Hey guys, I finally got around to setting my timing and set it to factory spec which calls for 0 advance, so I set it at 0 degrees.

I start driving it and it knocks under hard accel and when in overdrive at any speed. I tried going with 91 octane (highest I can get) and nothing has changed.

The motor is a rebuilt 383 stroker, mild hyd roller cam (.450", 200 dur@0.050"), 9.4 CR, cast pistons, stock 350 heads, Performer intake, Edelbrock headers, Flowmaster muffler....nothing special. I am running all the factory crap, and California emissions except for an EGR valve and CAT.

I can retard the timing and the knock disappears, but that can't be good for mileage or power.

What do I do now? Thanks guys.

1987 Camaro 4bbl. (factory LG-4 car)
700R-4
2.73 open rear

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Cable Bright
-'87 Camaro Z28 383
-'91 Caprice 9C1 (getting a new 350 soon!!)
-'70 El Camino 454 RAT

"....after all, people just want a normal life and a cool car....most people settle for the car."

 

You did remove the wire that advances the timing when you set it right? Try race gas and see if that helps. That should answer the question of whether it is engine knocking or whether something is loose.

 

Uhh Factory base timing is 6* advanced, not 0*. Might wanna start at 6* and work your way up. Remember to disconnect the tan/black wire on the passenger side strut tower.

 

Are you getting any knock sensor codes? I'm running like 8-10 degress advanced on 93 octane with 10.5:1 and i get knock sensor codes when not running race gas but it's just pulling timing it's not knocking or making any noise. what about exhaust leaks or bearings or engine noise?
Does it make noise in all gears park neutral 3rd 2nd 1st?

[This message has been edited by 1989gta (edited September 13, 2002).]

 

WRONG, the factory emissions sticker says 0* for the LG-4 305 4bbl. I'd be happy to send you a pic to prove it.


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Cable Bright
-'87 Camaro Z28 383
-'91 Caprice 9C1 (getting a new 350 soon!!)
-'70 El Camino 454 RAT

"....after all, people just want a normal life and a cool car....most people settle for the car."

 

I've never heard of an engine being timed at 0*....seems to me that if you timed if that far behind the spark wouldn't be able to get the charge ignited and fully burned before the piston started comin back up....I know my boss's 87 Caprice 4bbl 305 has a 6* factory timing, right there on the emissions sticker (I tuned it up for him last month.)



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TheGreatJ
1991 Camaro RS "Suzanne"
http://thegreatj.cz28.com

 

According to Chilton, it is 6 deg. Vin code S (2.8L) is 10 deg. Vin codes H, F (305) are 6 deg. Vin Code 8 is also 6 deg. These are not transmission dependent

[This message has been edited by aklim (edited September 14, 2002).]

 

I should take a pic for you guys, I am dead serious about my emissions sticker. I thought it was crazy too, but that's what it says!!

Maybe Cali emissions stickers are different?

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Cable Bright
-'87 Camaro Z28 383
-'91 Caprice 9C1 (getting a new 350 soon!!)
-'70 El Camino 454 RAT

"....after all, people just want a normal life and a cool car....most people settle for the car."

 

Not sure about CA. I just read what Chilton and other GM books say.

You said you retarded the timing and the problem went away. Makes me wonder if they really put in the right pistons. Why did you use cast anyway? I'd have used hyperutetic at the worst. On a motor like that, I used forged pistons. Do a compression test of a few cylinders and let us know what readings you get. You may have too much compression. Compression will not tell us that but with my motor I have around 180 psi compression which is a 10.8:1 motor. If you have 200 psi, that might tell us that your CR is somewhat suspect.

[This message has been edited by aklim (edited September 14, 2002).]

 

Yeah, compression check. I would be suspect that the pistons are wrong IF IN FACT you are picking up knock. Did you hook up a scanner? If not get a laptop, and a cable from AKM Electronics and use the free software to see if you are getting real knock. I hae somthing that sounds like knock in 3rd gear but my scanning equipment doesn't pick it up at all. Seems that its not spark knock. My Clutches are worn... real worn. Could be your problem.