Adjusting tappets, 426 Hemi with '70-'71 style cam...

[hemi68charger]

Hey gang...

Ok, I've got another one... I have my heads torqued down now.. I was reading my service manual to continue the next step of my valve/tappet adjustment.. I states you adjust the rocker to zero lash then turn the adjustment screw 1 and 1/2 turns.. Now, this manual doesn't refer to anything stating lifters pumped up or not.. It's a new camshaft, hence there's no oil in the lifters.. So, I'm thinking based on what I'm reading, I just loosen them all, then following the indicated intake/exhaust sequence, adjust the rocker adjustment to zero lash and then screw in 1 and 1/2 turns. The lifters will pump up and all be ok....

Guess my biggest concern about the whole process is brand new lifters.. All the directions and steps explained in the service manual make sense...

Thanks for any input..

Troy

[firefighter3931]

Troy, i adjust them to zero lash with the lifter on the base circle of the cam.....then set the preload by turning the adjuster. Ideally you want between .020-.060 preload....closer to .020 is better and you have the adjustability with the Hemi valvetrain so keep the preload at a minimum. 

1 turn after zero lash will be fine, inmo. You're correct....the lifters will fill with oil once the engine is fired. 


Ron

[Steve P.]

Damn that's purdy...   

[hemi68charger]

Troy, i adjust them to zero lash with the lifter on the base circle of the cam.....then set the preload by turning the adjuster. Ideally you want between .020-.060 preload....closer to .020 is better and you have the adjustability with the Hemi valvetrain so keep the preload at a minimum. 

1 turn after zero lash will be fine, inmo. You're correct....the lifters will fill with oil once the engine is fired. 


Ron

Hey Ron..
That all makes sense.. But, as I'm doing the exhaust rockers, the exh. push rod cup still touches the rocker arm.. It is shorter than the mech. exh. push rods I have.. Seems I can't get the zero plus lash on those.... The cam lobe is on it's base circle on this picture's example... The intake, 2 and 7 I've done thus far seemed to work out fine....

Troy

[69fuchs]

You need to have about 1 thread showing at the ball end of the adjuster.  I went with the hydraulic cam as well.

The mp pushrods were too long, just like yours.  I had to make a custom set of pushrods to get the correct adjuster position.

This is not an isolated incident.  If you have mp pushrods, you have defective parts.

MP tried to blame my pushrod issues on machine work, but nothing on my engine has seen a mill or machine shop at all in 37 years.  (my block is a 1970)

Long story short, I have talked to several people that bought hyd mp pushrods, they just plain don't fit!

[hemi68charger]

You need to have about 1 thread showing at the ball end of the adjuster.  I went with the hydraulic cam as well.

The mp pushrods were too long, just like yours.  I had to make a custom set of pushrods to get the correct adjuster position.

This is not an isolated incident.  If you have mp pushrods, you have defective parts.

MP tried to blame my pushrod issues on machine work, but nothing on my engine has seen a mill or machine shop at all in 37 years.  (my block is a 1970)

Long story short, I have talked to several people that bought hyd mp pushrods, they just plain don't fit!

Yeap, my pushrods are MP's !!!!! It's just what it looks like, too long.. I would think with the adjuster ball screwed WAY back, there should be plenty of clearance for the rocker arm to move freely... Damn, this sucks... I hate having to try and figure out the correct length I need.. So, the push rod length, is it a measurement from the bottom of the rocker cup to the tip of the tappet side? Since you have an unmilled block and head, did you have a length dictated by OEM specs or did you have to measure it? Well, I may have a friend here in Houston that has push rods... Seems the intakes are proper.. Did you have this experience as well with the intakes being ok?

My heads and block haven't been milled either.. The block is a brand new MP version.......
Thanks..
Troy

[69fuchs]

Both the intake and exhaust pushrods were too long on my hemi.  I cut one intake and one exhaust pushrod in half (and shortend them), tapped them for 1/4-20 threads, and installed a threaded rod between the two halves.  Instant pushrod length checker.

Going from memory here (1995),  the pushrods are measured from the bottom of the cup to the tip of the lifter end.  If mp would have done a total measurement from the end of the cup to the tip of the lifter end, they would be a lot closer to the correct length.

BTW do not buy the cut to length pushrods from mp.  They are junk also.  The cup end is supposed to press into the tube, but the dimensions are wrong, and the cups are so loose in the tubes that they wobble!!

Make sure that your adjuster has at least one thread showing on the bottom of the rocker arm.  If the intake side is showing one thread, they are fine.  Zero lash plus 3/4 turn is great plenty for adjustment.  1-1/2 turns past zero lash will cause the valves to hang open at higher rpm's.

[firefighter3931]

Fuch's advice is right on....a checking pushrod is the way to go. The pushrod pictured above is too long as mentioned. The 1-2 threads is correct and essential for adjuster/cup oiling.....you don't want to be burning up pushrods & adjusters. 

MP is not who i would use for pushrods. 

The "if it were mine" answer would be a set of custom pushrods from Smith Brothers. 

You could make (or buy) a pair of checking pushrods (intake & exhaust) and send them in to have your set custom made.



Ron

[hemi68charger]

Fuch's advice is right on....a checking pushrod is the way to go. The pushrod pictured above is too long as mentioned. The 1-2 threads is correct and essential for adjuster/cup oiling.....you don't want to be burning up pushrods & adjusters. 

MP is not who i would use for pushrods. 

The "if it were mine" answer would be a set of custom pushrods from Smith Brothers. 

You could make (or buy) a pair of checking pushrods (intake & exhaust) and send them in to have your set custom made.



Ron

Hey Ron..
Just emailed them with my problem.... I hate having to cut up one of the push rods to make an adjustable one to see what length I need... Any tricks to figure out the dimensions I need? I'm also assuming it's going to depend on the position of the adjuster ball in space then measuring to the top of the tappet cup once the tappet is on the base circle...

Troy

[firefighter3931]

Troy, you can buy a pair of checking pushrods.....or make some from an old set if you have any. I would try to return those MP pushrods and get your money back. If this is a known problem then the vendor should offer you some type of credit/refund. 

Ok, did some checking in my Comp Cams catalog and cam up with some part #'s ;

(1) 7904-1 : individual length checker 10.2-11.5 inch range
(2) 7909-1 : Cup adapter for 7900 series checking pushrods


You will probably need 2 of each because the pushrods are different lengths.....those Hemi engines are complicated ! 


I would call Comp just to verify that this is what you need and that these numbers are current (my catolog is 2 years old).

1-800-999-0853 or fax 901-366-1807




Ron

[John_Kunkel]

It's pretty hard for MP to deny fault with their pushrods when their product doesn't even meet the spec quoted in the MP catalog. On the last set of hydraulic Hemi pushrods I installed the exhausts were exactly 1/8" longer than the dimension quoted in the catalog.

Luckily, I have a lathe and used a 1/8" wide cutoff blade fed in right under the inner end of the female cup to shorten the exhaust pushrods; intakes were OK.

[hemi68charger]

It's pretty hard for MP to deny fault with their pushrods when their product doesn't even meet the spec quoted in the MP catalog. On the last set of hydraulic Hemi pushrods I installed the exhausts were exactly 1/8" longer than the dimension quoted in the catalog.

Luckily, I have a lathe and used a 1/8" wide cutoff blade fed in right under the inner end of the female cup to shorten the exhaust pushrods; intakes were OK.

John, I didn't dissect the push rods, but do the caps come off or unscrew? I guess I could go check now... I'm pretty disappointed in MaMopar needless to say.....