cam chain tensioner

[julian64]

Want to tension my camchain, but haven't seen a guide on how to do it.

Have removed the oil filler neck. The guide I have says you should just be able to move the guide away from the tensioner pin. Well on mine there is a good quarter inch using your finger, let alone levering with a screwdriver . Making for a slight rattle on tickover.

So here comes the problem. The tensioner bolt has a hole down the centre and a pin which slots in to push on the cam chain guide.

Either removing the single copper washer from the outside of the bolt and effectively screwing the bolt up with no washer would do it, but doesn't seem right.

Or removing the pin from the bolt, putting a small lump of shaped metal at te bottom of the hole and then putting the pin back in would lengthen the pin and screw back with the retained outer copper washer.

On the two engines I have the bolts and pins are identical with no sign of any adjustment to either external washers or internal pin dimensions.

So the question is, has anyone seen a different setup to this to indicate which way TVR used to do this??

[clive f]

hi Julian, I had the same when I stripped and rebuilt mine, it really is a lousy design, I found a 4mm length of bar fitted as a spacer underneath the pin when I stripped it down, and when rebuilding it I tried it without the spacer and the chain was to slack, so the spacer was popped back into place.

you would ideally expect a thin locknut on the bolt to lock it off when adjusted, so I ended up applying a nice dab of locktite when refitting and then checked the clearance via the screwdriver method.

[plumAJP]

how much clearnace should we be talking clive?

if i put the screwdriver through the oil filler hole and lever the tensioner how much should it be able to move?


cheers.

[clive f]

have a read up in the manual I sent you Shayne, from memory I think its so that you can just lift the tensioner off of the bolt, so I would say under 1mm.

[julian64]

Try lifting it with your fingers, then the screwdriver. You should be able to do it with one but not the other

Or at least thats how I interpret the rebuild manual.

On a different subject, do you happen to know the reason for the vacuum takeoff from the rear of the passenger airbox.

After fitting jools whirlwind, I had no vacuum in the airbox when holding your hand over the airbox entry. On closer inspection I found that the bottom of the whirlwind pipes were a little short for my airboxes, and in trying to make them fit by using jubilee clips they'd pulled the bottom of the trumpet plate open a fraction. this had removed, or at least greatly reduced the vacuum in the airbox, with the airbox sucking in the air from around the exhaust manifold.

I'm hoping that this cures the lack of top end sparkle I'm paradoxically getting since going from normal to whirlwind.

My airbox in now on the table in my garage having more securings round the periphery, but I was wondering what the takeoff getting no vacuum was doing?

[TT Tim]

I know yours is a 4.5 Julian, but are you sure it's a vacuum take off, and not the barometric pressure pipe for the ECU?

Tim

[spitfire4v8]

Dont use jubilee clips on the big bore end, I dont supply new jubilees for that end for a reason

the vacuum take off is for the baro pressure sender .. many cars just have the pipe dangling in the breeze .. if you have an effiecint clean air fiter there shouldnt be any appreciable vacuum in there anyway.

[julian64]

Without the jubilee clips the pipes would be hanging off at that end.

There would be a gap at the bottom of all the pipes? I might as well get rid of the airboxes to save weight.

I just thought my car was a bit odd with the positioning of the airbox wrt the inlets. Why no seal there?

I've not heard this mentioned by anyone else putting the kit on. Am I doing something wrong?

As for the vacuum, I'm not sure I explained properly. I took the front air filter and front pipes off leaving the air box only, and put my hand on the front of the airbox. At tickover I was getting a whomping great vacuum on the driver side that would stall the engine if I held my hand over. On the passenger side there was no vacuum and no appreciable difference if I held my hand over.

Does this mean all whirlwinds are scavenging from the engine bay air?

Colour me confused

Edited by julian64 on Monday 13th July 19:38

As a last resort I was going to make new airbox brackets to change the angle of the airbox slightly.

Edited by julian64 on Monday 13th July 19:40

[spitfire4v8]

sounds like your airbox might be further away than normal? they dont push on as far at the bottom but they still should go on .. there are cars out there with airboxes mounted further away from teh inlets because teh rivnuts have pulled through and people (myself included in the past) mount them on bolts, and the way they do it means you end up with a nut between the airbox and mounting bracket so the airboxes are further away than normal. if yours is in the proper place though they should meet

[julian64]

Nope rivnuts still there and no spacers. I'm going to mill the hole on the bottom of the mounting bracket into an oblong to allow me to slide the airboxes closer and bend the bracket to angle upwards a little.

Still not sure why you are against jubilee clips to the outside though. I think they look quite natty when on.

I willl say that whenever I look at a wirlwind setup from now on, I'll be sticking my fingers under the pipe to see what the gap is .


The alternative would be to cut down the inlet end to effectively lower the pipes and improve the angle but the pipes increase in diameter rather rapidly there and I would struggle for a seal if I did that.

Hopefully icreasing the strength of the lower airbow screws has meant that I can afford a little pulling without breaking the seal. I'll play about tomorrow.

Part of me thinks that my bored out inlet will fit fine if I cut the inlet end of the pipes down in this way, but that is some way in the future.

I'll get it to fit one way or another tomorrow, and get my vaccuum back.

[VPower]

julian64 said:

As for the vacuum, I'm not sure I explained properly. I took the front air filter and front pipes off leaving the air box only, and put my hand on the front of the airbox. At tickover I was getting a whomping great vacuum on the driver side that would stall the engine if I held my hand over. On the passenger side there was no vacuum and no appreciable difference if I held my hand over.

Sounds like your throttles are not balanced??

[spitfire4v8]

What method are you using to fit the pipes julian? I always fit the end to the airbox first and push it on as far as i can, then fit the end to the inlets .. have never had a pipe come off the airbox end. I dont send out jubillees because the air box end is a good tight seal of pipe over backplate tube (if it isnt then there's something funny about you car) and if you give people jubilees they only ever overtighten them and crush the airbox tubes which does then cause pipes to come off (whether short versions or the std tvr versions, in fact the short vesions should be better in this respect as they have more inherent strength because theyre shorter). You dont need clips for a good airtight seal at the airbox end if everything is as it should be.

[julian64]

Obviously I have an odd car .

However all back together. Now have decent vaccuum on both sides. Have altered the airboxes to cope, and have used the outward jubilee clips to make sure.

Now I'm sure all the air is comming from the nice cold clean air at the front of the car I think I need a new air filter though.

Did you do uprated standard air filters jools??