383 with ignition /knock issues

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
I've got a problem that is totally beating me. I built a 383 stroker last winter. It's got 10.5 to 1 compression ratio. I run 93 octane fuel. I installed a cheap Chinese HEI distributor in it. I verified that the timings marks are true top dead center. For some reason i cannot advance the initial timing past 0 or it spark knocks like crazy. Even if it's at 2* it'll knock. The only thing i think it could be is that cheap distributor but i figured I'd ask before i spend $500 I a new MSD system.
the knocking does only occur under light acceleration. I'll try disconnecting the vac advance line and see what happens.
The heads are aluminum.
I installed a high quality Cloyes timing set to factory timing. Would it help to pull the crank gear off and install it on the advance keyway?
I found the installation instructions for the Cloyes timing set. Looks like I could try advancing the cam timing to get better low end torque. I wonder how that would affect the spark knock?
http://www.cloyes.com/Images/Instruct/3 keyway instructions (general).pdf


'83 chevy K20, 383, Scat Crank, Comp Cams 08-408-8, Etec 170's, sm465
'97 chevy 1500 Silverado, 350, 4L60E


you can,t fix a damn thing until you have verified facts and know what your dealing with
start by verifying tdc on the damper and timing tab reflect reality, you could easily have a mis-matched damper or timing tab, then one that TDC, is verified, map the timing curve
and it sure would be good if you had degreed in the cam rather than just assumed the dot-to-dot was correct
(yes it should be close with a cloyes timing set, it it was properly installed)
and doing a compression test , verifying consistent fuel pressure, checking the valve adjustment, checking for vacuum leaks, verify the alternator puts out a consistent 14-15 volts,setting the spark plug gaps at a consistent .045 and checking the ignition wires condition and ohms resistance is under 100 ohms per foot, and posting clear pictures of the spark plugs to get a good idea of the combustion chamber conditions,
might provide you with useful info


reading links and verifying the facts,
may not be fun but it beats not having the car or truck,
run decent by a long way


http://garage.grumpysperformance.com/index.php?threads/finding-top-dead-center.967/

http://garage.grumpysperformance.com/index.php?threads/timing-tabs-and-indicators.1015/

http://garage.grumpysperformance.com/index.php?threads/verifying-your-real-advance-curve.4683/

http://garage.grumpysperformance.co...ouble-shooting-rebuilding-hei-ignitions.2798/

http://garage.grumpysperformance.co...lternators-and-oil-all-here.12628/#post-69303

http://garage.grumpysperformance.co...wrong-after-alternator-swap.13580/#post-70168

http://garage.grumpysperformance.com/index.php?threads/spark-plug-info.202/

a logical step by step approach and keeping accurate notes helps.
youll NEED a multi meter, a shop manual
and a timing light and fuel pressure gauge at a minimum,
set and verify your ignition timing, pull trouble codes,set your tps and iac,, then check for vacuum leaks on the lines and intake,then get out your multi meter and verify all the sensors, chances are good a logical step by step approach will lead you to the problem, youll be amazed at what youll learn reading links.
use of a shop manual and multi meter
BOTH can be very helpful ,
IN
ISOLATING PROBLEM ISSUES
1996_Corvette.jpg

MULTI METER
https://www.harborfreight.com/lcd-automotive-multimeter-with-tachometer-kit-95670.html
13487.jpg

https://www.summitracing.com/parts/anm-cp7838
CP7838.jpg


and rev the engine a few times and watch the fuel pressure it should in theory remain in the 38 psi-42 psi range for most TPI and TUNED PORT efi


having a few basic meters,gauges etc. helps

image_6238.jpg

MULTI METER

42545.jpg

http://www.testequipmentdepot.com/e...1100200223789&utm_content=All Extech Products
having the correct tool to verify the engines operational temps would be helpful
INFRARED TEMP GUN
timinggag.jpg

TIMING LIGHT
compgaga.jpg

COMPRESSION GAUGE
pressuregag.jpg

PRESSURE/VACUUM GAUGE
12cal.jpg

INFRARED TEMP GUN

TIMING LIGHT

COMPRESSION GAUGE

PRESSURE/VACUUM GAUGE
chartvac.jpg


read the links and sub links

http://garage.grumpysperformance.com/index.php?threads/verifying-your-real-advance-curve.4683/

http://garage.grumpysperformance.com/index.php?threads/carb-tuning-info-and-links.109/

http://garage.grumpysperformance.com/index.php?threads/holley-carb-power-valves.1639/

http://garage.grumpysperformance.co...oven-facts-if-your-in-doubt.13051/#post-69824

http://garage.grumpysperformance.co...u-need-to-know-setting-float-levels-etc.1115/


http://garage.grumpysperformance.co...-system-trouble-shooting-flow-chart-info.596/

http://garage.grumpysperformance.com/index.php?threads/1984-fuel-pressure.11776/#post-55675

http://garage.grumpysperformance.co...ard-starting-tpi-crossfire-or-lt1-vette.1401/

http://garage.grumpysperformance.com/index.php?threads/c4-c5-corvette-trouble-codes.2697/

http://garage.grumpysperformance.com/index.php?threads/replacing-a-c-4-fuel-pump.33/

http://garage.grumpysperformance.com/index.php?threads/c3-c4-corvette-vacuum-diagrams.1773/

http://garage.grumpysperformance.co...ckpressure-hurting-your-combo.495/#post-26600


http://garage.grumpysperformance.com/index.php?threads/locating-a-ignition-miss-in-the-engine.14591/

http://garage.grumpysperformance.com/index.php?threads/what-kills-o2-sensors.3049/#post-51701

http://garage.grumpysperformance.co...lay-switch-locations-and-info.728/#post-43477


http://garage.grumpysperformance.co...hink-logically-don-t-assume.12484/#post-62772

https://www.harborfreight.com/lcd-automotive-multimeter-with-tachometer-kit-95670.html
 
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