Engine Ping

[Long Island RT]

I get it under a heavy throttle in higher gears in lower RPMs (3-4000).  I probably get it in lower gears and higher RPMS but I can't hear it over the tires squealing.

Hears what I have:
512 440 source stroker kit
Ross flat top pistons with 4 cc valve reliefs
Eddy 84 cc heads - prepped by Hughes engines and bowl matched to my Indy dual plane intake 440-2D
Fel-Pro blue permatorque head gaskets (0.039" compressed)
NKG ZFR6FGP plugs
1.6 roller rockers
Hughes hydraulic cam 4650 3-bolt
  606 intake, 576 exhaust
  intake duration @ .050 = 246°
  exhaust duration @ 0.50 = 250°
  lobe separation = 108°
Cam installed and dialed in with no advance
Hughes 1160 valve spring (recommended by them for this cam)
Mathematically calculated 10.98:1 compression
Pro-comp 8027 distributor
MSD 6AL
Firecore wires
Holley 950 proform carb
93 octane gas - it's the highest I can get @ the pump

Timing is now set @ 34° total advance
I don't know what the idle advance is because my dial back timing light doesn't work well with the MSD
If I turn back the overall timing more than 3°- engine feels sluggish (if that's possible)and I'll get run-on after I shut it down and she stills pings (slightly less)
The idle actually likes more advance - the more I go, the smoother she idles

I've tried additives from 104 octane boost to Torco. 
The only thing that worked was adding 1 gallon of pure toluene to 10 gallons of fuel.  It actually worked really well - the engine responsiveness was amazing - I was able to get 36° total advance with no pinging noticed anywhere (even the smell out of the exhaust was sweet)


Does changing the cam to 4° advance help the situation in any way?
Other than changing to a 112° cam what are my other options? (will that actually work?)
Shim the heads?  Does that cause alignment port issues with the intake?
The toluene is expensive and not exactly a long term cure.


I know - Many questions.....
But you all love solving my issues so thanks in advance 

[Domino]

I'd recheck your compression ratio #s.

[Long Island RT]

I did all the boring math myself and then found this site tool some time ago:
http://www.csgnetwork.com/compcalc.html

It confirmed the same as me 10.98:1

4.375" bore (0.055 over)
4.25" stroke
4.410" head gasket bore
0.039" compressed head gasket thickness (Felpro-1009)
84CC combustion chamber
-4 cc valve reliefs
0.029" piston deck clearance (this was an actual measurement on each piston and no cylinder was off by more than a thousandth)

I noticed if I switched to the felpro gasket 1105 (bore 4.590 in. and 0.051" compressed thickness) I can lower my compression ratio to 10.6:1 but I feel like that bore is just too big of a gasket for my engine?

Even a 10 thousandths of a shim lowers me to 10.75:1

[firefighter3931]

I did all the boring math myself and then found this site tool some time ago:
http://www.csgnetwork.com/compcalc.html

It confirmed the same as me 10.98:1

4.375" bore (0.055 over)
4.25" stroke
4.410" head gasket bore
0.039" compressed head gasket thickness (Felpro-1009)
84CC combustion chamber
-4 cc valve reliefs
0.029" piston deck clearance (this was an actual measurement on each piston and no cylinder was off by more than a thousandth)

I noticed if I switched to the felpro gasket 1105 (bore 4.590 in. and 0.051" compressed thickness) I can lower my compression ratio to 10.6:1 but I feel like that bore is just too big of a gasket for my engine?

Even a 10 thousandths of a shim lowers me to 10.75:1

A few things stand out :

(1) There is no quench ; .029 piston to deck + .039 gasket = .068 which is too much to achieve the desired effect. Ideally you want .040-.060 to achieve "quench" with .040 being much better than .060  

(2) The cam is rather small and on a tight lsa which builds lots of cylinder pressure. To put it in perspective, the cam in my old 446 was 20* bigger @.050 and i had 66 less cubic inches   My old cam was also on a slightly wider lsa which tends to reduce cyl pressure....and i had less static compression and it was/is a tight quench build.

