LDA007 said:
Thanks for all of the input. I have had computer and weather problems but would really like to continue this discussion if possible. It will probably be confusing but I will try to clarify. Please ask questions.
I have had this engine set up for about 15 years. i put at least 30000 mile on it. I drove it back and forth on the weekend from school which was about 90 miles away. I let the car sit for 10 years and am trying to get it back into shape. I have always since day one had a timing issue. It seem to only start and stop correctly at 6 degrees BTDC until now. I have never found what initial timing is best for my engine set up. I was using a 1970 LT1 spec sheet because I was trying to mimic the engine.
The story starts like this:
My 600 cfs vacuum secondary never worked (I went through 12 carbs in 1 year but that is another story) until last year. I don't know what happened but all of a sudden it found at least another 100 HP with the same carb. The four barrel started working. Soon after it started leaking from one of the blanked off spots where a driver side gas connection would be made. Holly tech said use JB weld but I needed something fast so I bought Holly number 13 which is a 670 Street Avenger. I hope it is not too big. Since my last post, I replaced the intake and evidently I have had vacuum issue all along. Now instead of a choppy idle like what I thought a muscle car should sound like it sounds like a race car.
For clarification, I had a mechanic friend of mine install the timing chain. I can not be certain if it is correct without rebuilding it for the 4th time but he is an old school 1/8 mile drag racer so I trust him over me. I have left out a lot of info. Please ask if you are confused or just curious.
Let's jump to today.
1969 350 ci 4 bolt main bored 40 over.
1975 76cc chambered head that according to Hot Rod magazine were the ones to have on a budget and will run on pup gas. The heads were shaved twice. I don't remember how much material was removed. I am remembering 10 thousandth but that may be wrong. I installed thicker Mr. Gasket head gaskets with copper seals.
COMPETITION CAMS PART NUMBER: 12-212-2
ENGINE: CS 280H-10
GRIND #: CS 280H-10
INT EXH
VALVE ADJUSTMENT HYD HYD
GROSS VALVE LIFT: .480 .480
DURATION AT
.006 TAPPET LIFT 280 280
VALVE TIMING OPEN CLOSE
AT .006 INT 34 66
EXH 74 26
THESE SPECS ARE FOR CAM INSTALLED
@ 106.0 INT C/L
INT EXH
DUR @.050: 231 231
LOBE LIFT: .3200 .3200
LOBE SEPARATION: 110.0
RECOMMENDED CC VALVE SPRINGS: 981-16
Comp cam roller rockers and timing chain was in the kit.
Eldebrock RPM high rise intake.
Wimpy 270:1 rear end but it got good gas millage on my trip back and forth to school.
I don't know what spark plug to use. I have tried different one over the years.
I have HEI non-modified distributor salvaged from somewhere long ago.
8mm wires.
I am not sure what more to add. Please read and ask question.
)
Thank you in advance for your help.
Ya know, or maybe not, the Navy did a study comparing the failure rate of things in the warehouse to the same thing in use and discovered that they age at about the same rate whether you use them or not.
But lets start with the cam, generally the more aggressive the cam the harder it is to set up the engine, the harder it is to keep it (the engine) set up. The comp 280 is a pretty rasty piece and demands that not only it be spot on but everything else as well.
Compression, unless you're running flat topped or even a domed piston, there is no way this engine has enough compression for this cam timing with open chamber heads regardless of what Hot Rod has to say.
12 carbs in one year on one engine is quite a story, I'm sure you should share it as the story may let the rest of us in on what's going on with the engine. The likely hood of hitting 12 bad carbs is a row is statistically damn small.
Setting up the cam; parts get miss-marked and people make mistakes. Engine assemblers buy parts and bolt them on, engine builders don't assume the parts they have are correct. They put 'em on, take measurements, and take off and look again before things get bolted together in final fashion. This takes time and usually eats more than one gasket set.
The previous paragraph probably establishes where you need to start. Since the engine never ran right to begin with, the chances of something fundamental like the timing of the camshaft to piston position is probably incorrect. Or the cam was damaged right after start up and is now missing lobes. It needs to be looked at and that means it has to come out.
When it goes back, you need a new timing set gears and chain, 30,000 miles with an aggressive cam is actually quite a bit. The increased spring tension demanded by an aggressive cam and faster accelerations of the valve system is pretty hard on the cam's drive mechanism, especailly when used on the street with 2.70 gears. The engine is never spun very fast, this makes for long shaky moments being introduced to the cam where it's snapping back and forth against the chain as lifters ramping up want to slow rotation and lifters ramping down want to speed rotation. So the timing gears and chain take quite a beating. Higher RPMs doesn't eliminate this but eventually the revs reach a point where the parts don't have time to respond to the vibrations. Then other nasty things happen but the effects of this one diminish.
Then there is the problem of having a known good carb and distributor. It's a lot better than adding them to the assumptions about and issues within the motor.
There's some good books about engine blue printing out there here's one;
http://sabooks.carshopinc.com/product_info.php/products_id/46848/21
pick up a copy and follow it through your engine.
Bogie
imp: 
