Ignition Timing with a Performance Cam

[Tire Burner]

I have a Reasonably New Engine. It has about 3000 Miles on it.

Chevy 350 Block Bored .060
NEW Nodular Steel Crank Std/Std
NEW 4130 Rods with ARP bolts
Lunati Camshaft 284/284 (218 @.050) .458/.458 Lift
Stock 882 Heads
Flat Top Hyper Pistons
1.6:1 Roller Rockers
Hardened Pushrods
.600 Lift Springs
Edelbrock Performer Intake
600 CFM Edelbrock Carb

I had it timed where it barely sounded performance, but i recently took it to a Mechanic that likes to build Performance engines. He Said that i was completely wrong on my timing. He said that i needed 28 Deg of Timing. He Proceeded to turn my Distributor until it sounded loud and throaty. It really sounds good, but it seems like a bit too much for that cam. It actually Idles fine at 500-600 RPMs. I have had another person tell me that it only needs 12-15 Degrees. I'm worried about my Hyper Pistons. I don't want to melt them and i've noticed that the engine runs a little hotter. It's not Dangerously hot, just a little hotter. If the Timing is Wrong, it might damage my Pistons. What do you guys think?

[VileZambonie]

Do you have a vacuum advance distributor? Your initial timing I would set at 12° BTDC and then advance it from there. The old advance it til it pings and then retard it usually works pretty good but then check your base timing and advance @ 3,000RPM. Record your settings. Make sure it starts easy. If you find that it runs a little hot at idle try setting your vacuum advance on manifold vacuum not ported and adjust your idle speed down.

Sounds like you have a decent engine combo there but why the 1.6:1 rocker ratio?

[Tire Burner]

I'm a Rookie. This is my Learning Engine and i'm REALLY learning alot. I do have Vaccum advance. I asked the guy that adjusted my timing to retard it 5 degrees and then went on a 125 mile Road Trip. I found that the engine seemed stronger and didn't take as much RPMs to Acheive the same speeds. In fact, The engine used to give me no more power beyond 3000 RPMs, but now it actually LIKES to be that high. I had the Truck up over 100 MPH without a Problem. It was pulling about 3400 RPMS at that speed. I might have the guy put me back to what it was before i told him to go back and see what happens. Before he Timed it, it would lug when you tried to start the Engine Hot. After he timed it, that went away.

The Rockers were put on because i didn't know that all i needed to do was buy the Cam that i wanted. I will change the Cam soon anyway. The one that's in there now is a Single profile and wanted to get a good Dual profile with alot of Exhaust.

[VileZambonie]

Well if you are using a 1.6:1 rocker arm ratio then your valve lift is really .488"

[Tire Burner]

Yes, i learned that too. What you do is you take your Current cam's Lift and Divide it by 1.5. Once you have that number, you Multiply it by 1.6 to get the New Lift. The Mistake that i made was not buying a cam with the lift that i actually wanted. I had no clue when i bought my cam that i had to consider Duration, Lift AND Lobe Separation Angle. I also didn't know that the only Duration Measurement that really mattered was the Duration at .050. I am going to change to aluminum Heads and i'm also going to change the Cam. Since i want some good Off the Line AND some Top end, i would need a cam that has an LSA of 110 to 112. Right now my cam DOES have an LSA of 110, but the Duration is only 218@.050. I'm wanting to go to 234@.050 and still have the 110 LSA. I'm going to run Regular rockers if i find a good one that has around .500 Lift. If not, i'll reuse my 1.6s