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Alex's v8 re-build thread warning pic whore inside >:)


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Hi David well its definitely tracking of the belt that caused the issue . The reason well could have been a worn intermediate bearing which tilted the cam drive belt enough for run off . There are signs of a bodged rebuild before I bought it so I'd put it down to the intermediate pulley not being set at the right angle when tightening the snubbers and chain which ran the pulley at a lower angle letting the belt track . It doesn't explain the right belt going so lose though . All gates said after there testing was that it was within there tolerance allowance ??? Whatever that's suppose to mean . And yes the nip was checked just never took any shots . Just for the masses incase you didn't know the nip is the difference in height with regards to how high or low the liner sits in the block in relation to the engine block top edge

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You may have noticed on the video a real high pitched squeak this was down to a intake plenum gasket not sealing . Would have created boost issues later on after tightening the bolts more it stopped but one of the threads didn't feel very good so I've re cut all of them and heli 'd the lot so now I have a good steel thread to apply better torque on the plenum and not worry about it not holding next time .

post-14598-0-80275200-1406695348.jpg

post-14598-0-32268400-1406695386.jpg

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Hey Riz I bloody hope so if my fapping clutch arrives this year another phone call to mardi gras Motorsport today 7 days no 10 days no 14 days no next week no Monday now wed still nothing starting to grate my ass

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Check the end float of the cams. You may not want to bottom the seal so it rides on a slightly different spot on the cams. From your pictures it looks like you have a slight grooving where the previous seals rode. Lubricate the seals and camshafts liberaly before inserting the seals. Make sure there is a chamfer to make instaling the seals easier and there are no burrs. After installing make sure the springs didn't pop loose. The manual says to apply Locktite 480 to the outer surface to seal it to the head. It is possible you got some seals that were stitting on a shelf too long and that's why they leaked.

David Teitelbaum

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I have the 4 cylinder S4 so am not to familiar with the V8 engine design. But i don't see any woodruff key that the cam pulley locates on.

On my car this helps with the position of the cam/pulley and with drive but most importantly it can't slip. Seems a little risky just relying on the taper.

Suspension, brakes, chipped, chargecooler rad and pump,injectors,ignition coils and leads, BOV, highflow cat and zorst, Translator and tie rods, Head lights, LEDs to tail lights and interior,Polybushes to entire front end, Rad fans, rad grill, front end refurb with aluminium spreaderplates and galvanised bolts. Ram air, uprated fuel pump, silicone hoses through out, wheels refurbed and powder coated,much more, all maintenance.

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  • Gold FFM

Mr plumber ..this is one of the main things in the 918engine design and caused lots oft trouble on early productionrun :D

We V8 owners habe to live with it, or at least can key the main pulley loser down in the intermediate chain drive

  • Like 1

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to name the things if I see them, that's what I call integrity..

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I was a tool maker for some years and I understand the ability of a taper to lock it's self extremely tight, however not withstanding. One other thing, does this make setting the timing a little more differcult than it needed to be?

I can look up the answer to my own question but wondered what you thought.

Suspension, brakes, chipped, chargecooler rad and pump,injectors,ignition coils and leads, BOV, highflow cat and zorst, Translator and tie rods, Head lights, LEDs to tail lights and interior,Polybushes to entire front end, Rad fans, rad grill, front end refurb with aluminium spreaderplates and galvanised bolts. Ram air, uprated fuel pump, silicone hoses through out, wheels refurbed and powder coated,much more, all maintenance.

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so wayne there is no taper he idea is you attach the two belts onto all the cam pulleys then with the cam front bolts lose or not even in. the cam pulleys sit on the front shoulder of the cam and will rotate easy . Then with the engine in its timing position you basically apply glue to the thread of the bolt and insert and tighten to a set nm . Then rotate the engine a few times and check with tolerance pins in the holes on the first 4 cam holders and as long as they line up that's it . there are worries of glue not setting properly and oil in the threads not being cleaned properly allowing the pulley to slip and turn making the valves out of time to the piston and well you guess the rest . its just a mix of the right torque on the bolt and a clean glued hole .

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I understand now thanks. With your extremely meticulous and professional rebuild Im sure this design "issue" let's say, won't prove to be a problem. Your car may well be one of the best examples around when complete. Congratulations.

Hey Buddsy, small world indeed. Plumber now though. Still got access to workshop when needed, which is really helpful.

Suspension, brakes, chipped, chargecooler rad and pump,injectors,ignition coils and leads, BOV, highflow cat and zorst, Translator and tie rods, Head lights, LEDs to tail lights and interior,Polybushes to entire front end, Rad fans, rad grill, front end refurb with aluminium spreaderplates and galvanised bolts. Ram air, uprated fuel pump, silicone hoses through out, wheels refurbed and powder coated,much more, all maintenance.

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For those of us of a certain age, absence of dowels or woodruff keys to fix pulleys to shafts and reliance simply on friction is disconcerting.  A race-engine builder once said to me as we discussed this, "Scary, isn't it?"  However, it seems to work - the proviso being that meticulous care is needed during assembly.  A marked advantage of these systems is that cam timing is not under the influence of the nearest sprocket tooth or belt groove; it is exact because during assembly, wheels rotate on their shafts until final torquing fixes everything in place.  Well, until the belt stretches that is. . . The V8 is a case in point. Added to which is the small size of the cam wheels especially compared with the sprockets on the old twin-cam engines.

Edited by Winter
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Yes good point. But im not totally sold on the accuracy argument. A key slot can be machined within seconds of an angle on a shaft and likewise with the slot in the pulley, suppose if you want to alter the cam timing on each shaft it could be very useful.

Anyway my question has been answered fellas and I don't want to hijack Alex's thread. These engines were designed by smarter and better engineers than me so who am I?

keep the pictures coming please.

Suspension, brakes, chipped, chargecooler rad and pump,injectors,ignition coils and leads, BOV, highflow cat and zorst, Translator and tie rods, Head lights, LEDs to tail lights and interior,Polybushes to entire front end, Rad fans, rad grill, front end refurb with aluminium spreaderplates and galvanised bolts. Ram air, uprated fuel pump, silicone hoses through out, wheels refurbed and powder coated,much more, all maintenance.

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In my experience, as long as the taper fit is properly designed, calculated and fitted in the first place, there should be no problem with anything slipping. The female taper, is effectively 'stretched' over the male taper, and the friction between them provides the grip. A woodruff key isn't for stopping something turning on a taper, it's a location device more than anything.

 

As has been said, it's a tough one to get your head around, though!

Margate Exotics.

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  • 2 weeks later...

Hi Alex, hoping the rebuild works out, as a budding engine builder myself I was looking over the pictures with an aircraft engineer mate of mine and he pointed out a couple of things that worried him. He has a keen eye for detail working on helicopters, obviously and I wanter to pass on his concerns

 

post 398 dink in cam belt tensioner bearing oil seal - could cause loss of lubrication over time resulting in loss of cam belt tension !

post 412 swarf/crud in the LH cam hole -  I expect it was cleaned out prior to fitting but worth mentioning

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That's light not a dent does look weird though just a shadow . The cam lobe is where the old glue is removed and chased before cleaning drying and glueing the cam bolts in .

You and your friend have a very keen eye must have been looking in very good detail .

Worth noting that what you see might not be how things are left ! It's me working and grabbing the phone at random points to take a shot otherwise I just bury my head and keep going .

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