Did you check internal clearances on this engine when converting to 383.. Rod bolt to camshaft, rod nut to cylinder walls, crank throws and rod bolts to block?

 

I got a summit block already clearanced for a 383 and my Scat rotating assy has arp screws with the 12pt head for added clearance. I did rotate the rotating assy a number of times before sealing it up.

 

An exhaust leak can sound like you describe so start w/checking for an exhaust leak- especially the header gaskets.

You can use a mechanic stethoscope or a length of fuel hose to listen around the engine to isolate where the sound is coming from. If this is a new build, the tap could be the valve adjustment off on a valve, a bent pushrod, broken spring or damper, a pulled stud, etc. or heaven forbid, a lobe going flat on the cam.

 

This has a roller cam and less than 5 miles of driving on it. It has more idling time though. Everything else is brand new! new edelbrock e-tec heads (vortec) new custom pushrods, can a mis adjusted rocker arm only make noise certain times? I will get new header gaskets and check again. Is there a good gasket to get? I used the ones that came with my Doug Thorley headers.

 

This has a roller cam and less than 5 miles of driving on it. It has more idling time though. Everything else is brand new! new edelbrock e-tec heads (vortec) new custom pushrods, can a mis adjusted rocker arm only make noise certain times? I will get new header gaskets and check again. Is there a good gasket to get? I used the ones that came with my Doug Thorley headers.

You wouldn't expect a great deal of change in the sound between cold and hot if the rocker adjustment/lifter preload was real loose. IIRC you have aluminum heads so if anything the noise would increase as it heated up if the adjustment was off, but close. Any hydraulic lifter can get some debris in it causing the lifter piston to stick- this will cause a valve tic.

Still- check the header gaskets, and exhaust first. BTW, what kind of exhaust system/muffler set-up did you end up using?

 

I just had the headers connected to the factory muffler. So it has headers into 3" front pipes to the muffler (dual 3" inlets) and i think the tail pipe is a single 3" or slightly smaller? I will be replacing the complete exhaust system from the headers back to 2.5" pipes off of the headers into a turbo style muffler with a single 3" tail pipe. When I do it I will be taking it to a shop that uses mandrel bends front to back! That's if I don't drive it off a cliff first! ain:

 

Hes right about that could be an exhaust leak is the noise more pronounced on one side of the engine than another? Try no narrow down where it is coming from check your header bolts and tighten them up i know i had that same issue and had to retighten my headers several times. Also check your lifters they may need to be snugged up.. find a set of old valve covers and cut an inspection whole the length of them and run the engine and use the stethiscope to try and pinpoint. And im sure its not this but ive herd of a windage tray coming loose in the pan and getting hit by the rods but that would make a heck of a noise lol and most of all dont get frustrated if you do best to walk away and take a break i know how you feel.

 

What does the valve train look like while running, tighten many bolts after it has settled and heat cycled. Is oil squirting from one rocker area more than another.

Yes , lifters can make noises when cold , and quiet when hot or pumped up. Cold can leave clearaNCCES to rattle, and heat can expand the nooks causing rubbing scratching noises.

The sound is it tick tick , machine gun like, sound like your mom in high heels. Lets us know.

 

I just road tested it today with a couple of techs and it seem like there is a slight noise from the rockers and a little noise from the exhaust header collectors. I also have to run through a couple tanks of fuel to clear out the old gas that is over 2 years old! Major detonation!!!

 

If possible you should drain/syphon that crap out before you beat the Bearings & Pistons to death. :smash:
You could slowly add it back to something later, a Gal. at a time after tuning.
Some Hyd. Roller Lifters are known to be a little noisy, Comp for one.

 

I was almost tempted to idle the fuel out. Then I got mad and just filled it up with 14 gallons of 93 octane and added a container of 104 octane booster. It sounds better but has some detonation at part throttle ( I contacted the computer tuner and they added 2-3 degrees of timing at part throttle) so I guess that is why it is more pronounced then. I have 9.6:1 compression and a new battery but it has a slow crank (just a little slower than normal) but after driving it for a bit it has a much slower crank. I guess I have to do a draw test on the starter. I am going to remove the pass side valve cover tomorrow and check all of the rockers for play. Should I just check it cold one cylinder at a time again or do it running? Thanks for all of the replies!!!

 

I helped a friend start his car with old gas mixed with new gas. It seems the old gas gummed up all the valve stems (mostly the intake valves), and made the valves stick which bent pushrods and flattened out cam lobes.

