, good hot tanking, and at the very least a hone if not a boring as well. Also the crank should be cleaned up as well as the rods if they're going to be reused, or simply replace the entire rotating assembly, bearings, oil pump, hell everything but the block if it turns out to be rebuildable.

 

I really can't improve at all on what Infernal Vortex said. Everything he said is totally correct! As far as factory-offered 4 bolt blocks are concerned, yeah, trucks and Vettes are just about the only vehicles that got the factory-installed 4 bolt blocks. It's also pretty much a fact that factory style 4 bolt blocks really aren't any stronger than the 2 bolt blocks. In fact, it's been stated tons of times that drilling the extra 2 holes for the 4 bolt style caps actually weakens the webbing of the block in the crankshaft area. And like he said, old-school guys get all excited about the factory 4 bolt blocks, and stating that they're stronger than the 2 bolts, is mostly just an old wives tale. I run an old-school, flat-tappet, factory 4 bolt block in my 69 Camaro. Then I've got an 88, 2 bolt, roller cam 350 block in my 89 Camaro. That block was originally in an 88 350 Iroc car. I've ran both motors up to around 6500 rpm's on several occasions, and neither block has ever tried the thow the crank out the bottom. The aftermarket, splayed style 4 bolt cap setup has actually been proven to be stronger than either the factory 2 or 4 bolt blocks, and when converting a factory block to the splayed, 4 bolt caps, a 2 bolt block has to be used so the outer holes can be drilled and tapped at angles instead of straight down. These days, the aftermarket industries have comletely surpassed original factory stuff when it comes to blocks and cylinder heads. For example, the Dart Little M aftermarket blocks are FAR stronger than any factory block. As for heads, the old-school guys still get all excited over the fuelie, or camelback heads. In reality, CNC machined aftermarket heads such as AFR, Dart, Brodix, etc. outflow ANY factory heads by several country miles! And believe me, I'm not intentionally bashing on the old fuelie heads, as that's what I'm still running in my 69 Camaro. But believe me when I say I'd love to pony up the extra cash to replace those fuelies with an awesome set of aftermarket, aluminum heads!

 

OK , I found out my 350 block is only a 305.I cleaned some of the grub off the back of the block and there it was GM 5.0LG SGI J279 #14093627. The cylinders look very good.The under side of the heads had gunck caked up in the middle around the water passage I guess. I didn,t see any head gasket failer,and the area on the heads where #8 cyl. valves is was different than all the others.Darker and oily looking.No one has said why my oil was thin and smelled of gas. Is it possible the PO put somthing in it to try and clean out some of the build up?Is there any way to test an oil pump?I've got the heads off,Rockers and push rods out.It dose have the roller type lifters from what I'm seeing.There are brackets over the lifters.My 3.1 block didn't have them.You guys think this 305 is worth keeping.can head gaskets be re-used?The cylinders have some lip at the top.My 3.1 that had a rod bearing go had none.

 

Ok this is the perfect time for you to get a 350 roller block and call it a day.

Why?

Same cost to build as a 305, and you'll get more power out of it.

Any questions? (please no questions LOL)