max timing of vortec headed motor?

[rebel1mcelroy]

have vortec heads 062 on my 360 hobby motor and was wondering about timing, have heard not to run over 32', i am running it on 34' now and its running really good on pump gas! just dont want to hurt it! anyone have any ideas what could happen if i leave it there? thanks

[SLM98]

32-33* anything more was a power loss

[stockcar5]

same here. lost a good amount of power on the dyno over 32. best power was with 30.

[rebel1mcelroy]

good deal!! keep in mind the dist. is locked and no weights, i checked it at idle 1000 rpms and it was 34' ran it up to 3500 and it was 30 so i think ill be good! thanks

[merc123]

good deal!! keep in mind the dist. is locked and no weights, i checked it at idle 1000 rpms and it was 34' ran it up to 3500 and it was 30 so i think ill be good! thanks

If your distributor is locked it shouldn't go from 34 to 30... Mine is locked and if I set it at 34* then it it as 34* whether it be 1500 RPM or 4000 RPM with minimal variation (+/- 1*)... Locked means that the weights and springs are removed and it is welded.

I may be retarded but this would seem to me that this is the point of locked distributors...to maintain a timing no matter what RPM.

[dynoman14]

If your dizzy is an HEI, retard is pretty common. I am not a big fan of locking distributors as I feel the engine needs a timing advance curve that matches the acceleration rate of the engine. There is a significant advantage to using the ignition to your advantage to aid in the acceleration rate of the engine.

If you think of it is fighting the early firing of the plug, you will see how this can work to your advantage.

Why do you think most dirt cars won't fire and have to be push started to get back running...
#1 the battery does not have enough juice to fire the engine...
#2 the ignition is locked out and timing is too great to over come with discharging battery.

I have seen 602's and 604's run great @ 12* initial and 28* total at 4200rpms.

Another important aspect of your ideal timing is the burn curve of the fuel you are running. I run maybe 3-4 sets of components a week to get the CARB and Dizzy matched to the acceleration rate of the engine and the burn rate of the fuel. Do this on the chassis dyno optimizing acceleration of the engine and to maximize torque curve.

In general the vortec head like 5-10* less timing than conventional heads. Swirl and Combustion Chamber Efficiency contribute to making more power with less timing. This also applies to conventional heads if you can get it to work for your application. I have had good results with richer than normal early fuel curve, gradual advance curve and less total than most folks. For folks that run their engines on the dyno, I like .450-.500 on fuel up to about 5000rpm and then I start to tail off and lean out to .400-.425 up to 7000. I also like the timing retard that comes in above 6500 with most non-locked distributors. As you start to lean the fuel some it does not require as much timing to get the job done. I also run my plug gaps pretty tight in the .025"-.035" range depending on the ignition system capabilities.

This applies for most crate and stocker applications. Open engines are another animal.

[rebel1mcelroy]

Thanks for the info. If I run the dist. Unlocked it will not pull 14in. Of vac. At 1000rpm and as far as the timing I've got it welded and the pickup coil locked out(no vac adv.) and I do think the chain has some slack causing timing change. No starting problems here I run a 3hp mini starter.

[stockcar5]

the timing change is due to the fact that the magnetic trigger not being able to keep up with the rpm and the signal lags a little bit. its called magnetic hysteresis. some distributors are better than others but many of them seem to change almost 1 degree per 1k rpm. the only real fix is to use a crank trigger.
fwiw i've run locked timing for years with zero issues. never had a problem restarting when hot. even with a 14 to 1 406.

[perfconn]

Stockcar5 is right.Real race cars don't need less timing to start.Under race conditions your engine will never be low enough rpm to back up on timing.If it won't start under full advance then work on your starter and electrical system.

[rebel1mcelroy]

Good deal!! Been wondering why and now I know why the timing retards a little!! I've changed timing chain,set dist.end changed module. With the same results, no biggie though I've ran this motor for two seasons now and needed some spare parts!! Lol thanks