help bent push rods
 

Have a built engine my big concern is i have bent push rods #5 intake is really.bent. My heads are vortec heads dont know if the have bigger springs or not cant tell dont know how. An a lunati cam part number 60501 advertisef 525 546 lift if the valve springs are stock would that make my push rods bend it had a very rough shake to it an discovered the pushrods please let me in on any info thsnks

Re: help bent push rods
 

Who built it? Sounds like a high lift cam was installed, without measuring or paying attention to retainer-valve guide clearance, or spring bind.

Re: help bent push rods
 

Dont know who built it just Bought it this,was an would really like to drive it would u recomend a smaller cam an new lifters since there proble collapsed. im going to pick up my push rods today an dont wanna damage them again

Re: help bent push rods
 

If the old ones were bent and you install new ones without finding out why they got bent then you'll probably bend the new ones as well.

You're going to have to check a lot of tolerances. Valve to piston clearance. Coil bind. Underside of spring retainer to the top of the valve guide. Slot in the rocker if not using roller rockers can all produce an interference area. Something stops the pushrod from going upward and it gets bent.

Re: help bent push rods
 

Most likely, the bottom of the retainers is smashing into the top of the valve guides.

You can replace the push rods every day from now til the end of time, and twice on Sundays just for good measure, and it will still destroy them, EVERY TIME.

Sounds like somebody who didn't know what they were doing put that together.

First thing to do is to measure that particular clearance. Pop an int and an exh valve spring out and replace with some real light "check" springs; put your dial indicator on the retainer; and push down on the valve stem. See how far it goes before it hits something.

I'd bet this motor smokes, too? That'd be because the valve guide seals have been pulverized to little shreds.

Re: help bent push rods
 

Assume you mean 60105, which is a flat tappet - much more susceptible to damage than a roller. If you have an interference which is bending pushrods, this may have caused lifter face and cam lobe damage too. Might be best to whip the intake off and check it out, while you're checking your other measurements.

Re: help bent push rods
 

Ok sounds good any ideas on how to go about measuring these an what the specs should be. An i did push down on the lifters with the push rod an they felt rather stiff with barley any give is there any way to replace valve guides or removing the springs with out having to pull the heads off. I dont wanna do any more than i have too an is there any way to check if the springs are stock or aftermarket? Would i be better off buying cam an lifter kit to better match the heads?

Re: help bent push rods
 

Valve guides, no.

Springs, yes. All you need is a piece of rope and a spring compressor.

First thing to do is figure out why your push rods got bent. It's probably not the valves hitting the pistons. More likely, it's either spring coil bind, or the retainer/guide clearance problem. Both are EXTREMELY likely; the guide thing is ALMOST CERTAIN. In either case, odds are VERY high that at least one cam lobe is destroyed, meaning, you already need a new cam and a set of lifters. Until you find and fix the fundamental cause of the problem, and/or install a cam more suitable to the application at hand, you will keep tearing up parts. Which will SURELY make your experience in this hobby ALOT less fun than it might otherwise be.

Re: help bent push rods
 

a good deal more info on your engine clearances would help a great deal, but actually these are firm indications of clearance issues , most likely AGGRAVATED, or partly caused by improper valve adjustment, or not checking the valve train clearances correctly, since only one cylinder is showing contact,and bending a push rod , and because its takes HUNDREDS OF POUNDS OF FORCE, to bend push rods and damage pistons, you most likely bent a valve in that cylinder , or for some reason the clearances in so check all your valve train related clearances carefully before re-assembly.
I generally see results like this when guys install a performance cam with more lift & duration in a stock engine with-out checking clearances or guys that adjust valves with the engine not running on the engine stand who find they adjusted the valves incorrectly .
the eyebrow marks on the piston obviously indicate valve to piston contact and the fact that the valve contacted the piston outside of the valve relief clearance notch shows a clear indication that valve to piston clearance was most likely never verified


http://forum.grumpysperformance.com/...+vortec#p19304

http://forum.grumpysperformance.com/...g+vortec#p6078

http://forum.grumpysperformance.com/...php?f=52&t=399

http://forum.grumpysperformance.com/...php?f=52&t=181

http://forum.grumpysperformance.com/...hp?f=52&t=1376

Re: help bent push rods
 

Ok when i bought the car i drove it home 10 miles away an it had a sputter and ansolutely now power i got home adjusted the valves and the car had a bit more power and not sputtering but still had a really bad idle issue an a slight miss untill u reved the engine to about 2k to 2500 rpm an then it sounded great

Re: help bent push rods
 

That would be:

Come back and tell us what you find. Feel free to tell us as soon as you see the demolished valve guide seals.

