Prepping for Mopars at the Strip tomorrow

[CoronetDarter]

Tomorrow is the annual Mopar at the Strip car show in Sacramento. Taking the Coronet, first time to the track. Only my second time, first was Fremont Raceway in the early 80's. I have a few questions about prepping, but first a quick overview:
69 Coronet, all steel body, full interior. Stock stroke 440 0.030 over. Forged pistons and crank, Stealth heads with minor porting; 10.5:1 CR. Hughes hyd FT cam 232/236 @ 0.050 .536/.546 110LSA 106 ICL. Eddy RPM intake, Dougs headers running 3" full exhaust. Fitech EFI. Pertronix dizzy with Blaster III coil. 727 TF Dynamic 3,000 stall converter. 3.55 8 3/4 with SG. New HD leaf springs, adj pinion snubber, battery in trunk. Have about 2,000 miles on the car and drive train since the resto.


The motor likes 19* initial - setup by the engine builder, confirmed again last night with a vacuum gauge - 15" at idle. The motors been pinging at WOT so I've been backing off this entire time. Checking the Pertronix instructions, the silver springs let in 24* mechanical. Found the problem - way too much advance.

Install the "blue" limiter, now total advance is 35*, all in at 2,500. Took the car for a spin last night and the difference was incredible. Pinging gone at WOT and transition from cruise to WOT. Even seems more responsive right off the line, which I didn't expect.

So my questions are: based upon the other springs and advance limiters available in the Pertronix kit, is there a better combo than the silver spring/blue limiter I'm running now?



For drag racing, does the motor want all in earlier or later?
And mixing in racing fuel should allow more advance - how much is too much advance? And does it matter if the additional timing comes from initial or mechanical? Thanks for your help.

 

[malex]

Tomorrow is the annual Mopar at the Strip car show in Sacramento. Taking the Coronet, first time to the track. Only my second time, first was Fremont Raceway in the early 80's. I have a few questions about prepping, but first a quick overview:
69 Coronet, all steel body, full interior. Stock stroke 440 0.030 over. Forged pistons and crank, Stealth heads with minor porting; 10.5:1 CR. Hughes hyd FT cam 232/236 @ 0.050 .536/.546 110LSA 106 ICL. Eddy RPM intake, Dougs headers running 3" full exhaust. Fitech EFI. Pertronix dizzy with Blaster III coil. 727 TF Dynamic 3,000 stall converter. 3.55 8 3/4 with SG. New HD leaf springs, adj pinion snubber, battery in trunk. Have about 2,000 miles on the car and drive train since the resto.
View attachment 650114

The motor likes 19* initial - setup by the engine builder, confirmed again last night with a vacuum gauge - 15" at idle. The motors been pinging at WOT so I've been backing off this entire time. Checking the Pertronix instructions, the silver springs let in 24* mechanical. Found the problem - way too much advance.

Install the "blue" limiter, now total advance is 35*, all in at 2,500. Took the car for a spin last night and the difference was incredible. Pinging gone at WOT and transition from cruise to WOT. Even seems more responsive right off the line, which I didn't expect.

So my questions are: based upon the other springs and advance limiters available in the Pertronix kit, is there a better combo than the silver spring/blue limiter I'm running now?
View attachment 650115
View attachment 650116

For drag racing, does the motor want all in earlier or later?
And mixing in racing fuel should allow more advance - how much is too much advance? And does it matter if the additional timing comes from initial or mechanical? Thanks for your help.

---
It sounds like you're pretty much where you want to be. 36 degrees total advance all in seems to be the magic number for most RBs. So long as your initial doesn't drop off, yur off to the races I would say.

 

[Mike Gaines]

I run 37 total, all in at 2400 rpm...( l launch off the transbrake at 3600 so it is all in when I leave the line and I run 110 race gas with 12.2 Compr Ratio.

