strange thump or popping sounds????????

Posted By: Dakota_Don

strange thump or popping sounds???????? - 12/31/08 12:25 AM

New from the shop 410 SB stroker has a strange thumping or popping sounds, seems some of it is the fuel pump?? some of it sounds like its from the open headers but not sure.. Oil psi is very good at idle. it sounds like lower end, but not in one area i can not find anything banging or hitting under the truck, when i rev the engine it goes away. I would hate to think i would have to pull the engine again.

Would open headers make a popping sound ( almost like a thumping) this noise sounds the same no matter where i am on the truck, top, bottom,either side.. should i run it with exhaust? any ideas?

thanks

Don

Posted By: sogtx

Re: strange thump or popping sounds???????? - 12/31/08 03:24 AM

This is a loaded question . imo you will learn to ignore small sounds as you described when you install a seriously HP motor .. its not a sewing machine 318 anymore ..
However you will hear all sorts of stuff with open headers .

Posted By: goldmember

Re: strange thump or popping sounds???????? - 12/31/08 04:08 AM

Headers banging on the crossmember? Put the exhaust sytem on it and check clearance around the headers.

Posted By: Dakota_Don

Re: strange thump or popping sounds???????? - 12/31/08 03:42 PM

the engine does rock at idle, so this is what im going to do, install a meg-shift exhaust, open plug gaps from 35 to 40, install an engine hold down strap, adjust the carb, hopefully i can get the engine to not rock as much at idle.

as far the engine or headers hitting anything i cant see where.. I crawled under the truck with it running and it still sounds the same.. plus my hearing sucks from working in the factory. Hopefully with some kinda exhaust it will stop or i will be able to track it down.. I guess im trying to compare it with a stock 318 rebuild, nice smooth and quiet.....

thanks for the replies..

Posted By: 68CoronetRT

Re: strange thump or popping sounds???????? - 12/31/08 03:55 PM

Quote:

New from the shop 410 SB stroker has a strange thumping or popping sounds . . . Don

I would have not hesitate to get the "shop" involved immediately. The more time you play with it the less likely they'll stand by it.
A friend of mine once paid for HP motor rebuild on his Mustang. Shop even installed it for him and called him to come and get it. He drove about a block and half and saw there was no oil pressure. Stopped, pulled the stick and you guessed it - empty. Turned around and drove back to the shop and they had the gall to say it was full when it left here.
Get your mechanic on this ASAP.

Posted By: lewtot184

Re: strange thump or popping sounds???????? - 12/31/08 04:03 PM

you could be experiencing some piston slap. those stroker pistons probably don't have any off set in the pins, and shorter pistons have more tendencies to wobble, especially cold. if the noise goes away when the engine warms up then its probably the pistons.

Posted By: Dakota_Don

Re: strange thump or popping sounds???????? - 12/31/08 04:10 PM

the engine is from the machine shop, i installed the engine.. but i will call them and let them know..

Posted By: Lefty

Re: strange thump or popping sounds???????? - 12/31/08 05:28 PM

How much gap between the headers and torsion bars?

Posted By: Dakota_Don

Re: strange thump or popping sounds???????? - 12/31/08 06:56 PM

I called the machine shop. He assured me it was'nt the engine. There is'nt any torsion bars..

he said basically what was mentioned above..

The engine does shake a bit at idle espisially the trans tail-shaft area (stock Dak trans mount)

but i did'nt see anything hitting..

I am going to remove the dust sheild, add some kinda exhaust,add a hold down strap and try to smooth-out the idle.
I have the idle at about 1000 rpm now, maybe the plugs need a larger gap in them to.

I will just let it sit till i get an exhaust,remove shield and add a hold down strap then go on to the next step..

BTW
here are my specs
1972 360 built to a 410 stroker with 10.2 cr with .040ish quench

XE274H 230/236@488/491 lift cam is installed straight up(it was degreed) I do not know if this cam will have a lope to it, which could lead to the shaking of the engine. ported J heads
crosswinds intake (RPM airgap clone)
770 street avanger(out of box)
FBO ignition (which failed between 3 to 4 K miles)
Coil leaked oil and box went out, now im using accel super coil and mopar chrome box with FBO mech ONLY advance dist (which now needs and advance and recurve)
long headers
904 low gear set and 2500 to 2800 stall
3.73 gears
96 dakota

this is my fist engine with a cam in this size, will this cam have a lope to it? will that cause this shaking at idle and posible lead to the noise i am hearing and can'nt find..

thanks again

Posted By: MileHighDart

Re: strange thump or popping sounds???????? - 12/31/08 07:16 PM

Its your brain popping in and out of gear....

Mine does it all the time

It doesn't get better with age

Posted By: 1_WILD_RT

Re: strange thump or popping sounds???????? - 12/31/08 07:25 PM

Once tuned that cam will idle pretty smooth, not stocker smooth but it sure shouldn't shake the engine enough to have it rattling off things..How much base timing have you got in it? \Get you exhaust hooked up then look it over...

Posted By: Dakota_Don

Re: strange thump or popping sounds???????? - 12/31/08 07:52 PM

Quote:

Its your brain popping in and out of gear....

Mine does it all the time

It doesn't get better with age

you got that right..

Posted By: Dakota_Don

Re: strange thump or popping sounds???????? - 12/31/08 08:01 PM

Quote:

Once tuned that cam will idle pretty smooth, not stocker smooth but it sure shouldn't shake the engine enough to have it rattling off things..How much base timing have you got in it? \Get you exhaust hooked up then look it over...

thats kinda what i thought, my timming is set at approx 18 degrees at idle and a total of 35 degrees in at 3000-3300rpm.. but then this dist is setup for a different 360 combo w/same cam, heads intake and carb. Heck the carb may even need tweeked..

but before i go on, i need to cork the headers.. then move on..i beleive once i get it tuned right my thumping will go away.. i just hate the fact of adjusting this holley,ignition ?????
not sure where to start..

anyway thanks for the seggestions.. grrrrrrr

Posted By: GODSCOUNTRY340

Re: strange thump or popping sounds???????? - 12/31/08 09:02 PM

Before blaming the engine check your torque converter bolts. They may be hitting at idle, as you rev the engine the converter goes back into the trans and the knock stops.

Posted By: Anonymous

Re: strange thump or popping sounds???????? - 01/01/09 07:03 PM

i hear weird sounds in my 416 all the time. just gotta know if its a bad sound or just a normal sound.

Posted By: Dakota_Don

Re: strange thump or popping sounds???????? - 01/02/09 01:48 AM

update, after i installed a meg shift exhaust with thrush glass packs , i can hear the noises.. now i need to get the idle problem fixed, I beleive its the carb. then the rocking will stop and it should be smoother and quiter..

the exhaust does'nt sound bad, it dumps right after the cab,.