360 correct timing

So I picked up a 1971 Scamp a few weeks ago with a fully rebuilt 360 with a mild cam. This car can really move! My question is what would be the correct timing? By the way I came over from the C Bodies side...

joe

Well Joe,that's a loaded question.
My answer is 34degrees at 3200rpm with iron heads and 91 gas,and 3.55 gears,and in an A-body. This is of course with the vacuum advance defeated. This is a reasonably safe power timing.
Then we have idle timing, cruise timing and part throttle timing.

I guess the exact right answer is 1 or 2 degrees less than what gets you into detonation.
Unfortunately the engine is an ever-changing thing. There are times it might want close to 60*, and time it wants no more the 18*, so you the operator, are gonna spend this coming summer doing a lot of fiddling to sneak up on the perfect number.
Here is a ballpark set of numbers;
16*initial or idle timing, 34*power timing and 52* at minimum 2200 while cruising with the vcan added in.

Generally most small blocks run well around 12-14 initial 34-36 all in.

Oh...Welcome to the site.

I'll leave the tech up to smarter people than me....
Just wanted to say Welcome aboard!

Jeff

Thanks for the welcomes and replies. I am new to performance type engines, I always dealt with basically stock. This car runs fantastic, and I know I'm within a few degrees but I moved the distributor a 1/16 or so either way.

Fantastic is well, Fantastic !!!
Dont touch it !!!!!!

The only thing better than fantastic is fantabulous

Joe Zartler said:

So I picked up a 1971 Scamp a few weeks ago with a fully rebuilt 360 with a mild cam. This car can really move! My question is what would be the correct timing? By the way I came over from the C Bodies side...

joe

Click to expand...

(1) set the initial with the "vac gauge method" (2) set total (initial+slots,can capped) to 35 (3) toss the heavy spring with the elongated loop & sub in a mr gasket/transdapt/MP light spring in its place for a start & mix/match springs (always keep the OE light spring) so you are just under the pinging point up thru the gears on your hottest/driest (most likely to ping) day then (4) plug in the can to ported & adj it with a 3/32 allen wrench so you are just under the pinging point on your hottest/driest day in everyday driving under varying RPM/load conditions. there is silent ping so you need a slight cushion on the pinging setpoint plus different people have a different hearing threshhold. Google the "vac gauge method" & with it if the starter is balky when hot reduce the INITIAL (1) degree (not the vac (1) in hg, you'll see why the reminder on the distinction when you find the procedure) & retry & with that finalized, the set the total to 35 with the plate. The FBO $22 plate is the best/cheapest/easiest deal in town by far for limiting the total so I would order one right now (trust me on this).

my 360's have always likes 17 initial and 35 total in by 2200 rpm..

read through these articles.. no need to weld and file slots any mor ethough.. just buy this for $25.. FBO Systems

Dredging this thread back up because it is a good one and right in line with my topic. So I finally broke down and bought my own timing gun, should have done it a couple years ago. But there's a lot of stuff I should have done years ago, I suppose you guys know the feeling.

I went in and double checked the Scamp's timing (with LA360) because I thought I had the initial timing set at 8° ... my target was to set total timing at 35°. Well I bought the digital timing light that can dial back the timing by 0.1° increments.

When I first checked it with the timing light set at 0.0° offset, sure enough it looked about like 8° again. Now let me mention that what I'm looking at is timing tape that is somewhat reflective, and the timing marks on the block are blue. I should go in and paint the 0° mark white. Things are not easy to see. But not impossible.

However, when I dialed the timing light back to 8° so that the 0° marks would line up, I could see that I was indeed OFF with my previous measurement. So I played with the timing buttons and when I could finally distinguish as close to the 0° marks being lined up, I was at ~12° initial timing. And ~37.5° total timing. With all in being at about 2,500 rpm.

I'm going to say that those numbers are within ±1°. You guys would have to search (and I don't expect you too), but I've always said that El Scampo runs REAL GOOD. It hit 99.01 mph in the quarter mile with little bity 14" 215's (Pizza cutter) tires, while poodling off the line (due to the tires) with a 2.181 sixty foot time (slow). So, after I get it rolling, it pulls pretty darn good on those skinny tires. But not only that, the throttle response in just around town driving is great.

I see various recommendations of 34° to 36° and sometimes higher than that depending on mods. Since I know this 360 has a mild cam, I decided to just leave it where it is. I never hear any pinging, and I run 90 octane no ethanol fuel 80% of the time, and 89 octane no ethanol some too. Every once in a blue moon, when I'm just going to blow a tank of fuel away on the interstate, I'll run 87 octane no ethanol from Racetrac gas station (cause it's cheap). And I don't hear any knock.

I wanted to post this, just for others seeking timing info like the O.P. And I wanted to ask:

DO YOU GUYS THINK 37.5° TOTAL TIMING IS TOO AGRESSIVE?


7milesout

If it runs good, advance it until it doesn't and then back it down. No definitive answer here as everything has a part in optimal timing. Even one 'identical' motor to another.

No where near apples to apples, but mine likes 34 and is pretty sensitive to timing. Two degrees makes a big difference. I run a bunch of initial, to help it idle. Again not apples to apples. 22-24 initial. It never kicks back even when warm. I think tuning your initial by vacuum is the way to go. Just make sure your total stays where you want it. Its funny, they all seem to like 32-34 total.

furrystump - My 12° initial is without vacuum advance (it was plugged). If I apply the vacuum advance (I run manifold vacuum not timed vacuum) at idle, it's up in the 20's (from my memory) like yours. It idles pretty good.

After running this AFR gauge for a while, I have to believe that a lot of people's cars sound lopey at idle, not specifically because of the cam, but because it is idling a bit lean (not really lean, but leaner than they may expect). For example, if I run my idle down to 12.0 AFR on a completely warmed engine, my engine idles more steady. But I lean it to ~13.5 AFR (but it is jumping all over the place at idle from 12.5 or so to 14.9 or so, averaging about 13.5), and it does sound lopey. It sounds bad *** at that AFR.

I'm not so sure that tuning it to 12.0 AFR idling in my case wouldn't be so bad, because I idle it minimally, due to traffic, and the fact that since it's not EFI it doesn't like to shoot out the driveway as soon as it fires up. But in part I tune my idle between 12.0 and 13.5 when tuning my cruise AFR. Mine is fat while cruising at the moment. I just put in an Edelbrock 1905 and still have a good bit of tuning to do. I won't take it back to the quarter mile till I'm hitting my target AFR at WOT.

So while idling at 13.5, I always get the question, "that thang got a cam in it?" My response is, "well it won't run without one, so yeah."

I run my afr at 12.3 at idle. Idles nice there and because of what I’m doing with it and the carb I’m forced to run I need ALL the fuel I can get. Like leave the sec jets on the bench kinda thing. I tried running it with no rods in it. Was ok, but running through the pits it would hit a certain rpm and go pig fat. More throttle and it cleaned up. On track it pick up a bit, but didn't want to live with it that way so backed out the idle mixture screws a bit and accomplished the same thing with no drivability issues.