When my engine was assembled, I didn't have a timing light so the father and I were trying to do it by ear. When I try to start it, I pump 3 times and have to give it a bit of gas for a min or so to keep it going. After the minute its running on its own, but low idle till warm. I am wondering if it is because of my timing or because of how huge my cam is and it being too large for setup?

Also, I was told it is more common that the more you advance timing, the better the performance but I had to retard the dist. for what seemed like max performance.

Would a better intake manifold and carb help the start up issue?

 

You definately need to check your timing, Dont just guess.

 

Whoever told you that about the timing gave you wrong info. Actually, the less timing an engine requires indicates a better combustion process.

High compression BB Chevys generally need 40 degrees BTDC timing because of flame propogation problems so the spark has to begin earlier. Most performance SB engines only need 36 degrees, and many times less, to make max power.

More timing advance may "feel" better when you wing the throttle, but up top, the engine ususally either detonates or just plain lays downs.

I've seen a normally aspirated SB on a chassis dyno make over 700 HP with 32 degrees of timing.

Jake

 

So no possibility of it being a cam issue?

 

It's just as SD said, you must set the timing correctly.

From your first post, I couldn't figure out what engine and ignition setup you're running. Fill me in on that.

Jake

 

I have a HEI distributor. What else would you need to know?

 

I was just wondering if your distributor had weights and springs. If your timing is computer controlled then the only way to adjust the timing curve would be to have the ECM/PCM re-programmed.

But I think I'm getting ahead of myself. I'd first make sure the initial/base timing is correct.

I don't have enough info to help further because I don't know if your distributor has the base timing connector like the L98 engines have. If it DOES have that connector, then it must be unplugged when setting the base timing. Then the SES code has to be cleared, etc.

More specific information always helps us, those who are trying to help.

Jake

 

You cannot set ignition timing by ear. get a dial advance timing light.
Do not buy a digital timing light with a LCD display. They are junk.
Buy the one with a good old fashion dial on it.

On a motor with a big camshaft you must modify the distributor advance curve (shorten the amount of advance travel) to allow increased initial spark timing at idle but the same typical 32 to 36deg at max advance.

most "stock" GM HEI distributors have 20 to 24deg of advance.
so if you set the max total advance at 36deg that only allows 12 to 16deg at idle. Not near enough for your big cammed motor. Shorten the advance travel to 10-12deg.
Now with 36deg total at max advance, the timing at idle will be 24 to 26 degrees.

24-26deg at idle 12deg advance in the distributor 36deg total advance at high rpm.
Once you've properly recurved your HEI distributor with the right timing curve and set the timing with a timing light you can readjust the carb properly for 900rpm idle.

If you find the starter cranks over slow when starting the motor hot with this aggressive (but nessessary timing curve) either get a MSD "starter saver" (requires a MSD 6A spark box) or install a simple but effective dash mounted ignition cut off switch on the big red/pink HEI power wire that powers your HEI Crank it over and then throw the switch to power the distributor and it will fire easily.

What is the .050" duration of your .510" lift cam? If it is 244 to 246 @.050" ( typical) you can simply "lock out" the distributor advance curve and run full timing (36deg) all the time. You need a advance timing light or a balancer timing tape to set the total advance properly.
You can still run vacuum advance but it may need adjustment.
Do not eliminate the PCV.
Holley carb:
Your big cammed carbed motor will require that you swap the carb's power valve for a power valve that stays closed at idle. Usually a 3.5 to 4.5" power valve is right.
Edelbrock carb:
same as above but instead of a power valve you change the primary power piston step up springs (that controls the metering rods) for light tension springs. again either 3.5 or 4.5" rated spring pairs.