Did a burnout and went to pre stage when car just killed and would not fire. Checked distributor and wasn't turning, pulled it checked cam gear and wasn't turning, pulled valve covers and all vales were opening and closing except the 2 rear cylinders on each side, so there was the problem. Now I have never had a cam break before, I'm assuming possibly the oil pump may have froze (haven't checked it yet) and was the cause but not 100% sure yet. I don't think any valves were hurt being that they are all in the up position but until I do a leakdown test I really wont know for sure. Car was at idle when it broke.
Has anyone ever went through this and have any pointers before I go tearing into it.

A few year back there was bad run of BBC roller cams that were braking. Don't remember the brand.

This one is a Comp Cam from 2021. Has less than 100 total runs on it and 95% are 1/8 mile.

It's important to carefully look at everything as you take it apart. There are many ways and places a cam can break so put on your Insector's cap and don't be in a rush. I broke one (Crane) just behind the last lobe (Thankfully) so there wasn't any further damage.

Here comes my hardware rant

One of the things I've petitioned cam manufacturers for decades is to increase the size/strength of the timing sprocket hardware from 1/4-20 to minimally 1/4-28, or 3/8-24 with the larger (50mm or 60mm) cam cores. With the increase in spring pressures and RPM levels it makes sense to increase the strength of the cam sprocket hardware.

When a throttle stop hits, then goes off the cam is torqued/twisted back and forth and making any weak point subject to failure, that starts with the hardware (1/4-20 bolts). These days we are running far stronger valve spring pressures, greater lifts and higher RPM levels, shearing the cam bolts and the pin is not uncommon.

Off my rant:

Bob

One last "Mini" ramp:

If any debris passes through the oil pick up screen more than likely it will jam/seize the oil pump gears. Normally when the intermediate shaft shears, it usually breaks the cam behind the last lobe. Because this caused the cam to break, take the oil pump apart and if it did seize, replace both the pump and the intermediate shaft.

Bob

quote:

Originally posted by RPROGAS:
One last "Mini" ramp:

If any debris passes through the oil pick up screen more than likely it will jam/seize the oil pump gears. Normally when the intermediate shaft shears, it usually breaks the cam behind the last lobe. Because this caused the cam to break, take the oil pump apart and if it did seize, replace both the pump and the intermediate shaft.

Bob

Given that both intake and exhaust valves in the back to cylinders are up and not moving I am assuming it is broke in the rear lobe area. This is what's making me thing that the pump is broken.

Small base circle cam?

Had a friend do it a couple of years ago, Comp roller SBC. Just broke the back of the cam, no other problems found.

Anyone know if there was a bad run on Comp Cams and if so when It may have been?

quote:

Originally posted by SmokinChicken:
Anyone know if there was a bad run on Comp Cams and if so when It may have been?

Yes there was. They all had a "black" core and were made from inferior material imo.

quote:

Originally posted by Jonesz:

quote:

Originally posted by SmokinChicken:
Anyone know if there was a bad run on Comp Cams and if so when It may have been?

Yes there was. They all had a "black" core and were made from inferior material imo.

What manufacturer? and how can you identify the cams with issues?

Found out it was a comp cam, And it was a bad batch on the cores.

Were these some of their junk hardened cast cores or just not well hardened steel cores?

quote:

Originally posted by 1leg:
Found out it was a comp cam, And it was a bad batch on the cores.

What year was the cam manufactured? Wondering If this is an issue I have.

quote:

Originally posted by SmokinChicken:

quote:

Originally posted by 1leg:
Found out it was a comp cam, And it was a bad batch on the cores.

What year was the cam manufactured? Wondering If this is an issue I have.

2020 time frame for me

quote:

Originally posted by Jonesz:

quote:

Originally posted by SmokinChicken:

quote:

Originally posted by 1leg:
Found out it was a comp cam, And it was a bad batch on the cores.

What year was the cam manufactured? Wondering If this is an issue I have.

2020 time frame for me

What did they do to remedy the situation?

absolutely nothing. said prob should be using the 8620 billet core in my application.

Anyone have any recommendations on a good cam company besides Comp Cams?

quote:

Originally posted by Jonesz:
absolutely nothing. said prob should be using the 8620 billet core in my application.

yea they don't stand behind it even if there is a known manufacturing issue, that's what sucks.

We have had good success with Herbert Cams and Isky.

quote:

Hide Post
Anyone have any recommendations on a good cam company besides Comp Cams?

Bullet Cams.

Bob