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Whats the BHP


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Thanks Tony ............... I guess its going to be another couple of weeks yet due to time restrictions ...........

I guess were almost getting to the stage of a short motor now…………….

First job is to degrease the new cam and fit the woodruff key ……….. too many times I have seen a cam fitted and then the key tapped in whilst the cam is in place …. not good ……… FFS, do it properly on a V block

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Then the cam lobes are lubed with cam lube and the journals with build lube …… both same colour but not the same stuff ………

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Once the cam is in place it should look like this

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A word of warning here ………… some aftermarket cams have metric thread for the cam gear ………… the OEM is imperial ………….. make sure you order a bolt with the cam.

Time to fit the timing gear……… here I and using cloyes with a true roller chain. With cloyes you get the option to fit TDC, cam 4 degrees advance, or cam 4 degrees retard.

Advancing the cam improves the low end torque but then causes some inefficiencies at higher RPM due to valve overlap. With wasted spark this could cause a lot a exhaust flames…….. Retarding the cam loses some of the low end torque but provides slightly more power at high rpm …………….. I tossed the coin and decided to fit at TDC (neutral timing) as I feel the low end torque will be ample …….. but to change it later is no big problem…..

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If wanted to retard the cam I would use the next crank keyway and the timing mark shown here……..

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Now ….. not that I’m a fussy bar steward but I am going to check valve timing anyway…….. if I was fitting a vernier cam gear then this is how you set it up.

Set a dial gauge on the edge of the inlet lifter and set an angular gauge in the crank to zero degree at TDC. Then rotate the crank to the cam manufactures setting for beginning of lift at x degrees BTDC …….. in my case it was spot on ………. With a vernier you just release the allen screws, turn to cam to commence lift (on the dial guage) and then lock up the screws ……… otherwise known a dialling in the cam……….. a simple task but people write reams about it…… :rolleyes:

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Right ………….. I now have a short engine that will be covered over for a week or so whilst I build up the heads …….. I will try to demonstrate why you need to replace the rockers and shafts etc.

The bores are oil rag stuffed ready for the cover to go over …………. Anybody wanna buy a short motor …. :lol:

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:)

Ian

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Exellent workmanship .......and even better write up ........which takes quite a time too.

Bed SWMBO is happy that the crank pistons N Rods and Block don't come to bed with you any more :lol:

Sad thing here is in the future mnay will read this see the "Extra" lengths that you have gon to and say "Naah" - their loss as it makes such a difference but DOES take a huge amount of extra time and patience

Nige

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Sad thing here is in the future mnay will read this see the "Extra" lengths that you have gon to and say "Naah" - their loss as it makes such a difference but DOES take a huge amount of extra time and patience

I'm starting to think I'd seriously underestimated the work involved in getting my old lump back together ... :blink:

Don't see much point in doing it at all unless I'm going to do the job properly though.

All hinges on which truck I keep :unsure:

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Excellent info BBC.

I have an eblag purchased short motor sitting in my workshop. Supposedly rebuilt, but its going to get taken down again & treated as per your build.

It would be good to see this thread cleaned & transfered to tech archive when finished.

p.s. my only comment - bore snakes : i always prefered to use nylon brush versions. less likely to lose bristles, less damagung if they do & still removes the loose gunk.

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Geoff,

I hope I haven’t put you off the idea…………… what I am building here is almost a blueprint rebuild (almost but not quite) ………..

As long as you do the fundamental measurements (mostly feeler gauge stuff) and correct any errors found, then your engine should be fine.

If you do decide to rebuild, then I am happy to assist from a distance ………. I’m only a phone call away ;)

:)

Ian

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Geoff,

I hope I haven't put you off the idea…………… what I am building here is almost a blueprint rebuild (almost but not quite) ………..

As long as you do the fundamental measurements (mostly feeler gauge stuff) and correct any errors found, then your engine should be fine.

If you do decide to rebuild, then I am happy to assist from a distance ………. I'm only a phone call away ;)

On the contrary - although I'm wondering how I'm going to do all that grinding without seriously upsetting the neighbours... :unsure:

I fancy rebuilding it as something a little bigger than a 3.9 - rather liked the look of a 5.0 stroker kit in Real Steel's jazz magcatalogue, but cost is likely to mean it ends up as a 4.6 instead :D If I can get hold of all the ancillary brackets it'll end up as a serpentine with a decent oil pump (and no clockwork ignition).

