Looking for a little help.

Building up a 350, and I took some readings on the valve tips to rocker arm contact area. Most of the markings are perfect with the stock pushrods, however there are a couple that indicate a wear pattern on the intake side of the valve tip, requiring a longer push rod.

Is it normal to have different readings?

Do i really want to get a few longer pushrods to correct the few bad marks and have mismatched lengths?

Inside this engine is a new LT4 HotCam, new hydraulic roller lifters, and 1.6 roller rocker arms. Heads, valves, springs are all brand new. With all these new parts, I am surprised I have gotten inconsistent readings.

Anyideas???

 

Doesn't matter where on the valve stem the pattern is (within reason), as long as it's as narrow as possible.

Narrow = the rocker tip is "sweeping" across the stem the least possible, which means, the lowest amount of side loading on the valve guides.

Don't worry about where it lands; go for the narrowest you can get it.

The "readings" are ALWAYS inconsistent. The amount of tolerance in the castings and other such things, is HUGE; and that all affects it as much as the moving parts.

 

Thanks for your reply.

The few that are off center to the intake side are wider than the rest.

http://www.lunatipower.com/Tech/Valv...nGeometry.aspx This is a link that shows exactly what I have, pictures 4B and 4C show a centered narrow swipe and a wide swipe on the intake side of the valve.

I guess I will just have to use the stock length push rods and a few are going to have to be wrong.

Thanks for your help.

 

As you go up in the rpm ranges those patterns become much larger.........and that is where you start getting into problems. Press fit rocker studs will get forced out or screwed in studs could get broken or valve guides don't last very long,etc,etc.

The use of 1.6 rockers on a street car to make up a poor choice of cam will not be felt by the seat of your butt dyno. For one thing your not operating in the rpm range much where the effect is taking place.If it is race car and you want to pick up just "a little"(which is the end result),then it makes sense to have to go threw the issues to use 1.6 rockers.But on a street car is doesn't.

So here you are trying to maximize your combo and then saying what is good enough.Kind of a confusing end result................................??????????????

And one that "might" end in damages!!!.

 

So if I understand you correctly, your suggestion is that I mismatch the pushrods to make the contact points consistent all the way through?

 

Those patterns doesn't lie. The risk factor is there for damages. And comparative results isn't huge unless you are trying to pick up alittle for a race car application. Seat of the pants dyno wouldn't notice it. We when we want to run 1.6 ratio's on intakes do in fact run a mix of push rods. So I guess my answer is yes. I think for you to have a length checker would be a good investment so you know exactly how long you need.

You know off hand you would think the cam has a bigger lift on the intake and the pattern is reflecting that when you increase the lift with 1.6 rocker ratios.

 

Are you checking them all with hyd roller lifters and actual valvesprings? Not using a checking spring or simulated solid lifter?

If using the factory lifters its possible they bled down and thus are changing contact patterns because pushrod cup position in the lifter changed.

I'd verify using a solid lifter which you can make out of a hyd roller by removing clip and internals and filling with washers/nuts to take up the space inside. Or use a light checking spring for a valvespring so it doesnt compress the lifter

 

I have 1.7s on the intake and 1.6s on the exhaust. (not a street car)

My intake and exhaust pushrods are different lengths.

however The pattern on my valve stems are perfect.

 

I modified an old lifter to make it solid, used the same rocker, pushrod and solid lifter on all valves.

I am going to get specific measurements for each valve and order exactly what I need for each valve.

 

ya this eng im doing now took 8.200 long pushrods to get it set right.
and at $140 a set it sucks.. but ya do what ya got to do.
after all just a drop in the bucket.

 

Whose heads and cam are you using? Really shouldnt have different pushrods for each cylinder unless something is really wrong with the machine work on the heads, block, or cam lobes/base circle are different. Now you can have different intake pushrods from exhaust valve pushrods and also different for different rocker ratios.

Buying pushrods per cylinder requirement is expensive but will insure the best geometry.

I have been thru a geometry issue and after discussing with many engine pros, i have found various opinions on what is correct but the one i sided with is the midlift 90 deg method. Place valve at midlift for your cam including rocker ratio and you basically set up the rocker so the centerlines of the roller and trunion make a 90 deg angle with the valvestem. Should give the narrowest sweep pattern. Centered is more ideal but with stud rockers you cant do much to change where the rocker tip lands on valvestem. Shaft rockers you can

 

The heads are e-tec 200's, and the cam is am lt4 hotcam.

I'm going to have to look into the mid-lift method and compare the two. Most of the rockers are centered with a narrow swipe, but there are some oddballs.

 

Hmm whose rockers? Sounds strange that some would be way off like that, especially with edelbrock heads. Figured they would be machined well enough that valve stem location in the seat are uniform with other cylinders in the same head and rocker stud holes drilled correctly.

 

The rockers are proform, 1.6 roller rockers. I thought about the variable in the rockers, so I used the same rocker on all the valves.

 

Yeah thats a good idea. Wonder if the seats were all cut the same depth and at the correct angle? Other than having the heads checked, running different pushrods to correct the off cylinders is the only thing i can think of. Unless lifter bores and location/angle arent all the same. Some kind of core shift in the block or heads? Interesting issue

 

It is kind of interesting, have yet to get any concrete answers. Anxious to get actual measurements on each valve. I lapped all the valves and they were all perfect, I really don't know.

