Ok, When ever I go full throttle, I get a lot of pinging....

in first or second, I can full throttle, but have to shift fast to the quick revs.

under part throttle, I can spin up to 6500+ with no pinging or problems. I just can't floor it.

seems odd to me.

my afr is down around 11:1 at full throttle, so I am running plenty rich. I am running 93 octane, might have to add some xylene.

I am wondering if my throttle bodies are too large. I don't know if my air fuel meter can pick it up that quick.

I really notice it when I am in 5th gear and am pulling from around 2500 to 6500.

I do have a spare set of heads that I can get cut...

all right here is the specs...103 by 80. .125inch barrel shims gives me around .1" clearance and around 9.7 to 1.

megasquirted with twin weber throttle bodies and large injectors...

herb

too much advance?

advance is set at 12 and 28. Mallory unilite....

it is too advanced now though....trying to adjust advance to get lowest head temps..

temperatures are around 275 to 325. higher if I am at 4000+ rpm for 5 or 10 minutes...

Whats your deck height??? if it's .100 thats a lot of the issues, you don't have very good squish and its throwing off the efficiency. I use NO MORE than .060 deck under any circumstance.

It sounds like a bit of misconfiguration. If you need less than 26 degrees of advance to stop the pinging you can bet that you have a misconfiguration, tjhats a tell tale sign that something is wrong..

large T/Bs or carbs increase the ability for the engine to go lean, even if you are reading rich AFR, especially at peak torque.

STOP driving the engine if it's pinging as you are destroying the rod bearings and weakening the combustion chambers every time it happens. Pinging will kill the engine FAST.

9.7:1 is pretty healthy on pump gas, the .100 deck coupled with that is probably the culprit. 9.7 wityh tight deck is a much better combination as the added squish boosts efficiency and increases the detonation threshold quite a bit.

My 3 Liter runs 10:1 with .035 deck and won't ping no matter what you do...

What do the plugs look like after a full throttle run. When we put my race car on the dyno we used new plugs and pulled them after the first set of pulls to see the heat range. A/F was about 11.5 to 1 but they were a tad too hot so we went to a colder plug and the engine is happier. Not to confuse things too much but we found with 100 octane unleaded that we had NOT enough advance and the race fuels people said to run about 4 degrees more and when we did this head temps came down about 75 degrees. Seems we were buring the gas too late at high RPMs and it was really burning down the exhaust pipes! Oh yea, picked up 20 HP too when we were finally finished!

John,
We learned that years ago.....

Most engines running race fuel with ;less than 11:1 CR don't need it according to the dynamic CR dictated by the camshaft and many other parameters..

I don't run race gas till after 11:1 static CR with my engine designs- the engine makes better power without it..

runningrace gas with an engine that does not have the CR for it increases EGT just like retarded timing and kills efficiency and kills exhaust valves.

This will give me something to do this winter....
I will have to pull the heads and get a good CC #.

It will be easy to reduce the deck height, I can just shave my spacers.

I did not spend very much time on the heads...used, reworked big valve heads...

Jake, I think that we had a discussion on the valve size...you thought that they were too large. I was wondering if I needed more static cam advance...

Other than that, this thing kicks ass. revs and pulls fast. Just can't go full throttle.

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This will give me something to do this winter.... I will have to pull the heads and get a good CC #.

What was the CC to begin with?

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It will be easy to reduce the deck height, I can just shave my spacers.

BUT doing so without dishing the ppistons OR adding ccs to the heads will BOOST CR even higher and will probably make the situation worse.

QUOTE

I did not spend very much time on the heads...used, reworked big valve heads...

Big NO NO! Spend ALL the time and money on the heads!

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Jake, I think that we had a discussion on the valve size...you thought that they were too large. I was wondering if I needed more static cam advance...

The valves being too large can add to the problems you are experiencing

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Other than that, this thing kicks ass. revs and pulls fast. Just can't go full throttle.

BUT beware that ypu can still be damaging the engine EVEN IF AUDIBLE PING IS NOT HEARD! Pinging that can be heard is severe, inaudible ping is just as dangerous and is a silent killer.

I'd approach driving this one with extreme care, especially if its detonating @ 11:1 AFR.

Its all in the combo.

I am pretty sure my problem is fuel delivery related....

I killed my 2.0 from pinging and my 1.7 is doing that now....

so i'm taking the tank off to get it boiled out and sealed--inside and out.

I knew that was what you would say Jake....I was bustin' balls.

I am thinking about re-doing my second set of heads....call you or Len?
thanks, herb

No need to call either of us...

These combination below are the ULTIMATE for your combo (I know the combo well). If you want power to 6K RPM go with the first choice, for power to 7K go with the ultimate choice.. Either is based on a brand new head casting- we don't modify any used castings this far, they are all 30+ years old..

RAT 7442 heads


RAT 7456 heads

Both combinations get relocated plugs, are bored for your Nickies and have hand shaped (enlarged) chambers that will allow you to run .060 or less deck for proper quench instead of having to settle for lack of quench to attain moderate CR.

Ready to bolt on... and haul ass.

If you want to "Re-do" your existing heads, call Len BUT I'd say he will recommend the route I have here simply because of the work involved to make an old head parallel these new castings...

sorry to hijack....


So Jake, you say that the heads listed here are NEW castings, made from Today's metallurgy standards.......

like new heads, and not re-used used castings?

b

you are all over looking the dizzy we had a dizzy that would ping in 1st and 2nd when you mash the gas and it was a bad 009 dizzy the spring came of one side .This will cost a lot of money if you do not fix it quick

mine's a fuel problem....

yeah man either way ,fix it and do it right.....my dad "took care of it" and like 3K later it's still messed up.....do it yourself and do it right....remember only YOU will work on it till your satisfied...any mechanic will just fix it to run good till it leaves thier place....


b

QUOTE (bd1308 @ Oct 6 2005, 12:57 PM)

sorry to hijack.... So Jake, you say that the heads listed here are NEW castings, made from Today's metallurgy standards....... like new heads, and not re-used used castings? b

Yep...

I don't use ANY used heads for my engines except *SOME* 2.0 heads and never for a bore size this large, or an engine of this caliber, with Nickies and the amount of money he has invested....

Rebuilding a used, 30 year old head for a performance engine just isn't smart these days... especially considering you may pay equal to money of the new heads just to correctly repair your old ones...

Heads that are 30 years old have been heat cycled millions of times, that leads to cracks that sometimes no one or process can see.

I was thinking the same thing concerning reusing used heads........

how do the new heads handle heat cycles....have you done any long term testing on these?

QUOTE (bd1308 @ Oct 6 2005, 02:05 PM)

how do the new heads handle heat cycles....have you done any long term testing on these?

Yep- been using them primarily for the entire time I have been in business....

And I still use them, so that should speak for it's self...

QUOTE (bug man nrg @ Oct 6 2005, 01:57 PM)

you are all over looking the dizzy we had a dizzy that would ping in 1st and 2nd when you mash the gas and it was a bad 009 dizzy the spring came of one side .This will cost a lot of money if you do not fix it quick

he has a mallory unilite.....