Please take a look to the picture:

http://www.bilder-hochladen.net/files/1eer-1s-jpg.html

There are 3 camshafts. At the left side is an Edelbrock 3702 cam, itīs just for flat tappet lifters. I think, this is a peanut cam.
In the middle of the three cams is a vortec cam, i donīt know which specifications it has. But the lobe is bigger than the lobe on the Edelbrock 3702.
On the right side is my "stock"-TBI-cam. I think, the lobe is bigger than the lobe on the vortec cam. I donīt know, is it stock TBI or is it not stock TBI. Please take a look to the picture. Does the TBI-Stock-cam have a fuel-pump-lobe ?? Take a look to the lobes from exhaust and intake. Do you think, itīs stock ? Do you have a good picture from the stock 305 TBI-rollercam ?
I canīt make a better picture. The cam is in the engine and the engine is in the car at the moment... :-)

 

From the picture it looks like a stock GM cam, similar or the same as a TBI cam. Most of the stock GM cams have pretty lame figures. The vortec and TBI cams both had low duration and lift numbers. The only way to tell for sure what it is would be to remove the cam and mic the lobes and see what the lift is, or get the numbers off the cam.

 

The lobe on the "stock"-cam is flatter than the lobe on the vortec or edelbrock cam. But the altitude is the same.

I think:

Flat lobe = high duration
Petty lobe = low duration

????????

But the lobe mismatch, I donīt know....


( Sorry for my bad english :-) )

 

To determine the duration (or get a good guess), you would need to use a dial gauge and degree wheel. Its hard to tell just by looking at the lobes, especially when comparing stock cams. All of those cams have pretty low duration and lift. The edelbrock one is probably 204/214 intake/exhaust duration with around .432/.442" of lift. Not very much, but more than either of the stock cams off of the top of my head. Stock heads aren't good for very much lift.

As far as lobe shape, the shape of the flat tappet is different than either of the two rollers due to the fact that the tappet has a slightly crowned heel rather than a roller, so you need a different profile to get a smooth open/close cycle for the valve. As far as the shape of the roller lobes, thats just the curve that GM wanted the lifter to follow to get the desired valve motion. With rollers, you can even have nearly rectangular lobes due to the fact that a roller can traverse an extreme cam profile alot easier than a flat tappet.

Are you ultimatly looking to swap cams for more performance? Or just curious about the cams? If your looking to swap, the only thing you could really do with either of those factory roller cams is run them with high ratio rockers to have a moderatly high lift, low end torque motor. None of those cams are really all that geared towards performance due to the lack of duration and lobe lift.

 

One on the lfet is definitely a flat tappet cam. 2 on the right are roller cams. Roller cams ALWAYS have a more rounded nose on them than a flat tappet cam. It means exactly NOTHING just looking at them by eye. The actual specs at the lifter/valve could be identical but the roller cam lobe is always going to look more agrressive with big, rounded noses on the lobes.

This is one of the parts of an engine where your naked eyes are basically useless for telling you anything meaningful.

 

Thank you for the answers. I want to swap the camshaft for more performance. I know, itīs a lot of work. Last year, i rebuilt the engine completly with new gaskets. I made the picture from these camshafts. I would change the camshaft, too. I wanted to fit this Vortec-cam in the middle from the picture. But iīve seen, there is a little crack in a lobe. Then, i ordered the
Edelbrock 3702 cam. The webpage from the camshaftshop said, it fits to all L03, Vincode E engines. But, iīve seen, itīs a flat-tappet-cam and does not fit to my rollerblock. So, i installed the engine with the cam on the right side from the picture and installed the engine in the car because i had no time to wait for a new, better cam. The cam from the right side is the same which i remove from the engine, before i rebuilt it.

Now, I bought an used 94īcamaro z28 LT1-cam. See the other thread in this tbi-board. In this thread, I want to doublecheck this cam with the p/n numbers. I am afraid, itīs a lot of work and I donīt want to fit a cam withaut more performance. Do you think, i can change the cam without remove the engine ???

 

you can definately change it with the engine in the car -- at least that's what the pictures of Shifty's "tutorial" in the sticky LT1 cam digest thread are telling me and that's what i'm gonna do/try as a winter-project hehe
i know you have to take out the radiator though.. you should really look at the mentioned thread, it's great work.

 

The stock LO3 cam is what they guys on this board affectionately call the "peanut cam." It's a factory roller but the specs are super wimpy. If I read it right, that's what you put back in the motor before you buttoned it up again, so no change there from stock.

The Edlebrock cam is a step up from that, but still very mild and it's a flat tappet cam. BTW- you can put a flat tappet cam in a roller block. You just need a different timing chain, longer pushrods and, of course, you have to use flat tappet lifters.

The stock Vortec truck cam is also a step up from the "peanut cam" and it's a factory-style roller setup like your stock LO3 cam. The specs are still pretty mild, but ANYTHING is bigger than the peanut cam!

The LT1 cam is another step up from any of the above cams and is a popular upgrade choice for TBI engines. There's plenty to read about that cam in a TBI motor on this board.

 

Just as an FYI, the TBI truck engines had flat tappet cams. Thats why it said it fit VIN E engines. Its also not much different than the stock peanut cam. Edelbrock used an intake lobe with very little duration so the cam would run with the stock tune.

 

Ok I've been reading what everyone has, but still don't see oem, THAT'S STOCK SPECS., for my 1990 lo3 Tbi engine, auto trans. Does anyone know this answer, or where I can find it. Specific to a 1990 lo3 tbi engine?? STOCK SPECS! I'm already losing my hair, and do not want to pull any out!!! You exact help would be greatly appreciated!!!!!!!! Uncle bigbad.

 

Factory cam specs for the LO-3 are as follows:

Duration at .050 inch lift: 179 intake/195 exhaust
Lift with factory rocker arm ratio: 0.350 inch intake/0.385 inch exhaust
Lobe separation angle (LSA) is 109 degrees

An equivalent OEM cam is Sealed Power CS-793