Project Coalnotdole's Scimitar - Machining work: Speedometer Drive Unit 12/4/19

[DeeJay]

Don't always comment but cnd=well written interesting post.

[DodgeRover]

Likewise nowt helpful to comment but enjoying the write ups of progress.

How's the boat going?

[somewhatfoolish]

Catastrophic head failure? Breakthrough from a cooling gallery to an exhaust port seems likely if the exhaust is doing a sprinkler impression.

[coalnotdole]

Post Mortem - Part 1

At first I had a faint hope that it may just be an inlet manifold failure but there’s only really one way to find out...

The triple inlet manifold is quite difficult to remove without disturbing the throttle bodies, as fixings like this one show, The Cap headed hex bolt is obscured but the throttle arm and the fuel rail above. At one point I thought I was going to have to dismantle all of the throttle bodies and fuel rails...



After some messing about the inlet manifold came off with the throttle bodies undisturbed...



The Large amount of Red hylomar was Northampton motorsports answer a problem with an air leaks (there’s mention of it on one of the last owner’s invoices that relate to the engine)



There’s evidence that the gasket wasn’t seating correctly: Like here around the inlet / waterway at no 5 Cylinder (passenger side bank)



And again here around the waterway on number 2 cylinder but there is no conclusive proof that it was leaking, Only that the gasket wasn’t seated correctly...



As there wasn’t a clear cause I took the head off on the drivers side:



Close up around the valves number 2 cylinder:



And the block head gasket stiil in place...



A closer look reveals quite a bit of damage around number 2 cylinder:









Number 2 Pistion which is shiny having been steam cleaned...



Theres also damage to the gasket on no1 Cylinder:



I took the passenger side head off as well for compariston and found the gasket to be in much better condition...



no evidence of leaks though number 4 cylinder has an orange discolouration consistent with having run hot.



For an engine that has only done 5-6000 Miles there is an excessive amount of carbonisation, Its arguable that a fault with either the valve timing, or exhaust system caused carbon build-up which in turn has caused detonation and destroyed the gasket. A similar effect could be achieved if the map was set to be too advanced. Though in both cases I would have expected to see some degradation of the gasket on the passenger bank as well?

Equally could be that the gasket on the Drivers side was not properly torqued down, or it was torqued to an incorrect torque. I don't have a definitive cause so far... Thoughts welcome...

The next post is closeups of the Heads / Valves....

[coalnotdole]

Likewise nowt helpful to comment but enjoying the write ups of progress.

How's the boat going?

Dave got a girlfreind (she's very nice) but it means he now has a lot less time to spend on boats, cars etc..! That said I'm sure theres some progress to report.

[tooSavvy]

Dave got a girlfriend (she's a shipwright) it means he now has a lot more time to spend on boats, cars etc..! That said I'm sure theres some progress to report.

..... there's someone out there for all of us!

 

 

TS

[Guest Hooli]

I agree that timing etc would probably show on both sides. Dodgy/badly fitted gasket etc does seem more likely to only affect one head.

[garethj]

There's quite a difference in the colour of the combustion chambers, are all those injectors firing the same amount of fuel?

 

Head gasket looks extremely dodgy although it's difficult to tell if it could have worked fine, is it normal to use all that red Hylomar stuff on those engines?

 

Excellent thread, please keep at it

[DSdriver]

I get the impression that someone had a quick look, didn't like what they saw, so bodged it back together and sold it quick.

[cort16]

Bad luck on the engine but great thread

[coalnotdole]

There's quite a difference in the colour of the combustion chambers, are all those injectors firing the same amount of fuel?

 

Head gasket looks extremely dodgy although it's difficult to tell if it could have worked fine, is it normal to use all that red Hylomar stuff on those engines?

 

Excellent thread, please keep at it

 

The injectors should all fire the same amount of fuel, though if the valve timing were out, or there was excessive backpressure in the exhaust they could eaually cause pistons to look like that. Alternatively the hot running alone could have caused the discolouration.

 

Its not unusual to put a sealant on one face of the inlet manifold gasket ( effectively gluing it in place to prevent it sliding out of position when torquing it down) Some people prefer using superglue to hold it in place.

 

However smearing hylomar like that gives a look of "i'm desperate to stop this leeking" I've got a lot of copies of bills for work done to this engine (by the last owner) and there is a bill for inlet manifold reseating...

 

 

Any if you think that bit of the bill looks expensive there are 3 pages in total...! Most of the rest realtes to the installation and setup of the throttle bodies.

[Jim Bell]

PS, Likes and comments are really appreicated as they help gauge if people are interested... It takes a while to write stuff up and it makes a difference if I know someone is reading it!

