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opinion of stag engine options


cowman

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Hi, as ive recently sold my mk1 PI saloon recently im after another Triumph project here in OZ.

Stags have always been high on my list but the engine has always been a concern for me with all the horror stories about overheating/head gaskets.

Probably made worse as i live in a particually hot area of OZ with large distance club runs the order of the day.

Is the fix for the 3.0 more simple these days? 12 vane water pump, thermo fan/s and regular maintenance (common sense) the answer?

I have also looked at a stag with a 4.4 Leyland V8 that is a very nice car. It retains the original manual overdrive gearbox and diff.
I have been told though that the diff ratio would need to be much lower (around 2.8) due to the low rev / high torque compared to the original V8. Does this make sense? Has anyone done this or similar  conversion and have opinions?

Any help appreciated.
Thanks, Glen.

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Just some semi-random thoughts...

Of the two you mention, I would rather have the leyland if the conversion has been done neatly (although to be honest I'd rather have a Landrover 3.9 or 4.0 than a P76 motor, just for the easy EFI and the more compact shape).

Mine had a leyland (before I owned it), now it has a 4.2 litre Rover V8. It does feel a little revvy sometimes but it is not that bad; I do think 3.7:1 is too high but I definitely wouldn't go as low as 2.x :1, I would look at 3.45 :1 (triumph saloon or bmw), (or possibly a 3.08 :1 commodore IRS diff ..?). Mine has a toyota five speed though. I think you could live with the stock diff gearing as long as you needed to, it just means you'll be up around 3000rpm at 110 km/h (very rough guess, the true figure can be calculated). The thing is you'd need to drive it a while to decide anyway. If it just feels a bit lively and Datsun 240Z-ish with the 3.7:1 that might suit you once you're used to it.

As for overheating, I believe either motor can be kept cool with a few sensible steps - a good quality 16" electric fan and a chin spoiler for starters. Airflow through the radiator without a front spoiler is very suboptimal imho, you can see that just by looking at it but there are also some reports of people who have measured airflow which confirms this. Plus of course making sure the original cooling stuff is in good order.

I don't have direct experience with the 3.0 triumph motor but there are people running them in hot parts of Australia without trouble.

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Thanks guys,
here are some pics of the stag with leyland v8, im more tempted with this as the body/paint work is better than the other two triumph engined stags ive looked at so far in my budget.

I know it will reduce the value by not being original but i guess thats why its in my budget with a good body compered to what else i've seen.

It sits at around 2,850 rpm at 100kmh so your calculation is pretty good. The current owner is unsure of the diff ratio but presumes its standard stag.
I assumed the stag diff was the 3.45 from the saloon.
I didnt notice any problems on the test drive but that may be because i was simply listening to the excellent sountrack from the exhaust!!

This car has a 10" thermo fan fitted and larger radiator according to current owner. He has done about 200 kms in the last year only as he has finished a show condition stag a few months ago.

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I'd definitely go for the P76 Leyland-engined one. I love the sound of a Stag on the prowl, but the original engine has more compromises than I'd be prepared to live with, such as the position and sealing of the water pump. The Leyland engine will still need a good radiator mind, but the consequences of a meltdown won't be as severe. On long runs I often noted that while PI, TR and madder small chassis Triumph owners compared top speeds, Stag drivers compared temperatures.

Apologies to the UK backbone of this board, but you have to experience how hot inland Australia gets in summer to believe it, and I don't think Triumph designed Stags to keep cool in 40+ degrees. I just finished an 1100km drive, and even my modern Mitsubishi 4WD made evil gurgling noises whenever I turned it off. Today was just stupidly hot, and not Triumph weather.

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The Leyland 4.4 is from a car called a Leyland P76. It's a Rover V8 with more stroke, with the heads spaced upwards. It's generally accepted now that this was not the best way to get more capacity, so a Land Rover/Range Rover 4.0/4.2/4.6 is probably more desirable overall.  But when all you could get in the Rovers was a 3.5 the 4.4 was a very, very popular swap.

If it only has a 10" fan, wow. You can fit a 16" in front of the radiator and the difference in airflow and cooling would be out of sight

If it's not too expensive and looks good I would grab it, the engine bay could be made to look very nice too if you were so inclined. It looks a LOT tidier than mine did, and mine unfortunately was done in a way that requires a bonnet bulge.

I would find 2850 at 100 bearable I think. Slightly bigger tyres and it could be 2800 instead :)

Get rid of that corrugated hose though, what a bad idea. And sorry but lol at the two pressure caps, if I were having a Richard Dawkins moment I would say that they look like proof of evolution rather than intelligent design :)

Sorry to blather on, nobody around my house wants to talk about Stags with me.

