Guide plate issues with AFR heads.
Thread Starter
Team Owner
Joined: Nov 1999
Posts: 26,679
Likes: 17
From: This vette goes to 11 Milford MA
St. Jude Donor '03-'05
Guide plate issues with ARF heads.
Doh! Title should say AFR.:) I went to the machine shop to check out my new stroker and there is a weird clearance issue with the guideplates. They are too narrow and kick the rockers (Comp Pro Magnum 1.52 rollers) out in a "V", leaving the valve offset on the rocker tip. They notched the plates and pried them open a little to try to get them closer but they are still off. They got a set of PBM guideplates and they are spaced differently and look like they will center the rockers perfectly. Any ideas on why the AFR plates are off?
[Modified by Fastguy, 12:30 PM 3/5/2002]
[Modified by Fastguy, 12:30 PM 3/5/2002]
Thread Starter
Team Owner
Joined: Nov 1999
Posts: 26,679
Likes: 17
From: This vette goes to 11 Milford MA
St. Jude Donor '03-'05
Re: Guide plate issues with ARF heads. (dtorc4)
Even after trying to align them,they are off. Its the spacing in the plates themselves.
Thread Starter
Team Owner
Joined: Nov 1999
Posts: 26,679
Likes: 17
From: This vette goes to 11 Milford MA
St. Jude Donor '03-'05
Re: Guide plate issues with ARF heads. (dtorc4)
I'll have to have SloRvette call them since he purchased them new and I bought them from him unused.
Heel & Toe
Joined: Dec 2001
Posts: 17
Likes: 0
From: Casselberry FL
Re: Guide plate issues with ARF heads. (BlackRocket)
Just checked my new AFR 190's going on the 383 stroker going back in the car this weekend. I'm also using the Comp 1:52 roller rockers. Some of the rockers have a slight angle on the valve stem when valve is off the seat, but the roller is still in contact with the valve stem, i.e., the rocker side plates aren't hitting the valve stem. Compared the AFR guideplates with the OEM units used with the factory self-aligning rockers-the OEM slots are slightly wider apart. My Comp 1:52s are not self-aligning, so the guideplates are hardened. GM used the guideplates in the stock engines simply to hold the pushrods in place during engine assembly-they aren't hardened since the rockers are self-aligning. Don't know if this makes a difference in the slot spacing or not. I did align the guide plates when I installed the heads to keep the pushrods from rubbing on the aluminum portions of the head castings. Also, remember on non-roller engines, the stock rockers pivot from side-to-side slightly on the valve stem with no adverse effect. I do plan on calling AFR in the morning just to be sure, though. Will keep you posted.
Thread Starter
Team Owner
Joined: Nov 1999
Posts: 26,679
Likes: 17
From: This vette goes to 11 Milford MA
St. Jude Donor '03-'05
Re: Guide plate issues with ARF heads. (I-FLY-AF)
Its odd, I took the PMB guideplates and held them up to the AFR's and they were about .060" different. The PMB's are spaced correctly while the ones that came on the heads, and are even stamped AFR, are messed up. My engine builder told me that sometimes the guideplates need to be hit down the middle with a cut-off wheel, spread, and then hit with a quick TIG weld to get the proper spacing. Even after doing this, they were still off. The valve tip was on the rocker but on the very edge of the roller, not centered. I think the new plates will solve the problem.
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Heel & Toe
Joined: Dec 2001
Posts: 17
Likes: 0
From: Casselberry FL
Re: Guide plate issues with ARF heads. (Fastguy)
I spoke with Mark at AFR today. They are aware of the difference in the guideplates. Apparently the spacing between the intake/exhaust valves is a little different than the stock L98 heads. There should be a slight "butterfly effect to the rocker arms. Just make sure the guideplates are centered between the intake and exhaust valves, and that the roller contacts the valve stem. I noticed my rollers have some side to side movement across the top of the valve stem, and will center up. If a valve is under lift from the cam, you may not be able to slide the rocker around very much. I don't anticipate problems with the motor when I light it up this weekend, but I'll let you know!