The correct way to build this would have been using a dished piston and decking the block to achieve a zero deckheight. The dish would need to be in the 15cc range to keep it happy on pump gas with an 84cc chamber and .040 head gasket. It also needs more cam on a wider lsa  

You might be able to tune the current combo but it will require some distributor mods to the advance mechanism and playing around with the springs to adjust the rate of advance. It needs at least 16-18* at idle and based on the current specs (cam/static compression/no quench) you will have to limit the mechanical to 16* or less and keep the total around 32* if you want to run it on pump gas.

The other option is to spike the fuel to overcome the octane sensitivity.....


Ron

[Domino]

Have you tried to richen the mixture, this can cool things off too.

[firefighter3931]

Have you tried to richen the mixture, this can cool things off too.

Sometimes this works if the mixture is overly lean but see the comment below :

   
The only thing that worked was adding 1 gallon of pure toluene to 10 gallons of fuel.  It actually worked really well - the engine responsiveness was amazing - I was able to get 36° total advance with no pinging noticed anywhere (even the smell out of the exhaust was sweet)

Toulene is an octane booster that really does work and not just some quick-fix in a can like the others mentioned. The fact that it responds favorably to this fuel mix indicates that the current combination is octane sensitive and it's not a carb tuning issue. 


Ron

[Cooter]

Sounds like this thing wants the "Old school" 114 Octane fuel....YIKES! $8.00/gal...

[greenpigs]

$8

[Long Island RT]

Ron,

Thanks - great explanation.

Would you say a 10:1 or even a 10.5:1 compression ratio would require the same quench to maximize the potential of the motor? (therefore shimming ain't gonna help?)
When you say "bigger" cam - your talking duration not lift?
How does initial advance effect performance other than idle quality, since total is in well before 3000 - where all my power is?
What cam would you recommend?

I really wish I was on this site when I built the motor some 5 years ago....   That type of build would not have cost me a penny more!

Changing just the cam sounds like an improvement but I will still have the quench issue and therefore could only squeak a degree or two more on total advance.  Changing the pistons is a huge expense that I will not be able to do for some time     

Sounds like I have to find a good connection for toluene!  It's the only way I'm going to get the full potential out of this current build.
@ $15 bucks a gallon - it raises my 10 gallons of gas from about $4/gallon nowadays to about $5/gallon.  Still a lot cheaper than $8.

[68X426]

Sounds like I have to find a good connection for toluene!  It's the only way I'm going to get the full potential out of this current build.
@ $15 bucks a gallon - it raises my 10 gallons of gas from about $4/gallon nowadays to about $5/gallon.  Still a lot cheaper than $8.

Look around for a wholesaler of boat finish solvents. They use a product named toluol, which I believe is identical to toluene. You probably get best price buying a half pallet (5 gallon cans, 3 x 3 times 2 high equals 90 gallons) but the price is cut in half. Of course you may have a shipping and storage issue, but at least you can share it with racer friends. 

[Domino]

Have you tried to richen the mixture, this can cool things off too.

Sometimes this works if the mixture is overly lean but see the comment below :

   
The only thing that worked was adding 1 gallon of pure toluene to 10 gallons of fuel.  It actually worked really well - the engine responsiveness was amazing - I was able to get 36° total advance with no pinging noticed anywhere (even the smell out of the exhaust was sweet)

Toulene is an octane booster that really does work and not just some quick-fix in a can like the others mentioned. The fact that it responds favorably to this fuel mix indicates that the current combination is octane sensitive and it's not a carb tuning issue. 

