whitedevilTA

iTrader: (8)

Hi all. Just got my car up and running this spring, and am just curious what you all run for timing on your heads, cam, carbed motors?

I have a stock 355 bottom end, trick flow 195cc heads, and a comp cams 224, 230 dur on a 112 centerline cam. Performer RPM air gap manifold with an edelbrock 600 cfm carb......I know the carbs a little small, but it's all I've got to work with for now.

Currently I have timing set at 10 degrees initial with about a total of 32 degrees at about 2600RPM. Car runs good, but feels a little sluggish when you give it some gas. Should I be running more timing with a set up like this?

Ozz1967

iTrader: (4)

that sounds about right. You might try 12 initial. What torque converter stall speed are you running? Also, a 600CFM carb isn't too small. If you run the numbers for CFM on a 350ci motor it comes out to need only like 430CFM.

rjmcgee

26* base + 10* mechanical advance.

Vacume advance plugged into manifold vacume.

You should probably be running more base timing.

leeperryracing

i'm running a custom bullet cam 234/242 and .573in/.573ex lift @.050 on a 110lsa in a 355 and this cam ran like A$$ until i recurved the dizzy to put out 10* mech. and then ran 24* base timing....now it idles very "gently" for the size cam, exhaust is not burning my eyes anymore, picked up a lot in the 1/4 mile and throttle response is crisp! long duration cams with decent to a lot of overlap need lots of base timing....don't be afraid, as long as you come out to around 32-36* total you'll be fine.

89lt1

iTrader: (6)

my friend has aluminum l98 heads 540 558 110ls cam and a 750 dp carb no vacuum advance and runs a total of 42-44 degrees and turns 7000 rpm but he has a start retard because he runs so much initial

Sonix

iTrader: (1)

I run 36* base timing and no mechanical advance now.

When I had the comp 268xe cam, I ran 24* initial with 10* advance. Ran excellent. Less then that and I had to open the throttle blades WAYYYY too far to keep it running, so I was running on the main circuits. It killed the off-idle response.

bluegrassz

iTrader: (3)

Im running stock bore L98 with AFR 190's, comp xr282hr 112, RPM airgap intake, and a Holley 750 street HP carb. I am running 40* total all in by 3k.

Im guessing your combo should like 36-38 total.

What compression are you running?

whitedevilTA

iTrader: (8)

I'm right about at 9.5:1 compression. I'm gonna play with it when I get home because it runs good at 10* base, but has a little stumble while giving it gas when I'm driving. By the way, how do you know how much total NON mechanical advance timing your running? Do you have to do something with the weights?

Also, the car is a 5 speed, so no torque converter.

My dizzy is an MSD and has that adjustable vacuum advance with the hex key.....do you think that really needs to be touched or should I be fine with the "out-of-the-box" setting?

And thanks all for the help. Nice to have some motor combos to compare my timing to!

whitedevilTA

iTrader: (8)

UPDATE

Bumped base timing to 14 degrees and the car loves it. BIG improvement on driveability. I may go even higher, like to 15 or 16 to see how it likes it because it seems like it wants more. If it starts pinging, I'll just back it down a little. Now just need to get it on the road legally! Haha

rjmcgee

With your cam this is what I would do

Should limit your mechanical advance to 12 - 14 degrees. Then set your total to 34 - 38 degrees @ 3000 with the vacume can unplugged. Then plug your vacume advance into manifold vacume. Will give you a great idle and throttle responce.

cc 82Z-28

iTrader: (7)

I run 16* on my 406 that has a roller cam with .563/.574" lift on 110 lsa with Dart Pro 1 aluminum heads, air gap intake with 770 holley with a total of 36* by about 28-3000.

81MOD LAD

I have an 81 corvette with modified Vortec heads(biigger valves roller rocker 1.5, , comp cam 242 extreme energy 480 and 472 lift, headers, 600 cfm edlebrock, jegs performance intake...My car runs best with 19 degree base timing. I have messed around from 12 degree to 22 dergree...No doubt it loves 19...hope this helps! It churps best at 19 degree, it's an automatic, no ping no run on after shutoff...

sofakingdom

iTrader: (1)

I run mine where it runs the best. I pay NO ATTENTION WHATSOEVER to the "number". I [puffs out chest like Captain America] get to decide what "best" is. It's usually some combination of best power, lowest fuel consumption, cool running on the freeway, crispest throttle response, no pinging, and so on. Tempered by difficulty starting, excessive pinging, run-on after shutoff, requirement for expensive fuel.

My choice. YOUR choice, in your case.

If it RUNS good, it IS good.

Tom 400 CFI

^That^. Even thought this is a 15 year old thread, it's always good to remind people; "Feed it what it wants".

AlkyIROC

I've posted this in other threads so I'm going to post it again here.

Base timing is adjusted to best suit the camshaft that is installed. Total timing needs to be programmed electrically or mechanically depending on the distributor since increasing the base timing will also increase the total timing which the engine may not want.

10- to 12-degrees of initial timing when the duration of the camshaft is less than 220-degrees @ 0.050” of valve lift
14- to 16-degrees of initial timing with a camshaft duration of less than 240-degrees @ 0.050”
18- to 20-degrees of initial timing when the camshaft duration is less than 260-degrees @ 0.050” of valve lift.
More than 260 degrees @ 0.050" is normally a full race cam and a locked out ignition set to full advance with a start retard is generally used but you can still use a timing curve if you want.

Where your engine wants the total timing is best figured out on a dyno or dragstrip. 32-34* total timing is most common but higher or lower numbers can be used depending on how the engine is built and used. Power adder engines usually want less total timing while NA engines usually want a little more but there are a lot of other factors in there also.

Once your base timing is set based on your camshaft, it never needs to be changed. You adjust the advance to increase performance depending on when components used in the engine. Since not all engines are the same, nobody can tell you how much total timing your engine needs.

Rebuildman

Best max advance timing is the # that makes maximum cylinder pressure just after TDC. Remember, any spark prior to TDC will also work against the piston as it heads to TDC. The least amount of timing needed to achieve the max cylinder pressure after TDC is the best. Fuel burn rate associated with octane levels also play a part. As been previously stated, dyno testing is the way to nail down the best timing #'s.