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Stage II tuned engine problems


DocDelete

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It's clutching at straws time here.

I find myself in possession (long story) of a 2.5 engine that was rebuilt to so-called Stage II spec by Jigsaw Racing. However, it's always had a bit of a subtle tapping noise in it, and after 2000 miles I've decided to strip it and examine the thing.

The tapping isn't from the top, and when using a stick to sound out it sounded likely from the cam area. Anyway I've stripped down to the block, removed the sump, had a good squint. The wear pattern on 8 cam buckets looks circular and even, however, 4 have a straight line on the face, and uneven wear to the sides - so I'm guessing they've not been rotating well if at all. Possible noise cause? I hope so, the next bet might be sodding gudgeon pin?

Anyway, before I rebuild and plug this into my PI, I thought I'd better check the cam spec. Jigsaw provided me with a copy of their original bill of sale, and I've got their engine spec sheet (for what it's worth). However, Mark at Jigsaw says their build records have been lost and he can't tell me the spec of the cam!!

Does anyone else have a Jigsaw Stage II engine, can anyone shed any light?

My primary concern is that if the cam has too much overlap then I'll be heading into trouble with the PI and vacuum levels.

Cheers, Ken.

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Mark will usually build stageII engines to a Customer's requirement, so it the camshaft that was actually used could be whatever the original Customer asked for.  Have you any way of contacting the original purchaser and asking them what spec they asked for ?

Failing that, you could measure the cam timing and lift and then work out what cam it is.

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If you got it to that stage (!) of disassembly, then how about measuring the degrees on the cam shaft?
Protractor on the front, dial gauge on one of the cam followers, with dummy push rod in place.
Measure the lift/degree of rotation and the degrees between the peaks of exhaust & intake on one cylinder - all the rest should be the same.
Long job, but you can then compare with others.

Good luck!
John

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Fancy that somebody is having problems with a [removed at posters request] engine  ;D
Mark also destroyed the records from my engine! he said he does not keep them long! (Convenient)

Anyway Doc where in the country are you? I have a set of dial gauges that you can borrow if you’re nearby!
Alternatively on the end of the cam there should be numbers stamped into it this number may id your cam!
What are the valve clearances you have been given?
I have heard Mark uses German cams made for him by Bastuck but you never know!
The only way I could be sure of getting the cam I wanted was to strip and fit another!
Rob

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Thanks to all.

Bobbyspit - the problems with this engine are best left to 'stories down the pub' - suffice to say there were some shocking elementary component probs that I have discovered, particularly in the area of the rocker shaft.

I'm located in Solihull FYI.

The cam has a 300 scrawled into the end, with 'DD1E' stamped in. I doubt any of that sheds any light.

I'll try measuring from the cam, when I get time. It's all a bit here and there right now, basically 30-60 mins per week tops.

Ta, Ken.

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DocDelete wrote:


I'm located in Solihull FYI.

The cam has a 300 scrawled into the end, with 'DD1E' stamped in. I doubt any of that sheds any light.

Ta, Ken.


300° high performance camshaft, timing 47/73 83/37, stroke 8.22 mm, recomended for race and rallye engines !

You are a little far for me to make a visit!

Looks a little overcammed! for regular use! seems like simalar problems as I had with my [removed at posters request] engine! well I hope you have better luck than I did! Cams are available on Ebay and they come up quite often, it might be worth keeping a look out!

Keep us all informed please!

Rob

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Thanks Rob, the engine that's currently in my PI is good and strong, 170psi compression on all cylinders, sub-50k engine. The thing that makes the Jigsaw engine tantalising is the balanced 'business end' and gas-flowed head.

'overcammed' is right: it was running on twin HS6s with a 2500s intake, and rich needles. My guess is that fuelling would be optimum at race/high revs - so running rich all the rest of time, not appropriate for road use methinks. God above knows why the previous owner requested this (maybe he didn't) for a road car.

My thinking is now turning to using the regular 132bhp PI camshaft from the old engine, after checking pushrod lengths ;)

As I say, progress will be slow, but I'll post an update or two.

Cheers, Ken.



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Thanks for the comments PrecisionEngineer - but if you scan the thread you'll see I already have the engine - no money spent.

The previous owner went on a round-world holiday, sold his house - and being utterly p*ssed off with his car he gave it to me for a few beers. 18 months previously he'd spent over £5000 with Jigsaw - the engine alone cost nearly £3000. God above.

So, I have all the bits - the only concern (apart from the tapping from within the block) was the profile of the cam, being too hairy to successfully bolt-on my existing PI gear.

As far as spending money on cars is concerned, my guess is that I'm tighter than most. If I didn't already have the bits, then I wouldn't be doing any engine work. I'm not even keen on shelling out on a gasket set to stick this lot back together!!!! ;))

All the best.

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DocDelete wrote:

So, I have all the bits - the only concern (apart from the tapping from within the block) was the profile of the cam, being too hairy to successfully bolt-on my existing PI gear.


"Pi gear" - just that cam shaft, or is fuel injection a possibility?   I'm sure that Malcolm Jones at Prestige would setup the M/unit for you for such an engine, though if you don't intend to race, a modern EFI set might be better.   Or if you do race - no restrictions in the CSCC 60's series, unlike the old TSSC/TRR one.

John

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JohnD wrote:


"Pi gear" - just that cam shaft, or is fuel injection a possibility?   I'm sure that Malcolm Jones at Prestige would setup the M/unit for you for such an engine, though if you don't intend to race, a modern EFI set might be better.   Or if you do race - no restrictions in the CSCC 60's series, unlike the old TSSC/TRR one.