Ron

Ron, you're probably right so I'm taking a shot at easy things to try before he tears back into the motor. Maybe a loaner lower cfm carb.
I'd rule out a possible lean issue first, since it's easiest and cheapest to fix.  I'd think a massive octane boost could cover that up too. "happy fuel"

Extra fuel (or less air) can help the quench issue by increasing evaporative cooling, absorbing extra heat as the charge is compressed, thus buying a little time before self detonation occurs. 
Problem with a wide squish clearance is also lazy swirl and less mixing, resulting in poor burn so most of the extra fuel will be wasted for hp, but might buy lower octane sensitivity.
Of course extra liquid droplets, which don't compress like air, can cause higher pressure and thus heat so you're walking the line with this approach.

BTW with that extra info, I calculated 10.98:1 also.

[firefighter3931]

Ron, you're probably right so I'm taking a shot at easy things to try before he tears back into the motor. Maybe a loaner lower cfm carb.
I'd rule out a possible lean issue first, since it's easiest and cheapest to fix.  I'd think a massive octane boost could cover that up too. "happy fuel"

Extra fuel (or less air) can help the quench issue by increasing evaporative cooling, absorbing extra heat as the charge is compressed, thus buying a little time before self detonation occurs. 
Problem with a wide squish clearance is also lazy swirl and less mixing, resulting in poor burn so most of the extra fuel will be wasted for hp, but might buy lower octane sensitivity.
Of course extra liquid droplets, which don't compress like air, can cause higher pressure and thus heat so you're walking the line with this approach.

BTW with that extra info, I calculated 10.98:1 also.

Dom, i hear what you're saying. If this motor had anything but a PF950 i would have to agree but that carb is just about perfect for the 512 in question. I've recommended the PF950 to several members with almost identical stroker builds and it allways works well. One member installed his right out of the box and the A/F was perfect. That engine was broken in on Barton's dyno and Dave Barton said that this was a first for them. Of course most of their builds are a little more serious than a pump gas stroker but none the less he was impressed with the fuel curve. 

Something else that might work is going one heat range colder on the spark plugs...that will remove some heat from the chamber but a colder plug will sometimes be prone to fouling. 

I'd be curious to hear what a compression test yields for cranking pressure. 

Maybe we could have LIRT do one for us 

If it's making over 180psi with no quench that's certainly a problem. A larger cam with increased duration on a wider lsa will reduce the static pressure and make it livable....bleeding off cylinder pressure.

If the fuel cost works out to $5 a gallon with the toulene that's certainly an option and the path of least resistance. 



Ron

[GTXtreme]

if needed there's always that cam 2 pump on the corner of little east neck rd and straght path on the west babylon/wyandanch border and if your going my house is right there your more then welcome to stop by. 

[Long Island RT]

Wow - I didn't know that!
I'm right around the corner from you.

What octane do they sell and do you know how much it is?

[GTXtreme]

yea i live on the number streets right near the police station. I should be passing by the pump later so i'll check it out and post when i get home

[GTXtreme]

its cam 2 its 100 octane and its $8.50 a gallon.

[Long Island RT]

Sounds good - I will try some out.

From my calculations - Toluene (114 octane rating) has a much better bang for the buck when it comes to raising the octane.
1 gallon in 10 gallons of 93 = 95 octane (and that was my only attempt.  I could probably get by with a lesser percentage, maybe even only 94 octane total?).  At $15 a gallon - that increases my gas cost up $1.40 per gallon.

I would need 3 gallons of the Cam 2 in 8 gallons of 93 to get me to 95 Octane.  At $8.50 a gallon it would cost $2.30 cents extra a gallon!

Now I have a real good reason to burn up some gas!

GTX - shoot me a pm with your address if you don't mind.  I'd love to swing by your house sometime and check out your build.  That thing looks Fabtastic! 

[GTXtreme]

I had a hook up a few years ago that i was getting a 5 gallon barrel of 114 for $50 and i was mixing the rest of my fuel cell with 93 and i was running great and we have about the same compression. I'll try to make a call and see what the price is for it now. For the next week or so my cars gonna be n Port Jefferson, i dont keep the car at my house but when i get it back in the area i'll definetly let you know and we should definetly go cruzeing.

