Do GM crate 350's have soft cams ?

[mtnmankev]

I would like to hear feedback from anybody who is running or has experience with a 350 crate engine with 70K plus miles on it, and did the cam hold up well, or did it end up being soft and wear out prematurely ??
I know the fuel pump lobe on mine is soft and worn badly, and now I suspect the distributor drive gear has worn causing my distributor timing to vary.
I plan to install a crank kit in mine very soon, as it has developed a lower end tapping, and might get a new cam as long as it's apart.
Any suggestions for a basic affordable stock style or mild performance cam?
The truck is 83 C20.

 

[legopnuematic]

Have you been running zinc in the oil? Flat tappet cams will wear very quickly without a high zinc content in the oil.
As for a replacement cam I have a summit k-1102 RV cam in my 79 350. 103.99 with free shipping.

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[1987 GMC Jimmy]

Could you describe the timing variance in a little more detail? The timing chain could be at fault as could a worn distributor bushing. I’ve had the same concerns with a crate 305 I have with about 76,000 miles on it. Not so much from a fuel pump and distributor standpoint but valvetrain. I have a bit of clatter at startup, but everything does work as it’s supposed to. I imagine my oil has minimal ZDDP, but if I had been the one installing the motor or just the cam, lifters, and timing set, I would use an additive or a brand that has it in higher concentration.

 

[mtnmankev]

Over the years, I have heard stories of soft cams appearing in some engines from the factory, but I don't know any more than what I have heard tell.
The previous owner had installed the engine and he put the vast majority of miles on it, no clue what oil he ran.
I used to use only Valvoline up until a few years ago, then went Castrol GTX.
Have not added any zinc additive.
The engine has a brand new timing chain and gear set, I verified the harmonic balancer has not slipped, Distributor holddown bolt is tight and I cannot budge the dizzy without loosening the bolt, but twice now the timing has slipped from 10 BTDC to zero,
If I advance the distributor much more to maintain advance, it's going to be on a collision course with the vac advance hitting the carburetor.
Before I installed the distributor, I checked it for wear and bushing slack, and it was tight.
The distributor in my 383 stroker (I built it 20 years ago) is not rotated towards the carburetor anywhere near as much as the one on the 350, and I use the exact same setup method when installing them when I index the balancer at TDC #1 compression, then drop the dizzy in.
There has to be a difference in cam gears between the two engines to explain why the distributors end up in different positions.
One tooth off in the cam gear would throw everything way off.

 

[73c20jim]

You can probably remove the dizzy and put it in one tooth off and re time to get extra VA clearance.

 

[crazy4offroad]

A vacuum test will let you know if you've wiped a lobe. There are several charts online to let you know what to look for when running the test. Always use zinc additive for flat tappet cams. Could be the difference between <100k miles and >100k miles. If it does turn out to be wiped, an Edelbrock Performer cam is mild enough and cheap enough to be worth the change with a little bump in power and RPM range. Get the kit with new lifters and timing gears and double roller chain.

 

[73c20jim]

In my experience, always use new lifters with a new cam. With a used cam, always put each lifter back in the same exact position it came from.

Lost a cam not doing this.

 

[fussfeld]

i've not had a problem with soft cam on the crate 350 i had. My problem was that i think the previous owner may have overheated it and/or i didn't put the head back on correctly and it hydrolocked, but that's a different topic for another thread.....................

i used Redline 10w-30 oil. This has high zddp content. i changed it every 10,000 miles.

Now, do i absolutely believe every flat tappet cam absolutely 100% needs zddp? i'm not 100% convinced, BUT i looked at this oil as cheap insurance as it's about the same $$$ as conventional oil

 

[idahovette]

Whenever you wipe a cam lobe you have metal all through you engine. Depends on how soon you caught it but it's gonna screw things up in a hurry. You can try changing the oil a few times to try and flush it but there is a very good chance the engine has to come apart. Experience with a Summit grind cheapo at about 8K mile in my BB Chevelle. Now has a Comp Cams ,works great with ZDDP added(had it in the other too)

 

[roundhouse]

New cams also have to be broken in

You have to use special oil and the first time you fire it Up you rev it to 3000 and keep it at 3000 for like 20 minutes to harden the lobes


And just about every old small block Chevy I’ve ever seen has a flat lobe on the cam

Usually the one on the drivers side at the back

 

[73c20jim]

Usually the one on the drivers side at the back

Cam?? Driver side???

 

[mtnmankev]

That's okay, I'm just as confused as you are.

 

[SquareRoot]

New cams also have to be broken in

You rev it to 3000 and keep it at 3000 for like 20 minutes to harden the lobes


And just about every old small block Chevy I’ve ever seen has a flat lobe on the cam

Harden the lobes? Lol. Actually the high rpm helps splash oil on the cam from underneath from the crank counterweights.

Is a "flat" lobe still a lobe?

 

[73c20jim]

Hardened, no. Mate cam to lobe to prevent cam wipeout, yes.

 

[Old77]

Cam?? Driver side???