Today I went to put in my pushrods and roller rockers. I got the pushrods in and once i go to put the rockers in I realize that the rockers wont go down on the head bolts enough. I got stock size rods and the rockers are 1.6 ratio.

The block is brand new from m&r motors and its been decked. ALong with that I have a comp cams x282hr cam and a set of dart pro 1 platinum 200cc heads.

What do I need to do???

 

Buy a pushrod length checker to see what length pushrods you need and buy them at the proper length.

 

there not supposted to all the way down the rocker studs, the pushrods have to be the right legnth or it will cause side loading on the valve and rapidly weare the valve guides, there was an artical in car craft (I think) recently on how to mesure the pushrod and get the right size,als make sure you get the low tension temp. valve springs or the lifters will colapse when you try to mesure it

 

Im gonna call the motor company that did the bottom end and ask them. Hopefully they will know

 

For my motor I had to buy longer studs.

 

Bottom end has nothing to do with pushrod length except the camshaft. A small base circle cam will need different length pushrods.

Head design also affects pushrod length. The position of the valve seats in the heads can change the position of where the valve sits. The length of the valve can also affect pushrod length. If you can't obtain correct valve train geometry with stock rocker studs then a different rocker stud is required.

Using 1.6 rockers moves the pushrod closer to the rocker stud. The aftermarket heads should cause a restriction problem.

I still suggest you buy a pushrod checker and check your valve train geometry before changing any parts.

 

11 bucks for a checker and a few bucks for a low tension spring...its all good stuff. You should check it out for sure as its the only way to know

 

Are you installing the rockers with the lifters on the base circle of the cam?

 

I would recommend buy an adjustable length pushrod vs. the pushrod checker

I have used both and believe the adgustable length pushrod to be much more accurate.

 

I see you are using a hyd roller cam... did you happen to get pushrods for a flat tappet style cam? They are substantially longer than the roller cam pushrods. Measure the length and post it here... we'll know which type of pushrod you have by the measurement as they are quite different in length. Which ones are 'correct' are usually very close to the std length, but vary a little.

 

Im using a roller cam. the heads are dart pro1 platinums.


I got the head bolt kit that was suggested for the heads.

Heres what i was told to get on here.

http://store.summitracing.com/partde...6&autoview=sku

 

What do head bolts have to do with rockers? Do you mean rocker studs?

What size are the valve springs? 1.125, 1.437 or 1.550? The 1.550 use .100" longer valves.

You say you have a roller cam. The 1.550" springs are for a roller cam. You've got the wrong pushrods for those longer valves.

Those 7.800" pushrods are stock length SBC pushrods. Since you're not using "stock" heads, valves or valve springs, you need to check valve train geometry before ordering pushrods to know the proper length required.

 

stock length for our hyd roller motor cars is 7.2 inch. thats a 9.025 deck with .015 gasket i do beleive. you have way too big pushrods. 7.80 is for flat tappet stock chevys

my car i'm using 7.35" rods for a zero decked block with .041 gasket and LS7 lifters which have a deeper pushrod cup than stock sbc lifters

you have to measure

 

Ya i am getting the tool soon so im gonna be checking. I saw that stupid summit people recommended me the wrong size.

I have 1.437 springs and i meant i got the head bolts and studs all in one thing from arp.

And i didnt even realize how much bigger they were till just now.

could I have mathematically figured it out????

 

Not really... too many variables and things that are just too hard to get an accurate measurement of. Checker is the best way.

 

Okay so i just measured them and its showing like 7.25 inches. I am a little confused though as to what if I was off lets say .1 of an inch too short or too long? WIll it be okay? IT would just sit higher on the rocker stud or lower possibly right?

 

the length will dictate where the tip of the rocker passes over the valve stem tip.

too long or too short will move the contact point inward and outward. you want to make it so that the tip is centered on the valve stem at the mid way point of max lift. bring the valve to half of max lift and observe where the rocker tip is, and if its close to the center of the valve stem your good to go. i feel you can be off as much as .050" and not harm anything. 0.1 inch is abit of a difference but shouldnt really effect too much but i'd strongly suggest you get within .050"

 

7.250" are available from Comp.

Send back the ones you got and get the 7.250"-ers.

 

Ya i was actualy goin to go for 7.3's but what do you think??

Should the rocker be perpendicular to the spring at no load?

 

Send a PM to 'Sofakingdom' and ask him about it - he can give you the proper method for determining pushrod length setp-by-step.

It has to do more with how the tip of the rocker sits on the tip of the valve than the angle it sits at IIRC. Its been awhile since I did it, so I can't really remember now.

 

Ya i realized its gotta be on the stem at all times. SO i locked it down and looked to see how it all went. 7.25 should do the trick

 

I didn't mean just on the stem, lol, I just assumed you would know that much

I meant the rocker tip's location on the valve stem - ie. center, off center, etc... and how much it wanders accross the top of the stem during valve opening and closing.

 

You want to make sure you get the right ones and get the geometry right.I kept snapping rocker studs till i bought a pushrod length checker and realized the problem.I bought longer rocker studs as well as .02 shorter and not a problem since.The last time it snapped a rocker stud it ben two pushrods.It was at low rpm`s so I got lucky,it caused no damage but it could have.

 

ya well thats what i meant on the valve stem. I checked with some friends and got it squared away. Im crossing fingers now. lol