I finally got the engine put back in the vette. While it was out, I replaced the cam and loosened/tightened the crank and rod caps while I was trying to figure out why the crank wouldn't turn.

I have a book "How to build a smallblock chevy" that I followed. I degreed the cam and used lots of lube on the lobes and lifters. The book says to only turn it over for a few seconds as to not wipe the lube off the lobes.

When I went to start it, it sounds a little different when it turns over. It never did catch. I tried it three times for a total of about 10 seconds.

First question: What is the surface finish of the cam lobes on a new cam? My new cam lobes weren't polished like the old one. Is this what the break in period at 3000 rpm does? Would this cause the different noise I am hearing?

Second question: How long can I wind it over before I cause problems? I imagine it will take a while before the fuel pump gets fuel through the carb. Is there a procedure for starting the engine before cam break in?

 

Prime the carburetor. Don't wait till the fuel pump fills it. Prime the carburetor.

BigBlockk

Later.....

 

Did you pre oil the engine?

If it doesnt start for a few seconds and you lubed up the lobes real well, you wont hurt it

Even if after it starts and you have to shut it down immediately because of a leak or something and then restart, it should be OK.

BTW- The lobes and area that rides on the bearings should all be polished and shine out of the box.

 

I would disagree... while the bearing surfaces should certainly be polished, the lobe faces are more like an unfinished machined surface. they won't be polished super-smooth until they mate with the lifter faces.

rexx78 -- first off, did you replace just the cam and not the lifters? it's generally good to mate a fresh cam to fresh lifters. at the very least, if you're re-using lifters, make sure they all go in the same bores they came out of.

second. yes, depending on the carburetor, you should fill the fuel bowls with a small squirt bottle prior to startup. this will minimize dry cranking.

third... vizard's "rebuildin a SB" book is great, to a point. He walks through standard rebuild procedures, but they're very basic. There's a lot of little tricks he fails to mention in that guide.

For instance, on a fresh cam it's generally good to remove the inner valve springs during initial break-in. some builders will disagree, usually because removing and reinstalling those inner valvesprings is a time consuming process, but it will reduce the open seat pressure which will help minimize the lobe wear at max lift.

I'm guessing your issue is fuel delivery. look into filling those bowls before trying again. Also, double and triple-check that your initial timing is set properly. pay close attention to vizard's procedure for re-inserting the distributor.

good luck

 

also... some builders swear by this method... during cam break in, over-fill the engine with 2 extra quarts of oil. This will produce a better windage cloud, getting more oil up on the camshaft during break in.

following cam break in, change your oil and filter, and re-fill with the standard volume of oil.

 

read this article

http://forums.corvetteforum.com/show....php?t=1372617

 

Thanks for the replies.

I pre-oiled the engine with the proper tool until oil came out of the tops of all rocker arms. I found a set of three pre-oil tools (chevy, ford, dodge) from Princess Auto (a girly name but an awesome store) for $20.

I recently found the paper by Jughead on how to break in an engine, it is a good read. He mentions that hydraulic lifters are a little noisy until they fill with oil. I hope this is the noise I am hearing.

I replaced the lifters and cam, then adjusted the valves to 1/2 turn past zero lash. It's good to hear the lobes may not be as polished as the bearing surfaces.

I will add an extra 2 litres of oil, 1/4 cup of gas down the carb, pump the throttle to get the gas flowing, and fire it up... hopefully.

That article is a good read.

 

Skip the extra oil, Fire that baby up and and let it run @2500rpm for 30-45 minutes. Listen for real noise and look for serious leaks during this time. When the time is up bring back down to normal idle and set timing and idle mixtures. Correct any leaks retorque head and manifold bolts, valve covers, etc. Then change oil and drive that bad boy!!!!!!!