429CJ Pings

[Mach_One]

I have  a stock 429CJ.  When I step on it, it pings despite using "premium" 91 octane fuel.  That do you guys recommend?  AV gas?  104+ octane boost?

 

[TommyK]

If 100LL is available that would be the ticket. Try a 50/50 blend. Or use this:

http://www.jegs.com/i/Race-Gas/814/100032/10002/-1

 

[SLO-RIDE]

If 100LL is available that would be the ticket. Try a 50/50 blend. Or use this:

http://www.jegs.com/i/Race-Gas/814/100032/10002/-1

It may be as easy as checking the timing. It may be advanced too far. It's worth a try

 

[72HCODE]

you can also disconnect and cap off the vacuum advance, run on mechanical only and see if the engine still pings. reduce timing as needed.

when ping stops then reconnect the advance and retest, if you have an adjustable advance then turn the screw counterclockwise, 2 turns at a time until ping stops.

if the engine just started to ping and didn't before then you need to inspect the fuel system for problems, clogged filters, issues with carburetor, problems with accelerator pump circuit.

problems with the cooling system can also cause ping as the engine could be getting hot from a clogged coolant passage.

additional can be bad gas it is not unheard of as a new car has a knock sensor and can adjust the fuel air mix as needed.

the adjustable vacuum advance was also called the bad gas compensator back in the day.

 

[TommyK]

The early 429's and 460's with small chamber iron heads and flat top pistons have compression ratio's in the mid 10's. This coupled with relatively small cam profiles make for a DCR that is to high for today's pump gas. Recurving the distributor and running a 160 degree tstat can help but probably won't eliminate pinging without some additional octane.

 

[Mach_One]

UPDATE: Tried some Lucas Oil octane booster, what a joke in a bottle. There's $12.00 I'm never getting back.  So today I filled the Mach up with a 50/50 mix of LL100 AV Gas and the 91 Octane premium unleaded and took her for a rip.  The 429CJ sings like a sweetie and sounds totally wicked with all 4 barrels open....all without a trace of ping!  So happy!!

 

[boilermaster]

UPDATE: Tried some Lucas Oil octane booster, what a joke in a bottle. There's $12.00 I'm never getting back.  So today I filled the Mach up with a 50/50 mix of LL100 AV Gas and the 91 Octane premium unleaded and took her for a rip.  The 429CJ sings like a sweetie and sounds totally wicked with all 4 barrels open....all without a trace of ping!  So happy!!

Mach-One,

You might want to read up on the 110LL av gas.

I am reading that it contains 8 t0 10 times the amount of lead that our cars had back in the day !

pretty sure it will run much leaner than 91-93 octane availiable today.

it may do more harm than good.

the racegas stuff does work.

                                            Boilermaster

 

[73pony]

UPDATE: Tried some Lucas Oil octane booster, what a joke in a bottle. There's $12.00 I'm never getting back.  So today I filled the Mach up with a 50/50 mix of LL100 AV Gas and the 91 Octane premium unleaded and took her for a rip.  The 429CJ sings like a sweetie and sounds totally wicked with all 4 barrels open....all without a trace of ping!  So happy!!

Mach-One,

You might want to read up on the 110LL av gas.

I am reading that it contains 8 t0 10 times the amount of lead that our cars had back in the day !

pretty sure it will run much leaner than 91-93 octane availiable today.

it may do more harm than good.

the racegas stuff does work.

                                            Boilermaster

+1. You might want to check you timing.

 

[TommyK]

UPDATE: Tried some Lucas Oil octane booster, what a joke in a bottle. There's $12.00 I'm never getting back.  So today I filled the Mach up with a 50/50 mix of LL100 AV Gas and the 91 Octane premium unleaded and took her for a rip.  The 429CJ sings like a sweetie and sounds totally wicked with all 4 barrels open....all without a trace of ping!  So happy!!

Mach-One,

You might want to read up on the 110LL av gas.

I am reading that it contains 8 t0 10 times the amount of lead that our cars had back in the day !

pretty sure it will run much leaner than 91-93 octane availiable today.

it may do more harm than good.

the racegas stuff does work.

                                            Boilermaster

AVGAS 100LL contains about half of the lead (TEL) that the period leaded gas used to have, hence the Low Lead designation. Another advantage of avgas is it doesn't go bad over time and it won't gum up your fuel system.

 

[Mach_One]

UPDATE: Tried some Lucas Oil octane booster, what a joke in a bottle. There's $12.00 I'm never getting back.  So today I filled the Mach up with a 50/50 mix of LL100 AV Gas and the 91 Octane premium unleaded and took her for a rip.  The 429CJ sings like a sweetie and sounds totally wicked with all 4 barrels open....all without a trace of ping!  So happy!!

Mach-One,

You might want to read up on the 110LL av gas.

I am reading that it contains 8 t0 10 times the amount of lead that our cars had back in the day !

pretty sure it will run much leaner than 91-93 octane availiable today.

it may do more harm than good.

the racegas stuff does work.

                                            Boilermaster

I did read up on Av Gas in fact, and I find it surprising that there's so much misinformation out there.  People saying that the high lead will "ruin your engine" and such.  I find it laughable that TEL will hurt an engine (429CJ) that was designed to use it in the first place.

The "LL" in LL100 means LOW LEAD.  Low Lead because they used to put a lot more TEL is Av Gas than they ever did in car gas.  1975 leaded gas had 1.7 Grams per Gallon (GPG) lead, today's AV Gas has 2.11 GPG in it.  Leaded race gas has much more lead in it than LL100 does.

I'm not running straight Av Gas anyhow, it's 50/50 blend of 91 octane premium and LL100, which gives me 95-97 octane and a hair over 1 GPG lead, which is close to the lead content of leaded gas after July 1, 1977. (.9 GPG)