What is a good timing for my set up..

[pedal2themetal]

HI,
What I have is a 75 318. gasket matched heads
stock piston and bore
450 cfm Quick Flow Holley
1" spacer square bore to spread bore
performer intake
0* timing set
Cam is .420 lift at .50 In and Ex. duration 270 In, and Ex. 110 lobe separation.
Stock exhaust manifolds true duels out.
Under hood sticker calls for TDC @750 rpm . but that was with stock 2 bbl, with stock single exhaust and stock timing set and cam.
So if someone has some kind of idea for a good idle timing or all in timing would be appreciated.. Automatic. stock type distributor.

Thanks take care be safe
tim

 

[ykf7b0]

I would start in the neighborhood of 12 degrees BTDC with vacuum advance plugged.

 

[RemCharger]

35-36 max mechanical. Of course use aftermarket light springs and ditch the dreaded never- get- there factory heavy duty ones.

 

[turbine68rt]

First you need to know how much mechanical your distributor provides at full advance and go from there. If you want more initial you can always limit the top end with an FBO limiter plate.

 

[Budnicks]

(75, Is that a POS lean-burn era dist. & controller ?
get rid of it if it is, lots of stuff on-line)

IMO with a low-compression engine like that
8:1 maybe (?)

I'll bet it's far closer to 18*-20* initial timing, at idle
maybe as much as 38*- 40* total at like 3,500rpm
optimal
May need to put a degree tape on the balancer to get an accurate reading
or use a timing light with the degrees on/in it...
(As said above;
you may need to get an FBO advance limiter plate,
if you can't control 'the ping'
if springs on the mechanical advance & initial distributor timing setting,
can't control the vacuum advance, from adding too much advance,
But;
the vacuum advance will still aid in 'around town driving', economy even
at your performance levels, it will be probably near '50*s of total'
with the Vac. adv. in play, at your performance levels)

the rest of the add-ons, your cam, carb, intake & the spacer
are a bandaid to compensate for the lack of compression,
'trying to make a lil' more power'
It can still be done

you can always,
do the 'disconnect the vac. adv.', plug the side going to the carb,
losen the dist. so it can be moved easily enough, but not too loose
set the idle to like 2,500rpm-ish, and advance the dist.
until you get the highest RPM, you'll need a tach or can listen carefully
(&/or vacuum)
& back it off "just a tad", maybe 1*-2*s
check it with a timing light to see what it actually is
for further reference sake

reset the idle screw, to a reasonable idle again

go out & test it,
if it "pings" especially under cruise, part throttle
with an actual load on it, like going up a slight grade
then back it off (retard it) maybe 2*
reset the idle speed

then road test again
& repeat it until it sounds & feels OK

(*or use better fuel, so it doesn't ping, I doubt that an issue thou
not with that low of compression)

every engine, every combo, no matter what,
they will like a specific advance #
your combo, is not an exception to that rule
& rarely 'ever' is it even close to TDC 0*s, not for any performance levels
'maybe smog crap'

If any of that makes sense to you

Good luck

 

[Mike Brini]

Turn it up till it pings then back it off till it doesn't.

 

[pedal2themetal]

(75, Is that a POS lean-burn era dist. & controller ?
get rid of it if it is, lots of stuff on-line)

IMO with a low-compression engine like that
8:1 maybe (?)

I'll bet it's far closer to 18*-20* initial timing, at idle
maybe as much as 38*- 40* total at like 3,500rpm
optimal
May need to put a degree tape on the balancer to get an accurate reading
or use a timing light with the degrees on/in it...
(As said above;
you may need to get an FBO advance limiter plate,
if you can't control 'the ping'
if springs on the mechanical advance & initial distributor timing setting,
can't control the vacuum advance, from adding too much advance,
But;
the vacuum advance will still aid in 'around town driving', economy even
at your performance levels, it will be probably near '50*s of total'
with the Vac. adv. in play, at your performance levels)

the rest of the add-ons, your cam, carb, intake & the spacer
are a bandaid to compensate for the lack of compression,
'trying to make a lil' more power'
It can still be done

