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What timing does a 140 like?
Posted by: Cataldo ()
Date: April 17, 2017 05:00PM

I know that the stock specs are 18* with 18* of advance on a 65-66 140 distributor.

That is where I have it set now and runs well.

My motor is a stock bore 140 with the chambers and ports mildly cleaned up (Previous to me rebuild) with essentially the Otto 20 cam (270).

The gasket step is at least milled down some and is running copper head gaskets.

I am not sure how much work was done to the chambers or the quench but better than common would be my guess.

is 38* of mechanical advance where these motors make best power? I know it is no modern chamber that likes 30* or less but generally where do they make the best power? 34? 38? 42?





Also what vacuum advance can would work best for this set up as my diaphragm is torn. IIRC stock on my distributor is 11* of vacuum advance. So that puts total timing at 49*

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Re: What timing does a 140 like?
Posted by: MattNall ()
Date: April 17, 2017 05:14PM

Sadly that's Dyno time.....

I limit all mine to 36 total, but in by 2400 rpm...then for a streeter.... I dimple the VA can so it doesn't start to pull in until 10" hg...

No 140's right now.... have have been able to run 89 octane at altitude and sea level..

Just on days over 100f do I ever get pinging.





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Re: What timing does a 140 like?
Posted by: davemotohead ()
Date: April 17, 2017 05:34PM

No porting was done on your heads, they were deep seated and the chambers cleaned up, the staking was done before the deep seats were installed, the cam was a old LS Corvair grind similar to a Isky 260, If its running good with no ping leave the timing where its at and install a good set of secondary's for more power, that engine is full of good parts but it is a mild built 140.



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Edited 1 time(s). Last edit at 04/17/2017 05:36PM by davemotohead.

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Re: What timing does a 140 like?
Posted by: BobV66Vair ()
Date: April 18, 2017 09:08AM

Dave, I'm puzzled. Why would you leave the rough edges of the staking like that? It seems that they would overheat and lead to pre-ignition. At the least won't they reduce, albeit slightly, the smooth flow of air just before combustion?

Bob Vinnacombe
Sandy, Oregon
1965 Corsa 140 stock
1966 Monza Soon to be race car
1968 Monza Parts for now

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Re: What timing does a 140 like?
Posted by: davemotohead ()
Date: April 18, 2017 09:24AM

BobV66Vair Wrote:
-------------------------------------------------------
> Dave, I'm puzzled. Why would you leave the rough
> edges of the staking like that? It seems that they
> would overheat and lead to pre-ignition. At the
> least won't they reduce, albeit slightly, the
> smooth flow of air just before combustion?
-------------------------------------------------------
I did not do the heads, But do not think those small dimples will cause a problem, lots of heads have been run like that thru the years with no problems.



Email me at: Dave Motohead

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Re: What timing does a 140 like?
Posted by: 66vairman ()
Date: April 18, 2017 10:56AM

davemotohead Wrote:
-------------------------------------------------------
> No porting was done on your heads, they were deep
> seated and the chambers cleaned up, the staking
> was done before the deep seats were installed, the
> cam was a old LS Corvair grind similar to a Isky
> 260, If its running good with no ping leave the
> timing where its at and install a good set of
> secondary's for more power, that engine is full of
> good parts but it is a mild built 140.

Agree - I run conservative on timing. There are better ways to make power. Decades ago when I was young a buddy kept increasing the timing in his car and the improvement in power was noticeable. No pinging, yet one day a piston developed a BIG hole in it.

Look up "Pre-Ignition" or excess early timing, not the same as detonation (ping) and it's a silent engine killer.

The vacuum advance has NO effect on maximum power, it only advances timing under LIGHT throttle load to improve cruise mileage. Under WOT (wide open throttle) there is little, if any, vacuum advance. Always set static timing with NO vacuum advance present.

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Re: What timing does a 140 like?
Posted by: Cataldo ()
Date: April 18, 2017 05:59PM

If I ever pull the heads I will sand those dimples flat, but probably not much of any negatives now (Probably filled with carbon anyhow).

Dave,

Do you know how much was taken off of the heads?

And head gasket thickness?

So I can figure out the compression ratio.


66Vairman,

10-4 I agree that conservative timing is best.

I do need vacuum advance for fuel economy, I see that Autozone has vacuum advance cans for our cars.

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Re: What timing does a 140 like?
Posted by: Seth Emerson ()
Date: April 19, 2017 03:32PM

You don't like Dave's dimples? So Sad. (I recommend 36 max initial + Mechanical)

Seth Emerson

Check my new Performance Corvair Web site [www.perfvair.com]

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Re: What timing does a 140 like?
Posted by: 66vairman ()
Date: April 19, 2017 04:51PM

The Autozone unit is a "one size fits all" vacuum advance can. Might work, might not. The Corvair had many different vacuum cans depending on the engine configuration.

Clark's sells the various vacuum canisters for the different engines, but you have to look in the supplement - not in the regular catalog.

See [www.corvair.com]

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