I just swapped my LG4 out for a 1994 350. The motor that I have can be either a roller or flat tappet cam. Can I jut take off a rocker arm, pull out a push rod and measure to find out?

 

If it's a 1994, it should be a roller.

 

It came from a chevy fullsize workvan though. I hope its a roller. Would this method verify that?

 

Yes, the pushrod length should tell you which you have.

 

How long will roller pushrods be? How long will flat tappet pushrods be?

 

I have never heard of a 94 350 block with flat tappets.

 

I hope your right and I do have rollers. I just want to know for sure before I start ordering parts.

 

This is the 1st time I have ever found Flat Tappet Lifters for a newer style block. I did this search on Summitracing.com.. If you search the year make and model and engine size it will show you 83 different styles of lifters of which 99.9% are Hydraulic style. Unless someone swapped the cam and put a cam button in and changed all the lifters and pushrods out, "Which is unlikely", I would say you would have the stock Hydraulic Lifters on a roller cam.

Rhoads Flat Tappet Lifters Part Number 8178X from Summitracing.com are for 1967 - 2000

Rhoads Hydraulic Lifters Part Number 1158 from Summitracing.com are for 1987-2000

 

I agree that there is probably a roller cam in this engine. How long would the push rods be if there is a roller cam? Like I said, probably and maybe ususally just ends up getting me in trouble.

 

I remember what everything looked like when I had the intake manifold off a couple weeks ago. Is there anything that I could have seen in the lifter valley that would tell me if I had a roller setup?

 

Did you see a piece of sheet metal bolted to the bottom of the intake valley, with fingers that went between each pair of lifters?

 

Yes if looked at the center of the valley in between the heads. You would have noticed a piece of metal that was bolted in 3 places holding to the center of the block. This metal is used to keep the keepers in place which keep Hydraulic lifters in the proper position so the rollers stay straight on the cam. If you didn't see this then you would have flat tappet as they don't need retainers

 

Yeah I saw that in the 305 that I took to the scrap yard today. The 350 is definitely flat tappet. Oh well, you win some you lose some.

 

some of the truck blocks of the 350s had the provision for the roller lifters even though they came with flat tappet cams in them. If there are three raised bosses down the center of your lifter valley aproximately 1 inch tall then it is set up for roller lifters and you can use the oem type roller lifters which are much cheaper that the retro fit roller lifters. You can get the parts you need from a used engine at a bone yard for cheap.

 

Could I use the roller setup from the 305? There is a chance that I could still get that.

 

Yes, if the machining to mount it is finished in the 350 block, which it almost certainly is.

 

The casting number says that the engine is roller or flat tappet on Mortec. Would that mean that I have the roller provisions? Or not necessarily?

 

I was looking at summit and I noticed that I can buy an entire flat tappet kit for less than just a roller cam. What the heck. I will need new springs and seals and so-on so I'm kinda tempted just to stay with flat tappet. Is it possible to use a flat tappet cam and roller lifters? I realize that this may be a really stupid question. I just can't justify spending almost $1000 on a roller cam kit when i could get a flat tappet kit for around $250. What gives anyway? Why is the roller stuff so much more expensive?

 

You can't use flat tappets on a cam designed for roller lifters, nor the other way around. The roller cam will be more expensive but you can re-use your roller lifters from the 305 (along with the spider, dog bones, cam button, etc.). You're going to swap springs either way.

With oil quality concerns today I wouldn't go flat tappet if I could avoid it, especially with a block ready for a factory setup. There's a reason the factory went roller too, efficiency and performance wise. Don't go backwards.

 

Light trucks didn't get roller lifters until 1996 (the advent of the "Vortec" engine).

Many of the blocks were machined for roller lifters, but none of the hardware was there. Flat tappets fit in them just like previous blocks.

I guess I didn't repeat that in this thread because it's been said so many times before.

If you want to put roller lifters & cam in, first verify the block has been machined for them. The easiest is the 3 nubs in the lifter valley on top of the oil passage - if they're drilled and tapped, most likely the rest of the stuff was done as well. You will need the cam, lifters, anti-rotation dog-bones and the retainer "spider", push-rods, cam retention plate & screws, and roller cam timing set. The lifters are re-useable, finding all of this stuff on eBay or from a throw-away 305 would probably be the cheapest way to get all of it. Note of warning: Two different cam retention plates were used; they had different bolt spacing. If you have to buy all of this stuff new, a flat tappet cam makes more performance $'s sense. Oil is simply a matter of using a diesel/gas rated oil (CI-4+/SL - this is my choice http://www.amsoil.com/storefront/hdd.aspx ).