John


I've got a complete running 1970 PI, and need to revive the engine bay. Having this Jigsaw lump sitting here is a tantalising option, but with the PI camshaft. So, the injection gear is standard off my car, and the MU was set-up already by Malcolm to allow for a 6-3-1 manifold and better breathing. Soooo, in theory, it should be as plug and play as it could be - and a nice warmed up road car.

Modern EFI - tempting, but even if I wanted to part with the dosh that a basic DIY megasquirt would still cost me, I'd spend it on a better summer holiday ;)

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Right chaps - small update.

I've summarised my 'intentions' such as they are on my blog at
http://www.davidson-igd.co.uk/solarplexus/?p=390 with some pics of engine guts for those who like metal porn ;)

Now, remember I want to do this as cheap as poss, hopefully only buying some gaskets - so bear this in mind when reading the following:

The Jigsaw engine has a fully-balanced bottom end, 'improved' rocker gear, unleaded and flowed head, BUT it's a MM 2500s engine as a base! So 8.5:1? Compressions came out at 155psi per cylinder. Let's also assume I'm ditching the lairy 300deg camshaft!

My PI engine has 44,000 miles on it, seems okay. Compressions come out at 170psi per cylinder. It's a 9.5:1 engine.

The billion dollar question - 132bhp PI cam in the Jigsaw engine, or leave the PI engine as is. I've heard tell that the 132 PI cam doesn't work too well in a 8.5:1 engine. But then there's the temptation of a balanced engine, spinning well ;)

Opinions count! You chaps are far more experienced here, and your even your 'bloke down the pub' comments are valued ;)

Ta, Ken.

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We've recently had an interesting discussion elsewhere about raising CR. Seems the sensible thing(and very cost effective solution) would be the PI cam in the Jigsaw engine, with some careful measurements being taken to workout the correct CR and get the Jigsaw head skimmed.
Coould you post some more details of the jigsaw head? depth and casting numbers would be good. Any pictures of the combustion chamber?

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GT6boy wrote:
We've recently had an interesting discussion elsewhere about raising CR. Seems the sensible thing(and very cost effective solution) would be the PI cam in the Jigsaw engine, with some careful measurements being taken to workout the correct CR and get the Jigsaw head skimmed.
Coould you post some more details of the jigsaw head? depth and casting numbers would be good. Any pictures of the combustion chamber?


Okay GT6boy,

Numbers of the head from left to right...
V3288 - 313248 - 34 - then on the flat surface: RB119 219016 - 3

The height of the head from block face to rocker gasket face is 89mm - here are a couple of pics of the combustion chambers...





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Don't know if that's recession, according to Jigsaw it's supposed to be a so-called 'unleaded' head - and only 2000 miles since the engine was supplied 'as new'. However, it was running rich beyond belief - that bl**dy camshaft and megarich needles in the SUs.

I started to wipe one of the valves, and with a little effort (WD40 on a rag) it looked like it would come up clean and smooth (not pitted). The soot is still gum-like - it's that fresh!

3.475" approx. 89mm, so that checks out. Confirms the 2500s credentials, and 8.5:1 CR.

I'm beginning to think I'll mate the balanced bottom end to my existing PI camshaft and cylinder head, with just a decoke to that head.

Any more pearls of wisdom anyone? I'm enjoying this.

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Oh dear. That head looks a little challenged as is. What about any work done 'gas-flowing' on the inlet/exhaust ports?
The picture emerging of the Jigsaw engine as a whole is a less than flattering one. To be honest, there seems to be more negatives than positives- the mismatch of components by who-ever built it has left a real question mark in my mind as to the quality of their entire engine re-build :-/?
I certainly wouldn't fit another engine in my car until I had a clear idea as to it's exact specification and standard of build :).


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Hard to tell in those photo's  :P

But has the areas around the sparkplugs been 'tidyed' up with a die grinder? and on the other side of the combustion chamber?

A standard 2500S head is 3.475 deep, the compression ratio will be even lower than a standard 2500S engine. The combustion chamber looks like the modifications suggested in Vizard's book.

I would clean that head up; see if it has had inserts and take it from there.

ps yes the PI head & cam are a better bet.

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According to Jigsaw's paperwork here's the stuff done to the head...

Skim head to raise CR (**hmmm - at bang on 88.6mm it doesn't appear to have been done**)
Port head, gas flow, measure and equalise combustion chambers
Equalise inlet ports
Match inlet manifolds and gaskets and dowel to head
New unleaded valves, seats, springs, bronze valve guides
Recon rocker shaft

...I'll bang up some pics of the ports tomorrow.

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Looks like it has had some work done in the chamber.  The edges have been taken off the squish ramps and the area around the plug.  Pic below shows the shape of a standard chamber (2.0L but much the same).

With that much material removed and the valves cut really low the compression ration will be VERY low!  Not a great bit of work IMO - detuned from standard I'd say.

Odd thing is that the 219016 head normally has smaller exhaust valves and thus a bit of a gap between the valves.  That hasn't.  2nd pic shows a 219016 head with original size valves.  It has also had some work.

Nick

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Good point Nick. I can see why someone would want to smooth the 'hard' edges in the chamber, but not proceed to take them out to the full extent of the tangent. This *is* a 2500s head, so they've enlarged the exhaust valve, the seat, and therefore presumably the immediate opening into the port.

So, we've discovered it's not been skimmed much, if at all, *and* the combustion chamber has been enlarged. Intuitively I reckon we lose more in lower CR than we gain in gas flow.

Isn't the 2500s head supposed to flow better as standard anyway? So any improvement was always going to be marginal.

More pics later horror fans!

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