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Difficult warm/hot start

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Location
Jamestown NY
I think my question to the Group is about timing, but AFR seems meaningful in the tune also.

I have a ’71 charger that starts right up and runs well, but when I try to restart the warm engine it’s like I’ve lost my battery – it does that fraction of a crank to compress that 1st cylinder and stops. Let off the key – try again and again. After a couple of tries it cranks to the 2nd compression, hits a spark and starts. Let it cool down for a couple of hours and everything is cranking good again.

383, bored and stroked to 413, Comp Cam 270H. Holley Sniper w the dual point distributor. The Sniper tracks the AFR and timing – current settings: Crank @ 0*, Idle @ 20* & 14.0 AFR, Cruise @ 33* & 14 AFR, WOT @ 35* & 12.2 AFR

The rest of the Car: Tremec 5 speed, 3.91 in 8 ¾ rear, no air conditioning

20* at idle seemed crazy high, but the engine loved it – bumping up the timing from 15* the rpm’s kept coming up. I didn’t bump it past 20*, and reset the idle back to 850

I’m running a 160* thermostat on Summit 3 core radiator and 2 stage electric fan. Running around town with any wind in the radiator it stays at 160-180*, but let it idle and the temp creeps. (stage 1 at 190*, stage 2 at 205*) It never overheated at idle – the fans hold it pretty good at 200*. The fans run after the engine is off and the temp continues to rise up to 209* before it starts to cool down again.

Does anything look off?

Greg
 
Sounds like a possible bad starter. Way back when we would use a Sunnen VAT 40, and check the starter draw.
 
Does it hot start better at *15 timing? I would look at timing first and starter next.
 
Does it hot start better at *15 timing? I would look at timing first and starter next.
I think he has the ability to set an initial timing during cranking and has it set at 0 degrees.
0 degrees is certainly not too far advanced to create the kickback he describes.
I agree with checking the starter/cables or even battery possibly.

By the way my ignition timing at idle is around 30 35 degrees on my 383.
 
Last edited:
20* initial [ idle ]? I am surprised it didn't need more. See the link.

If you are using a stock starter, then that is probably the problem. Fixes:
- check all the starter cable/lug/connections for corrosion
- get a more powerful starter [ one rated at 3hp or more ]
- use man connected vac adv to advance to advance the timing AFTER the engine starts. Example: stay with 10* init & add 10* plus with VA, engine running.
- put a switch on the dash that grounds the coil [-] lead. Turn the switch 'on' [ to ground the connection ] while cranking hot engine & then switch 'off' once the engine is cranking to bring in the ign.

img267.jpg
 
I think he has the ability to set an initial timing during cranking and has it set at 0 degrees.
0 degrees is certainly not too far advanced to create the kickback he describes.
I agree with checking the starter/cables or even battery possibly.

By the way my ignition timing at idle is around 30 degrees on my 383.
Hi,

The starter is a (new) Mini. It does crank over fine when engine is cold.

The engine does seem to like timing, but one of the threads I read here suggested too much timing will cause heat/detonation which could give me difficulties w the hot start.

I will put the idle timing back to 15* and test.

BTW: I do like the Sniper. Once set up - all of these adjustments are taps on the hand held. I've added a snapshot of a Data log. I am no expert on this, but I am amazed w the information that is available. Just in case someone is curious I hope the attached picture is readable.

Legend/description of the Data log picture:

Bottom green line: Throttle Position Sensor - it all starts here :)

Top Blue line: AFR - the average is 14.0 the rich dips happen with loss of Manifold vacuum (push on throttle)

Middle Green Line: Timing - upper limit is 36*. The average lower limit is at 20* (set for idle timing), but the sniper is using the timing to adjust other engine conditions and bounces between 25* and 12*

Yellow Line: MAP - Manifold Absolute Pressure. Atmospheric pressure is (nearly 100 kPa), the maximum vacuum at idle is 20 kPA - a hard push on the throttle reduces the vacuum to 86 kPA (approaching Atmospheric Pressure) - causing the AFR to dip to 11, timing stayed at 36*

Sorry - TMI?

1718196111790.png


Greg
 
There is no reason why the timing should be capped at 36 degrees unless you're at full throttle.
During cruise conditions it could be 45 - 50 degrees.
See if you can adjust the vacuum advance settings to add 10 - 15 degrees of vacuum advance (manifold vacuum if you have that option)
This will have no effect on your starting problem but will make for better economy, throttle response and a cleaner engine long term.

If the starter is good you can try a couple more things (test hot if you can) one at a time.

1. Try a different known good battery.
2. try temporarily connecting a jumper cable from the starter main stud to the battery positive.
3. try temporarily connecting a jumper cable from the battery negative to a good clean engine block location.
 
