Ok here's the problem,i have a intermitten noise coming from valve train,runs great but has a rattle that comes and goes pulled off cover and checked rockers while running backed off then thighten a 1/4 turn after they stopped ticking no change,also the Comp pro mag rockers do not ride straight on the valve stems,1 is bad it put a slight mark in the top of the valve stem,I'm running iron bow tie phase 3 heads,comp 5/16 pushrods,comp guide plates#4808,comp rockers7/16 1.6,ARP rocker studs 7/16,the rockers also have alot of side to side movement.I'm running a Comp flat tappet cam XFI 268,Could this noise be a stuck lifter not spinning?It's not a lifter tick.It does go completely away at times??TIA for any help with this.

 

Update: called Comp cam,was told too elongate holes on guide plates to adjust What do you guy think about that??Could my intermitten rattle be a bad rocker?What kind of noise would a stuck lifter make?Would a lifter stick intermitten? Thanks

 

Are the rocker studs still tight in the heads? I've had studs back out on mine before.....use a crow's foot to check'em.

May be an oil pressure issue. Keep and eye on the pressure gage when ticking noise is present and when it is not. Same goes for the engine temp.

 

Does it cold or at 200*,oil pressure 50lbs,I'm going back out to garage to see if I can move the guide plate around.the rattle has me baffled.

 

Check to see if the rocker's roller tip (assuming it as a roller on the valve contact end) for the "marked up" valve has a flat /low spot.

 

Just took a close look the rockers do not line up with valve stem tips, gets worse when opening a valve, the body of the rocker starts to ride on stem,rockers have a bunch of slop 3/16 side to side

 

Did a search,CFI-EFI posted last year bow tie heads take a different guideplate?Maybe he can chime in,the heads are phase3 iron bowtie.Would i be better off with isky adjustable?or bow tie? TIA

 

You should be able to find "witness" marks if there's a valvetrain geometry problem.

Check the underside of the rocker arm for shiny areas which would indicate contact with the retainer. There may also be witness marks on the retainer itself.

Check the pushrods for shiny areas which would indicate the rod is riding against the guide plate slot.

Check the opening in the head where the rod passes through for indications that there is contact.

Higher ratio rockers can cause this to happen, as they did on the early L98 iron heads that came on my 86 Vette.

There are adjustable guide plates available if that's all you need to get the clearance.

If you look really closely, I'll bet you'll find the cause.

Jake

 

I know for a fact that the Phase 6 Alum Bowties had the valve and rocker spacing moved around in them and required special guide plates as I spent many a night in my fathers shop cutting guide plates in half and elonging the holes back in the late 1980's to fit those heads (ISKY didn't make those nice 2 peice ones back then and you could never get the part number the GMPP book called for from GM but thats a bit off the subject).

However I don't rember the cast iron ones requiring anything special for guide plates and its been a very long while since I have touched a set of them, so I went and looked it up. It gives a part number for the recommended Studs and Guide plates but says nothing about altered valve/rocker spacing which would require something not standard. Also the part number for the guide plates required for the Cast iron Phase 2&3 head (P/N 3973418) is different than the one called for the Alum Phase 6 head (Pushrod guideplates P/N 14011051).

Any way this strait out of my old GMPP book. It states about the Phase 2 and 3 cast iron Bow Tie heads:

The Phase 3 Bow Tie cylinder head (casting P/N 14011034) has the highest performance potential of any cast iron Chevrolet head. It is intended for off-highway applications only. Although the Phase 3 cast iron Bow Tie cylinder head has the same casting number (14011034) as the Phase 1 head it replaced, there are several significant differences between these two heavy-duty cylinder heads. The Phase 3 cast iron Bow Tie head can be identified by its redesigned outer water jacket wall with a machined bar between the exhaust manifold flanges. (Phase 1 castings have a raised parting line between the exhaust manifold flanges.) The area around the tapped water temperature sensor hole is also machined flat on the Phase 2 head. The Phase 3 Bow Tie head has a revised combustion chamber design with a true volume of 64cc's.

The quench areas beneath the spark plugs are filled to increase compression in competition engines. The intake valve seats are machined for 2.02" diameter valves; the induction hardened exhaust valve seats are finished for 1.60" diameter valves. The intake and exhaust ports are identical in Phase 1 and Phase 2 cast iron Bow Tie heads. The 184cc intake runners will satisfy the airflow requirements of most competition engines while enhancing throttle response and mid-range torque. In unmodified form, the Phase 2 Bow Tie head will flow more air than any production cast iron small-block head. Extra-thick wall sections allow the ports to be enlarged to increase their flow capacity. The manifold heat riser passages are deleted in Phase 2 Bow Tie heads to produce a cool, dense intake charge.
Technical Notes: The valve spring pockets in cast iron Bow Tie heads are machined for up to 1.50" diameter competition valve springs. The rocker stud bosses are tapped for screw-in studs; studs and pushrod guide-plates are not included. Use GM Performance Parts studs P/N 3973416 (3/8") or P/N 3921912 (7/16") and hardened pushrod guide-plates P/N 3973418. Use 5/8" hex-head spark plugs with tapered seats and 3/8" reach. A bare casting weighs approximately 42 pounds. Valve seats are heat-treated. The Phase 3 Bow Tie Head Casting, PN 12480034, replaced the Phase 2 casting in 2000. This casting was only changed to add machining stock for the machined rocker cover rail. Universal spark plug seats are also provided in this head. (See chart for specifications.) (Recommended service parts: 3973416 - 3/8" rocker stud; 3921912 - 7/16" rocker stud; 39373418 - push rod guideplate.)
Technical Notes: This cylinder head does not include rocker studs or guide plates.

In recent years I have used a few sets of the ISKY adjustable guide plates and IMO they are great... Much better than cutting guide plates apart with a die grinder and TIGing them back together again. If your rocker alignment probles are that bad they usually will enable you to fix it.

Will

 

thanks for the info,Question do you have to weld the isky guide plates together?

 

No you do not have to do anything other than TQ the ISKY guide plates down. They have a "tang" in the middle of one half and a "notch" in the other half to interlock the 2 halves.
Will