My 77 has devoloped some real problems in a short time. High speed miss, then added mid speed miss and "spitting" through the carb. I have run all diagnostics I can think of: good ignition to each cylinder, compression check great, timing checked many times, manifold vacuum steady at 15", carb clean with no clues.
My cam is a 268 HE with about 500 miles, new lifters and no "noises".
A friend had similar problems with a SBC and found cam wiped out.
And one more thing, new Mallory HEI. It all ran great until recently.
Thanks

 

check out these websites and compare there break in proceedures to yours... i would think the vacuum gauge would show something if it were a wiped lobe....you can always pull the valve cover and look at the opening and closing of the valves....perhaps feel the exhaust manifold and look for one cylinder that is not warming up as quickly as the rest and concentrate your efforts on that cylinder first....good luck


....http://www.holley.com/products.asp?product=60103

"Installation Notes
WARNING: These are the MOST AGGRESSIVE hydraulic flat tappet cams ever produced! If recommended break in procedures are not followed, these cams
WILL FAIL! See the Master Lunati catalog for spring, retainer and keeper specifications or call Lunati Tech at 901–365–0950"

and more info:
http://www.holley.com/data/Products...cal/INST150.pdf

"Without a doubt, the vast majority of all cam and lifter failures occur when the new cam and lifters are installed and the engine is fired up and run for the first time. The first 10 minutes of initial cam break-in is the most crucial! If the appropriate instructions and installation procedures aren’t followed - with the correct components - failure is likely imminent.
One of the most common problems we find with cam and lifter wear results when a new cam is installed with USED LIFTERS! Even lifters that have only a few minutes of running time on them cannot be used with another cam. NEW LIFTERS MUST ALWAYS BE USED WITH A NEW CAM due to the immediate wear pattern that begins the instant the engine is fired up and run. Although appearing to be flat across the bottom, lifters are actually convex shaped with a crown of approximately .002”. This crown shape and the taper ground into the cam’s lobes promote the lifter’s rotation while the engine is operating."

 

It does sound like you might have wiped out an exhaust lobe or loosened an exhaust rocker. Remove the valve covers and check for valve lift or loose rocker. If it's "spitting", it should be obvious.

 

Yes, do that but when you fire up the engine, see if all the pushrods are spinning as idle. The one(s) that aren't are gonners and you don't need to check anything else but your bank account balance and the availability of weekend time.

 

Mox,

dump the oil and run it through a T-shirt and look for metal. Remove your oil filter, cut off the shell and inspect the insides for more metal. Tell us what you find. Check for loose rockers.

I know you mentioned it was a new dist, but what is your timing set to? initial - mechanical - total

good luck

the blonde weasel