[Long Island RT]

I'd be curious to hear what a compression test yields for cranking pressure. 

Maybe we could have LIRT do one for us 

If it's making over 180psi with no quench that's certainly a problem. A larger cam with increased duration on a wider lsa will reduce the static pressure and make it livable....bleeding off cylinder pressure.

If the fuel cost works out to $5 a gallon with the toulene that's certainly an option and the path of least resistance. 



Ron

Finally got a chance to check the compression on cranking:
195 psi 

[squeakfinder]

  I can't comment on that compression, but I have a similar problem that might be suited for another thread. What I've been doing is going to the local airport and buying 100 low lead. I put about a gallon and a half or two in with each tank of 92 octane. It takes care of the pinging and knocking. Larry

[Long Island RT]

 I can't comment on that compression, but I have a similar problem that might be suited for another thread. What I've been doing is going to the local airport and buying 100 low lead. I put about a gallon and a half or two in with each tank of 92 octane. It takes care of the pinging and knocking. Larry

Thanks Larry,

That is where I'm headed until I can tear down the motor for a piston change...

Today I tried 1 gallon of Toluene into a full tank (19 total gallons) of 93.  @ 35° total advance she ran very well, maybe still a little ping but barely noticeable if at all.

At 114 octane with a 18:1 ratio I'm just peaking over 94 octane.  Last time I tried it I put 1 gallon in 10 gallons of 93 (and that ran very well...but a calculated 95 octane)
2 gallons of 100ll won't jump me that high. (plus - I don't even think I can buy it here...)

A local paint supplier will sell me the toluene @ $12.50 a gallon for a 5 gallon pail.  Not too bad.  It was $14 for 1 gallon.

I hit the 600 mile mark today and revved the engine up to 6500 in 3rd - that took me just over the 100 mph mark very quickly (and carefully on a desolate road... )  The scary part is that I had to back off the throttle to keep the my crappy tires stuck to the road.  Time for some new ones.

On a good note - I did get an average of 12 miles to the gallon of mostly around town cruising from my last tank!  Not bad for 500 cubes with (guesstimating) 600 HP.

[MSRacing89]

http://www.projectpontiac.com/ppsite15/compression-ratio-calculator

Check this link out.  It will help you calculate dynamic compression, which is really the number you need to know if you want to run a higher compression street motor. 

I run a very similar set-up.  Same compression with with aluminum heads but a stock stroke 440.  My dynamic compression is around 8.5:1.  Anything above 9 is going to be tough to run on pump gas.  I think you have a few things to try:  (1) A colder plug may be needed for your set-up.  Try going to a NGK 7 range and see if that helps.  (2) Check your WOT AFR's and make sure you are not leaning that thing out. 

[Long Island RT]

Nice link!

Dynamic compression ratio = 9.62
I can get it below 9 by changing the cam - 112 duration and at least 260° on the intake duration. 
Is that available?

Can WOT air fuel ratios be checked on a chassis dyno?

[firefighter3931]

I'd be curious to hear what a compression test yields for cranking pressure. 

Maybe we could have LIRT do one for us 

If it's making over 180psi with no quench that's certainly a problem. A larger cam with increased duration on a wider lsa will reduce the static pressure and make it livable....bleeding off cylinder pressure.

If the fuel cost works out to $5 a gallon with the toulene that's certainly an option and the path of least resistance. 



Ron

Finally got a chance to check the compression on cranking:
195 psi 

Yep, that's a problem ! 

Nice link!

Dynamic compression ratio = 9.62
I can get it below 9 by changing the cam - 112 duration and at least 260° on the intake duration. 
Is that available?

Can WOT air fuel ratios be checked on a chassis dyno?

Sure a custom ground cam in the 260*@.050 range can be ordered. You can also reduce the static compression with a thicker headgasket. 

Ron