Re: help bent push rods
 

Lol valve seals where not blown.to pieces suprisingly but i do wanns replace the cam instead of having to machine the heads to handle that much lift unless there is a different way to do so with springs an retainers. my friend has an unused edelbrock.performer plus cam part #2102 420 with stock rockers intake and 442 exhaust. Duration is 278 intake an 288 exhaust lobe speration 112 i still want a noticable thump an power will this do the trick or can i get springs an retainers to fix my problem

Re: help bent push rods
 

That cam is small for a 350, and a lazy outdated generic design available from several manufacturers, and certainly not a 'thumper'. There are much better younger designs around - check out others in the Lunati Voodoo range, Comp XE series, etc. I wouldn't go to the hassle of sticking a lesser cam in my engine, just because it was free.

If you want 'thump', that equals overlap, and a much larger duration cam. What kind of intake do you have? TPI and TBI computers don't play nice with large overlap. This will also raise the powerband, so you'll probably want a higher stall if an auto, so it's not so much of a dog off idle.

If you want higher lift capability without machine work, there's a set of springs + retainers that claim to give up to .550 clearance that seem to be the hot ticket atm:

https://www.thirdgen.org/forums/afte...ec-spring.html

However, before you go throwing money at parts, you'll HAVE to follow the advice given in posts above and figure out the basic interference problem. Also make sure to check out the cam lobes, every one of them - you might have a ton of ground metal in the oil.

It sounds most likely that you have stock un-machined vortecs with their low lift clearance, and someone has stuck that cam in without thinking or checking.

Re: help bent push rods
 

Right on do u have a part number on witch springs are recomended i have a carb set up edelbrock 750 with a gm performance mid rise intake

Re: help bent push rods
 

Ok i checked out the thread an it does require machining the valve guides down more or less there is no getting around that lol.

Re: help bent push rods
 

If you run beehive springs (Comp 918-16) and their retainers (Comp 787-16) you get a lot more clearance. Usually around .525ish or so, but you will need to check. Vortecs dont really respond well to lifts above .500 or durations past the mid 230s anyway. You start getting less and less performance gains in the high RPMs and you start to give up a lot of the great torque those high velocity ports make. Vortecs are GREAT performance heads, but they have limits in a street car.

That 60105 cam is actually a really good cam, but very aggressive. It will never make much low end torque in a 350 and it doesnt really suit Vortecs. Something like a 60103 is really nice for a streetable, quick Vortec 350. Probably in the 325hp range and may work well with the 918-16 springs. But there are other beehive style springs available that may work. They just cost $180 or so per set. The 60103 is a little more reasonable, and you may be able to get away with some cheap LS3 springs, but you would need to check the spring pressures and spring installed heights and coil bind heights and max lifts pretty closely, with the right combination of shims and properly set installed height, they would possibly work well for a 60103. They're around $60 new.

Do a search for beehive vortecs and learn a little bit.

Also do some research on flat tappet break in.

You may want to just convert it over to roller cams and be done with it, but you need to do some research and figure out what you want to do.

Re: help bent push rods
 

Thanks man that was alot of help im gonna do some reasearch on these items. And a roller cam i do not know much about roller motors ive never built one whats the bennifits for those sorry for all the questions

Re: help bent push rods
 

If i were to go roller what do u think of comp 268xfi

Re: help bent push rods
 

Don't worry about the cam just yet.

Measure your heads and see what they'll support. Find out what it will take to make em go farther, if they're not enough yet. Go from there.

It all starts with the heads. Nothing else matters as much.