New 454 pinging - Chevelle Tech
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post #1 of 30 (permalink) Old Dec 31st, 07, 5:38 PM Thread Starter
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New 454 pinging

Hello everyone, I have a problem with the 468 I just fired up for the first time last weekend. I have a 454 .060 over with .200 domed pistons, pistons .005 below deck, 049 heads milled to 119cc's, ROL head gaskets with 9.47c compressed volume and .039 thick (I get just under 9.6:1 compression ratio) Is this quench .044" aceptable? The engine also had a UDHarold cam 223/227 duration @.050 and .539/.550 lift on a 112 LSA ground with 4 advance and installed dot to dot for a 108 intake centerline. Ignition timing is set at 17 base 37 total timing in by 3000rpm. The engine runs like a dream, but has a problem with slight detonation inder hard acceleration, like when getting on the freeway. Should this combonation be pinging? I did not think the compression ratio would be high enough to worry about. I do run it on 91 octane. I have 3 options the way I see it. I can either resort to runnig octane boost in every tank of gas (Not my first choice since I drive 150 miles per week), I can retard the ignition timing but then I can hurt performance and run the risk of overheating or I can change the cam timing. The way I understand it, advancing the camshaft will bleed off a little more cylinder pressure and move the horsepower and torque up in the RPM range. Is this correct? Does this sound like the best way to solve my problem considering the fact that I don't want to pull the pistons. Are there any options I have not thought of? Thanks for the help.

New car smell is over rated. I prefer the smell of burnt rubber and leaded gas myself.
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post #2 of 30 (permalink) Old Dec 31st, 07, 6:09 PM
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Your timing is right on with 17 base/37 total @ 3k rpm with the cam your running.

I am not surprised at all that it pings under load with only 223 deg dur @ .05 cam in a 468 with 9.6 comp.

The comp could be even a little higher if you didnt take into consideration a decked block and heads when you figured compression. In that case the compression could be closer to 9:8- to maybe even 10:0 comp if a thin head gasket was used and alot of material was removed from block/heads when decked for flatness.

If it doesnt ping when at part throttle cruise or when accell from a start it's not too much timing comming from the vac adv .

You say it pings under hard acelloration so the vac adv drops out when the intake vac goes away when throttle is opened hard so you only have a few choices without going into the motor to lower compression assuming your already running highest oct fuel avial which is 91 octain in CA.

You can retard the timing untill it stops the ping and loose power & use more fuel or you can buy some real lead kemco booster ,1qt kemco per 28-20 gals 93 fuel increases oct to 97-98 and that will stop the ping and give you some more power.

If the car is not a daily driver it will only cost you approx $100 yrly to retain the full power/perf of your 468 which is what i do with my mild 396 insted of retartding the timing loosing power/perf.

For a wk end cruiser only the kemco is the way to go in your case where the timing is dead on correct and all you need is a hit of kemco to boost the octane.
Search the Kemco site to find the "kemco supreme 130 octane booster" .

Other then doing the above you would have to install more cam to bleed of more cyl pressure,install thicker head gaskets, replace the pistons with lower comp units,or install heads with larger comb chambers to lower comp.

And for all you guys that are going to chime in (like last time ans a post like this one) to say my 540 run's on 91 or 87 fuel with a huge 260 deg @.05 cam & 10-11:0 comp thats compairing apples to oranges in this case,end of story.

I say this because large duration cams bleed off a lot of compression/cyl pressure allowing the use of lower octane fuel in thoses cases even with high comp ratio's which is not his case here. His motor has a farily short dur cam in almost 470 cubes with compression likely above 9:6 closer to 9:8 + on crappy 91 oct fuel used in CA . Keep in mind this is in a 35-40 yr old design motor not desinged to run on low oct fuel and or not built specifically to run on 91 fuel with larger cam to bleed of comp or using flatop pistons for lower comp or larger chambered heads. There motors were designed to run on 98+ oct fuel back in the day which = roughly 96 oct for todays fuel which is still 5 points short for his motor that is running on 91 fuel in CA.

It just confuses the issue in cases like this with a mild perf motor with ping issues being compaired to larger motors with tons of cam duration or even same size motor with a much larger cam bleeding of comp.

