CHI 3v 225 Heads Guide Plates

I think my CHI 3V 225 cylinder heads have Ford Motorsports guide plates and there are no clearance issues.

What rocker arms are you using? 

Crower

I purchased an engine with CHI 2v heads, bad move, terrible mess. Different heads but check everything, sounds like your engine builder is checking clearances. With these heads the rockers were miss-aligned in line with the valves, they would need the Manley guide plates either replaced or cut apart and rewelded. Some pushrods also had wear marks on them because they were rubbing in places on the pushrod slots in the heads. The pushrods also were too short with the wear pad on the valve too close to the rocker, the bronze valve guides were badly worn because of this. Check everything.

Good info thanks!  I also had trouble getting the rockers aligned on the valves. 

I am trying email correspondence with CHI and see if they reply with a complete valve train recommendation.

As you can see, I had a very similar experience with my 4V CHI heads. 

Comp Cams 4803 guide plates, Comp Cams 1630 1.7 ratio rockers on ARP studs. 

 I found this misalignment upon inspection after my engine builder had finished. Needless to say I was concerned, especially as I had notified him previous to the assembly of this exact issue you are experiencing, as I’ve seen previous owners who have been down this road before. 

 I elected to go to my second choice builder, who in hindsight should’ve been my first choice, and had him completely tear down all of the engine checking everything.  I very clearly clued him in on the guide plate issue.  Before he installed valve covers I inspected the valve train and found no alignment problems. When I asked if he had changed guide plates or had cut them and welded,  he said all he did was invest the necessary time to get them properly aligned. He said the studs and the guide plate holes were not a press fit and the “wiggle room” available was enough to find the sweet spot for proper alignment. 

 The engine has since spent time on a engine dyno and delivered a very smooth  454 FWHP @5700.

 The moral to my story is in any similar guide plate issue,  the first step should probably be checking to see if there is wiggle room on your assembly to allow proper alignment.

Larry 

In my case all guide plates were cut and re-welded and mostly the end cylinders, had to have the pushrod slots in the heads "modified" so the pushrods did not rub. The camshaft did not have large lift.

Two things come to mind. Pushrod length will influence how close the pushrod comes to the back of the guide plate slot near the bolt. Not sure which way it goes but to long a short may be the issue. Sideways alignment of the rocker is not uncommon. Sometimes one of the holes that the stud goes through is bigger so you have wriggle room. Also instead of cutting and welding I have cut the middle of the guide plate 3/4 the way through and mounted them in a vise and bent them slightly like a boomerang (I'm from downunder lol). You don't need much to change the alignment. However depending on how hard they are, they can break. Then you have to weld.

There are adjustable, i.e., two piece guide plates.

I have them for my AFR Windsor heads. They actually aren't easy to use since you need to check the alignment at full lift. The one piece are much easier to use and align properly.

You do need to get this right since you will bend the pushrods and/or damage the rocker arms.

Because of these issues you are better off using heads that are meant to use the original Ford valve train components.

I would go with what CHI says to do and if that doesn't work then the most likely scenario is the heads are not machined accurately and see if they will honor replacing them under warranty? This may not be able to be something that you can correct if the geometry is off that much from the manufacturer.

The location of the studs on these heads has also be controversial as far as I am concerned. It's the angle of the boring and threading of the base that can be an issue?

Using an incorrect length pushrod is a bad mistake. It causes unnecessary wear on the valve stem / guide as it does not push down directly on the valve tip. I went with Scott Cook heads which are cast with the stock looking outside appearance. No problems with pushrods rubbing on the slots even with a high lift cam. I also used Yella Terra rocker arms which do not use or need pushrod guide plates.

Finally heard back from Mark at CHI via email.  I asked him what combo of rocker arm, guide plate and lifter he recommends but he didn't answer.  This is what he replied with.

#Yes you could grind clearance in existing guide plates and stay with 5/16” if you like. We always use at least 3/8” pushrods to eliminate flexing.

#I’m sure Manley have a 5/16” version of the same guide plates we use.

#Don’t use BBC rockers, they are longer on the nose and won’t sit on the valves right.

I am going to buy one Manley guide plate and take it the shop and see if it helps the clearance and pushrod issue.  Probably going to have to hope things can move around to work or just cut and weld the plates based on what everyone has reported.

It all worked out.  Rockers lined up with valves okay with the Manley plates.  Onto the rest of the build

have you also checked your link bars for free play at full lift?

very common oversight that leads to disaster, i'd check them every single valve not just one set / one lobe up

How do you do that?

wiggle 'em?

basically you just need to be sure they're not in danger of binding at max extension as installed

Ok I will check that 😀

if the link bars don't gave at least some free play at full extension they're at risk of damaging themselves and breaking the pivot pin and the whole rest of hell loose. probably the #1 reason for roller cam / lifter failures, cam lift exceeds link bar travel

Party On!

Awesome.  I hadn’t heard of this.  Hope the builder checked. Fortunately I haven’t put the intake on yet.  Thanks!

Checked all the bars with a wiggle at full lift on each lifter.   They were all free.  Thanks for the tip!