V12 Jag / Daimler engine questions...

I used to get 23 to 24 mpg with my XJ-S. HE engine and stock TH400. Of course the motor was modified: elimination of the Jaguar-always-running-A/C compressor-even-when-the-air-is-not-running and many other things. Many of my mods are listed in the Kirby Palm book mentioned in a previous reply. My V12 was extremely powerful, extremely nice sounding, extremely fast, and the mileage I was getting was up from about 12 mog when the car was bone stock.

At the end of the day this V12 is just another large bore, short stroke 326 cubic inch engine. It weighs a lot and holds a lot of coolant, so mileage when the engine is cold is reduced because it takes a while for them to heat up. One reason the engine could not sustain modern emissions regs.

If you run the engine with a good capacity radiator - a radiator capable of cooling a 400 HP motor - you will be fine.

 

A friend had a v12 Etype 2+2 4 speed. He said the most he ever got was 16 Mpg.

more like 10 to 12 around town.

 

For an early engine / transmission such as this, does anyone know of a repair manual online for this??

For manuals to aquire, which jag year make and model should I use and which manuals would you recommend to make appropriate repairs??

Thanks again

 

As both a former and current Jag owner...I've always preferred a 6 to the 12's. A friend bought a similar Jag engine for $20 for the purpose of turning it in to a coffee table . My preference for a modern 12 is a BMW...E32 engines can be found for reasonable prices depending on where you look (but my E38 is a little more advanced, and fun!).

But the price for yours was right! They can be decent engines when they are correctly tuned and maintained, but as it has been said...be prepared to shell out a few dollars should anything need major servicing. You have a cool car to put it in to, and I'm always a fan of V12's (both my daily driver and current project are factory V12 cars )

 

A rodder here in Australia, Phil Medlin has put one of these motors in a T roadster . Fabricated a twin 4 barrel carb manifold. In 2004 he drove the car from Western Australia to Lake Gairdner then ran it on the salt at 144+ mph. He then drove it home again after the event. Holleys appeared to work well.

http://www.dlra.org.au/2004-03.htm

 

Ive always went by the old saying less is more

 

I think I read every post and I'm suprised that no one has mentioned that those are not SUs but Strombergs (horrid things that burn the piston diaphram with one backfire). If you want to run the stock manifold I would suggest that you get rid of those and get a set of SUs instead, although I believe that with a little ingenuity you could make a much more efficient down draft set-up with 2x4s or maybe a set of six 94s or 97s would look cool in a Graham.

 

Correct . They are CD Strombergs.

 

Here's a jag V-12 w/ 2-4s.

 

Yeah i read through this thread to see if anyone else picked it up. CD's are good carbs though. Save them in case you meet an E type owner who wants to keep his US spec Car stock for shows or what ever.
Think long and hard about installing a Megajolt lite ignition. You can then tune the engine to the Nth degree to make a smooth powerful engine which will eat the the old BW trans.... At least they are cheap and easy to build. I'll put money on those CD Strombergs having one or two broken diaphragms too. Often it was only the reason the engine was swapped out for an SBC. A lot of SBC powered Jags are actually slower than they were stock...something else to ponder.

 

Do you have a link or any more info. on those intakes? I searched Ebay and Google with no luck.

 

Some may love me, some may hate me... I like the engine because it is a unique and pretty engine... I'm not going for speed - so the modifications made are for necessity not power... I will be keeping the engine as close to stock as I can in attempts to keep cost to a minimum.

The engine is being use because it was a "barter" thing... I helped a buddy out with his car, he gave me the engine and transmission assembly (so the price is right).

for the intake... I cut, inverted, and welded... and I'm still narrowing the overall width. I will be posting photos of progress soon and this will better explain the "cut, inverted, and welded" description. I should have asked, but does anyone anticipate major issues from this?

thanks

 

I would like to see the intake when you can.

 

I would really like to find one these 2 - 4bbl. intakes though.

 

I almost made the 2 - 4bbl. intakes, and I figured I already had the Strombergs so why buy more?? The 2 - 4bbl. intakes can be done by taking the drivers front and making it the passenger rear etc. (criss cross the intake manifolds) and cut off the big "mounting boxes" (the part that I flipped in my manifold). Weld them together, do a little trimming, and weld on a mounting plate. Although I make it sound easy, if you can weld aluminum - it is just time consuming but shouldn't be bad to make.

As for what I have done (which is where I am questioning myself), I cut, inverted, and welded the "boxes" that the carburetor mount bolts to and turned the carburetors "inboard". I will be making some "raisers" (approximately 1.5" tall) to give appropriate clearance needed for the carburetors over the intake manifold (as seen in "intake flip2").

Does anyone see issues so far? I don't... which is why I am second guessing myself.

Thanks

 

Only that the carbs may try and scavenge air from each other.
(Bear in mind I know nothing!)

 

Looks like it should work. The A/F mix makes a few turns here and there but shouldn't be any worse than the stocker. Did the stock carbureted version circulate coolant thru the carb. adapters? If so it probably helped keep the mix atomized on the stock intake. Have you given the linkage much thought?

My engine is a fuel injected HE version and I'm still debating on which way I want to go for the induction. I'm hoping I'll get a lead on one of those 2-4bbl set ups. If not I'll fab something up. I actually like TIG welding aluminum better than steel.

