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Old 07-10-2003, 01:27 AM
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383 stroker knock

Please Help!!! I just built my first 383 (actually for the third time).I currently have a knock that seems to be coming from cylinder #6 or #8. The engine has been clearanced as well as the rods to accomodate the 400 crank. The reason for the first redo on this engine was improper balancing. After I had the machine shop install brand new Rods and rebalance the rotating assembly, I put it all back together and wound up with my "knock". I only drove the truck approx. 15 miles before i tore it down again to find the source of the problem. I checked EVERY spec I could think of (main and rod bearing clearances-crank end play- ring gap) EVERYTHING checks OK. Installed new fuel pump and pushrod- New bearings (again) and built it a 3rd time. The knock is still there!!!! It is always present at cold startup(oil psi is great) then seems to get quieter as it warms up- sometimes almost becoming non existent untill it cools down again. It really doesnt seem to be a lifter "tic" . It truly sounds like a rod knocking . Piston pins seem to be fine too. ANY IDEAS????????Thanks in Advance!

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Old 07-10-2003, 02:02 AM
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kinda sounds like cold piston slap, they expand as the piston gets hot and the knock goes away. in fact some years ago, the new dodge trucks rolled off the line with loud piston slap until it warmed up. however years ago, we did a rebuild on a 350 sbc, rering and bearing job, we reused the TRW forged pistons that had been used in the rebuild the first time, after about 1000 miles, it had a loud knock, and we did the same checks as you, we finally pulled it and pushed out the number 6 piston, when we did the skirt fell off, problem found.
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Old 07-10-2003, 11:30 AM
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Have you checked the cam clearance? Sounds like a pin or piston rock to me as well. Do the bearing show any wear at the time of overhaul?(s)
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Old 07-10-2003, 03:24 PM
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The first 383 my dad built for his truck did the exact same thing as you're talking about. He tore it back down and build it again using a differnt block (he thought the block was bored to loose)The second time he kept the piston clearance tigher,but it still has that same sound kind of like a really quiet diesel.
We've just come to the conclusiion that they are just noisy engines.
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Old 07-11-2003, 09:30 PM
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piston clearances usually have the most to do with tempature related problems like your describing, did you check all the pistons to see that they all have the same clearances and that the piston to bore clearances are within the tolarances, have checked plunty of sets of pistons and had 1 or more out of specs, also not realy the exact same noise your describing but happenes a lot in those bilds is the oil pans were different on 400s towards the rear in the sides of the pan to give the rods clearance, 350 pans will hit sometimes when using 400 cranks.
good luck
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Old 07-12-2003, 07:44 PM
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Make sure the crank counterweight is not hitting the piston in the area below the pin, things get real close on 383's and I have seen them just touch there, also make sure the top outer edge of the rod bolt isn't hitting on a cam lobe.
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Old 07-12-2003, 10:06 PM
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are you using pressed pins? if your using pressed piston pins what you are desribing sounds like a wrist pin knock...
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Old 07-13-2003, 03:12 PM
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Thank you all for the replies!!!--- I have been leaning toward all of these responses. The only thing that I left out in my first post was that after my first rebuild, the machine shop screwed up 1 piston (broke land while pressing in a pin) and ordered a new piston for me after the original boring was done (different shop bored the block to match the pistons). After all this - and all your responses, I know what I need to do... Thanks again everyone!!!!!
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Old 07-13-2003, 03:20 PM
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P.S. Yup - sounds like a diesel!!! Replaced Cam bearings. Checked cam clearance (Bolts ground down). Pressed pins- but new...... I never did check the piston to wall clearance on the piston that they denied screwing up but replaced for me after I proved that that they did... To anyone listening------ Once you find a good machine shop, NEVER, but NEVER switch !!!!!!!!!!!!!!!!
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Old 07-13-2003, 03:22 PM
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Never switch when you find a good machine shop that you trust!
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Old 04-28-2011, 09:57 PM
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Check your oil pan

The most common problem i've noticed is oil pan clearance. A lot of people end up with a small nick in the oil pan, usually cyl 6 but sometimes 5, 7, or 8.
My first stroker had that exact problem and it drove me crazy. Hopefully this helps somebody, i know you fixed your problem already but maybe this can save someone else a lot of hassle.
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Old 04-29-2011, 12:00 AM
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