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bob uk
Unregistered guest
Posted From: 80.6.168.241
Posted on Thursday, 09 October, 2008 - 01:05 am:   Edit PostDelete PostView Post/Check IP

A friend whose has an average E-type Jag recently had engine trouble so he brought the engine in bits to me. Everything was kippered. Plus a cracked block.

So I suggested a used XJ 6 engine. He found a 3.4 and fitted it.

Now you would think that 3.4 instead of 4.2 would make a big difference. No, the car is slightly slower but the engine is much smoother allowing more revs. MPG is about the same.

The car is a 2+2 coupe the least valuable but the nicest to drive.

(Message approved by david_gore)
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David Gore
Moderator
Username: david_gore

Post Number: 840
Registered: 4-2003
Posted on Thursday, 09 October, 2008 - 10:17 am:   Edit PostDelete PostView Post/Check IP

Bob,

Is the capacity difference between the engines being that one is "undersquare" and the other "oversquare"??

Your comment about the smoothness of the engine intrigues me.
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Peter Colwell
Frequent User
Username: peter_colwell

Post Number: 65
Registered: 3-2005
Posted on Friday, 10 October, 2008 - 08:12 pm:   Edit PostDelete PostView Post/Check IP

The Jaguar 2.4 litre. 3.4, 3.8 and 4.2 litre engines were all the same family, based on the same design, which ran from 1949 to 1994. All used the same stroke of 106mm, except for the 2.4. Some used two SUs and both the 3.8 and 4.2 versions used three SUs in the E Type.

The 3.4 used three Weber carburettors in the famous D Type.

The 3.4 was the original and was generally regarded as the optimum model. The later 3.8 produced only 10 more horsepower, 220 versus 210, both at the very high speed of 5500 rpm for such a long stroke engine.

The 3.4 was the base model from which all the others derived, and was considered the smoothest.
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RogerSouthern
Unregistered guest
Posted From: 83.218.3.103
Posted on Tuesday, 14 October, 2008 - 11:28 pm:   Edit PostDelete PostView Post/Check IP

David, the 3.4 engine is almost 'square' and as such was always the smoothest of the XK units. When fitted to the XJ6 it had an extra 500rpm to the red line over the 4.2.

(Message approved by david_gore)
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David Gore
Moderator
Username: david_gore

Post Number: 845
Registered: 4-2003
Posted on Wednesday, 15 October, 2008 - 09:39 am:   Edit PostDelete PostView Post/Check IP

Thanks Peter and Roger,

I was assuming the XJ6 engine was a different engine to the classic XK versions hence my interest in the bore/stroke configuration.

I didn't expect Jaguar to undertake the development work Crewe did on the R-R V8 to comply with the emmission specification changes over the years.

(Message edited by david_gore on 15 October 2008)
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StevenBrown
New User
Username: stevenbrown

Post Number: 2
Registered: 10-2008
Posted on Friday, 24 October, 2008 - 02:26 am:   Edit PostDelete PostView Post/Check IP

The XJ6 used the XK version until 1987. Family was into Jaguars in the 1980's. 3.4 though was not offered in North America. Its kind of a shame in the Americas XJ6/12's, etcetera are hard to find in good working and overall condition. Nice cars when new. From memory and personnel experience driving 4.2L series III as my own vehicle and Mom having a 5.2 12 cyl version. Not much difference between the two in feel. Hard to notice the small power loss with those two, so probably the same with this swap. Add in the smoothness and should be really hard to tell.
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bob uk
Unregistered guest
Posted From: 80.6.168.241
Posted on Monday, 27 October, 2008 - 04:44 am:   Edit PostDelete PostView Post/Check IP

There was also a 4 cylinder version of this engine which was never produced.

The clever thing about the XK engine is that at the time (1948 )no one made a twin cam OHC engine that was MASS PRODUCED thus keeping the cost down.

The 4.2 was the ultimate "stretch" of capacity which made it rougher than the smaller ones.

In the 1800 kg XJ6 it was pushed to give the car enough power.

Jaguar fans well often dispute this but 80,000 miles was enough to wear one out.

Most Jags were sold new to people who kept them only a short while so the the lack of durablity was no concern of Jaguar Cars.

There was also a 2.8 Version which was for Italy until their tax laws changed about 1973.

If this engine was thrashed it gave loads of trouble if driven gently it would burn the pistons if driven with a bit of speeed then it was OK. Usless lump of metal.

XJ are nice cars that were built down to a cheap price.

The best ones are the 3.4 versions. But these are ones that were not fully equipped.

My ideal XJ would be one fitted with the Rover V8. In 3.9 fuel injected guise this engine has more power than the 4.2 and is smoother than a 6. Plus a weight saving.

I did suggest this very engine for the E Type but got told off for suggesting such a stupid thing.

The e type is not as smooth as the XJ so it shows up engine vibs more.

I drove a XJS with a 5.7 litre GM V8 fitted and it was quite fast because the engine had been breathed on quite a bit and the owner reported 400 bhp ( probaly only 300 --I told you a million times not to exagerate )

The 5.3 V12 will go to about 350 bhp with out any problems.

But what is often forgotten is that an engine that produces 350 bhp will use 350 bhp worth of petrol as well.

I have a mate who has a 560 Merc coupe thingy, very fast car but he rarely goes faster than 60mph and accelerates about 0-60 in 20 seconds a 2 litre engine would do the same job.

(Message approved by david_gore)
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StevenBrown
New User
Username: stevenbrown

Post Number: 5
Registered: 10-2008
Posted on Tuesday, 28 October, 2008 - 02:39 am:   Edit PostDelete PostView Post/Check IP

The last from Bob UK very accurate on Jags. I'm also a fan of the 560SL in styling, a modern classic car. Have a 500SL currently. I don't consider either Mercs as fast sports cars because also have 3 Porsche 928's (was 5) and two 944's. The latter are being put into one for a Porsche Club America track toy! Selling the SL and 928's making room for a Bentley Turbo R (future).

My 4.2L 1987 XJ6 would stall at lights. Replaced fuel pump, ECU, spent a small fortune correcting this problem with my mechanics. Was the third owner and had this car in 1997/8. Working in car sales management, so didn't really need a vehicle. She overheated on the way home. Kept driving until the thing stopped running. Left on side of road and called cab. Planned on leaving it and let whatever tow company who removed her deal with disposal. Friend who owned repair shop recognized it and had her towed to his business. Ended up selling it to him for parts.

Great handling and love the styling of the series III. The 5.3 V12 when tuned right are wonderful sedans. They did not sell these in the U.S, so they are rare finds in good rust free condition good running order here. Only sold in Canada and in the 1980's bulk of these only sold well in The Provinces of; Ontario, Quebec, (these two winter and salted roads) and British Columbia (mostly salt aired coastal region), so rust free and well tuned examples again are very rare. In North America the Daimler name is used by Mercedes, so these are called Vaden Plas and the XJ series III V12's sold until 1994 in Canada. For the money it would cost in buying and sorting out one of these or even a 560SL Merc, Id rather buy a Bentley Turbo R......................