Rachet style Chain tensioners

This is a long-standing Hyland modification that has been used for at least 20 some odd years. Properly sized (i.e., 0.200"), they will exactly pick up the slack in a brand-new chain with the engine off. Grinding down the ratchet arm teeth provides a similar but different function.

Without grinding down the ratchet arm teeth, the ratchet will stay extended to whatever length the chain stretched to at high engine speed. So while the plunger on the tensioner will retract, the ratchet foot will not because of the ratchet teeth. The Idea of grinding down the teeth came about as a way of allowing the ratchet to compress back into the tensioner casting and not hold the chain under tension with the engine off.

The problem with this is that the hydraulic piston will compress to the amount the internal spring allows. After your engine has some miles on it, this can represent enough slack to make noise and create potential problems in the engine before the oil pressure rises to the point it extends the piston and pushes the tensioning arm against the chain. You are probably OK the majority of the time. It is the one or two times you are not OK that are problematic.

The spacer never lets the piston retract to the bottom of its well and, at 0.200", maintains a very light tension on the chain with the engine shut off. This mod will not break timing chains. What breaks timing chains is two-step launches that load and unload the cam drive chains as the engine tries to maintain a predetermined launch rpm. The on-again, off-again whipping of the drive chains eventually will break a link somewhere. Two steps with or without the tensioner mod are tough on timing chains. The tensioner mod is designed to maintain a minimum tension on the primary drive chains when the engine is shut down, so the next start is clean and silent. It absolutely will not hurt a primary chain — look at the mechanism and think about how it works.

Cutting teeth off the ratcheting arm will prevent the chains from being held in a stretched and tensioned condition after racing. Removing the ratcheting teeth will not prevent the piston from settling down at spring height or possibly lower after shutdown. The 0.200" spacers will.

When you assemble the tensioner and install it for the first time, you will discover it is best to install a single bolt, compress the plunger in its well, and rotate the tensioner into position. Once in position, put the second bolt in and begin to screw it in while holding the plunger compressed and the tensioner in position. While one person can do this after they develop a little skill for the task, it is much easier with a third hand. You will know what I am speaking about the first time you do an install.

The 0.200" spacers will give you about but a little bit less than what Matt has for free play in his setup. The decision to run the ratcheting arm is a personal choice. If something is not necessary, I tend not to use it. If you choose to, make sure you get enough teeth ground down so it is not accidentally standing proud when you don't want it to.

There is another follow on failure attributable to the sustained chain loading when the engine is shut down.

The sustained chain loading stresses all the links and anchoring pins in the silent driver chain, which is undesirable. It also does something else that is damaging in the extreme. When the engine shuts down, and the primary drive chain tension is not released because of a locked ratcheting plunger, it loads the front cam journal on both sides of the engine pinching off the oil film. The front journal on the driverside is at the end of the lubrication food chain and gets oiled last.

When the engine shuts down, and the primary drive chain tugs downward on the cam nose because the tension has not been released, in the now pinched off oil film between the cam and the head, the #1 cam journal experiences metal-to-metal contact. The repeated metal-to-metal contact continues at each new start and roughs up the cam and the journal bearing in the cam saddle. The cam eventually seizes in the head, and the broken chain, bent valves, and broken guides damage saga plays out.

If you check, many, if not most, broken chain histories will almost always have a seized cam journal in the litany of damaged parts — for the reasons we are talking about. There are three things you can do to mitigate this;

• The Tensioner Mod we have been talking about,
• Use of an Oil Accumulator,
• Use of an oil additive — I highly recommend ProLong

The Oil Accumulator is not widely used or recognized. Canton offers them under the trade name Accusump™ and Moroso as an Oil Accumulator. They can be installed to perform two different functions. The first function is pre-oiling the engine before startup. Both firms offer a kit to allow the oil accumulator to flush into the engine prior to startup. This will protect those tender cam journals that get oiled last. Their second function is to protect from uncovering the oil pickup and drawing air into the lubrication system.

After the accumulator is set up, for example, to discharge below the engine's operating oil pressure, say 45/50 psi, when the oil sloshes to the back of the pan, for example, exposing the pickup, the oil accumulator will begin to discharge its supply of oil into the oil system making up for the temporary reduction in oil volume or quality to the bearing surfaces.

Oil accumulators come in various sizes up to a 3-quart capacity. In general, they only hold about 1/2 of that capacity. Their design uses an o-ring sealed piston with air behind it at atmospheric pressure. As the engine runs, the oil pump pumps oil into the engine, and the accumulator pushes the piston up against the air-filled chamber, compressing it to a pressure equivalent to the engine's oil pressure. Fully compressed, about half or a bit more of the cylinder is oil and the other half is compressed air, so your three-quart accumulator is actually 1.5 quarts or a bit more. Buy the big unit. These things are a poor man's dry-sump!

ProLong and other oil additives are an emotionally charged topic. I was historically an anti-additive guy. I got talked into using ProLong at an NHRA event decades ago — it saved an engine for me, at that event. I have been a ProLong bigot ever since. If you elect to use it buy the gallon bottles off Amazon for $65. They are a better deal than the 12 oz auto parts store bottles for $20.

Dave R said:

So, I got my tensioners off, spacers made, and then started to put them together. Uhoh! I have different tensioners than what I've seen all over. Consensus was to get a new ford set so I did and the spacers work. I'm leaving the ratchet stop out. I know they say for racing only but if this falls apart, I'm not thinking this one piece is going to be want causes a catastrophic issue. That'll happen before. So, pics of my tensioners (that I find no part number or likeness anywhere on the net) and the new ones with spacers installed. I really think they could be slightly less than 0.2" but that's me. I'll go with what's recommended. Thinking though, Wouldn't it be better if the check ball was removed insode the tensioner as well so it could surely collapse onto the spacer stop to ensure it doesn't stay pumped or do they bleed down anyways?

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Dave,

The reason for the spacer is to eliminate the need for the ratchet. A 0.200" long spacer will set the idle tension for the chains. When the engine speed increases and the chains begin to stretch, the engine oil system will project the plunger outward taking up the new found chain slack. When you let off the throttle and the engine speed decreases, the previous chain stretch disappears. If you have the ratchets in place they do not allow the chain to relax and will maintain chain tension as if the engine were at high rpm.

The net, net bottom line is the chains, and other expensive parts are unnecessarily abused by the presence of the tensioner ratchet in a performance focussed version of the engine. Even worse, when you shut the engine off while using a chain tensioner ratchet, the chain tensioner ratchets continue to tension the drive chain and pinch off the oil film between the cam's #1 journal on each side and the saddle in the head. That means at the next cold start, you have a metal-to-metal abrasion occurring until oil gets to the cam journal.

The cam journals are at the end of the engine's oiling system food chain and get oiled last. Because they get oiled last and because they are experiencing a metal-to-metal style of abrading contact, the bearing surfaces begin to accumulate surface damage. Eventually, the surface damage is sufficient to seize a cam, ruin a head and break a chain. At that point you will begin to destroy a significant number of other costly parts also.

The oil check valves in each tensioner are different and should not be intermixed or left out. They are a key part of a successful operating tensioner.