Hot street cam info?


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By unibody madness - 11 Years Ago
Hello all. My truck project was tuned and running when it developed a knock when warmed up. The Gent that rebuild it was in his eighties and three years later his shop won't answer the phone...hopefully he is on a long vacation.

To the point.  I did a R&R with a 292 rebuild I later bought, that has a Neilsen  "Hot Street cam and was wondering what I should set the timing. The motor wont start unless its past twelve degrees and max amount of vacuum is 15 at thirty five degrees.

 The cam is a Nielson Cam, 280M Grind   Adv.Dur. 280    .050"Dur 232    Valve lift 1.43 Ratio .432" Valve Lift 1.54 Ratio .465"

Since this is all Greek to me I would appreciate any and all help.
By Ted - 11 Years Ago

That camshaft sounds similar to the Crower Monarch camshaft that’s being used in the 312 dyno mule other than the duration at 0.050” being slightly less in the Nielson camshaft.  You didn’t mention what distributor you are running but assuming it’s a ’57 and up distributor, then the ignition timing should be set with the vacuum advance unhooked from the distributor.  Total timing will be ideal in the 38° range while the initial timing could be as high as 14-18° depending upon the rpm the engine idles at.  The higher the engine rpm, then the higher the initial timing will be assuming again that an older Load-O-Matic distributor is not being used.
By unibody madness - 11 Years Ago
Ted, the distributor is indeed a later type, has a notch on top of the shaft for the rotor, running pertronix , with the vacuum blocked off.  It is now set at between 22 and 24 degrees and reads 12 lbs of vacuum, at about 650/750 rpm. I have used two of the larger  manifolds facing rearward with dual exhaust. I am using the original 2v carb that ran great on the block that developed a knock, rebuilt and tuned just past lean, to where the temp drops back to just before 160*. The grinder recommends headers and multiple carbs on his literature.

The engine is hard to start, has slow throttle response in both directions, and wants to run with the choke cracked  a little. I will try increasing initial timing, but can only get @ 15 lbs of vacuum at about 30 initial*. I have checked and have no vacuum leaks but am running a brake booster.

Thanks for giving me a starting point.                                                                                                                                                                               john                                                                                                                                                                         

John
By pcmenten - 11 Years Ago
Just for fun, you should try running it with the brake booster port plugged. I have found two leaking brake boosters. One on an MGB, the other on a S10. It can happen.
By unibody madness - 11 Years Ago
Due to a long list of friends and family members who have 'moved on' in recent months, I am just now getting back to this thread.

Art, my engine builder, has unfortunately also moved on .  He was a kind old gent with a twinkle in his eye and a vast knowledge and experience in engine rebuilding and racing.  R.I.P.

Nielson cams sent me an e-mail recommending .20 on the valve lash.  I will be getting back to the motor in a week or two, my efforts will be on getting "Arts" block in running order, so Baca machine shop in S.S.F. can  have a run at it. I wish I had some of the skill found on this site, but my skills lie in other directions so I have to let the experts do it.
Thanks for all the help and comments, I will post results as I find them.