Given how long it'll take me to find the time and funds for this project, I might just keep then engine and do it even if the range rover gos, then buy something to put it in when it's done.

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  • 1 month later...

Ok………. After a short forced layoff due to fitting a kitchen and spending some time abroad, I have finally been able to put some more time in on the rebuild.

So far we have a reasonable short motor assembled and its now time to look at the heads in closer detail.

First off its time to tackle the rockers …………. So many times I have seen these just cleaned as a unit and then refitted ………….. here is why that is just NOT the right thing to do. :rolleyes:

Top end rocker wear is common on RV8’s with any decent mileage, however, due to the hydraulic lifters then engine will not give any indication of tappet noise.

First job is to strip the rocker shafts ………. Use gentle blowlamp head to expand the rocker posts as they are an interference fit on the shaft. If you drift them on and off you will damage both the shafts and posts.

Once stripped the shafts look fine from the top,

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But, turn them over and have a look at the thrust side ……… oh dear…. :blink:

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The rockers have also worn oval ……………

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A measure here shows that I have a worst case of 28 thou wear ……. That’s both shaft + rocker ovality.

By leaving these I would destroy some of the reasons for the rebuild ………….. the rocker ratio is 1.6:1, so 28 thou wear equates to 45 thou of lost lift …………but the story doesn’t end there …………. To take up the slack the cam will turn slightly further before lift is commenced, so the valve timing will be retarded ……….. I have never bothered to measure it, but a degree or so would seem in order.

Another issue is the amount of sludge that will be in the old shaft ……… without disassembly no amount of cleaning will get that out.

So, a nice new pair of moly chrome shafts and OEM rockers will do the job just fine. Remember that you need 8 L/H and 8 R/H rockers…… 4 of each on each shaft.

It is important to get the shafts the correct way round to ensure the correct oiling …… the oilways go towards the valley and to the bottom of the shaft…….

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Again, use heat to warm the posts and they will readily slide onto the shaft, then just drop a bolt in them until they have cooled.

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When assembling make sure you get the L/H & R/H rockers correct,

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One complete , together with an original……

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A few hours later we have the finished articles………….

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:)

Ian

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Now we move onto the valve cleaning, grinding, fitting etc…………..

Although I have ported the heads, poppet valves are not good for air flow, so we need to make sure that the ‘flow’ side of the valve creates as least air flow resistance as possible. This is best achieved by mirror polishing ………

To clean the valves I use the lathe …..

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Once cleaned, each valve is inspected for pitting and stem wear …………

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That is not rust on the left of the vernier . it’s a reflection …. :huh:

All these valves seem in reasonable condition…….. this is to be expected as when I stripped the motor I noted that recent work had been done on the top end.

Eventually, after many hours, I end up with a full set of valve that look like this…

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Next, is time the discard the valve springs …………… here is the reason…

Using a straight edge, 2 new springs and a flat surface, it is possible to measure how far the springs have ‘set’

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These were 60 thou for the best and over 100 thou for the worst …….. :blink:

Time now for a head inspection with regard to the threaded holes.

The exhaust manifold bolts always come loose on these engines (I guess its due the the different expansion / contraction of the ally & cast steel) and consequently the threads suffer from the ham fisted grease monkeys.

These threads were past their best so I decided to helicoil them……

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And finally all the coils fitted

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Make sure you get all the tangs out ! ;)

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Its now time to clean up the heads to a reasonable standard ……….. paying particular attention to the oil way and bolt holes

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A question often asked on here is “ how old are the heads” ………… look for the week / year in the casting by the exhaust ports ……… this one is week 24 of 1990

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Then the valve grinding ……… the bit that we all hate ……… <_<

All you are looking for is a continuous grey line around the valve and seat ………. It is widely argued that the thinner the line the better ……….. but don’t get carried away……. The valve banging against the seat several hundred time a minute is going to provide a better gas seal than you can by grinding (as said by a Shelby engine builder) …….. all we are doing here is providing a good basis for the gas seal.

