Vortec 350 Timing Table

[Frankenchevy]

hey,

just messing around with software setting up my timing. I initially set it to what the interwebs said was stock vortec timing. I'm wanting to confirm if these settings are accurate. also, I've heard on here that tbi 350s came out of the factory with really low timing values and they can take more advance. I was wondering if my research was pointing to similarly conservative timing values that I could also advance.

my values are 15 idle, 36 cruise, 32 WOT. my curve is not really a curve, more like a curb--its all in at 1600 rpm. I'm going to play with smoothing that out a bit.

what is the consensus from the greater wisdom here? what is a good starting point for idle, cruise, WOT and all in?

Thanks!

 

[hirschdalechevy]

I know nothing about computer controlled anything , but for all my old hot rod engine's timing , initial , curve , cruise , and all in depend's on cam and heads. There are more factor's that come into play , elevation , air temp , etc... but we wont go into that stuff.

Anyway , for a stock set up its all about the heads , tbi heads are bath tub cambers, (not the best) so you can throw more timing at them , (36 to 38 total) , and (in the mid to high 40's) cruise , but be careful you don't want detonation. I alway's went for a (curve) all in by 3,000rpm and then played with it from there to see what the engine liked with out any detonation.

With true vortec heads,(96 and up) they have the heart shaped chamber's (fast burn) and are way better , so they don't need or like more timing. When I have used vortec heads I always kept timing no more than 32 , all in , but ran the same curve , all in by 3,000 as a start and then played with it from there. Cruise I played with a bit with vacuum adv. , (high 30's to low 40's) or what the engine liked with out detonation.

All the engine's I have messed with had non stock cams in them so as far as initial goes , (more cam likes more initial timing) for the most part. Fast burn heads , (vortec , gm aluminum , afr etc...) don't need as much leed time for the spark because they have a way better chamber design.

I only mess with old stuff so I put timing tape on the balancer , rev her up to 3,000 and set the total first , then that pretty much sets the initial and then I go from there , vacuum advance cans and stops , recurve kits , several test drives etc.....

This may not help you at all since its all old school but I though I would share some of my timing knowledge I have learned over the years.

 

[Frankenchevy]

I built this timing table by hand last night. much like what you stated. the pink area represents cruise timing at 36*, but looking at it now I realize it needs to be modified so that it can be there at a realistic cruise rpm of ~2500rpm while under 40kpa of manifold absolute pressure(MAP). I have my base set at 15* and WOT at 32* all in by 3000rpm. the kpa about 105 to the left of the graph is not utilized as I don't have forced air (boost)

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[Frankenchevy]

just broadened my cruise plateau to hit 36* at 2500rpm with high manifold vacuum(<46kpa). still 32* all in by 3000rpm in the lower vacuum areas(WOT).

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[Frankenchevy]

@hirschdalechevy , yes stock gm cam and heads. engine is a new GM longblock L31-r vortec. I have read most guys say 29-32 degrees is perfect for WOT. I've been reading quite a bit about actual GM vortecs and it sounds like the engineers really put a lot of time and effort these guys. 3 angle grinds on both sides, 480HP potential naturally-aspirated, and valve train is rated beyond 7k without float. its even mentioned that they're still making power above 6k. although, I've set my rev limiter to 6k with warning light at 5700--i'll never be up there anyway in my truck.

i'm sure you've read this thread before, but just in case--it has some interesting information about the history, production and tuning capabilities of vortec heads.

http://nastyz28.com/threads/vortec-cylinder-heads-the-definitive-guide.56505/

 

[bluex]

Have you looked at the timing map from the Holley tbi terminator system from that article? Im running it right now an it works well. I was hoping do just leave it alone when I went to vortec heads.

If anything you could take that map an scale it back/down to the values you want. When you figure it out let me know so I can steal it from you for mine!

 

[Frankenchevy]

Have you looked at the timing map from the Holley tbi terminator system from that article? Im running it right now an it works well. I was hoping do just leave it alone when I went to vortec heads.

If anything you could take that map an scale it back/down to the values you want. When you figure it out let me know so I can steal it from you for mine!

that table puts you at 44 total, which according to the general consensus is about 10 degrees too high for vortec. I was trying to figure out a way to just squish it down in the software, but couldn't find a way to do it. If you can, let me know...especially after you go to the holley tuning school! i'm still learning the software. I want to trim all the 105+ kpa stuff off there since I don't need it anyway. it just makes the part of the graph you're modifying smaller and harder to see. which brings up a suggestion i'd have for the software coders, a zoom function would be great.

none of the software (sniper, v4, v5, etc.) seems to have a pre-programmed base calc for vortecs, which is too bad. I am going to call holley tomorrow and ask if they have a vortec file or suggest that they make one since it's such a common swap for gen 1 sbc guys.

