|11-07-2012 04:31 AM|
Could be OLD GAS that you mentioned. 4 year old gas, even mixed with fresh fuel, will gum up the intake valve stems which will make the valves stick, which will cause the push rods to bend and flatten lifters/cam lobes.
Happened to me. I had to pull the heads and hammer out the valves and use lacquer thinner to get the varnish off, and change the cam and lifters and push rods. old gas can make a big mess in the valve train.
|11-07-2012 04:17 AM|
Sound tracking gear.
For checking noises from engines my neighbour lent me a" mechanics stethoscope" . It looks like a doctors piece of gear that has two ear pieces and the listening proble is either a steel or wood screw in pointer. You place the pointer on the engine where you think the knock is and listen. As you think it is no.8 rod bearing , if you could listen with a probe on the sump, you may track it down. I had a bad cam and lifters in my 347 stroker, (caused by a "loose" cam gear retaining bolt.) and pinpointed the equivalent lifters/rockers with this piece of gear. Sorry i dont have a picture of it but i think you will get what i am describing here.
|11-06-2012 10:30 PM|
did you check cam to rod bolt clearances ?
I seen one that the new distributor cap was arching thru and made it knock also
|11-06-2012 05:30 AM|
|1Gary||Because it is only on number 8 I agree it is internal and the more you run it "trying" to test it the more damage you are creating.Take it back apart and the hell with a video.A knock is a knock and it is serious.|
|11-06-2012 05:20 AM|
it does get faster if the engine is rev'd but it kinda has it's own beat at times.
I did think about disconnecting the flex plate from the crank to isolate it but it going away when I pull spark to #8 makes me think it's something inside the engine.
The summit block was bare and clearanced for a stroker already, I installed a Scat rotating assy. and used the rod bolts they supplied. I did use all arp studs on the crank. the rods did not have stud/nut combos...they came with 12 point screws for added clearance.
|11-06-2012 05:09 AM|
It has full floating pins with a standard type clip.
|11-05-2012 04:23 PM|
Here is some questions you need to ask yourself:
What kind of oil pressure does it have??. Kind of low??.
What does the oil look like??.
Do you think even if you could get the pan off,you could clean out the engine from a bad bearing let alone check the crank??.
Does it have press fit piston pins or full floating pins.What kind of locks if full floating pins??.
Decide right now the worst and be willing to accept it.
You can run tests like you did pulling plug wires,but at the end of the day sounds like there is something very wrong that needs to come back apart out of the van.Do not run it much anymore.
|11-05-2012 01:50 PM|
Thanks for the reply!
I bought the block from summit already clearanced for a stroker crank. I swear I triple checked all of my fasteners but I guess you never know if you missed something. I thought to check the flexplate also but haven't yet. The pan should be a real PITA to pull in vehicle! It is a really hard knock and almost feels like something is hitting the inside of the manifold. This engine has the poppet injectors that are all concealed inside the manifold... I was thinking that maybe the #8cyl. poppet popped out and compression is banging it into the manifold? I'm so lost I was just trying to think of anything else it could be other than a rod bearing. The weird thing is that it does not make the noise directly related to RPM. It does kinda have a pattern but if you gas it it doesn't seem to be based RPM solely.
|11-05-2012 10:58 AM|
|chucksrt||I just listened to it again and the knock is not consistent . i am going to pull the valve cover but it sounds like it is in the intake manifold. this engine has the spider assy fuel injection...is it possible that the injection popped out of the manifold and that compression is banging it against the upper manifold? i just wanted to see if anyone has had a similar issue before i go ripping everything apart again.|
|11-03-2012 02:04 PM|
383 build knock?
Hey guys, I built a 383 stroker for my 96 Chevy Express 1500 Van a while back and had a ton of issues. I haven't really driven it other that to move it around. It has had noise in the engine that I thought was due to bad gas (a mix of 4yr old and new 93 octane gas 50/50) I found that my MAF was dirty and when I cleaned it, it was not as noisy. I have babied it when I did move it. I moved it today and I drove it around the block to get the juices flowing and it was ok (it's normal noisy self... I thought I needed to check the rocker arm adjustment again) but I stopped it and ran in the house came out and it was making a heavy knocking souns. So bad that the intake manifold felt like it was being hit. I pulled plug wires to see if the noise would stop and it did when I pulled #8 cylinder. Is that the tell tale sign that it has a blown rod bearing? This van is a PITA to work on ,even to just remove the valve covers!!! I thought I triple checked everything when I built it but I guess I missed something. I have had solo many issues with this build I am at a loss!! So if the spark is pulled and the knock goes away does that mean the rod bearing is bad? Sorry for the long post. I am sad!!!