How little timing can I run and not hurt anything??

Posted By: FlyFish

How little timing can I run and not hurt anything?? - 05/29/13 04:17 PM

I have my small block stroker currently at 25� total timing. I'm wanting the car to slow down another 2 tenths, so I was going to pull the timing down a few more degrees...will this hurt anything? Can I run 20� total timing and not damage anything? I know it will cause more exhaust heat, but is that it?

Posted By: Thumperdart

Re: How little timing can I run and not hurt anything?? - 05/29/13 05:13 PM

Can`t be a happy motor at that point I would think........why not tune it to perfection then limit full throttle. This reminds me of nos guys who retad their timing manually instead of using electronics killing power and TRYING to make it up w/nos but hey, that`s just my opinion.

Posted By: FlyFish

Re: How little timing can I run and not hurt anything?? - 05/29/13 05:39 PM

I'm just trying to get this thing to run in Sportsman (12.0 bottom dial). I'm real close...just need a little more. This is what I have done so far:

I added as much weight to the car as possible (safely). I removed the secondaries on the carb (now its a 2 barrel), backed the timing off 10 degrees (25� total currently), and I'm short shifting at 5500 RPM (I normally shift at 6500). This combo has slowed the car a little over a second from high 10.7x ET to 11.87 (calculated from my 1000' time on my last 3 pass when I lifted at the 1000' cone and ran 12.05)....I just need to kill a little bit more to get to 12.0 so I don't have to coast the last 320'.

Posted By: BradH

Re: How little timing can I run and not hurt anything?? - 05/29/13 05:45 PM

From what I've been told by a former NASCAR engine build is you really don't want to rely on retarded timing to restrain the engine because the exhaust valve temps can skyrocket under those conditions.

Posted By: MR_P_BODY

Re: How little timing can I run and not hurt anything?? - 05/29/13 05:46 PM

You will be suprized how much timing you would need
to pull out to slow it .2.... what rpm do you launch
at... lower that and shift 500 less than you are shifting
now... I have a mech throttle stop on my dom set at
1/3 open and launch soft and shift real early to go 10.0

Posted By: FlyFish

Re: How little timing can I run and not hurt anything?? - 05/29/13 06:11 PM

Unfortunately I can't shift any lower RPM, my converter flashes to a little over 5K, so I'm pretty much shifting as soon as I see the tach move (which is about 5500).

Posted By: MR_P_BODY

Re: How little timing can I run and not hurt anything?? - 05/29/13 06:31 PM

Put a mech throttle stop on it.. at part throttle the
conv flashes/stalls at a lower rpm due to not making
the torque like full throttle

Posted By: JohnRR

Re: How little timing can I run and not hurt anything?? - 05/29/13 07:08 PM

Quote:

I have my small block stroker currently at 25� total timing. I'm wanting the car to slow down another 2 tenths, so I was going to pull the timing down a few more degrees...will this hurt anything? Can I run 20� total timing and not damage anything? I know it will cause more exhaust heat, but is that it?

You are going to melt something , as it is your headers must be cherry red by the end of the pass .

Posted By: FlyFish

Re: How little timing can I run and not hurt anything?? - 05/29/13 07:12 PM

So should I turn my timing back up to 35� (or close to it)?

Posted By: J_BODY

Re: How little timing can I run and not hurt anything?? - 05/29/13 07:13 PM

Ever researched the "ET genie" ?

Posted By: FlyFish

Re: How little timing can I run and not hurt anything?? - 05/29/13 07:16 PM

Quote:

Ever researched the "ET genie" ?

Yeah, but I'm not dropping 500 bucks to go slower. I just want it slower for a few races.

Posted By: JohnRR

Re: How little timing can I run and not hurt anything?? - 05/29/13 07:24 PM

Quote:

Quote:

Ever researched the "ET genie" ?

Yeah, but I'm not dropping 500 bucks to go slower. I just want it slower for a few races.

Can you run the class in your daily driver ?

What have you done to SAFELY ADD weight ? Adding weight is the best way to do it , can you swap steel you added for LEAD ???