Thread Starter
Team Owner
Joined: Nov 1999
Posts: 26,679
Likes: 17
From: This vette goes to 11 Milford MA
St. Jude Donor '03-'05
Re: Guide plate issues with ARF heads. (ralph)
So are you guys saying I should re-install the AFR plates and leave one rocker crooked, or crow-feet both in a V, or just leave the PMB plates there?
Heel & Toe
Joined: Dec 2001
Posts: 17
Likes: 0
From: Casselberry FL
Re: Guide plate issues with ARF heads. (Fastguy)
I plan to stick with AFR guideplates-any trouble and I've got a fallback position that I discussed the situation with their tech rep. I was comfortable the guy knew what he was talking about, though. Look at the number of guys on this forum that are using AFR heads!
Le Mans Master
Joined: Oct 1999
Posts: 6,366
Likes: 34
Re: Guide plate issues with ARF heads. (I-FLY-AF)
I have the AFR 190 heads, I used thier guide plates, no problems.
Yes the rockers do look like a "V" now that I know what you mean by that.
To run the AFR guide plates or not???
this is from AFR web page:
"GUIDE PLATES:
USE ONLY THE GUIDE PLATES SUPPLIED BY AFR! Push Rod Guideplates are supplied with each set of AFR Aluminum Heads and installed correctly as shipped. Studs should be torqued to 60ft./lbs. Silicone sealer is recommended on aplications where the stud hole intersects the intake port. The 190, 195, 210 & 220 Heads require the long slot of the Guide Plate to straddle the exhaust push rod. The 227 Head requires two differnet guide plates, one for cylinders 2,3,6,& 7and another for cylinders 1,4,5 & 8. Put AFR guide plates onto corresponding cylinders. Guide Plates are stamped with cylinder #'s. For proper alignment of the rocker arms over the center of the valve, simply loosen the rocker studs and shift the guide plate back and forth until the proper alignment is achieved, then torque to 60ft./lbs."
Why only use thier guide plate? I dont know....
Yes the rockers do look like a "V" now that I know what you mean by that.
To run the AFR guide plates or not???
this is from AFR web page:
"GUIDE PLATES:
USE ONLY THE GUIDE PLATES SUPPLIED BY AFR! Push Rod Guideplates are supplied with each set of AFR Aluminum Heads and installed correctly as shipped. Studs should be torqued to 60ft./lbs. Silicone sealer is recommended on aplications where the stud hole intersects the intake port. The 190, 195, 210 & 220 Heads require the long slot of the Guide Plate to straddle the exhaust push rod. The 227 Head requires two differnet guide plates, one for cylinders 2,3,6,& 7and another for cylinders 1,4,5 & 8. Put AFR guide plates onto corresponding cylinders. Guide Plates are stamped with cylinder #'s. For proper alignment of the rocker arms over the center of the valve, simply loosen the rocker studs and shift the guide plate back and forth until the proper alignment is achieved, then torque to 60ft./lbs."
Why only use thier guide plate? I dont know....
Drifting
Joined: Oct 1999
Posts: 1,722
Likes: 0
From: Gloucester Va
Re: Guide plate issues with ARF heads. (bill mcdonald)
I've noticed the "V" thing and off center deal myself. If you lossen the studs and move the guide plate you can get them just about perfect. It takes a good amount of time though. I found I even had to move the guide plate up some on one side and then over. Some are still off center but not much. The biggest pain of it all is you have to adjust the rocker to make sure its OK, which means you have to turn the crank for each firing. So that the set of valves are closed.
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: Guide plate issues with ARF heads. (Fastguy)
Mine took a bit of playing around with too. I changed to 7/16 studs, so I had to play a bit anyways. They will be slightly off center and will look like a v as described. I just split the difference and made sure the pushrods were not touching the guides when the RR were installed. I will try to post a pic:
[Modified by ski_dwn_it, 7:30 PM 3/7/2002]
[Modified by ski_dwn_it, 7:30 PM 3/7/2002]
