Crossflow Tappet Adjustment

[BrianHorn]

A subject which I'm sure has been covered often on these pages but,.........I've had the car in the workshop last week to have the noisy tappets adjusted and............well, it's just plain pants if I'm honest

 

I took it the people who rebuilt the engine a couple of years ago and they did the work however when I collected it they were still rattling away, worse if anything than before 😔

 

He says, "that's normal. if I reduced the clearance any more the valves would burn out".

I'm confused because although it never ran completely quiet, I would have thought it should sound a bit quieter!

 

So, how quiet or noisy should they be?

 

Brian

 

Common sense is in spite of, not the result of, education.

 

--Victor Hugo

 

[Sheds Moderator]

Not very noisy. I think you do these hot (see the manual/consult cam manufacturer). You can get some wear on the rockers (dishing) that means you can't get an accurate gap with a feeler. One test is to have it idling with the lid off (assuming it doesn't throw oil everywhere) and push down on each rocker (carefully!) with a finger. If it's out then the rattle will decrease.

[DaveMorris]

Brian,

whether to set tappets hot or cold depends upon which cam you have.

If you post the cam details here then I'm sure people can advise setting for you.

 

ISTR that Peter T posted in a recent thread about how to set up tappets when the rockers had become dished,

 

Dave

[BrianHorn]

Thanks guys.

Dave: As far as I know the cam is a standard 1700 super sprint cam. 234? Are the clearances different from a standard 1600 Ford Kent motor?

boss: An interesting suggestion but I would think that oil IS going to get thrown everywhere! I was led to believe that the clearances should be set cold at .50mm inlet & .55mm exhaust.

[Big Brother]

.022 intake / .024 exhaust (set cold) are the recommended settings for a 1700 Supersprint engine (234 cam)

 

Steve

 

 

SE7EN-UP!

-----_{Ever noticed that the word enviromentalist contains the word mentalist!}-----

 

[Bricol]

As those are in good old English measurement, they equate, in this new fangled metric stuff, to

 

0.56mm Inlet and 0.61 exhaust according to my Kent Cams leaflet .

 

So not so far off at 0.5mm . .

 

Bri

 

[millsn]

i think you can set them at almost any number and convince yourself that they're ok if you don't know what you're doing. My Ford garage have proven this theory a number of times. As does many a fiesta that drives past me.

[JampJ]

As already mentioned, the rockers are prone to wear, which is not usually taken into cosideration by a lot of mechanics. To measure the gap correctly, a thin gauge is required that fits in the worn groove in the rocker face, ie not bridging the gap as ordinary wide gauges do. Or alternatively, remove the rockers, and carefully flat the faces down using a carborundum stone. I say carefully, because if they are badly worn, taking to much off will remove the hardened surface.

Cheers J&J

 

JFDI

(Just F*****g Do It)

[Neal Worth]

I'm fairly sure that Gunson do a tappet adjuster, Clikadjust I think it's called, that sets the distance taking into account any wear in the rocker face. Not 100% positive though , so don't quote me on it.

Maybe someone else has used one and can shed some light?

[JampJ]

The CLICKADJUST is still available, works by screwing the rocker down to close the gap, then after refering to the instructions, the tool is unscrewed so many clicks that correspond to measurement required. I still prefer thin gauges!

Cheers J&J

 

JFDI

(Just F*****g Do It)

[BrianHorn]

Thanks guys. Is it only the rocker faces which wear or do the pushrod ends also wear?

 

I guess the camshaft is the next point of wear but it would be the rocker faces first?

 

It's quite quiet at tickover but as soon as the revs rise that's when it's more noticeable.

 

Edited by - BrianHorn on 30 May 2007 09:23:47

[Sheds Moderator]

Pushrod ends *do* wear which is why tappets need readjusting. However they don't dish, you just get a round end.

 

The ClickAdjust tool is a good one, I remember them.

 

Clearances and whether hot/cold *do* vary with the cam, it may not be the same as for the std cam.

 

Fiestas are indeed a bastard to do, I remember well. Finally Brian, you'd be surprised how little oil flies around in most (pushrod!) engines with the cover off. In particular the Triumph engine is fine, never tried it with a XF.

[Neal Worth]

Not sure if the pushrods ever really wear that much as they are in contact with the valve train in a different way to the rockers. Rockers move over the top of the valve stem and so wear a groove in their working face.

As you say the cam can wear but, as long as you've got lubrication to it and you don't adjust anything so that the oil film could break down between it and the followers it shouldn't be a problem. I'm not saying it'll never wear, as they can, but you'd have noise coming from the cam area of the block as well as up top if it was worn.

Hope this helps.

[susser]

I've got a click adjusting wossname for Fords, but that has the 1/2 " AF socket and the slotted screwdriver adjuster. The principle of The X Flows that I've messed with recently have all had the hollow adjuster with the self locking feature. (Presumably to reduce the reciprocating mass.) This includes the Zetec E ? (X Flow).