I plan on running a table or two I built and data logging everything to see if i'm producing more or less vacuum across the range. if it turns out, i'll send you a copy of the file so you can cut and past the timing table when you go vortec.

 

[bluex]

You can scale the table down to remove the pressure readings you'll never see. I think its covered on that article. Its been a while since I've done it so I'm a little rusty.

As far as moving the whole table down you can select a range of cells an there is a key combination that you press to raise or lower the whole selection by various amounts. I think you can do 1% to 5%.

It's possible you could find someone with hp tuners an get them to screen shot the vortec timing table. We should be able to build a copy of it from that.

 

[hirschdalechevy]

@hirschdalechevy , yes stock gm cam and heads. engine is a new GM longblock L31-r vortec. I have read most guys say 29-32 degrees is perfect for WOT. I've been reading quite a bit about actual GM vortecs and it sounds like the engineers really put a lot of time and effort these guys. 3 angle grinds on both sides, 480HP potential naturally-aspirated, and valve train is rated beyond 7k without float. its even mentioned that they're still making power above 6k. although, I've set my rev limiter to 6k with warning light at 5700--i'll never be up there anyway in my truck.

i'm sure you've read this thread before, but just in case--it has some interesting information about the history, production and tuning capabilities of vortec heads.

http://nastyz28.com/threads/vortec-cylinder-heads-the-definitive-guide.56505/

Thanks for the link , a lot of reading , have to get started on that.

I am working on a vortec 350 in my blazer , (that I just dropped in) as we speak. I am playing with ignition curves and vacuum advance cans right now to get her where I want her and then to the holley off road carb.

My roller cam is a 215int 223exh @ .050 , .473 , .473 lift on a 108 lobe sep. so it may need more initial timing but I am playing with that at this time to see what it likes, then I will limit the total to 32 and play with vacuum cans to get the cruise where she like's it , maybe start at 45 degree's and work from there.

Again , thanks for the link.

 

[4WDKC]

@hirschdalechevy , yes stock gm cam and heads. engine is a new GM longblock L31-r vortec. I have read most guys say 29-32 degrees is perfect for WOT. I've been reading quite a bit about actual GM vortecs and it sounds like the engineers really put a lot of time and effort these guys. 3 angle grinds on both sides, 480HP potential naturally-aspirated, and valve train is rated beyond 7k without float. its even mentioned that they're still making power above 6k. although, I've set my rev limiter to 6k with warning light at 5700--i'll never be up there anyway in my truck.

i'm sure you've read this thread before, but just in case--it has some interesting information about the history, production and tuning capabilities of vortec heads.

http://nastyz28.com/threads/vortec-cylinder-heads-the-definitive-guide.56505/

thought all in timing was supposed to be 2400 rpm? Think thats what I had set mine to. The stock cam was also retard 6 degrees making it even worse. I have read the vortec .57 cam was used in the Caprice/Impala also so you could use those timing tables as a starting point also.

 

[Frankenchevy]

thought all in timing was supposed to be 2400 rpm? Think thats what I had set mine to. The stock cam was also retard 6 degrees making it even worse. I have read the vortec .57 cam was used in the Caprice/Impala also so you could use those timing tables as a starting point also.

I think the head was different though. I’ll look at their tables to see if they’re closer than what I’ve found.

Thanks!

 

[4WDKC]

I think the head was different though. I’ll look at their tables to see if they’re closer than what I’ve found.

Thanks!

ish.. they are cast iron lt1, they took what they learned from them and used that info when developing the vortec head for the sbc

 

[Frankenchevy]

Okay, so my motor didn’t like the posted curve. The base tune runs smooth for now.

There is a Holley dealer in Sacramento I may be able to get a global config file from if I can’t get it right. They also have a dyno, worst comes to worse I can pay for a dyno tune. Not sure how that works with a/t tires...

 

[bluex]

It should work fine as long as you dont have super wide tires or crazy offset wheels. Call them an ask what the max width they can handle on the dyno an make sure your not over that.

 

[4WDKC]

found this one, calimed to be stock

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better yet

http://www.gearhead-efi.com/Fuel-In...Black-Box-Computer)-Open-Closed-Throttle-ONLY

@Daveo91Burb did you see this?