I recently ran a post asking for what motor setups were running on what oct fuels and not detonating and in most every case there were large 255-260 deg + deg dur @.05 dur cams being run in 454-540s bbc with the higher comp ratios that were not detonating on 91 or 93 fuel which was no surprise to me.

But when someone has an older gen sbc/bbc built with stock type heads and higher comp above approx 9:5 & up with a short dur cam in his case here that's often a rcp for ping on todays fuels.

Running the kemco to avoid having to break a new engine appart to lower comp is a good solution to his problem not to mention the additonal octane will likely give the motor more power esp when retaining the full perf ign timing curve your currently running which is riught where it belongs.

Scott

SCOTT
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Last edited by SWHEATON; Dec 31st, 07 at 7:07 PM.
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post #3 of 30 (permalink) Old Dec 31st, 07, 6:38 PM
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Re: New 454 pinging

What piston are you using?

Did you measure the heads or is it a guess?

You may be closer to 10 to 1 on the comp ratio

And last, who picked the cam numbers, they look a bit small for 468 inch big block? It may have been picked with lower compression in mind!

Harry P.Hunter
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post #4 of 30 (permalink) Old Dec 31st, 07, 6:47 PM
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Re: New 454 pinging

maybe use a thicker head gasket???
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post #5 of 30 (permalink) Old Dec 31st, 07, 6:57 PM
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Re: New 454 pinging

first and only question: Are you running vaccum advance? If you are,disconnect it and go for another ride and report back.
If it still pings,your total timing is more than 37 and it is still advancing at higher rpms.
I am running Harold's grind: 223/231 @.050 .525/.550 112 LSA with 10.5 to 1 compression in my 454 and I have no issues running 25* initial/38* total with NO vacuum advance.I have been running this combo for 7 years and have been driving it for 17K+ miles and drag racing it as well.It runs fine on 92 or 93 octane.
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post #6 of 30 (permalink) Old Dec 31st, 07, 8:23 PM
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Re: New 454 pinging

and what about the 4 deg adv in the cam....this would BOOST low end cyl pressure.
Mighta been OK if you had 9:1......probably not what you wanna have in a engine with 9.5, 9.75 or even 10:1 AND only 223/227* dur. In a 396 this would be a fairly large street cam and you'd do OK. A 454 sucks up a 223/227 cam like it was nothing, makes it a fairly mild grind.....

When my 454 eventually comes together, I'll have around 10:1 so I'm gonna run 238/248* dur

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post #7 of 30 (permalink) Old Dec 31st, 07, 9:16 PM Thread Starter
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Re: New 454 pinging

Quote:
Originally Posted by HP Hunter View Post
What piston are you using?

Did you measure the heads or is it a guess?

You may be closer to 10 to 1 on the comp ratio

And last, who picked the cam numbers, they look a bit small for 468 inch big block? It may have been picked with lower compression in mind!

Harry P.Hunter

I'm running Keith black forged pistons part number 9919-060 they are a .200 dome piston. The heads were CC'd, well one chamber in each head was CC'd at 119cc, the head gasket are ROL .039 thick, 4.345 bore. The block is decked so that the pistons are .005 down in the hole. I get a calculater compression ratio of 9.58:1 and a quench of .044 inches. Thanks for the replys but I'm still kind of stuck, I guess everyone is saying that unless I want to retard ignition timing, run octane boost in every tank (I drive the vehical about 110-130 miles per week) or pull the engine apart to lower compression I'm pretty much screwed. Do I have any other options? Can the cam's timing be altered to help (Retard or advance)? The detonation is slight, but any detonation is too much in my book. Thanks again for the help, I look forward to hearing your input.

New car smell is over rated. I prefer the smell of burnt rubber and leaded gas myself.
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post #8 of 30 (permalink) Old Dec 31st, 07, 9:28 PM
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post #9 of 30 (permalink) Old Dec 31st, 07, 9:33 PM Thread Starter
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Re: New 454 pinging

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Originally Posted by mr 4 speed View Post
What distributor are you using? What rpm are you at with 37* of timing ?
I'm using a MSD pro billit. 37 deg is in at 2900-3000 or so.