A click adjuste (er) can't work with this configuration. The principle of the click adjuster, however, can;

The idea is that you loosen the locking nut with the handle, torque down the adjuster until it contacts the valve stem and the central screwdriver clicks (as a torque limiter.) Next, undo the central screwdriver a prescribed number of clicks (in other words, a specified angular rotation), and lock up the locknut with the handle.

 

The principle being that of a micrometer;

at 40 teeth per inch, a complete revolution of the handle will open the jaws by 25 thousands of an inch (in old money). Therefore, a 1 thou gap will be generated by a 25th of a revolution and so on.

So,

If you know how many teeth per inch you have on your adjuster, then you can calculate the angular rotation required for a given gap.

QED.

 

Don't I run on ?

[BrianHorn]

So, just recap and fine tune a few points........the std valve clearance on a Caterham built 1700 Kent motor should be .022thou and .024thou inlet and exhaust respectivley? Or, are these settings for a standard 1600cc Ford built Kent motor as fitted to Escorts etc?

 

If the first is true then that equates to .05588,(.56mm) and .6096, (.61mm). Correct?

 

*ISTR that Roger King suggests 0.5 & 0.55. Am I correct

 

I think that the chap who did mine has set them at 0.50mm!! Both sets! How far out, in real terms is this?

 

*I wanted to add to this earlier but had a customer in.

 

Edited by - BrianHorn on 30 May 2007 14:37:00

[Neal Worth]

.022thou inlet and .024thou exhaust are correct for a standard 1700 supersprint cam.

As I understand it, and I'm up for being corrected, the valve, or tappet clearances are set by the cam manufacturer to allow for correct clearance at all engine temps. Although I'm led to believe it doesn't change as much as some people make out. Too much clearance and it becomes very noisy, too little and there's a risk of the valve not being able to seat properly.

The clearances also mean the correct timing of the cam, this is the debate point, if the clearances differ to the manufacturers then to a some degree the actual cam timing differs to the manufacturers spec.

It always pays to take your time and get the clearances as close as you can, that way you won't be far wrong.

 

[susser]

Agree with that;

No point in spending time/money on valve opening lift and duration and throwing it away with a slack valve train.

I would have thought that hydraulic tappets have no disadvantages.

[Neal Worth]

I just hope none of the K-series boys reads that last comment.

We'll never get to the end of this if they do. 😳 😬

[Sheds Moderator]

Provided you give them oil and not air/oil foam hyd tappets are great. If you are pumping foam your big ends will soon let you know that hyd tappets are the least of your worries.

[BrianHorn]

So, just recap and fine tune a few points........the std valve clearance on a Caterham built 1700 Kent motor should be .022thou and .024thou inlet and exhaust respectivley?

If the first is true then that equates to .05588,(.56mm) and .6096, (.61mm). Correct?

 

*ISTR that Roger King suggests 0.5 & 0.55. Am I correct?

 

Would that not reduce the clearance and make them noisy? In fact, these are nearer what it is set at at the moment

 

[susser]

Neal

I am a K series boy.

I've got them in my Rover V8 and never had a problem.

batteredoldsupersport.

I hadn't considered the foaming issue.

I guess it's Apollo Onto My Upgrade List time then.

[Neal Worth]

Brian

I've just re-read the thread and there seems to be some confusion over the cam you're using. After looking at my old build manual the 1700 supersprint spec. cam is listed as Caterham BCD. You refer to it as a Kent cams 234 which, if I'm not mistaken and I'm setting myself up here, is a completely different cam.

Both of the above cams have valve clearance figures of Inlet 0.56mm

Exhaust 0.61mm

 

If you took your car back to the engine builder and he's set it up to different clearances are you sure you've got one of the above cams?

May pay you just to double check that way you'll not be being misguided.

 

Susser, I'm not surprised you've never had problems with the Rover V8 tappets. They're usually quite a lazy old lump when it comes to revs.

[BrianHorn]

Neal, I guess there is no way of telling exactly which cam is in there without opening it up again, is there?

 

I can speak to the engine builder but I'm guessing he just refitted the original cam if it wasn't worn.

 

I thought that the standard SuperSprint cam was a '234'. I didn't realise that Caterham had their 'own' camshaft.

[BrianHorn]

[Neal Worth]

Brian, Have just checked on my half rebuilt engine and it looks like the cam data is stamped on the gearbox end of the cam. Medically I'm unable to take any bits off my engine, otherwise I'd double check for you, as my new cam was a Kent grind but, looking at my last cam, Newman, it has the profile data on that end, as does the Ford GT one that was originally fitted.

I know that isn't really what you needed to hear.

If you got a receipt from the engine build you may be lucky and find that it has the cam spec. written on it, that is if a new one was fitted.