you can always,
do the 'disconnect the vac. adv.', plug the side going to the carb,
losen the dist. so it can be moved easily enough, but not too loose
set the idle to like 2,500rpm-ish, and advance the dist.
until you get the highest RPM, you'll need a tach or can listen carefully
(&/or vacuum)
& back it off "just a tad", maybe 1*-2*s
check it with a timing light to see what it actually is
for further reference sake

reset the idle screw, to a reasonable idle again

go out & test it,
if it "pings" especially under cruise, part throttle
with an actual load on it, like going up a slight grade
then back it off (retard it) maybe 2*
reset the idle speed

then road test again
& repeat it until it sounds & feels OK

(*or use better fuel, so it doesn't ping, I doubt that an issue thou
not with that low of compression)

every engine, every combo, no matter what,
they will like a specific advance #
your combo, is not an exception to that rule
& rarely 'ever' is it even close to TDC 0*s, not for any performance levels
'maybe smog crap'

If any of that makes sense to you

Good luck

HI,
Yeah , I know it was going to need more.. but TDC with all the smog crap on it the tag under the hood does say TDC at 750 rpm's.. but that's all gone really wasn't that much anyway.. mostly just the air pump..
yeah lean burn the plugs are white , but I do run premium in it. I do have a dial timing light..

thanks again be safe take care
tim

 

[Runner 68]

(75, Is that a POS lean-burn era dist. & controller ?
get rid of it if it is, lots of stuff on-line)

IMO with a low-compression engine like that
8:1 maybe (?)

I'll bet it's far closer to 18*-20* initial timing, at idle
maybe as much as 38*- 40* total at like 3,500rpm
optimal
May need to put a degree tape on the balancer to get an accurate reading
or use a timing light with the degrees on/in it...
(As said above;
you may need to get an FBO advance limiter plate,
if you can't control 'the ping'
if springs on the mechanical advance & initial distributor timing setting,
can't control the vacuum advance, from adding too much advance,
But;
the vacuum advance will still aid in 'around town driving', economy even
at your performance levels, it will be probably near '50*s of total'
with the Vac. adv. in play, at your performance levels)

the rest of the add-ons, your cam, carb, intake & the spacer
are a bandaid to compensate for the lack of compression,
'trying to make a lil' more power'
It can still be done

you can always,
do the 'disconnect the vac. adv.', plug the side going to the carb,
losen the dist. so it can be moved easily enough, but not too loose
set the idle to like 2,500rpm-ish, and advance the dist.
until you get the highest RPM, you'll need a tach or can listen carefully
(&/or vacuum)
& back it off "just a tad", maybe 1*-2*s
check it with a timing light to see what it actually is
for further reference sake

reset the idle screw, to a reasonable idle again

go out & test it,
if it "pings" especially under cruise, part throttle
with an actual load on it, like going up a slight grade
then back it off (retard it) maybe 2*
reset the idle speed

then road test again
& repeat it until it sounds & feels OK

(*or use better fuel, so it doesn't ping, I doubt that an issue thou
not with that low of compression)

every engine, every combo, no matter what,
they will like a specific advance #
your combo, is not an exception to that rule
& rarely 'ever' is it even close to TDC 0*s, not for any performance levels
'maybe smog crap'

If any of that makes sense to you

Good luck

Good 'Ol Budnicks still kicking out Sage advice.

 

[threewood]

You can't just turn it up. You need to stick a vacuum gauge on it and give it what it wants around max vacuum them back it off a touch. All the while backing the curb idle down.

Since you advanced the initial,, you will also need to limit the mechanical advance since it will be over max and will probably ping or detonate. Depends on your distributor.

 

[Cranky]

I agree with Bud too.....give it what it wants and I found years ago that the lower the compression, the more timing they like/need. So far I've had 2 engines that actually liked 50 total!! Yeah, surprised the snot out of me the first time that I used 3 different timing lights and confirmed that the ring on the balancer hadn't slipped. First one was a rebuilt 440 with low compression forged pistons that were way down in the hole and another was a stock 318 with some bolt on mods. The 440 was in a 67 Coronet that easily ran low 13's with no traction and the teen was in a 72 Demon that ran a mid 13 with nothing but mismatched parts. The Demon ran 102 mph so with a better converter vs stock, it probably would have run 13.30's? The 102 mph sure points to that.