 

I think its safe to say that everyone is interested and everyone is emotionally invested in this rollercoaster of a thread. Please keep the updates going.

[coalnotdole]

I think its safe to say that everyone is interested and everyone is emotionally invested in this rollercoaster of a thread. Please keep the updates going.

 

Cheers, Might try and write the next bit up now before I have to creosote the facia at the front of the house...

[Asimo]

Thinking through the past sealing problems this engine has had, are the dowels still a good enough fit to locate the heads accurately enough? 

 

Is the manifold dowelled to the heads? That inlet manifold gasket has a lot to do doesn't it! Are they thick and squishy when new? 

[DeeJay]

Are all surfaces flat?

[Captain Furious]

Have the heads been skimmed? And if so was a corresponding amount skimmed off the inlet manifold? If not it has the effect of narrowing the vee slightly and the manifold sits too high causing all sorts of sealing woes.

 

Great write-up though, following with interest

[Guest Hooli]

Have the heads been skimmed? And if so was a corresponding amount skimmed off the inlet manifold? If not it has the effect of narrowing the vee slightly and the manifold sits too high causing all sorts of sealing woes.

 

Great write-up though, following with interest

 

Oh that's a good one. I'd have never thought of that, but it's obvious now someone has said it.

[billyboy406v6]

All that red snot does not look like good engine building to me ?

[coalnotdole]

Thinking through the past sealing problems this engine has had, are the dowels still a good enough fit to locate the heads accurately enough? 

 

Is the manifold dowelled to the heads? That inlet manifold gasket has a lot to do doesn't it! Are they thick and squishy when new? 

 

The dowels look pretty good, Inlet manifolds have no dowels and are only located by the the bolts. Gasket that came off looks like a Burtons one they in my opinion quite cheap and I've got a slightly nicer payen one which can go back on.

 

 

Are all surfaces flat?

 

As they are thick cast heads they are not prone to distortion, they look flat to me but I will have them checked before refittiing.

 

Have the heads been skimmed? And if so was a corresponding amount skimmed off the inlet manifold? If not it has the effect of narrowing the vee slightly and the manifold sits too high causing all sorts of sealing woes.

 

 

it looks like the heads might have been lightly skimmed recently they certainly appear quite clean, The inlet manifold is aftermarket so all machining looks quite new on it. You would hope given the reputations of the companies and idividuals involved that they would have made sure it was a reasonable fit...

 

 

 

[coalnotdole]

Slightly delayed as I've been out smearing the front of the house in creosote...

Post Mortem - Part 2

With the heads off I was torn between getting a replacement set on there quickly and taking advantage of having them off to fit the screw in rocker studs, and roller rockers from my old engine. I've had first hand experience with the pressed in Ford studs pulling out of the head on my old engine so It seemed sensible to do this while I had the head off.

So I started stripping the head down and quickly found I had a problem with removing the Inlet valves, They would move up and down in the head ok but it was almost impossible to get them to drop all the way out. There were also some unusual wear marks on the stem, All 6 were In very similar condition with quite a large carbon build-up for the amount of miles they had done.



All the valves from passenger side head:



Inlet Valve Close-up:



The inlet valves that came out are  Stainless burtons big valves 46.25mm but the exhausts are standard 37mm which seemed odd as I was under the impression that for stage 4 The exhaust valves should have been increased to 41.3mm...

A closer look at the heads revealed the valve guides had been replaced with a K-line type and had moved in the head, Some had sunk others had risen and made the stem seals difficult to remove.





One had even cracked the cast iron top of the k-line insert!



With the valves out It was possible to see some unusual carbon deposits in the inlet ports.





To refurbish the heads I have ordered a set of burtons bronze valve guides and have sent the heads to Saunders Motorworks in Hampshire. I had wanted to get the exhaust valves upgraded at the same time but all the machine shops I spoke to were unhappy about machining the head to take valve seats that big for fear that they would hit the water-jacket and scrap a set of polished and ported heads...

Taking the heads apart has led me to reassess what the engine is in comparison to what it was sold as, There are clearly a few things that don't quite add up...


.

[DeeJay]

All those specs go right over my head, but I assume it's been bodged.

[Sigmund Fraud]

"Liked" for the progress, not the findings...

 

Taking the heads apart has led me to reassess what the engine is in comparison to what it was sold as, There are clearly a number of things that don't quite add up...

 

Very disappointing, especially considering what the complete engine must have cost. Do you think the previous owner was aware ?

[coalnotdole]

All those specs go right over my head, but I assume it's been bodged.

