Strange problems with lifters...

[crometooth]

Sorry this is kinda a long post, I'll try to keep it short. I have a 72 Jimmy that has a 350 in it. A few years ago I rebuilt the motor and when I did I succumbed to the temptation to hop it up a little. It has 10:1 compression Vortec heads and a comp cams Magnum 270. After it was rebuilt all seemed fine and then one day on a long road trip I had a lifter collapse. I pulled into some po-dunk town and replaced the lifter. Shortly thereafter another lifter started making all kinds of noise that I couldn’t adjust out. I thought I might have gotten a bad batch of lifters and replaced them all. That seemed to fix it for a while but the lifters started making noise again. It wasn’t bad so I just let it go for awhile. I noticed that when I would change the oil the lifters would make more noise for about 100 miles and then quiet down some. Finally, I couldn’t take it anymore and pulled the lifters and measured the lift of the cam. Several of the Lobes were worn so I replaced the cam with a comp cams extreme energy 268. While I was at it, I put in roller rockers and new springs. Broke the cam in, everything seems fine except the lifters are still noisy! I have adjusted them several times both hot and cold. I suspect that I might have an oiling problem, but I see oil at the rockers dribbling out at idle so I don’t know. Any Advice/suggestions?

 

[RootBreaker]

this probably has nothing to do with it but the cam you have in there is .470-.480" lift of a cam.....

I know summitracing told me .474 would be pushing it for the vortec heads.....
did you have any work done to them?
too much lift makes them bottom out as something needs to be cut out for higher lift cams....

that is why I went with the Xtreme 4x4 X4258HR Cam as it would be .458" lift and not stress out the heads.... didnt have the extra $300 to have the guides cut, enlarged for bigger springs and pressed studs removed and swapped for screw ins...

hope that helps a bit...

 

[4X4HIGH]

What kind of oil pressure do you have? What brand of lifters did you install? How are you doing your valve adjustment? I'm assuming this is a hydraulic cam since you said you had a lifter collapse.

 

[crometooth]

Thanks for your replies...

The heads have been modified so I should be good to about .550 lift

Oil pressure at the guage looks like about 30-40 PSI at idle when cold and when it warms up it drops down 20 to 30 PSI when warm

I was thinking maybe there is some gunk in the lifter oil galley somewhere. I don't know of any way to check though. Also, I see oil gurgling out of the lifters at idle but I havent checked it at any higher RPM (afraid that'll be messy)

 

[crometooth]

Oops. Missed a couple of questions there.
The lifters are from scoggin dickey, I think they were TRW or federal mogul.

The lifters were adjusted cold by cranking the engine over until the exhaust valve just started to open and then adjusted the intake to zero lash plus 1/2 turn.

Adjusted hot they slowly back off until they just started to clack and then tightened until the clack went away plus 1/2 turn. (I hear this is not a good thing to do but I am at wits end)


Yup, hydraulic flat tappet cam. The specs are 224 and 230 @ .50 with an LCA of 108 (I think).

The roller tip rockers are self guiding 1.6's and they are an off brand but appear to be very good quality (look just like comp cams magnum roller tips). I am also using comp cams poly-locks.

As a side note, if you have ever torn a SBC apart you might have noticed there is a small plug under the rear main bearing cap. As I understand it, that plug diverts oil to the filter and if its left out your oil pressure will be poor and unfiltered. I have a high volume pump installed and It has bugged me for a while, but I wonder if I left that cap out? Anyone know what the real world symptoms would be? I don't think I forgot it, but I am really, really second guessing myself.

 

[1979jimmy350]

if you think that you might have some gunk in you oil passages run some seafoam through your oil that should help

 

[crometooth]

Could be, I'm not a big fan of "mechanic in a bottle" though.

Maybe I'll switch to solid lifters....

 

[chevyk2500hd]

I really wouldnt consider seafoam a mechanic in a bottle. It is a very good stablizer and engine/fuel additive.

 

[crometooth]

Yeah, I,ve heard people say that. Lots of people swear by Slick-50 too, but that sort of thing aint for me.

I just tried to adjust the lifters again... They still make a ticking sound all the way down until they start to hold the valve open.

This sucketh mightilly....

 

[Slapperbar]

Seafoam ain't crap.It's good sheit. really.

 

[crometooth]

FYI.

I talked with a tech rep from comp cams, he said some lifter noise with that cam roller rocker combo is to be expected.

I dunno if my noise falls into the "normal" range but it might be helpful to someone else...