New car smell is over rated. I prefer the smell of burnt rubber and leaded gas myself.
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post #10 of 30 (permalink) Old Dec 31st, 07, 9:33 PM
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Re: New 454 pinging

Are you using vacuum advance?
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post #11 of 30 (permalink) Old Dec 31st, 07, 10:31 PM Thread Starter
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Re: New 454 pinging

Yes it has vacuum advance. I tried dis connecting the vacuum advance without changing the actual timing (Without moving the distributor) to see if perhaps it would cure the problem. It did not. The pinging is not under light acceloration, it is only inder hard romps, althought I have not really jumped on the engine too hard yet as it is only about a week or so old and I only have about 75 miles on it. When getting on the freeway I gave it about 1/2 - 3/4 throttle and it had SLIGHT detonation. When cruising at say 2500 rpm and I lightly press the throttle it will not detonate, if I press the throttle hard at those speeds I can hear a slight rattle. I pulled the plugs and they all looked good with no aluminum speck or anything, so the problem is not exreme. Tomorrow I will try to pull 1 or 2 degrees of total timing out and see if it helps. I am just aftraid that after the break in period (400-500 miles) when I'm able to I push the engine hard it will have a more serious problem. I'll give it a shot tomorrow and see how things go. Any other suggestions?

New car smell is over rated. I prefer the smell of burnt rubber and leaded gas myself.
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post #12 of 30 (permalink) Old Jan 1st, 08, 12:03 AM
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Re: New 454 pinging

What park Plugs are you using???? Wrong spark plug heat range will cause one to ping.
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post #13 of 30 (permalink) Old Jan 1st, 08, 12:52 AM
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Re: New 454 pinging

Quote:
Originally Posted by LeLynn View Post
Yes it has vacuum advance. I tried dis connecting the vacuum advance without changing the actual timing (Without moving the distributor) to see if perhaps it would cure the problem. It did not. The pinging is not under light acceloration, it is only inder hard romps, althought I have not really jumped on the engine too hard yet as it is only about a week or so old and I only have about 75 miles on it. When getting on the freeway I gave it about 1/2 - 3/4 throttle and it had SLIGHT detonation. When cruising at say 2500 rpm and I lightly press the throttle it will not detonate, if I press the throttle hard at those speeds I can hear a slight rattle. I pulled the plugs and they all looked good with no aluminum speck or anything, so the problem is not exreme. Tomorrow I will try to pull 1 or 2 degrees of total timing out and see if it helps. I am just aftraid that after the break in period (400-500 miles) when I'm able to I push the engine hard it will have a more serious problem. I'll give it a shot tomorrow and see how things go. Any other suggestions?
What type of carb are you running? If its a Holley you might be getting a lean condition form a slow opening power valve. You can help this problem by replacing the existing p.v with a higher than stock number like a 8.5 or a 9.5. With your cam, I would almost bet your engines vacuum is really high when rolling into the throttle as you described. If you do a short wide open blast (like getting on the freeway) and it doesn't ping, I would look at the power valve.

Todd
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post #14 of 30 (permalink) Old Jan 1st, 08, 2:36 AM
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Re: New 454 pinging

Take 3 or 4 degrees timing out of it. You're noticing detonation under WOT, this will not involve the vac advance since there is no noticeable vacuum under these conditions. Your timing is aggressive enough so you can drop a few degrees with out killing the engine. It would be good to reduce the amount of mechanical advance since since it's at WOT and above your full advance RPM.

You've built an engine with too much compression ratio for iron heads and a short cam. I've harped on this for years and I'm getting tired of typing it. Plus, I'm in a bad mood.

Tom
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post #15 of 30 (permalink) Old Jan 1st, 08, 8:13 AM
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Re: New 454 pinging

Since you have all ready tried it w/o the vacuum advance...what Tom said.
I am actually suprised it pings with 37* total and no vacuum advance. I get away with a small cam and too much compression w/iron heads myself. I have .100 tall domes and 101 cc chamber heads (piston .008 below deck and .039 head gasket)
The small dome/tight chamber deal is probably less detonation prone than the large dome/large chamber maybe.
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