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Finally after a few hours we have a complete assembly

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Now, we go onto more interesting stuff………….. like fitting the head.

On this build I am discarding the head bolts an using ARP studs

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These have next to FA stretch in them and the 7/16 stud with a torque of 65ft/lbs will provide a clamping force of 14,200 lbs.

A normal set of head bolts will cost just a few pounds …………. A set of ARP studs is about £120 :rolleyes:

It ids important to follow the ARP instructions here ……….. if assembling with light oil, then torque to 80 ft/lbs ………… if assembling with ARP moly lubricant, then torque to 65 ft/lbs

So, in go the studs with the moly lub…..

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It is important to only fit them hand tight.

Then on with the composite head gasket………

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Here I have the head fitted and all the nuts at 65ft/lbs torque………….. note that I have left off the outer row nuts ………. These will be fitted last and only torqued up to 20 ft/lbs (just hole fillers). On later engines this row was discontinued as it was found that if the manufacturers suggested torque was applied to them, the head would slightly tilt and eventually ‘blow’ into the valley.

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So ………. Just repeat for the other head and then I almost have a complete engine. Once the other head is fitted, then it is time to check the preload on the lifters …………

:)

Ian

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Ian a few questions.

How did u decide & control how much to take out of the ports? I am a little scared of going too far & breaking into an ajacent oil way or something.

I can exactly identfy my heads. they have the later 40/34mm valves, but where you find the LR part number on others i only have:

612571

<BIRMAL>

10

also the spring seats are different that in your picture. where you have a raised part around the guide, i have a trough. I assume that there were dual springs on mine.

Do you think i can safely fit a single spring?

IMG_0271.JPGIMG_0272.JPG

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Birmal is /was the Birmingham Casting co ………..

Yes, that looks like a dual spring head ………..

I thought that all dual spring heads were pre SD1……… but your valve sizes indicate SD1 or post SD1 ……….. but it still looks like an early Rover car head.

Dual springs will be expensive, but I can’t see any reason not to use a single spring.

To decide how much to remove………. Use a tin valley gasket as a template for both the head and the manifold. Then cut to the gasket size and carefully flow it into the chamber.

At the valve throats, cut away the excess material around the seats and also CAREFULLY blend the throat to port ridge to a nice curve.

If you look in tuning V8’s by Hardcastle there is a cross section of a V8 head ………. Do you need me to scan the pictures and post ?

HTH

:)

Ian

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Cheers - i have said book. It talks about multiple templates used to shape the port. I'll go with your method.

I'm beginning to wonder if i have Pre SD1 heads which have later had larger valves fitted.

I am unsure if someone has done some porting already. They dont look to have been talken out as far as yours, but they are definately not virgin casting. Was it normal to in the factory to do some smoothing/blending?

Another problem - the LR V8 rebuild manual shows the valves pressed in based on the height above that raised part (which i dont have) i'm now not sure of the correct height...

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I am guessing here ………………….others here know more about bolts and fasteners than I......... :D

I always thought that stretch bolts have quite a different structure from a normal bolt and when fastened with the correct preload, they retain some of their sketch as elasticity. Where as a normal 8.8 bolt (or whatever carp rover used for the heads) tends to stretch and not return to its normal state. I guess that the fact that the head and block are ally may also have an influence. :unsure:

ARP studs have been used for many years as a solution to improve the ‘clamping’ of critical engine components………….for those interested the studs are rated at 190,000psi and are quoted as having a clamping force of 14,200lbs when fastened to 65ft/lbs torque (threads coated with ARP Moly Lub)

I guess we really need somebody like Bishbosh to give us a more definitive answer……. ;)

:)

Ian

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My reason for using studs was that you screw the stud into the block with a relatively low torque (no danger of doing the threads in with too much yang) and then you apply torque to the nut once the head is on, so you're torquing a steel nut against a steel stud rather than a steel bolt into an ali engine block. All the science stuff is beyond me :unsure:

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good thread; don;t want to interfer but someone was aksing about opeing the heads and I happen to have some photos - delete as necessary.

as said, lay the gasket on top of the port, mark and grind away.

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once done, you can see the difference between the ports how they left the factory (right)and after grinding (on left)

.

