i've got a comp cams extreme energy cam (262) and CC's 1.52 roller tipped rockers. There on 292 bowtie heads. here's the prob:

I set it to tdc, just when the intake on 6 is opening and the exhaust on 6 is closing. I tighten cyl 1's adjusting nuts till the pushrod barely spins between my fingers, then I go a half turn more. But the rockers roller tip will slide off the valve stem pretty easily. This doesn't seem right at all. It's that way for all the rockers at different times.

Amongst other problems, am I supposed to have guide plates? if so will I need hardened pushrods? what length?

I've got a feeler gauge. I thought I heard of a way to test the lash even if it is hydraulic lifters..

Thanks for the help, this engines taking me forever to finish!

Scott

 

i set lash like you did when engine is on a stand. after it's in the car i set it with the engine running, back the nut off till it makes noise and then tighten until it quits then 1/2 turn or so more. don't have you cam specs handy but you'll need about .050 more push rod for every .075 more lift. don't worry about it untill you need a +.100 push rod, when you do you should have guide plates and hardened push rods, except for SA applications.

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ICON Motorsports

1st & 3rd

 

so it's ok for the rocker to slide off the valve stem? That just seemed really weird to me. Plus I have to run it for 20 minutes. Is it also ok if there's tapping for 20 minutes?

Thanks for the reply,

Scott

[This message has been edited by Surreal86z (edited February 20, 2001).]

 

no the rocker shouldn't even come close to sliding off the valve tip.
yes you need guideplates and hardened pushrods of the proper length.

You get rocker arm geometry right by using the proper length pushrods.

ODB

 

That sucks. Upwards of 200 for that setup.

How do I check the pushrod length then?

 

Look at your heads, where the push rod comes through them. Is the hole a slot that fits pretty tight to the pushrod? If so, you're in good shape. That's the factory configuration in those older stock street heads.

On the other hand, is the hole a ... well, a hole, that the pushrod is nowhere close to? and do the heads have screw-in studs? If so, you need guide plates.

I'd suspect you'll need guide plates. Nobody in his right mind attempts to build a hot-rod motor with press-in studs; and since those heads are now over 30 years old, they've probably been machined on at least once, which makes the odds pretty high that they've been set up for screw-in studs and guide plates at some point in their life.

If you do use guide plates, you probably should also use hardened push rods, but it's probably not a real big deal with the rest of the parts you describe. With an extremely mild cam like that, no push rod length change from stock should be necessary.

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"So many Mustangs, so little time..."
ICON Motorsports

 

well, the hole is huge. that's made me think i might need plates. it does have screw in studs also. It figures that the great ppl at the speedshop who sold me the heads, and studs would have said something. If I have to buy the plates I might as well buy the hardened pushrods since they'll have metal to metal contact. The cam is pretty small also, I'm not sure of the specifics but neither the int or exh are over .480".

So, just to make certain because i'll order that stuff now, I need sbc guide plates. Hardened pushrods @ stock length. right?

Thanks a lot for the help, she's getting closer to running (and not blowing up)

Scott

 

That is all exactly right. You can get guide plates from all sorts of places, from Comp or Crane, or GM, etc. They're not too expensive. You will need the type of studs that has a big flat hex at the bottom. When you take them out and put them back in, use some kind of non-hardening sealer (not silicone) on the threads, they go directly into the water jacket. I use Permatex 300 (brown gooey gunk). Torque them to about 60 ft-lbs.

That's a real mild cam, especially for going in a motor with those heads which are like the most double-hump head there was with straight plugs. Those are one of the castings that benefits the most from having big valves installed, because they can be made to flow so well. I don't recall for sure though: do they have accessory bolt holes in the ends? If not, you'll have a problem on your hands when you go to put your alternator on.

Ede's method of adjusting valves is about the same as I do, should work fine for you.

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"So many Mustangs, so little time..."
ICON Motorsports

 

I told comp cams what I had and they gave me that. I told them I had 2.02 heads. They didn't know that these were the double humps and they've been ported. But, I also have a bone stock shortblock.

i went to comp camps and here's the card:
COMPETITION CAMS CAMSHAFT SPECIFICATION SHEET

PART # 12-242-2
GRIND NUMBER: CS XE268H-10
ENGINE: CHEV SML BLK 265-400
INTAKE EXHAUST
VALVE ADJUSTMENT HYD HYD
GROSS VALVE LIFT .477 .480
.006 TAPPET LIFT 268 280
VALVE TIMING OPEN CLOSE
AT .006 INT 28 BTDC 60 ABDC
EXH 74 BBDC 26 ATDC
THESE SPECS ARE FOR CAM INSTALLED
AT 106 INTAKE CENTER LINE
INTAKE EXHAUST
DURATION AT .050 224 230
LOBE LIFT .3180 .3200
LOBE SEPARATION 110
THIS CAM SHOULD USE SPRING # 981-16

I have the 268. I posted the 262 up there by mistake.

