first i have never messed with small block fords, so i'm not sure what these are or called. my grandson has a 351w ford engine. he broke a intake bolt so we pulled the head as i don't have a welding machine setup at the house. i noticed the exhaust valves have a sleeve that sets around the top of the valve stem but does not cover it. on this head 3 of the are removeable but one looks like the valve tip was hit and has a little spot holding it. what are these and is there anything i need to watch for when putting the valve train back together? i take it they are only used on the exhaust valves.
Pictures??? Valve lash caps are typically only used on solid lifter engines or those equipped with roller tipped rockers and running big cams. I have only ever dealt with 351W's with hydraulic lifter cams and have never seen valve lash caps on a Windsor. Is it part of a damaged seal or guide that may have been pushed up the valve stem?
When Ford went to the rail type rocker arms in 1966, they realized quickly that there was excessive side loading with wear on the valve stems. The caps were introduced shortly after. I don't remember seeing them on 351s. @Crazy Steve to the white phone....
let me make a correction, these are a cap that covers the tip of the valve stem. the engine is a hyd flat tappet. ok pics tell more to the story, and it looks like one has had the top broke off to me. another question. do the rocker bosses have to be cut down to make the valve train adjustable?
These are hardened steel caps to protect the valve stem from wear. This was used with rail rockers. Do not confuse the late 70s-00s SBF pedestal rockers with ‘60s rail rockers. It’s confusing since the later pedestal rocker system looks like a rail. The rail rocker debuted around 1966. Pre-66 the pushrods were located by tight slots (think of it like a cast in guide plate) in the head with a conventional rocker. This required a hardened pushrod. ‘66-latter 70s maybe into the 80s SBF used the Rail Rocker arm with heads that have a larger round hole for the pushrod. The rocker with it’s “rails” are the only thing that locate the pushrod. The pushrods do not have to be hardened. It was found that the slack of the free floating pushrod can can pound the valve stem, causing wear, especially on the exhaust valve. When the valve stem wears it can mushroom and pounds the retainers loose, dropping a valve. That little cap is supposed to prevent valve stem wear and engine destruction. There’s lots of info about rail rockers..... This is one reason why Ford performance cams of the period tend to be lower lift.
You really need to research this...... Make sure it’s all correct and in spec. Through the years parts get mixed up. The rail rocker system has to be in spec otherwise valves drop..... Parts mixed and matched can be disastrous. Pre rail and rail rockers are technically “non adjustable” but they are adjustable to set lash. It’s a Ford thing. Basically earlier SBFs can be adjusted like a SBC for initial adjustment. With rail rockers you have to make sure all that stuff is in spec or a dropped valve is very likely.
^^^^ What he said. The rail rockers went away in 1978 when Ford went to the pedestal type stamped steel rockers and one head for 302s and 351s. To go to an adjustable valve train, the pressed in studs have to be removed, the bosses machined down, and guide plates used. Easier to buy an aftermarket head. This 351 I put together several years ago.
The other part of the picture is you really have to be careful when swapping different Factory Ford heads. While all SBF heads will fit, the combustion chamber size differed depending on displacement and year. You could wind up with either very poor CR to very high CR. Depending on the year of your heads, the factory heads had very restrictive exhaust ports especially if they had the air injection lumps cast into the exhaust port. I suggest a copy of Tom Monroe's "how to rebuild small block Fords" book. Why would you want an adjustable valve train unless building a race motor? The set-up you have allows for adjusting the correct lifter pre-load.
1964.....289 Conventional Rocker head guided pushrod Notice how high the spring comes up on the valve stem. The retainer is very close to the top of the stem. Notice the very tight pushrod slot. The head locates the pushrod. Notice the simple conventional rocker.....
I was told those were used when valve stem length came up short after a valve job. I've never personally seen them on a factory motor. If the valve stems were short, the rail rockers could contact the valve spring retainers, allowing the locks to come loose and dropping a valve. I have seen that failure. The caps were a cheap fix to avoid buying new longer valves.