One thing not mention in the post is that there must be a gap between the woodruff key in the camshaft ands the slot in the gear wheel - this is to allow for oil to get to the timing gear - now it may be that the hole drilled in the block serve the same purpose. If the gap it too small, the key needs to be filed down - the haynes book tells you all about it.

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I presume, then, that putting tensile stress on a thread while not rotating (as with the stud in the block) is a lot safer than doing the same while rotating the thread (as with a standard bolt)?

The stretching thing seems to make sense to me, which probably means I haven't thought hard enough about it :unsure: - but I've always considered 'because it works' a pretty good rationale for doing something... :lol:

I think the calculations are supposed to scare you into buying their bolt calculator software to do the nasty maths for you :ph34r:

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  • 2 weeks later...

With the heads on its now time to finally fit and adjust the rockers ……….. yes that right, I said ADJUST the rockers ;) . This may seem strange as it as hydraulic lifters, but read on.

First on the list for attention is the push rods. As I want the oil to drain very freely back to the sump via the camshaft, the push rods need to be polished to help this process. Each rod is spun in the lathe, cleaned with 120 grit emery, then given a few minutes with 400 grit wet n dry, and then finally finished with 800 – 1000 grit wet n dry lubed with paraffin. Then each rod is rolled on a piece of plate glass to ensure that it is straight. I know ........ sad :lol:

Here we are half way through, 8 done and 8 to go

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Great ……… all 8 finished.

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On with fitting the rebuilt rocker shafts so that the lifter preload can be checked. The preload is important………. it can be likened to the tappet clearance (in reverse) to that of a conventional solid tappet pushrod engine. The important measurement is the clearance between the retaining clip and the spring loaded pushrod seat when the lifter is on the heel of the cam…….. here I am looking fro 20 – 60 thou.

The measurement can be carried out by using a bent piece of rod / wire that is of a known thickness. This picture shows the measurement process, here I am using a 60 thou brazing rod …….. another good rod to use are the earth wire from 1mm twin & earth (43thou) .

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OK, measurements taken and a cry of Oh F**k

I t looks as though these heads must have been shaved before ……….. and now I have shaved them another 50 thou or so …………. The preload measures at 204 thou ………. Yes that’s 0.2 inches :blink: . To leave this would mean the valves would not close properly and I also run the risk of a valve and piston coming into contact.

A good method to see what shims may be required is to release the rocker bolts and allow the posts to be held up under spring tension ………. I need 90 thou shims.

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When calculating the shims remember that the rocker ratio is 1.6:1, so effectively I will remove 144 thou of preload with 90 thou shims.

Off now to order some shims ………… if I cant get them that thick then I will need to use adjustable rods ……….. lots of options.

:)

Ian

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Ooops :(

On the basis of this check the inlet manifold base alignment on the head studs, - you may find you'll need to have the base surfaces of the inlet base also skimmed so as to have the bolts and holes line up.....

Otherwise looking fine and fitting isn't far away :)

Nige

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The manifold fitting was the first thing I checked, and it is OK…………..it was quite nice to see my port alignment marks match up. B)

After giving it some thought this morning, I guess I might just be unlucky and everything (valve train wise) is on the high side of the tolerance allowance.

I know that the factory motors had the preload set really high (anything from 100 to 120 thou) , to ensure that the engine stayed quiet as parts began to wear.

So, a quick calc shows that if my pushrod tolerance is on the upper side and giving 120 thou when fitted as bog standard, then add in the 30 thou head skim (50 thou skim, but 20 thou will be taken up by using a composite gasket) together with the rocker ratio, then it calculates out like so,

120 + (30 x 1.6 ) = 168 thou …………..

Then if we do the same calc assuming that the heads may have had 20 skimmed off in a previous life,

120 + (50 x1.6 ) = 200 thou………

Yes, that works for me …………… ;)

The shims come in 16, 48, & 32 thou ………………so I am going to deviate from the ideal world and use 80 thou of shim under each rocker post (48 + 32) ……….. that will give me a worst case preload of 76thou and the best will fall in at 55 thou.

In terms of CR ………… we know that 20 thou off the heads increased the CR by circa 0.6:1…………..therefore 0.6 x 2.5 (50thou) = 1.5……………

So the CR will be something like 9.35 +1.5 = 10.85:1

:)

Ian

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