Last edited:
There is no reason why the timing should be capped at 36 degrees unless you're at full throttle.
During cruise conditions it could be 45 - 50 degrees.
See if you can adjust the vacuum advance settings to add 10 - 15 degrees of vacuum advance (manifold vacuum if you have that option)
This will have no effect on your starting problem but will make for better economy, throttle response and a cleaner engine long term.

If the starter is good you can try a couple more things (test hot if you can) one at a time.

1. Try a different known good battery.
2. try temporarily connecting a jumper cable from the starter main stud to the battery positive.
3. try temporarily connecting a jumper cable from the battery negative to a good clean engine block location.
Thanks Don
 
Backing off timing to fix a starter problem is a baaaaad idea. The fix is a more powerful starter or procedure outlined in post#6.
 
I was reading today of good results with hot starting by blocking off the heat crossover on the inlet manifold valley pan.
 
I was reading today of good results with hot starting by blocking off the heat crossover on the inlet manifold valley pan.
That might help for a vapor lock condition with a carbereuter. (Fuel boiling after you shut it off for 5-10 minutes)
He has EFI and the symptoms sound more like poor cranking power due to something else.
 
This morning was a good.

I gave the idle and cruise a little more gas (idle: 14 to 13.5 AFR. Cruise: 14 to 13 AFR), and ran the car down the road.

The engine ran cooler than it's ever been, it pulled nice and hard - the cooling fan never kicked on. I parked the car at 185 degrees and it started right back up.

(I actually had too much crank/choke enrichment - leaned that down from 200% to 175%. 2nd warm start was 1,2, 'vroom')

I think I will play w the timing. From this Forum and other reads, 20* of timing isn't too high - the engine might like more, before I reintroduce a heat problem.

(Love the EFI - clicks on the handheld vs jets/rods, timing light, weights and springs - is so much easier.)

I appreciate all the help

Greg
 
Check your battery/starter connections, and be sure the cable is not getting exhaust header/pipe heat soak.
 
I am runnin hp manifolds on my 440, original looking starter.

I had the same symptoms as you, while rebuilding Z-bar I discovered something black on top of starter, I put my hand up there and my fingers went black, gasket between manifolds and collector had a tiny leak straight on to starter.

When the starter got hot from exhausts it behaived just like if it wasnt getting enough juice from battery.

This was probably not your issue, but same symptoms
 
I think my question to the Group is about timing, but AFR seems meaningful in the tune also.

I have a ’71 charger that starts right up and runs well, but when I try to restart the warm engine it’s like I’ve lost my battery – it does that fraction of a crank to compress that 1st cylinder and stops. Let off the key – try again and again. After a couple of tries it cranks to the 2nd compression, hits a spark and starts. Let it cool down for a couple of hours and everything is cranking good again.

383, bored and stroked to 413, Comp Cam 270H. Holley Sniper w the dual point distributor. The Sniper tracks the AFR and timing – current settings: Crank @ 0*, Idle @ 20* & 14.0 AFR, Cruise @ 33* & 14 AFR, WOT @ 35* & 12.2 AFR

The rest of the Car: Tremec 5 speed, 3.91 in 8 ¾ rear, no air conditioning

20* at idle seemed crazy high, but the engine loved it – bumping up the timing from 15* the rpm’s kept coming up. I didn’t bump it past 20*, and reset the idle back to 850

I’m running a 160* thermostat on Summit 3 core radiator and 2 stage electric fan. Running around town with any wind in the radiator it stays at 160-180*, but let it idle and the temp creeps. (stage 1 at 190*, stage 2 at 205*) It never overheated at idle – the fans hold it pretty good at 200*. The fans run after the engine is off and the temp continues to rise up to 209* before it starts to cool down again.

Does anything look off?

Greg
Had the same problem. High torque mini starter solved it right away.
 
Thanks so much for these responses/ideas.

I thought I had this problem solved w AFR and Timing, but engine temps of 200 still have a problem cranking. I'm running the fans for 3 minutes after engine turn off - the engine temp seems to top out at 209 (on these warm days)

It could be a heat problem on the starter. I'm running TTI shorty headers. I'll double check for a leak. I considered heat on the starter being a problem - I made a shield to protect it from the pipe heat . . . no difference.

The starter is a Robbmc Mini-starter (#3005) . . . I'm not sure if that is 'high torque' - it came strongly recommended. It cranks fine cold.

The battery is rated at 1045 amps. it is relocated to the trunk w 1/0 cables. . . cranks fine - cold. . .

The engine is a new build (383, bored and stroked to 413) . . . I'm hoping the builder doesn't have anything 'too tight' that is binding when hot. I'm still running conventional oil through this, the 2nd year of 'break in'. Current wonder is to switch that over to synthetic.


Thanks to all.
Greg
 
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