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Quote from "How to Power tune Rover V8 Engines"page 40
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"All of the aftermarket camshafts that can be used without creating valve spring coil binding have one common feature, they have no more than 0.43in/10.9MM of actual valve lift."
Regards Philip A
G`day Brett .
They are easier to measure with the heads off but the thickness pads are .....
Diagonally corner to corner to the extreme you`ll see the 4 machined surfaces .
2 short are on the exhaust side below the last head bolt on each end for that side .
2 tall are on the inlet side below where the corners or rounds of the rocker gasket are .
The valve spring flat surface is approx 4 mm below the cast surface beside where the spring rests . One i have here is in the range of 4.1mm and 4.3mm .
I`ve replaced all the valve springs insit`u on a range rover , don`t know if a discovery firewall is different . I used air and a screw on spring compressor . You would need to make a tool to fit the stem seals because of the valves stems being there still . If they don`t go on square they will distort .
I`ve not long replaced the head gaskets on our 4.0ltr , i didn`t look at all the lobes on the wade cam it uses but the ones i looked at still have the peak shape and were not rounded at all , the lifters were worn as in not convex any more , i intend replacing the lifters shortly if the cam still looks ok .
Couple of weekends ago it had to do 1200kms towing a tandem trailer and 600km of them with a range rover on the trailer . It may not seem much but with the car on it was able to pass B doubles on the longer climbs and keep pace with traffic . There wasn`t a huge difference between petrol and gas other than with the heat it would run a little cooler on petrol on the climbs . It doesn`t have injected gas like yours .
What i`m saying with the above if the wade i have a 259a , i think , was at all at fault i`d consider i should have found out about it by now .
If you get a factory 4.6 spec cam don`t forget it can`t be a 4.6 cam as such because you have a distributor and the factory 4.6 cam can`t drive it .
EDIT .. Just had a look at the wade 259A stuff and 268 intake , 267 exhaust cam lift , 0.402 intake , 0.400 exhaust , valve lift
couldnt convince myself of just doing lifters. pulled cam out.
have started replacing valve stem seals.
typing on phone so when on laptop shall put up pictures.
have most parts worked out which i need EXCEPT cam.
still trying to understand why 4.6 cam so different to 3.9/4.0 cams. is it due to bore/stroke? would like to decide whether to
just copy 4.6 cam grind onto my new camshaft
bung in standard 3.9 cam
or go back to a wade again
does this topic get touched on by des hamill or any of his equivalents specifically related to the 4.6?
hi brett, couldn't find that timing cover OR retrieve your number on friday, many apologies:(. the 4.6 cam is totally different at the nose where the gear bolts to, afaik the grind may be so close to a 3.9/4.0 as to be 'not different':DQuote:
Originally Posted by pibby
personallly, i would fit a standard 3.9/4.0 cam profile.
jc
G`day Brett ,
i could just say no or not that i`m aware of to your last question but ...............
Hamills book under Cams is not capacity specific .
Starts with all factory cams are very similar in timing and duration and all produce identical valve lift , max HP at 5000rpm max torque 2500-3000rpm .
Torque curve is suited to road car .
Virtually all afterrmarket with similar to factory duration will give better performance .
Aftermarket appear to be much more reliable .
Talks of P5 P6 SD1, road engines , high performance road , full race .
Unless i missed it there is no mention of Range Rover Discovery or either the 4.0ltr or 4.6 engines as far as the camshaft chapter is concerned , specifically to do with any cam .
The book has alot of useful information and as it states in the begining the entire book must be taken into account as in , different bits tie in together . There may be something elsewhere that i`ve not seen .
The Hardcastle book i have was published pre 4.6 so also has no specific 4.6 either.
The thing of both these books is , one says power tune for road and track and the other , best performance for road and competition , i`d suggest although they have alot of useful information neither is bias towards a four wheel drive .
Geeeeeez, I’m already confused and all I’m doing is putting the valve stem seals back on.
Installed height of valves should be 47.63mm max according to manual and an earlier post by PLR. mine are reading around 44mm taken from the base where the spring sits to the top of the valve. Around 40mm if taken from the flat area around the valve area.
So when I put the collets on the distance between the collet and top of the valve stem seal is approx 290-300 thou. This is pulling the valve up to gain max height.
So if the standard 3.9 cam has 390 thou lift at valve then the collets are going to bang into the valve stem seals and the thinner waist on the valve stems as it reduces for the collets will pass the upper lip of the valve stem seal. Surely that can’t be good for sealing?
What have I got wrong here??
Have attached photo to save me writing a thousand words! the last photo is with the collet on.
The free valve spring length is fine.
manual says top of valve guide should be 24.13mm (I’m assuming protrusion from where recess where spring sits but I couldn’t see picture) but mine are reading around 19mm.
the heads are fresh off the shelf of All Heads in braeside vic which specialise in this stuff.
two of the photos show the old seals in place and one has the new seal sitting adjacent which shows how much of a bashing they were getting.
from PLR -
"There are pads on the heads to measure thickness if you can locate them , there are 2 tall on one side and 2 short on the other ,....