 

i saw the intakes awhile back when i was looking for some parts for my gmc v12. i think the guy was using them to install the jag engines in boats, and was located somewhere in florida

 

I have more questions... I am posting 2 pics with numbers on it... I am sorry for the grease hiding the details, but I think you get the gist.

There appears to be two thermostats (A/B #1, #13) Is there a way to combine the two to either have one thermostat or one "upper hose"???

The big reason for doing this is to gain about another inch or so in width. If these are "relocated" then it will affect more things like...

What are the lower ports for (A/B #2, #14)??

There are four covered ports in the center on either side (sorry but there is barely one visible - A #3) - What are these for? Can I tie them in together somehow to improve cooling or clean up the engine "clutter" at all? (See ex1, ex2, ex3 - sorry I don't have higher resolution photos, or I would probably see what they connected).

I am assuming B#4 is to the lower radiator... is B#5 what needs to connect to A/B #1 and #13 and or #2 and #14??

How should I plumb this machine?

Thanks in advance.

 

The HE motors can be cleaned up a lot in terms of plumbing. My memory is not too good on the pre-HE's in terms of details you asked about, sorry, and I don't have one handy to look at.

The stock cars to have an overflow tank that has coolant flowing through it. They also ahve two radiator caps. One is atop the engine and is primairly used to bleed air out of the system. The overflow tank has its own radiator cap and that is used to top off the system. The Jags these engines went into had very low hoods so there was no room for a radiator cap atop the radiator. Since that is not a problem for you, you can eliminate all of the plumbing associated with the air bleeding, and that probably includes the overflow tank, too.

I would recommend running a temp gauge on each bank, at least until you
get things sorted out. The two banks can run at different temperatures. That is a sign of somethig wrong, but you need to know.

It might be cleaner to run two top hoses. Note that you need thermostats with the jiggle pins. This lets the air out. See Palm's book and note the sections on eliminating the one-and-a-half-pass stock radiator.

 

Per our other discussion on the topic, it is probably really tough to get an HE engine to run on carbs. These are high compression lean burn engines that were allbuilt with EFI. The racing V12s were pre-HE (or flat head) engines. You can clean up the wiring and plumbing on an HE so it looks good.

Eliminate the air tubes and plug the holes in the manifolds with 1/4" nail anchors - use the stock orings and a smear of silicone. Split the fuel rail and mount them along the intakes where the air tubes ran. Connect the injectors with short lengths of FI hose. Now the vee is open and the motor looks better. Create a new inejctor harness that routes the wires more neatly.

 

I want to thank everyone for the information you all have been providing me through the forum and in PM's so far... I hope to get more photos soon to show progress...

more to come!

 

I found some interesting photos, so thought I would resurrect this thread.

This is a Jag V12 that belonged to a friend of mine. He invested a great deal of money into building this twin Whipple supercharged Jag V12. The motor - and, obviously, the car - were highly modified to handle the power. I had the good fortune to have had the opportunity to drive this car, and I will say that it was absolutely awesome.

As you can see, good old hot rodding techniques can be applied to any engine. Added value: the hood was louvered!

Unfortunately, my friend passed and I am not sure what happened to the car. I heard a rumor that it surfaced on eBay at least once. I have a feeling that the builder responsible for most of the work on the car ended up owning it. Wherever it is, I hope that it loves on.

 

I finally found the intakes, and added a couple of 450 Holleys among other things. It will probably end up in the Diamond T in my avatar.

 

Very, very cool.

Your motor is a pre-HE, yes? I don't remember.

Make sure that your thermostats are new, that you tested them in a pot of hot water (many defective out of the box), that they have jiggle pins (drill a 3/64" hole if they don't), that you run two temp gauges (one on each bank, even if just until you dial it in), that your vacuum advance diaphragm is sound (can repair it with parts from a SBC unit) and finally that your distributor centrifugal advance is not seized.

Those items account for the vast majority of problems with these engines (they go unnoticed and then the motor overheats and seizes).

 

This motor is an HE. I think it will work with the HE chambers, but the real proof will be known once it's up and running. If it doesn't I'll just swap every thing over to an early engine.

 

I read through this thread with great interest and considering your space problem with the Graham, imagine what somebody must have gone through with the MGB, the Corvair, and the Miata.

Now the Moretti, no way Jose. It was a 750cc or 44 cubic inch short lived Italian DOHC engine based on a Fiat block. I think the whole car weighed around 1500 pounds. Mine was a coupe and looked like a baby Ferrari.

Incidently, I may be the only person in the world to have owned a Moretti and a Doretti considering how few of either were ever made.

 

It will be really interesting to see how an HE motor runs with carbs. You are probably breaking new ground. As you know, the HE motors like very lean mixtures. How are you handling the ignition? Pre-HE or HE distributor/advance curves?

Please keep us informed of your progress as this is really interesting. If you can get an HE to run on carbs, it opens all sorts of possibilities as pre-HE motors are a lot harder to find and come with their own limitations.

 

Are you Sacco or Vanzetti?

 

I re-curved the factory magnetic pickup distributor and removed the vacuum advance feature. I'll experiment with mechanical advance curve to see what the engine likes best once it's installed. Will be using a good ole MSD-6AL as the ignition box. I'll let you know how it goes.