I think the $500 will be cheaper than the potential damage you are going to do ....

Posted By: Al_Alguire

Re: How little timing can I run and not hurt anything?? - 05/29/13 07:38 PM

As already pointed out the only potential damage will likely be the exhaust vavels. Well it will also run a bit hotter normally with that much out of it.

Posted By: FlyFish

Re: How little timing can I run and not hurt anything?? - 05/29/13 07:43 PM

Ok, I'll put the timing back in it then. Thanks everyone....and yes, using my tow vehicle as a race car is sounding more and more likely for these races.

Posted By: wyoming

Re: How little timing can I run and not hurt anything?? - 05/29/13 08:42 PM

Leaving in 2nd will get you close, you wont spin either, another trick is a restrictive little air cleaner

Posted By: GTX MATT

Re: How little timing can I run and not hurt anything?? - 05/29/13 08:56 PM

Forced induction cars run 15-20 degrees, but that is with the aid of electronics and only when necessary

My forced induction job runs as little as 10 degrees at certain rpm/load conditions and exhaust temps don't pass 1100 degrees. That being said it isn't 10 degrees throughout the rpm range, and that is only under full load/boost conditions.

Posted By: JohnRR

Re: How little timing can I run and not hurt anything?? - 05/29/13 09:52 PM

Quote:

Forced induction cars run 15-20 degrees, but that is with the aid of electronics and only when necessary

My forced induction job runs as little as 10 degrees at certain rpm/load conditions and exhaust temps don't pass 1100 degrees. That being said it isn't 10 degrees throughout the rpm range, and that is only under full load/boost conditions.

I didn't know that , but how does that help with a car not running forced induction and a timing computer ? He doesn't want to pony up the 5 bills for the ET thingamabob , I don't think he is going to pony up for forced induction so he can roll back the timing more ....

Posted By: GTX MATT

Re: How little timing can I run and not hurt anything?? - 05/29/13 09:56 PM

To be more specific I should have said they run as little as 15-20 from the factory, because at certain points they will be in a normal 34+ range.

But still exhaust temps are reasonable, they should remain reasonable in an NA application, although my car also runs around 11-11.5:1 AFR under said conditions. I'm just playing devil's advocate.

Posted By: JohnRR

Re: How little timing can I run and not hurt anything?? - 05/29/13 10:03 PM

Quote:

To be more specific I should have said they run as little as 15-20 from the factory, because at certain points they will be in a normal 34+ range.

But still exhaust temps are reasonable, they should remain reasonable in an NA application, although my car also runs around 11-11.5:1 AFR under said conditions. I'm just playing devil's advocate.

Ever break in a cam with the timing at only 20-25 degrees ??? You won't get half way thru the break in before the radistor is boiling over ...

Posted By: GTX MATT

Re: How little timing can I run and not hurt anything?? - 05/29/13 10:22 PM

Quote:

Quote:

To be more specific I should have said they run as little as 15-20 from the factory, because at certain points they will be in a normal 34+ range.

But still exhaust temps are reasonable, they should remain reasonable in an NA application, although my car also runs around 11-11.5:1 AFR under said conditions. I'm just playing devil's advocate.

Ever break in a cam with the timing at only 20-25 degrees ??? You won't get half way thru the break in before the radistor is boiling over ...

I wouldn't try to operate the engine at speed for extended periods of time with the timing retarded because it would surely overheat, but for a track car for 12 seconds at a time I think he will get away with it, just lock the timing out OR run vacuum advance on manifold vacuum to prevent overheating at idle.

At WOT my forced induction car sees the timing curve below, the car has been operated at WOT for in excess of 12 seconds many times without exhaust temperatures surpassing 1100 degrees.

I know that his car is not forced induction, and he SHOULD better explore other ways to limit his power, BUT

RPM Total timing

800 8.13
1200 13.05
1600 13.05
2000 12
2400 11.29
2800 9.89
3200 9.54
3600 9.54
4000 11.29
4400 12
4800 13.75
5200 16.21
5600 16.57
6000 19.03
6400 20.43
6800 23.25