The Triumph Dolomite Club - Discussion Forum

The Number One Club for owners of Triumph's range of small saloons from the 1960s and 1970s.
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PostPosted: Thu Feb 04, 2021 3:50 pm 
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Early sprint cranckshafts are crossdrilled and with no effect as these bores are plugged. From mid 1974 all crankshafts are the same. All are interchangeable through the whole range and year of build.

Jeroen
Well that helps date my engine because it has a cross drilled crank.


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PostPosted: Fri Feb 05, 2021 11:33 am 
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Joined: Thu Oct 06, 2011 12:13 am
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Location: The continent
It's purely a production difference. The cross drilled ones were stanpart items. The same as for more parts. The first sprints had stanpart brakedrums and from early 1974 Leyland logo drums made by a different supplier. I do not know the exact dates and if all was changed at the same date, probably not.

For competition purposes I saved all the crossdrilled cranks from my early engines. The plugs can be removed/drilled out.

After mid 1974 these crankshafts weren't normal production items anymore. When you find one in a later engine it's not the original but I suggest you would be very happy with it. It only benefits when taking the plugs out.

Jeroen

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PostPosted: Fri Feb 05, 2021 2:10 pm 
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Location: St Annes on Sea, Lancs.
From the state of the engine when it was reconditioned in 88 or so, I'm fairly sure that the crank in the 78 ym TR7 Sprint was not a replacement: It fitted with the supposed approx. 57,000 miles when I got it. But some of that was on the Belgian Pavé at BL's test track in Solihull (Webb lane or Load lane?) with no protective coatings and equipment to spray salt water into all the soft spots under the body. So that had rotted a bit. But the engine wasn't in too bad a state before the garage it was in burned down.
But I suspect the engine is much earlier than the car it was used in, because these hundred or so CH engines were made as part of the SD2 programme that ended in 1975, and only later used in the production of the TR7 Sprints to keep the 16-valve TR7 in competition when the TR7V8 was delayed.
It's the ancillaries that are special on the TR7 Sprint engine, not the engine itself, so that's not an obvious deduction. But, given this additional evidence of an earlier engine part, It starts to seem credible to me.

I still think that SD2's EFI system (which is nowt like the TR7's) would have made a great addition to the production Dolomite Sprint - supposedly giving about 170bhp at the flywheel:

Image

There's some discussion of the bunging of one of the journal holes on the cross drilled crank here: https://forum.triumphdolomite.co.uk/vie ... php?t=3484
But this, which apparently came originally from Ken Wood, don't suggest this stops the crossdrilling having any effect.

Graham

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The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).


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PostPosted: Sat Feb 06, 2021 12:15 pm 
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I still think that SD2's EFI system (which is nowt like the TR7's) would have made a great addition to the production Dolomite Sprint - supposedly giving about 170bhp at the flywheel:
Talking to Gordon Birtwhistle a couple of years ago, he told me his favourite TR7 was a fuel injected Sprint engined automatic one that he drove and took home as often as he could.

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PostPosted: Sat Feb 06, 2021 2:21 pm 
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Location: St Annes on Sea, Lancs.
There was an early UK spec matt black TR7 David Knowles mentions, and which is rumored to be the only factory injected sprint engined TR7. The one I think that was is being restored I'm told. If there are any pics at all, I think I can pass them to the current owner, and I suspect he'd appreciate it.

Graham

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The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).


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PostPosted: Sat Feb 06, 2021 10:20 pm 
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Location: Christchurch, New Zealand
There have been some interesting comments on this topic of what to do about the wear marks on a Sprint crankshaft pulley.

One suggestion was to find another pulley that does not have any wear marks. I have nothing here amongst my collection of spares. I suspect that I would be lucky to find one elsewhere.

Jeroen’s suggestion that a shortened 1850 crankshaft pulley would provide clean surface is an admirable suggestion but involves some lathe work, something which I cannot undertake in my workshop.

Another suggestion was to weld up the grooves. Some in this country use metal spraying techniques to restore shafts, a process a little outside my budget.

I attempted to purchase a speedi-sleeve this week but there are none available in this country to fit the standard Sprint pulley.

A number have suggested that I reposition the seal in a different place. This seems to me to be the most pragmatic solution.

I have purchased a double lipped seal where the inner sealing lip sits a little further in from the back of the seal. By positioning the seal a little proud of the timing cover case the back lip will run on the unmarked surface between the two existing grooves. The front lip on the front face of the seal will also sit on an unmarked surface.

It should enable the engine to run for another 40 years before it will need to be replaced.

Sometime in the near future, within the next 40 years, I expect the car to be converted to an electric drive and the issue of leaking seals and misplaced timing marks, if a modified 1850 pulley is used, will disappear.

Robert


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