ProjectIrocZ28

i've been having trouble setting up my 355 to run right. its been pinging like crazy at 2250-2500 rpms. i pulled my distributor and put stiffer springs in it, lined it up again w/ piston 1 tdc compression, .

now i try to start it, and it starts for a little while, runs poor w/ some throttle then at idle it just dies. the timing light is telling me im at 12° BTDC (vac. adv. disconnected). the only thing is, before i pulled the distributor, it ran ok at 8° BTDC (vac. adv. disconnected). now i know i have pretty nasty cam, but i want to avoid locking the distributor because i'd like to be able to hot start the car. i was going to run the vac. advance to boost my timing at idle. is that even an option for a cam like this? also, any clue as to why it did run at 8° before and now it wont at 12°?

the specs on the cam are....
Crane Solid Lifter 110921
-lift w/ 1.5:1 rockers @ zero lash .518 int .535 ex.
-@ .050
-int opens 19° BTDC closes 45°ATDC -duration ATDC 244°
-ex opens 55° BBDC closes 17° ATDC -duration BTDC 252°

Sonix

iTrader: (1)

I'd try something like 24* base timing at idle. Shorten your mechanical advance to be ~12*. Then hook up your vaccum advance to ported vacuum, and limit that to about 10* or so. Make sure you can pull all the 10* of vacuum timing, at the vacuum level you generate at cruise, or else lighten it up so it'll come on at a lower vacuum level.

when it pings at 2250RPM, is that with vacuum advance hooked up to what?
have you dialed in the carb? might be running lean at cruise, it'll ping just like it has too much timing.

244/252 .518/.535" is a big cam. 355 with 416 heads? i'm curious how that'll work out.

what compression ratio, and what gas are you running in it?

ProjectIrocZ28

the compression is in the neighborhood of 10.5-11.0:1, so i cant run a whole lot of advance at cruise, or at all. I run 93 or 94(if im near a sunoco) octane gas.

how do you limit the mech. advance? no matter what springs i put on, that doesn't limit the travel of the advance.

it would ping at 2250-2500 w/ or w/o the vac advance hooked up to ported vac.

as for the carb, i got a holley 750 for it, but it has a small vac. leak at the butterfly linkage that was only at idle. i did run w/ that carb and it ran better, but still gave the same symptoms after warm up. (pinging, hesitation, missing). this carb ran on a 454, so it should supply a 355 i would think. the igniton system is 3 months old, so i know thats good.

eric17422001

Sonix is dead on- with more duration, you need more inital advance.

As far as limiting your mechanical advance from what the distributor has in it you may need to weld the slots in the advance mechanism to limit it's travel. It is a try it and see process, you'll really need to get or borrow an advance timing light to do it.

Sonix

iTrader: (1)

That's right, the springs will just bring in your advance later, but not limit it. I had to disassemble my dizzy, and weld one of the slots to 1/2 length. This gave me 24->12* advance. Makes sense?

Then bump up the initial.

Definately run 93+ octane. That cam will bleed off some pressure, so pump gas should be doable.

You can try running ~10* base timing, and then manifold vacuum advance. Then keep your mechanical timing the way it is, medium springs sorta thing. That *might* work, it is pretty trial and error.

45* at cruise is acceptable, since it's lightly loaded. Once you drop the hammer and your vac advance disappears, you're back down to mid 30's, which is good for power.

Plug gap? heat range? How do they look?

ProjectIrocZ28

i have to find someone with a welder, as i dont have one, so thats why i want to try the base/vac advance setup. if not then i'll do like you said
the plugs are for a stock 305 (heat range, reach) plug gap is .045 they look dead on perfect, except there's only 500ish miles on them. should they be chocolate tan/brown already? or is this "glazing"? should i use a colder plug too? i didnt even think of that when i bought them 2 months ago.

my starter is giving problems now. i should have expected it. it either came lose or its had enough of repeatedly spinning my high compression engine over. so now im stuck on waiting for the weather and possibly money for a new starter.

Sonix

iTrader: (1)

yea, it'll be hard on your starter from now on.

sofakingdom says that the stock starter on these cars is some ancient technology POS... I'd look into a stock LT1 starter, or some aftermarket ministarter, it'll last longer. Do a search about that.

Yes, with that high of compression your plugs are probably wayyyy too hot. I'd go down about 3 heat ranges. I run delco R42T, or the Champion R8Y I think it is.

I would have also closed down the gap.

But hey, if the plugs look good, I won't argue that. Your mixture must be good. If you have a magnifying glass, you can check for bits of Aluminum in them, signs of detonation. It'd just be confirming what you already know though.

You just have to close the gap a bit on the distributor, welding is commonly used as most people have a welder (yea right eh?) Any way you can shorten that gap will work. Brazing, epoxy - metal filled stick style epoxy that is, maybe even solder... etc

ProjectIrocZ28

that clears a lot of things up. this is my first high comp/ big cam motor build(can you tell?) its a lot different to get running than just a stock/near stock one.
well thanks for all the help. i'll post back when i actually can get something done given the weather/finances.