GUIDE PLATES

[bvillestang]

Been searchin' for if I need guide plates and still ain't sure. I am putting together a 331 stroker. I have a new set of gt-40x aluminum heads. I am putting in the XE274 hyd flat tappet CompCam and the Magnum roller rockers that came with the cam kit. I checked for pushrod length and ordered them Friday. Does anybody know if I will need the guide plates with the gt-40x alum heads ?

thanks for your help, Duane

 

[mrmustangman357]

if you have roller rockers you will need guide plates

 

[bvillestang]

Thanks. Straight to the point, thats what I needed. I was getting dizzy reading all the other posts.

 

[D.Hearne]

GT-40X heads are set up for pedestal rockers. No guide plates needed. To convert to screw in studs and guide plates, the rocker bosses will need to be cut down .300" and the pedestal bolt holes enlarged to 7/16NC

 

[bvillestang]

So, are you tellin' me the Comp Cams 1442-16 roller rockers that I have are no good, and I need to buy pedestal mount rockers ?

 

[D.Hearne]

So, are you tellin' me the Comp Cams 1442-16 roller rockers that I have are no good, and I need to buy pedestal mount rockers ?

Unless Ford or someone else converted those heads to stud mount rockers, yea, you've got the wrong set.

 

[bvillestang]

Thanks for your expertise. I had those rockers bolted on and about ready to take the motor to the dyno. I am now looking for a set of pedestal bolt on rockers so I can set this up correctly.

 

[D.Hearne]

You had em bolted on? Then someone's already coverted them to stud mount. Pedestal rockers are bolted down using a 5/16" bolt. Stud mount rockers have the stud screwed into the heads first (semi-permanently) with the rockers fitting onto the stud. The holes in the heads for the studs are 7/16NC" with either a 3/8" or 7/16" top portion the rocker fits over. Stud mount rockers need guide plates(this is the reason the rocker bosses need to be machined down if the heads weren't set up for em originally), pedestal rockers are guided by the pedestal being locked into position with guide channels under em.

 

[bvillestang]

I have a flat boss machined and the tapped holes in my heads are 5/16. I ordered the studs that I used for the original roller rockers with that 5/16 bottom thread and put the rockers on like normal. I am assuming now that I will need to buy the channels along with the pedestal rockers and bolts.

 

[dcstang67]

Seeing how you already have the conversion studs all you would need is guide plates to hold them in place. You shouldnt need to buy anything else.

 

[bvillestang]

I have them installed right now with the guide plates. They have not been milled down per the above information tho. Would this be a problem ? I checked for push rod length and had to get 7.050 ones and my contact path is from the middle outward on the tip. I could not get it to come in any more.

 

[D.Hearne]

I have a flat boss machined and the tapped holes in my heads are 5/16. I ordered the studs that I used for the original roller rockers with that 5/16 bottom thread and put the rockers on like normal. I am assuming now that I will need to buy the channels along with the pedestal rockers and bolts.

The original Cobra roller rockers didn't use studs. They were pedestal mount. This uses a 5/16" hold down bolt,& a machined pedestal that fits under the rocker. The pedestal fits into a stamped steel channel that fits under each pair (intake and exhaust) of rocker pedestals. If you're not using this setup, I guess you're using std roller stud mount rockers that work with screw in studs (7/16 bottom and either 3/8 or 7/16 top thread) But instead have 5/16 bottoms. To use this setup, you'll still need to machine the pedestal bosses down to make clearance for the guide plates normally used with studs. The pedestal channels do not work with screw in studs.

 

[mrmustangman357]

pics would help

 

[dcstang67]

to give you a simple and to the point answer you need to measure the thickness of the guide plates and then have that much machined off of the rocker bosses on the heads. You may need shorter pushrods to get the valve tip in the middle of the rocker roller.

 

[D.Hearne]

pics would help

x2