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The British Leyland small block V8 was also a pushrod OHV engine, however it was an all alloy block like the British Rover V8. Unlike the Rover V8, the British Leyland V8 had a 60 degree bank and a capacity of 4.4L. The motor was originally designed and fitted to the Leyland P76 sedan, although due to its light weight and narrow bank, has been used by some street machiners in vehicles that would normally be powered by I4 powerplants. - http://www.wheelsofitaly.com/wiki/index.php/V8

http://en.wikipedia.org/wiki/Leyland_P76

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Errm, I've seen a couple of stripped P76 engines, and can promise you they're a 90 degree V! The Wheels of Italy page is interesting but that gem of information is incorrect.

The 4.4L engine was an Australian budget stretch of the Rover V8, and they didn't change any more than nexessary. P76 heads are the same as RV8 for example, and a lot of parts are interchangeable, but the longer stroke and greater deck height means that if you want to use a Rover or Buick 215 inlet manifold, you need to make up some spacers to fit between the heads and manifold faces.

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Yeah, selling the PI could be something that i regret latter on but its gone to a really nice guy over in Andy Thompsons part of the world in Perth.

The sound of this stag is simply fantastic - it has extractors and a brand new exhaust system and produces a much deeper growl than the stag engine.
This is the part where the heart cannot over rule the head and i have a long term stag owner form the Victorian Triumph Club going to have a look for me for an unbiased opinion.

When you talk about heat, today is typical of the last 4 months - 43 deg C in the shade. If i still had the Saloon i would have had a club run today (Australia Day)of about 350kms. Not once did that saloon even look like getting hot on days like that.

On a recent combined state triumph club run we had 14 triumphs of which 7 where stags - the only topic of conversation for the satg owners with original engines was engine temp - this is what makes me gun shy and probably for no reason.
Only one had any issues and was soon rectified.

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My Stag copes with + 40 just fine especially on an open road but also in traffic with the aircon running. The key is a well built engine and a good rad. That said temp gauge paranoia is omnipresent with the original V8.
The key to a Rover or Leyland V8 conversion is making sure that they were done to a high standard not a S/H uncertain heritage V8 bunged in without any thought to future serviceability/access to tricky parts - ie cooling, exhaust manifolds, WIRING , PAS , DIFF.
A lot of conversion are RIGHT in this category as owners bankrupted by unsuccessful Triumph rebuilds try anything to get the car mobile LOL
However good coversions are great. Bear in mind  that a Stag V8 loves to rev and is geared for an engine redlined at 6500 whereas a Rover V8 is all done by 4500-5000rpm

Personally I would try and get a 3.08 diff in a 4.4

Oh and Stag diff (LD prefix) is 3.7 . You can fit a 3.45 from a saloon but you will need a Mk1 back casing as a genuine Stag rear casing has different bolt spacing.

100 kph in OD top is 2500 rpm in my Stag (3.7 diff and 195/70 x 14)

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  • 5 months later...

Stick with the Triumph V8, flush the engine, then buy new hoses, only ever put glycol 50/50 coolant in never never put cheap methanol mix in, then re-core the rad replace the pressure cap (Triumph rad core galleries are too fine and are easily blocked the fine core rad matrix that was fitted to Triumphs was withdrawn in the after market).  someone in the past may have mistreated a basically good engine. If you do that thinking about putting a Buick/Rover V8 will just fade from your mind.

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fit a gm holden 5.7 engine, nice and light, modern yet simple ohv, 350hp as standard, 25+mpg- why would you fit an old heavy underpowered stag engine, or leyland engine? the rv8 is ok but doesn't make anywhere near the efforftless power/ torque of the gm engine. plenty of old monaros or ute out there to butcher!

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xyv wrote:
fit a gm holden 5.7 engine, nice and light, modern yet simple ohv, 350hp as standard, 25+mpg- why would you fit an old heavy underpowered stag engine, or leyland engine? the rv8 is ok but doesn't make anywhere near the efforftless power/ torque of the gm engine. plenty of old monaros or ute out there to butcher!


Thats exactly what I have done wth my 77 Stag, fitted an all alloy 5.7L Chevy LS1. Details are on some of the Stag forums. Turns the Stag from a pussy cat into a monster. Some wont like it but its fun! Spin  :)

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2271 wrote:
Stick with the Triumph V8, flush the engine, then buy new hoses, only ever put glycol 50/50 coolant in never never put cheap methanol mix in, then re-core the rad replace the pressure cap (Triumph rad core galleries are too fine and are easily blocked the fine core rad matrix that was fitted to Triumphs was withdrawn in the after market).  someone in the past may have mistreated a basically good engine. If you do that thinking about putting a Buick/Rover V8 will just fade from your mind.


50/50 is too strong. Anti-freeze has a poorer cooling effect than water. You only need the anti-freeze for its corrosion protection properties in most cases, so going above the manufacturer's (engine and anti-freeze) recommendation of 25% is counter-productive and a waste of money.

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