SirGillsparagus

Hi all. I had rod knock and replaced the bearings, as well as putting in some aftermarket parts. It was running ok, i did give some quarter turns to some lifters that seemed loose to me, i know big no no.. its a flat tappet cam, and i underestimated how loud they should be. I had an electrical grounding issue at that time but i dont think its related. and after that ive had that fade out kinda noise and it wouldnt go past 1800 rpms. The crank seemed tight, so pulled it apart, i had a shaved journal from the original rod knock so i was using undersized bearings, but they were pinching where the two bearings would meet on the journal. so i put in new crank/pistons. The last video where Im having the sound it kinda just sounds like bad audio quality, but it actually sounds like that and it seemed like the car was shaking more than usual. so i put up when i first ran it and it started having a problem. I thought it was ign timing related, but coming down in rpms the noise is still there so im thinking its something with the cam or the cam bearings. Sadly i think it might just be from when i tightened the lifters extra. Im taking out the cam to check it and the bearings and the lifters. Im not sure what else to look for or if that even is what the issue is with it. The closest sound clip online i could find to it was of a bad cam bearing. Any help would be greatly appreciated if anyone recognizes it, thank you.

F-BIRD'88

Predetonation as a combustion term does not exist.
But Pri ignition (self ignition before the spark occurs) can be followed by detonation . ( charge explosion after the ignition point. Detonation is charge explosion VS charge BURNING. (normal engine combustion.

Detonation takes out rod bearings and piston ring lands fast.

Pri ignition makes detonaTion more likely.

Detonation over time (more WOT combustion cycles) often leads to run away pri ignition.
Can be engine melt down.
Its all bad.

SirGillsparagus

So I took out the lifters. I dont know how how their supposed to be but 13 of them I couldnt move without a tool if I tried. I bought new ones just to be safe. I also drilled the pushrod holes because the aftermarket ones i got were just smaller than the hole on the head and had rubbed off the coating as well.
As of now when I turn it on, the fade noise isnt there anymore. It goes up to 2800 now which is higher than before, but then kindave hesitates and pings if you give it too much throttle. It doesnt overheat either.
I was driving it stock, had a oil seal go out and had a cracked rod bearing. It was running full range 800-6000 rpm with the new cam kit, intake manifold, and sniper ecu. I had used an oversized bearing next to a regular one so they eventually got seized together.
I did run some different parts along with replacing the crank rods and pistons. I think when I had it revving the full range after the cam upgrade I had the timing gear set to regular, however after dealing with the seized bearing i put it on advance its been on 4* advance since. I dont know if that could be just not good for my application, but Im gonna try and put that back on 0 and give it a try again.
The only other difference I can think of would be the arp studs I put in with the new crank. Which i didnt get the strongest ones and I thought It might be fine but they are stronger than oem. so maybe thats whats throwing it off? I have been reading about that so maybe i should just get some new stock ones?
Im sorry for the long post, It just seems like its soo close and theres just one thing that im missing here that is causing it to be slightly off.

dabomb6608

iTrader: (3)

To me that sounds like your EFI is putting it in a limp mode and reducing max rpm with a hard limiter. What is your sensor warning?

If your lifters were stuck, you might have wiped some cam lobes. What cam, what lifters and what springs did you use and what break in process did you perform on the new cam?

Aaron R.

Well this is going to hurt feelings, but you need to either call it quits and turn all this work over to someone who knows what they are doing ($$$) or be prepared to spend $$$ learning about the many nuances of Chevy small block engines.

Sounds like you have any number of possibilities for something wrong in the engine mechanical, fuel, or ignition system. If you brought the car to me as a mechanic and told me this stuff I would tell you brace for a whole engine rebuild (which is probably what should have been done in the first place). Otherwise I have no idea where to start unscrewing up the whole mess and it's probably gonna end up the same cost anyway.

Good luck with your project, and I mean that sincerely.

dabomb6608

iTrader: (3)

I agree. There are a lot of red flag variables going on here that aren't adding up. Like using different sized bearings but no mention of actually having the crankshaft worked over at a machine shop, stuck lifters, what sounds like multiple engine teardowns...

You will go nowhere fast while burning loads of $ if you keep blindly throwing parts at problems you think match your symptom's. It is likely time to completely start from square one with an individual who is competent with these engines. That means full engine tear down, parts checked by a good machine shop, any machining needed being performed, correct parts selected to work with said machine work, and then the engine built by an experienced individual.

SirGillsparagus

Called a shop, guy told me the bearings may probably be a problem down the road, but if it's able to turn on it wouldn't keep it from doing the range. He asked about the timing gear right away said some aftermarket cams have advance ground in already. So put that back on standard and it ran the rpm range with no clanking.
Thanks all, I appreciate all the help along the way