Thanks,

Scott

 

That's better... a 268 ought to run like a bat out of hell in that, if it's a 350. That's about the least cam I would suggest with those heads, otherwise you should sell them and get some lesser heads with smaller ports. Put something like a Performer RPM and a 650 Holley (4777) on it, and a set of headers, and enjoy.

People all the time say they have "2.02" heads, but that doesn't really mean much by itself. You can put the large valves in the crappiest imaginable heads, and not improve them one iota. That's usually what happens: people have 882s or some such garbage with the big valves stuck off in them, and then can't figure out why it just doesn't run very strong. 292 heads are the real deal though.

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"So many Mustangs, so little time..."
ICON Motorsports

 

There are a lot of guys who have problems adjusting the preload on their lifters so don't feel like the Lone Ranger.

I'm sending you a file on how to do it. There are a lot of different ways, but the key is to make sure that the lifter you are adjusting is on the base circle of the lobe its riding on.

The directions in the Service Manual and some of the Haynes books is unnecessarily complicated and can easily lead to mistakes. Looking at the #6 in order to set the #1 is a prime example.

The procedure I'm sending you insures that the lifter will be on the lobe's base circle when you search for zero.

Let me know how you make out.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

[This message has been edited by JakeJr (edited February 20, 2001).]

 

you HAVE to use hardened pushrods if you run guideplates, or you will be sorry.


there's a couple ways to find proper pushrod length.

the easy way is to use a checker (can get from summit or speedshop). Just make sure you get the checker for your application and stud size.

the other way is to put some kind of marker (like anti-seize) on the roller tip of the rocker and install it on the stud, rod, and valvetip. Turn the engine over slowly and watch the roller contacting the valvetip. Remove the rocker and observe the witness-mark (antiseize) that it leaves on the valvetip.
you want the roller to pass across the center part of the valvetip (not near or falling off the edge). When the witness-mark stays in the center part of the valvetip after two complete rocker lift cycles then you have the right length.
you may swap out different length pushrods during the testing or use an adjustable pushrod.

I use method number one (the checker) first thing to get me in ballpark on length. Use a feeler gauge between the valvetip and the checker to judge length changes. Then I use method number two to make certain that everything is right where I want it.
Once you know the length you need, then get a good quality hardened set of rods.


This does make a lot of difference so take the time to do it right. Don't trust a questionable mechanic to do this for you.

good luck
ODB

 

and also,
I do not set valve lash anything like you described, and especially not with the engine running.

 

You CAN set valve lash with the engine running.....it's done by a lot of DIY engine builders!! The "proper" way to do it however is by tightening the nut on the rocker while spinning the push rod! When you just feel slight tension on the push rod as you turn it, then stop and turn the nut another 3/4 of a turn and you're done!

With the number one piston at TDC, adjust the following valves: #1,2,5, and 7 INTAKE valves and the #1,3,4, and 8 EXHAUST valves!! Then rotate the crank 360 degrees (#6 piston at TDC on compression stroke) and adjust the following valves: #3,4,6, and 8 INTAKE valves and the #2,5,6, and 7 EXHAUST valves!!

About your roller tip rolling off the valve stem....that's definitely not good!! To find the proper length push rod that you need to have, check it with the checking push rods mentioned in a previous post!! You install two of these adjustable push rods....they have a nut on them to adjust the length!! Turn the crank slowly and watch the roller tip! It should first contact the valve stem about 1/4 of the way up on the stem....then it should pass through the center of the valve stem....then finally go to 1/4 from the top of the valve stem! Just make sure the roller first touches the valve stem 1/4 of the way from the bottom of the valve stem and you're ok! If it doesn't start at the point mentioned then adjust the nut on the push rod and try again....keep doing this until you get it right! Once it's right, pull out the push rod and this will tell you the length of push rod you need to get!! I've actually heard a story of a guy who just installed them like you have and he started the car and within 10 minutes, 2 of the roller tips busted because the rollers were rolling right off the valve tip!!

Hope this helps out! Sorry this was a bit long! If you have any ?'s just email me!

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1986 Trans AM
305 TPI
200,000+ miles (speedo/odometer non-funtional! Odometer reads 142,000)
4 Wheel Discs
9 bolt Borg Warner Rear
Completely Stock
Soon to upgrade to a 350 converted from TPI to Carb, Edlebrock Carb, Edlebrock Performer RPM Intake, Headman Shorty Headers, Vortech Heads (possibly ported), comp Xtreme Energy cam, proform HEI distributor kit w/MSD 6-AL Ignition box!!
Current project: Keeping my car running until I get the money for the above mentioned project! :-)

 

I do all of my adjustments with the engine running. I get as close as I can with the help of a feeler guage,then after cam break in I do a final adjustment if nessacery. The problem with spinning a pushrod in your fingers waiting for a "slight" resistance is slight is a subjective term and covers a wide range of adjustment. A good guage doesn't lie. I think the majority of the people on this board do thiers while the engine is running, for whatever it's worth.

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Remember, Behind every successful man is a suprised mother-in-law.
-Gallager
Qsac