 

Well the depth of the seat and the angle it was cut in can change the location of the valve tip slightly. A good shop or manufacturer that has quality equipment and quality control measures shouldnt have inconsistancies from valve to valve and head to head lol. But strange things happen. Heads used? Original seats and guides?

 

Oops, double post ...

 

The heads are brand new edelbrock e-tec 200's. They came bare except the guides and seats which were machined by edelbrock.

 

Yeah.I'd start with the basics and measure everything.Trust who you shave every morning sort of thing.

 

iv seen rocker arms. with the same part numbers. but the push rod cup. is set deeper in a few other rocker arms... this will call for a longer push rod.
in diff spots.

and every thing els.. is the same.. making you go WTF

also make sure your cam is not a used one.ya got at a yard sale..(just sayn)

make sure ya have no bent push rods..(safe side)

make sure all your push rods are the same size now....just chekn

 

Cam is brand new from summit. I used the same rocker to mark all the valves, I'm thinking it has to be some variation in the valves and/or seats that is making the readings off.

I'm curious if the guys here who have done this generally do all the valves or just one and run with it???

 

it should start off just off center. to the intake side.

at the push.. it sweeps across. then back.

making the print on the tip. and always just a tad to the intake side.. just a hair.. there are a lot of good books on this..

now a stock eng like all the makers toss together are all over the place.
and that's fine for a stock eng/work horse.that never see's 6500 or more rpm...

 

To be honest i only ever done intake and exhaust on one cylinder and bought pushrods for all cylinders. I just assumed heads were cut the same and valve tip location were all the same. Never had a problem doing it that way and after running the motor and inspecting things, all patterns looked similar so its worked for me. My last build i thought my pattern looked good and ended up having intake guide wear problems. Exhaust seemed fine so i guess intake side didnt want same pushrod, however that was before i was aware of midlift and also using a high offset rocker which may have contributed to the issue. Also not sure if my valve float issue was a cause or not. Either guides went bad and caused float or springs werent stiff enough to begin with and caused guide wear from float! Lol who knows

I likely will look at more than one valve this time for my pushrods but i now have a shaft rocker system and aligning things is much easier

 

when your putting money and time into a eng.
you will want to check them all..

you want every thing the same... for parts sake.. you can make do with what works.. but are you sure. its right?

you can check all the valves (how long ea one is) without taking the heads apart..easy this would be what I would do.

I just had to buy a stud girdle from AFR. cuzz nobodys would fit ther heads
but hey..ya never know.

edit to add:
in checking new parts over the years. I have found

rock arm cups unfinished = will eat a pushrod over time

rocker arms with diff cup depth = diff push rods size to use them..(same part number)

heads with diff valves (by as much 50 thow)

heads that only take parts.. made by the maker of the heads....(that good of maker?)

evan after market blocks iv seen..and used...oil pump studs off by a hair..had to masag the studs.
to get them to just slide on...(stock stuff always falls together)

that's just the tip of it...

just had compcams make a mech roller for me.. wanted a pressed on cast gear.
what I got was a super hard cast roller cam..(not what I orderd)
they remade the cam to what I orderd.. the way I wanted it.. (was some goof up)
it would never lasted with my springs...lol
(free of charg) they even sent a call tag for the first cam!

always check all your parts..even when new in box!

 

Artic, lot of good lessons learned there. Double check everything just to make sure its correct. As I've worked through this build this pushrod deal is the first hang up I've run in to, hopefully the last.

 

Man how true!!!.Soooo Summit takes back a cam and re-boxes it??.

 

a quick way to see if it's a valve height problem with the heads already installed is to put a good straight edge across all the valves and see if there are any that are high or low. If your readings get longer or shorter to one end or the other it could mean that the head was milled 'crooked' relative to the valves - it will show up as the required pushrod getting slightly longer/shorter towards one end of the engine vs the other...

 

Ok here is a quote the day the guy installed the mill."Hey Joe go out to the truck and get the level"."Joe"-"oh hell that back at the shop!!.Shssss,we'll just eye it up".

I do think there are more reasonable sensible reasons for his issues.

 

yep..it was there goof. cam part # should have been ended in a 9.. they put a 8...oops!

my name is on the camcard. im sure it will be a summit yard sale item..
it was a shame to send it back..but I want what I want..so I don't have to worry about my springs eating the cam..ya know..

summit has always done right by me... even when I have had parts sitting for over a year....(yes a year)...

 

Well after another session of measuring, this time with the adjustable pushrod to get more exact numbers, I have 2 rockers that are making a wider swipe just to the exhaust side of center with it set at 7.300". The rest are fairly close to each other, and have a narrow swipe pretty much centered. The original 7.2" pushrod I was using gave me readings in the middle and to the intake side, you would think those cylinders that were centered with 7.2 would then be off to the exhaust side with 7.3, but only two were. Must have been some kind of error/inconsistency in the way I measured them originally I guess.

I ordered a set of 7.3's, just going to run with that, making them all the same.

Thanks for all the advice ...

 

I want measurements of all the lobes of the cam.

 

New thread on the subject.
Pictures and analysis.
https://www.thirdgen.org/forums/tech...y-looking.html