[Guest]

I just started my 351W after replacing the cam with a CompCams XE. Anyway, it started right up, and I increased the RPMs to 2000 and let it run. At about the 15 minute mark, it began to overheat some, so I shut it down. Question is - is the new cam/lifter system adequately run in? Also, when it started to get hot, it acted like there was some fuel starvation. Vapor lock?

 

[charlie65_67]

As I recall the breakin is supposed to be 20 min, so at 15 min, I expect your good. Can't say about the apparent fuel starvation. Could be vapor lock, could be the engine was hotter than you thought and was in the early stages of trying to seize up. I trust you had good oil pressure during all of this?

 

[whisperer]

I'd still want to run it for a while longer for the cam break-in. Many times you will get an overheat in the first few minutes because the block and heads are not completely full of coolant. As soon as the thermostat opens it boils over. There's 2 things you can do to prevent this in the future - drill a small hole in the thermostat off to the side of the valve part to eliminate the air lock, or loosen the heater hose on the top of the intake to bleed the air off while filling the radiator.

I'd say make sure it's full of coolant and fire it. Let it run at 2000-3000 RPM's for another 1/2 hour and you will be safe. Also all the air will be out of the cooling system by then.

 

[Guest]

Good oil pressure and no unfriendly noises - just hot! Valve train rattled a bit, probably due to the need for more precise adjustment.

 

[camachinist]

Sounds good...likely you'll need to "burp" the radiator a couple of times to get all the air out, which will, along with the initial run-in friction subsiding, cool things off.

Usually, by the time I get things squared away (carb adjustments, timing, looking for leaks, etc), the engines in the race car have run in and are ready to see a load. I generally fire the car on stands or its cradle and cycle the trans, warming it and the rear end up at the same time. After about 1/2 hour of this, down it comes for some part throttle passes (nothing over 90 or so) to check the systems before heading to the track.

After fire checks would include leakdown, valve lash, coolant, oil and ATF levels and visuals for leaks. Any odd noises, if present, are noted for future investigation/monitoring. I usually wait to final-set the timing and carb mixtures until I get track so I can get an accurate plug reading.

Good luck with your new engine!”

 

[Shaun @ Street or Track]

Hows the timing? That could cause it to get hot...

Remember to change the oil after the run-in.

 

[Sportsroof1970]

These experts have already nailed it perfectly. I just wanted to add that this just happened to me as I was breaking in my new lifters. I changed the oil afterwards.. topped off the coolant, and thought all the air would've burped by this time. It was still running hot a couple days after. Checked the radiator, and, whoops, it had burped again and needed another half gallon of distilled water! I went whining to the forum about it when it just needed time, like Pat says, to belch that air out. Excellent suggestion here about cracking the heater hose for an air relief. I'm going to try that one next time /forums/images/icons/smile.gif

Good luck, I'm sure it'll be fine. Oh, and I think I read on the Crane Cams website that it's o.k. to drive a car while you break in the cam... you would just want to make sure that you'd be able to hold the rpm's around 2000 rpm or so, so that would be harder to do in heavy traffic (plus people staring at you like, what's this guy doing).

I varied the engine speed during my break-in, because I've read that it allows oil to be splashed on different areas of the camshaft. I used the idle speed adjustment screw and moved it from around 1800-2500 rpms every couple of minutes. (can't hurt right)

 

[Guest]

Thanks for the help. It's much appreciated