 

[Kern Dog]

Probably too late for my words to make much difference but here is what I have learned through years of doing it wrong:

Engines will reach a point where additional timing advance is detrimental. Adding race gas to a car that is not detonating AND cranking up more advance often does not improve anything. For efficient cylinder heads like pretty much anything made today, the B and RB engines do perform best between 34 and 37 degrees of TOTAL timing. The "all-in" RPM number is something that can be tailored to come in later for engines that are detonation sensitive. I had some trouble getting my engine to stop knocking and I tried many things over the years.
I run about 17 degrees initial, 33 total with the full advance in around 2500. I also run vacuum advance. I am at 10.07 to 1. I have mine set up like this just to be on the safe side and to prevent any knocking.
Years ago I was closer to 11 to 1 and the car would ping/knock/rattle/detonate when I floored it....Or anything over 3/4 throttle. I tried different cams, advance curves, race gas, carburetor jetting, different spark plug heat ranges... 110 octane leaded fuel was the only thing that completely eliminated the knock but I didn't want to be at the mercy of hard to find $10 per gallon gasoline. I ended up porting the heads and adding thicker head gaskets. No knocks now.

That is a nice looking car. I don't recall seeing it before.
See you tomorrow.

 

[CoronetDarter]

I run 37 total, all in at 2400 rpm...( l launch off the transbrake at 3600 so it is all in when I leave the line and I run 110 race gas with 12.2 Compr Ratio.

Mike, I've been reading up on your threads and posts in the Racers Hangout. I learned a lot of good stuff.

 

[CoronetDarter]

Probably too late for my words to make much difference but here is what I have learned through years of doing it wrong:

Engines will reach a point where additional timing advance is detrimental. Adding race gas to a car that is not detonating AND cranking up more advance often does not improve anything. For efficient cylinder heads like pretty much anything made today, the B and RB engines do perform best between 34 and 37 degrees of TOTAL timing. The "all-in" RPM number is something that can be tailored to come in later for engines that are detonation sensitive. I had some trouble getting my engine to stop knocking and I tried many things over the years.
I run about 17 degrees initial, 33 total with the full advance in around 2500. I also run vacuum advance. I am at 10.07 to 1. I have mine set up like this just to be on the safe side and to prevent any knocking.
Years ago I was closer to 11 to 1 and the car would ping/knock/rattle/detonate when I floored it....Or anything over 3/4 throttle. I tried different cams, advance curves, race gas, carburetor jetting, different spark plug heat ranges... 110 octane leaded fuel was the only thing that completely eliminated the knock but I didn't want to be at the mercy of hard to find $10 per gallon gasoline. I ended up porting the heads and adding thicker head gaskets. No knocks now.

That is a nice looking car. I don't recall seeing it before.
See you tomorrow.

Greg - took the car out again tonight. Hammered it on hwy 65; no pinging throughout the range. I run vacuum advance too so i was flooring it from a steady cruise and again, no pinging. So 35 seems to be within the sweet spot. You've only seen the Dart. I haven't seen your Charger yet either, so we'll both pop our cherries tomorrow.

 

[Kern Dog]

Uhhh....
Not together though.

 

[CoronetDarter]

10 - 4.
I was talking figuratively.

 

[biomedtechguy]

we'll both pop our cherries tomorrow.

Uhhh....
Not together though.

10 - 4.
I was talking figuratively.

 

[dvw]

I don't see an important item in the specs. What rear tires does it have?
Doug

 

[CoronetDarter]

I don't see an important item in the specs. What rear tires does it have?
Doug

BFG 295/50 15

Disappointing day. Ran twice, both times suffered fuel starvation right off the line. About 2/3 down the track there must've been enough airflow to lower temps because then the car perked up. By then it was too late. No pinging though, but got some fuel issues to sort out.

 

[CoronetDarter]

But, on a positive note, the Coronet got grease pen on it's windshield for the first time. Looked cool driving home.

 

[BSB67]

BFG 295/50 15

Disappointing day. Ran twice, both times suffered fuel starvation right off the line. About 2/3 down the track there must've been enough airflow to lower temps because then the car perked up. By then it was too late. No pinging though, but got some fuel issues to sort out.

Great that you went to the track

If it was fuel starvation at first hit, your problem probably started before that. Did you idle for an extended period with the hood down in the staging lanes?

A fuel pressure gauge near the carb that you can read while driving will tell you a lot.

 

[Dennis H]

 

[CoronetDarter]

Great that you went to the track

If it was fuel starvation at first hit, your problem probably started before that. Did you idle for an extended period with the hood down in the staging lanes?

A fuel pressure gauge near the carb that you can read while driving will tell you a lot.

You're pretty close. Because there's also a hot-start heat soak issue with the starter, the car idled for about 20 minutes, but with the hood up. The coolant stayed at 190 which was promising, but no doubt the idling contributed to the vapor lock.