Camshaft type?

[capriceowns]

Do certain blocks use dif types of cams? Im looking at jegs trying to buy my new valvetrain parts but dont know were to start

my engine is a 1981 Chevy 350 4 bolt. When I bought it had no valvtrain at all cept for the heads and springs, which I threw out. (not the heads, lol)

Can I use a hydralic cam or is my block a roller or mechanical? or does it not matter. is one of the types best for performance?

Should I just get the LT4 hot cam kit and not worry bout finding good parts? Will the LT4 hot cam work in my Gen I SBC?

[silicon212]

Your block being a 1981 is not set up for factory rollers, so that rules out an LT4 cam without serious work. You're going to want to stick with flat tappet lifters.

[capriceowns]

Originally Posted by silicon212

Your block being a 1981 is not set up for factory rollers, so that rules out an LT4 cam without serious work. You're going to want to stick with flat tappet lifters.

does it matter if the cam is a hydraliuc flat tappet or mechanical flat tappet?

[silicon212]

Not particularly, but keep in mind that if it's mechanical (solid lifter), you will need to set the valve lash on each valve with feeler gauges, and you will need to periodically measure/adjust them. Unless it's an all-out race engine, you're better off with hydraulic lifters, which are set-and-forget.

[capriceowns]

Originally Posted by silicon212

Not particularly, but keep in mind that if it's mechanical (solid lifter), you will need to set the valve lash on each valve with feeler gauges, and you will need to periodically measure/adjust them. Unless it's an all-out race engine, you're better off with hydraulic lifters, which are set-and-forget.

thanks silicon. Im going for a hydralic flat tappet cam now and GMPP hydralic lifters.

I would have been one very un happy camper if I blew the 600$on a LT4 hot cam kit and found it didnt fit/work. lol

you wouldnt happen to know if the stock valve springs are 1.445" tall?

[silicon212]

Installed height is closer to 2 inches, actually in the area of ~2.050. The 1.445 might be a spring diameter for a certain type of spring. It could also be max compressed height before coil bind - where the coils touch.

[capriceowns]

Originally Posted by silicon212

Installed height is closer to 2 inches, actually in the area of ~2.050. The 1.445 might be a spring diameter for a certain type of spring. It could also be max compressed height before coil bind - where the coils touch.

I was looking at the comp cams beehive ones, and they make some specially for LT1 LS1 and stuff like that but they have a universal one. the 1/445 is its outer diameter they dont give any more on it.

Do cam bearings need to be put in by a shop? my block doesnt have any in it right now.

[silicon212]

Originally Posted by capriceowns

I was looking at the comp cams beehive ones, and they make some specially for LT1 LS1 and stuff like that but they have a universal one. the 1/445 is its outer diameter they dont give any more on it.

Do cam bearings need to be put in by a shop? my block doesnt have any in it right now.

Yes, cam bearings are pressed in and the two rear bearings are a little smaller in diameter than the front three. You can do it if you have the special tool, but having a shop do it is cheaper than the tool if you don't intend to rebuild a few of these.

[Blue Bowtie]

Just my 2¢, but for anything I'm building in the future I'm going to strongly lean toward a roller, or at least direct-lube lifters and a HV oil pump. Even if the block is a plain old 2-piece RMS, no-dogbone/spider, and 2-bolt with cast crank, I'll be wary of using a flat tappet. The removal of antiwear additives from most engine oils is going to make life very tough for flat tappet cams in the future. Even some of the truck oils are reducing or eliminating ZDP, sulfur, and baruim based additives. Roller-cammed engines don't care much, but flat-tappets are going to wear faster unless you are very careful about the oil or additive you use.

Beyond that, rollers offer the opportunity to have greatly increased ramps, so stupid-big lifts can be had with a reasonably short overlap, so street manners are a lot more easily maintained. Aftermarket rollers have been around for decades, and are probably actually better than the factory setup for rotation control.

[silicon212]

Wow, I didn't know they were modifying the oil to remove the antiwear additives. I've always used an HV pump on a rebuild (most of the time with a 35 psi spring, as in my car now), and I was leaning toward a roller setup considering my block is ready for one, but now I have more incentive.

Is this pretty much across the board (re: oil antiwear) or certain brands? I've always been a firm believer in Castrol GTX.

[jveik]

yeah this is the argument people give for thier reason that they run diesel motor oil in their gas engines. the diesel oils apparently have more zinc in them that is a key antiwear thing to have

[capriceowns]

Well thats gay! are they doing this to fade out some old technology?(like my flat tappet cam)

Ive always been a Quakerstate/Pennzoil/Amsoil guy.

What does a roller block have that mine doesnt? Would I be able to get about 40,000 miles out of my flat tappet cam with the less additives? my block was about .002 over in each cylinder it doesnt have much wear left before needing a bore.

[silicon212]

In a factory roller block engine, there are three bolt bosses in the lifter valley, on the main oil galley, that the 'spider' retainer for the roller lifter locks, is bolted to. There are also two bolt bosses behind the timing cover for the camshaft retainer plate. You can go with an aftermarket type of roller setup (as Blue Bowtie says, these have been around for decades) with lifter pairs that are attached to eachother and a camshaft "button" that holds the cam back in the block.

Most aftermarket roller type cams are machined from billet steel - a steel rod in untechnical terms, and are sufficiently soft on the distributor drive gear that you MUST run a bronze distributor gear to prevent the distributor drive gear on the cam from failing and taking out the distributor - and oil pump.

Roller lifters must be retained in the block and not allowed to spin - if one does, the damage is catastrophic.

[maxwedge]

Originally Posted by jveik

yeah this is the argument people give for thier reason that they run diesel motor oil in their gas engines. the diesel oils apparently have more zinc in them that is a key antiwear thing to have

Good info jveik, there are reduced anti friction additives in sl and sm oil, zinc and phosphates are almost gone, bad news for flat tappet cams, any of the popular racing oils as well as 15-40 diesel still have high concentrations of this additive package, the break in is the critical issue with the cam as we all know.

[capriceowns]

Originally Posted by maxwedge

Good info jveik, there are reduced anti friction additives in sl and sm oil, zinc and phosphates are almost gone, bad news for flat tappet cams, any of the popular racing oils as well as 15-40 diesel still have high concentrations of this additive package, the break in is the critical issue with the cam as we all know.

I know about cam break in. my comp cam came with instructions on how to, I also bought a crane cams cam break in oil additive. But should I use like a 10w-40 oil in my engine all the time? (thats diesel grade right?)

what are "racing oils" like royal purple, redline, and Mobil 1? this is all very new news to me, I had no idea bout this.