The tall for a std new head are 62.56mm and the short are 22.94mm ."
i think i found these pads. i get 22.92 for one heads (couldn't access it on the other head).
and 62.93 and 62.65 for both heads so all in spec i would have thought?
G`day Brett ,
other than magic what`s holding the springless valves up ?
I measured only using 1 exhaust valve but a variety of seal guides ect and for guides a different but same cast # head coz 1 has seals fitted and 1 not and the valve length is the same as the 7 others in the set and the heads have approx 250k on them but are cleaned so the stems seals are used but not at all crushed and the faces stem/valve/seat are all good .
The measurements are not exact
Spring base to stem top = 45.4mm
Guide flat to stem top = 40.6mm
Collet top to stem top 3mm
Collet base to seal top = 12.4mm
Collet holder base to seal top = 12mm
Collet holder base to stem top = 13.5mm
Collet thickness = 13.5mm
Spring flat to bare guide top = 14.1mm to 14.5mm
Guide flat to bare guide top = 9.9mm to 10mm
Spring flat to seal top = 19.6mm to 19.9mm
Guide flat to seal top = 14.9mm to 15.2mm
Seal top to stem top = 25.6mm
I haven`t compaired anything to yours yet but the extra figs may be useful maybe .
thanks peter - i reckon the difference between yours and mine is the amount the valve guide sticks up. i've put some of my measurements up against yours.
Spring base to stem top = 45.4mm mine 44.4
Guide flat to stem top = 40.6mm mine 40.0
Collet top to stem top 3mm mine 3.0
Collet base to seal top = 12.4mm mine 7.5 so 5mm difference
Collet holder base to seal top = 12mm
Collet holder base to stem top = 13.5mm
Collet thickness = 13.5mm
Spring flat to bare guide top = 14.1mm to 14.5mm mine 19.2 so 4.7mm diff
Guide flat to bare guide top = 9.9mm to 10mm mine just shy of 14.5mm so approx 4.5mm diff
Spring flat to seal top = 19.6mm to 19.9mm
Guide flat to seal top = 14.9mm to 15.2mm
Seal top to stem top = 25.6mm mine 21mm so 4.6mm diff
so this is leading me to believe the issue is with the valve guides protruding around 5mm too far ie they need to be recessed a further 5mm to stop the collets banging into them.
if that's the case what can be done - speak to place which reconditioned the heads and get another set of heads sent over to put on or is there something insitu to do???
what's holding the valves up? i'm only working on i cylinder at a time so i put it to the top of its stroke. the valves only seem to drop 3 or 4 mm so no prob putting springs/collets back on and off. i bought a spring remover to do the job and looks like i should be able to do all insitu. given the potential prob thinking i may as well stop doing this till i speak to the machine shop.
btw - i screwed up my first seal trying to tap it on with the right size socket. then tried a 1/2 inch socket upside down. it makes four good points of contact so feels good tapping seal on and doesn't touch the rubber on the seal at all.
Boy that is an obscure one.Quote:
Spring flat to bare guide top = 14.1mm to 14.5mm mine 19.2 so 4.7mm diff
Guide flat to bare guide top = 9.9mm to 10mm mine just shy of 14.5mm so approx 4.5mm diff
Here are some copies from RAVE Disco11 which has the same casting number of heads as yours HRC 2479
12.Check installed height of valve.
lValve installed height, end of valve to base
of spring seat, 'C' = 44.163 to 45.288 mm
(1.741 to 1.802 in).
13. Check condition of valve springs.
22.Fully fit guide using tool LRT-12-039A and
distance piece tool LRT-12-208
lValve guide installed height 'A' = 15.00 mm
(0.590 in).
23.Ream valve guide to 8.70 mm (0.342 in).
Note: Service valve guides are supplied with aninternal diameter of 8.1 mm 0.025 mm (0.319 in).
I origially thought Eureka, but then I looked at RAVE and found the above. Looks like the guide height is correct.
Regards Philip A
Hi Brett , yes that would make sense of the problem .
You may need to do some acrobatics but looking into the inlet and exhaust ports with the aid of a light you should be able to see and possibly measure how far the guide protrude inside .
The factory way is to heat the heads and fit the room temp guides not unlike the liners .
The replacement guides are normally over size to make for a better fit .
A head reco business may not use factory parts as there are aftermarket parts of the same dimension for most every part of the engine maybe not the same makeup of metal but they usually give little if any trouble .
Yes i`d say after you check the inner depth of the guides a call to the head mob will be next .
I`m not aware of a way of pressing you guides insit`u , someone that does it for a living would know if it is possible .
edit .. when looking at you pics it struck me that there didn`t seem to be enough length of valve stem visable as compaired with what`s in the shed .