Had to pull the head, hammer the valves out, clean the valve stems and guides with lacquer thinner, change the cam, lifters, and push rods.

do a compression test and drain the tank.

 

was that gas that was so old that it wouldn't run on it with out mixing it with new fuel? or was it so old that it was like a varnish? My gas was round about 2 years old but the van did run off of it prior to mixing it with new fuel. I think I will drain it half way and check what comes out, if it is nasty then I'll drain the whole thing if not I'll just suck a half a tank out of it which should make it like 3 parts new fuel to 1 part old fuel.

 

not sure how old it was. But it did smell funny.

 

For what it is worth. When we first fired up the 454 that I built for my buddy, you would swear that every lifter was out of adjustment, but I knew they weren't. Turned out that every one of the rocker arms was making contact with the gasket flange on the fabricated aluminum aftermarket rocker covers. A little work with a die grinder and burr on the flanges and all is well.

 

I'm going to pull the valve cover off in a bit to check. I will look at the inside of the cover for signs of hitting. Thanks!

 

I'm going to pull the valve cover off in a bit to check. I will look at the inside of the cover for signs of hitting. Thanks!

You might start it up and let it idle with the covers off to see if the noise is gone. That's how I found the problem was with the covers. It wasn't easy to see where the rockers were hitting the covers.

 

My rockers are blue so if they are hitting I should see scuffing. Will oil shoot all over if I run it without the valve cover?

 

My rockers are blue so if they are hitting I should see scuffing. Will oil shoot all over if I run it without the valve cover?

At about 600 rpm idle there should only be oozing of oil out of the pushrods. If the oil is shooting out, then you likely have a bad lifter. Let us know what you find.

 

What a pain in the *****!!!! Never buy a Express van! I had to remove practically everything to get the valve cover off. alt, coolant bypass hose so I had to drain the coolant, every wire connector, ect!!! what a pain. Well I got everything off and removed the valve cover and started it up. It was quiet as a church so the rockers must be hitting the valve cover. I had it run for a short moment to look for oil coming out of the rockers and I didn't see any and bam then I see oil coming out of the #2 cylinder rocker (the first one? ) It was flowing really good but none of the other rockers had oil coming out of them? How long should it take for everything to pump up? The first rocker had iol out of it's ***** but nothing from the rest? I shut it down because oil was starting to get on the exhaust and I didn't have the drive belt on and I drained the rad. I am at a loss??? What should I do now?

 

My buddy just stopped by and we looked it over and seen that the rockers are getting oil it just takes time for all of them to start flowing. I have http://www.summitracing.com/parts/SUM-G6937-16/ rockers and the pivot part that mounts to the rocker stud has a good amount of play if you twist then left to right? I don't know what is acceptable if any? M friend thinks that they are junk rockers and I should replace them. I think they are hitting the baffle in the valve cover but I am not positive. what do you guys think? Should I get a steel set of roller rockers? if so what's good? thanks!

 

First thing would be to fix whats causing the noise. Then before you screw down covers, hold them on, start motor and rev up a few times. Shut engine off, remove covers and check that oil appears to be getting to all rockers. You might have to dry the rockers a little to make it easier to tell when there's new oil in/on it. I hope you understand what I mean. If there all getting oil, button it up and happy driving.

 

I believe the rocker is hitting the baffle in the valve cover. I do have narrow 1.5 rockers but I guess not narrow enough! My friend has me worried about how much play the rockers have, they do move a good deal if you twist them side to side! You would think they would be tight (not able to move side to side by twisting) what is acceptable?

 

I believe the rocker is hitting the baffle in the valve cover. I do have narrow 1.5 rockers but I guess not narrow enough! My friend has me worried about how much play the rockers have, they do move a good deal if you twist them side to side! You would think they would be tight (not able to move side to side by twisting) what is acceptable?

There is nothing in the design of chevy rockers to keep them from twisting in the rocker stud when twisted by hand. You did notice that they do not twist when the engine is running. The geometry of the valve train keeps everything straight. Get rid of the problem of the rockers hitting the covers and you should be fine. Maybe get a set of tall covers like I have on my engine.

 

Tall covers will not work on my van (there is no clearance) I am stuck with standard height valve covers. Now if there is a aftermarket VC that might have more room or a smaller baffle then I may consider them! My heads have provisions for both center bolt or perimeter bolting (idk if one may have more clearance than the other?)