 

I don't know about bodged but some of the work done on the engine is clearly very nice, for example the polishing and porting on the heads is first class... however some of the specs and parts don't match up to the description.

 

"Liked" for the progress, not the findings...

 

 

Very disappointing, especially considering what the complete engine must have cost. Do you think the previous owner was aware ?

 

I really don't know for sure there are plenty of things he should have known about....

 

If anyone is interested the advert is here... :http://www.ebay.co.uk/itm/rs3100-3-2-litre-high-spec-race-engine-classic-touring-car-ultimate-essex-v6/152140126661?hash=item236c4219c5 and no that is not the price I paied.

 

I also had the following decription from the seller:

 

i sent the engine to Specialised Engines in Essex to be rebuilt to their Stage 4 spec including taking it out to 3.2 litres and using some cosworth pistons and the engine was delivered to my friend who was rebuilding my car in October 2012 (I can include the invoices for this work if you want them?) There were a few odd things when it first arrived, the triple weber DCNFs were on back to front and without the spark plugs in the engine was really stiff to turn over. So we asked John Hoad from JPH motorsport to have a look as he lives just down the road and he found the standard of the build was not matched by the price i paid. There was nothing fundamentally wrong with it but it was a collection of expensive performance parts bolted together and not carefully machined and matched. I got my money back through the credit card company and John set about stripping the engine back and rebuilding it. John used to work for Williams F1 and still works as a consultant for them so he was able, for example, to take the heads up to their factory and crack test and gas flow them matching them up with the inlet manifold which he ported out correctly. I have no receipts for this work hence it is not included in the advert, it was done by John as a friend of a friend.

 

So i was left with a very nice engine with triple dcnf carbs. try as i might i could not balance the carbs and get her to run well so i took it up to Northampton Motorsport for a rolling road setup and it was whilst here that Troy found a couple of small air leaks around the carbs which was causing the issue with the mixture. We discussed the fact that i was trying to develop a solid reliable road car and he showed me some of the throttle body conversions he had done in the past and i agreed to let him convert the car to fuel injection.

[Guest Hooli]

That's a bugger. Nothing good about finding your engine is a lashup to a lower spec than you thought.

 

Still at least you can do it right this time.

 

ETA, It doesn't say enlarged exhaust valves for stage 3 in the advert. Where did you get stage 4 from?

[coalnotdole]

I thought I'd read it in the specialiesd engines era paperwork that came with the engine, but looking at it again it appears that I was mistaken. Stage 4 does have standard exhaust valves...

[Guest Hooli]

Just wondered, thanks for answering.

 

I'm surprised stage 4 doesn't need larger exhaust valves, guess that's proof these engines are restricted on the intake side.

[coalnotdole]

Probably the single biggest thing thats unexpected with the engine spec is the pistions:

 

The seller claimed it to be using a set of Cosworth 3.2 pistions.

 

 

After getting the heads off I remembered that when I took the sump off last year I took a couple of photos of the bottom end...

 

The enlargement shows the following part numbers:

 

FV101/95.3 Points to: http://www.burtonpower.com/accralite-forged-piston-ford-v6-essex-3-0-95-3mm-11-0-1-fv101-95-3.html

 

Those pistons are for a 3.1 but are 11:1 which is very high compression for an Essex. As standard it would probably run at 9:1 and I would expect a 3.2 Essex to run at around 10:1

 

Weather the high compression alone could account for the state of the heads & gaskets is a bit unclear. 

[Sigmund Fraud]

Hmmm... He has carefully avoided mentioning the size of the exhaust valves in the advert !

 

Unfortunately, his description of the engine as a "collection of expensive performance parts bolted together" still rings true.

 

Considering what you've found so far, perhaps it's a good idea to measure combustion chamber and piston top volumes and calculate a static ratio yourself. You may well find it above or below 11:1. If the ratio was too high, I would expect clearly visible detonation damage. Unless the engine management system has been running the engine too rich to defend against that, which could explain your findings ?

[Bren]

Interesting thread - I have seen less sealer in a bathroom.

[tooSavvy]

Interesting thread - I have seen less sealer in a bathroom.

Buying a motor '@£spec' and then stripping it and finding x£ parts + slapdash assembly is a downer.

 

I picked up a 930[sunbeam 1litre] engine for free... Stripped it, took the pistons/rods around to a 'boring shop', nr Durham, and said 'bore this IMP 875 block till these fit, ta!'

 

Lashed it all together (with a Talbot 930 h/g) & it went like a train

 

... just lucky, I guess...

 

 

TS