1968 302 with rail rockers 302 4V marked head..... Notice the large round hole for the pushrod. Compare that to the tight slot on the ‘64 head. I was expecting to find the hardened caps on the valve stems. Nope.... Notice how tall the valve stem is above the retainer and spring. Compare that with the ‘64. To use rail rockers, there must be that amount of valve above the retainer. If a short valve is used....my concern is the cap could pop the retainer loose. Wrong parts? Wrong fix? You need to make sure. This may not be applicable if it’s an 80s head with the pedestal rockers.
ok the engine came out of a 79 merc, it was rebuilt before i got ahold of it. i pulled the engine and put it in my father inlaw's truck and was run for about a year and ran very nice. the rockers just have a bolt go through and the ball bottoms out on the pedestal with no adjustment. the reason for asking about making it adjustable is grandson wants to add a cam at a later date. i'm going to replace the one bad cap and check the rocker out cause something isn't right there the way it is worn and the top broke off, and didn't have no valve noise either.
Ford specifies a minimum stem length of 5/16" (.3125") above the top of the valve retainer/locks for rail rockers on 302s and 351s. That's for a retainer that sits flush to the valve locks as shown in post 11. The OPs retainers are recessed (mixed parts...) so you may need more length or different retainers. Rebuilders who don't know that will dress the stem end of the valve to below that number, or cheat with the lash caps. The correct fix is new valves...
The nut that holds the rocker down is an "interference" nut that unless really worn will not loosen. Replace the hardened caps, start tightening the nut while rotating the pushrod until resistance is felt turning the pushrod. then tighten the nut 1/2 turn to load the lifter. Changing to a higher lift cam will not change this procedure but may cause the rail on the rocker to contact the valve retainer as the geometry changes. Another surprise is rail rockers on a 79 motor. Ford phased them out in 1978. Maybe earlier heads?
Yeah, more cam needs more clearance. Sounds like somebody did some mixing of parts without being aware of the differences. FWIW, I've ran rail rockers with a big cam and high RPM (6500+) with no issues... as long as they're set up right.
They have several uses. I just used a set on my exhaust valves (only) to alter the stem height in order to get the rocker contact (sweep) pattern centered on the valve stem.
I'm going to have him lay all the parts on the table, I know there is at least one bad rocker. I'll check the push rods and grab my calipers to check the stem heights. These have no stud or nut, they have a bolt then it bottoms out on the cast pedestal.
Ford used a higher rocker arm ratio than Chevy did, so, when designing to a given valve train hertz stress level, the Ford engines with the higher rocker arm ratio would have a little lower cam lift. Everyone operates under the same physics rules and constraints.
Now that I have been into it closely..... I should have paid closer attention to your photos. You have Pedestal Rockers.....IE late rockers Rail rockers are only 1966-77ish. Conventional Rockers 1962-1965 Anyway all flavors of SBF rockers have been posted. Those caps may have used a lot on post 76 valve stems. I’m more familiar with the 60s engines. I do know they were used on worn stems for earlier models. The main thing is..... Make sure there’s enough clearance for the retainer.
Now that we understand that you have the later non-adjustable rocker system, the rebuilder probably used the valve stem caps to get the lifter pre-load into range as Steve commented. At this point, the best bet is to replace the worn/broken parts like for like and re***emble. Changing to a higher lift cam at a later date with an adjustable valvetrain will require machine work and parts such as I pictured.
that's what i needed my heads, the valve caps. i'm putting 1.7 ford 302 shaft roller rockers on my buick 350. don't asked why. thanks for that info.
Ok rather then start another thread I'll keep it here. In the bottom of the pivot dish on the rockers there is a groove you can grab with you nail, the pivot also has a ridge on the outer edges. To me they look worn out. All of the pieces are like this. Is this a ford thing or do we need to get new valve train?
That is the standard oil p***age groove. More measurements would have to be given to determine if it is actually worn out or not.
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