Possibly too small of a torque converter?

[1980RS]

It's not that the cam is too big, it's the cam has a LSA of 107° which means less idle vacuum. Crank in some timing unless you have Vortec heads and see if it's any better. 20° initial timing and the rest in the distributor.

 

[sandlapper]

for street automatic; way too much cam for pistons & heads (1974 compression).
Bet dollars to donuts you'll never like it in traffic; be driving like crazy just to keep it in power band.
reference a rebuildable L31 Vortec 350 --- along with judicious project planning.

A cam's sound has No impact on my cam choice.

 

[benforseter_21]

You could try going back down on the rockers and seeing if the Nox Vidmate VLC drivability improves. What gears are in it? Are the mixture screws responsive when you turn them? Idle vacuum?

 

[Onewildcat54]

Hi All, recently I just upgraded my 350 to a comp cams 12-601-04 cam with 1.6 rockers which now makes it a .510 lift cam. When attempting to drive this car it goes in to gear, and will roll slowly. If any attempt is made to cut the wheel hard or fully the engine will stall HARD. I also put a summit 2200-2800 stall converter with long tubes. Is it possible that the converter needs a higher stall? Car is reluctant to accelerate as well.

Ended up tearing back into the motor. Almost every lifter was cooked. One was so bad you could see right through. Cam was not broken in right and it naturally just failed.

 

[tom3]

I wouldn't blame the break in procedure too much. Cam failures are a current reality that is more likely due to garbage castings and lifters. Used to coat new cams with STP, double valve springs, long starting process and initial tuning without even thinking about a cam failure. Today we use special coatings, weak springs, break in oil, 2000 rpm run ins, cams wipe in a couple miles. Really sucks!

 

[Bandit723]

I just do have to wonder why OEM's now days or even back in the day don't go thru this.

 

[rotinrob]

Now a days everything is roller cams with a roller cam in order not to have trouble with the rollers sliding you want a little bit of friction between the cam and roller. Back in the day, like prior to 1980 or so, 99% of the components were North American sourced. There was no "best value country" sourcing going on then. Also if you look at the cam lobe profiles of the day they were pretty mild by todays standards. Look at the camshaft for the LS6 454 just over .500 lift (.520 advertised) and not a bunch of duration with 242° @ .050. The aftermarket hydraulic flat tappet cam in my Chevelle has about the same specs (a Wolverine Blue Racer that was made in Michigan at the time). Even the ZL1 2nd design cam in my Monte Carlo is somewhat tame by todays standards. The factories just couldn't tolerate a bunch of camshaft failure on the line or in the field. I worked at the Old stealer back in the day when we had all of the Olds Diesel cam failures, what a pain. The profiles that were used didn't stress the cam lifter interface as much as what we are doing today. Add in the "best value country" sourcing that goes on today and that is why we have these problems. I don't beleive it has as much to do with the oils we use today as people think. My ZL1 cam has run just fine since day one with oil that has less than 1000ppm zinc, my L78 was built to run Mobil 1 20-30 that is around 900 ppm zinc, no problems. I have never lost a cam by following a proper build, clean with plenty of lube, a good pre-lube, and running at a high idle for 20 min. or so. Not a big fan of break in oils either other than start it on what you are going to use for the life of the engine but change it after the first time it is driven, that's my break in oil.

rotin

 

[langss]

You absolutely nailed it... more about the materials than the method. Back in the early 70s, I took a donated cam, slapped a set of new lifters on it, and fired the engine up, set the valves, set the timing, and took the car cruising. All happy with the new rumpty rump....Four years later and two other cars, the engine was still running just fine...Got sold when the last ride got totaled, and was still going strong when I came home from the service.

 

[annamartino]

Hi All, recently I just upgraded my 350 to a comp Nox Vidmate VLC cams 12-601-04 cam with 1.6 rockers which now makes it a .510 lift cam. When attempting to drive this car it goes in to gear, and will roll slowly. If any attempt is made to cut the wheel hard or fully the engine will stall HARD. I also put a summit 2200-2800 stall converter with long tubes. Is it possible that the converter needs a higher stall? Car is reluctant to accelerate as well.

Does the engine rev up and not go, or does the engine bog down and has no power?