MG Sports Cars

Hi,

It’s my first post here, fantastic web site!
I am carrying out my first ever V8 conversion on a 72 BGT and have decided to
go for a 4.0 Rover V8. Has anybody done an EFI (Gems) conversion with this engine?
Looking at the web I have not seen any of these as most use a carburettor and distributor
conversion.

Any help would be appreciated.

Regards,

Kevin

Kevin,

Presumably you have done some investigation and realise that to fit the rover V8 in a 72 shell does require quite a bit of modification to the engine bay and steering. The 75 and on cars are almost a bolt in.

Re your thoughts on the engine, you may or may not have heard that the 4.0 and 4.6 engines suffered fron block cracking behind the liners and this results in liner slippage and pressurisation of the cooling system.

Any of the later 4.0/4.6 engines being boughtsecond hand should be treated as suspect unless it can be proved it has been pressure tested and is ok.

Personally I would use a 3.9 with hotwire injection and convert it to Megasquirt which means you can get rid of the airflow meter and have full programmable fueling and ignition. The Gems system has it's ECU set up for emissions and runs lean which is not good if you want to modify the engine for a bit more power and the Gems plenum will not fit under a MGB or MGRV8 bonnet. They can be chipped but it's very expensive, approx £800 + setting up, a MS2 V3 will cost under £300 so no contest.

If you need any more information including sources for an engine and the EFI don't hesitate to ask.

This comprehensive article will explain it all although there are now more versions of the rover V8 available and cheaper.

[www.mgcars.org.uk]

Kevin. ( Talking to myself again.)



Edited 1 time(s). Last edit at 09/01/2009 10:38AM by castlesid.

Okay, for the fun of it I'm going to play devil's advocate and disagree with everything Kevin Jackson just said. Why not?


Kevin, if your Rover 4.0 came out of a running vehicle then cracks in the block are unlikely to be a problem for you. Period. All this talk you hear about cracking and porosity is just idle fear-mongering. There are lots of 4.0 and 4.6L RangeRovers motoring happily about. Your MGB is so lightweight compared to a RangeRover that you'll never really stress the engine. With its four bolt mains (etc.), the later engine is actually a stouter motor.

The GEMS-vintage intake manifold, plenum bottom, trumpets, fuel rail, and injectors are all pretty much the same as the earlier 14CUX system. The plenum top is taller and boxier, but it can still be cut down in height. I have both systems here (in storage) and the two plenum tops are clearly interchangeable, so you could buy and use an earlier plenum top on your 4.0 engine. (These parts aren't hard to find on eBay.) Photographs and measurements of the two plenum tops, side-by-side, appear in this thread: [forum.britishv8.org]

Kevin has warned you that the GEMS ECU is set to run lean. Big deal! You're going to throw it away anyway, right? You're going to put a MegaSquirt controller on this puppy, right? When you do that, you can map the mixture however you want it.

What Kevin Jackson missed is that crank-fired ignition is a significant technical advantage over using a distributor.

Curtis,

We are not far apart except on opinion on the late block problems, in the uk loads come up on e-bay with "suspected" head gasket problem which in reality in most cases is a crack behind the liner.

I also said that if he really wanted to go with a late engine to make sure it didn't have a problem.

We basically agree on the EFI and yes if you get the gems engine and EFI you can swap the plenum for a 3.9 which will fit under a RV8 hood/bonnet without modification, and I did say the Megasquirt would control both the EFI and ignition.

Regards,

Kevin Jackson.

Gents,
Thanks for the replies.
Kevin- I am aware of the mods to the car, I have read the books and now have all the parts to carry out the modifications (at last). The car is going to be restored so the bulkhead ect will be changed to accept the engine, steering rack ect, rubber bumper cross member.
I have read about the bock failures, as the engine is going to be overhauled I will have this pressure tested and if it fails, then I will have to get top hat liners installed. The engine was a bargain off eBay (accident damaged Range Rover) so I will have to take a chance. I have been told that this is the best engine due to the Cross bolts and extra strength. We will soon see
Few questions on the engine fitment-
1. Have any others machined the plenum to fit under an RV8 hood? I have read about the hot wire system in the books but not the GEMS plenum.
2. Will the engine fit with its current front cover/ longer crank&pulley? Most seem to use a P6 front cover and convert this to carb? Or the Range rover set up but this is very close to the rad.
3. Will the engine fit with the current oil filter set up or is there a modification as per the 3.9 systems with the remote take off.
Ideally I would like to retain the EFI system but if this is too difficult then I may have to change over to carb and distributor.

Curtis- Thanks for the thread, I have been looking for this but could not find it. Did Michelle ever mange to fit the plenum or was the 3.9 plenum used in the end?
Thanks again for all the advice!

Kevin,

Good to hear you have done your homework and have a good understanding of what is required.

If the 4.0 came out of a crashed vehicle then there is a lot less risk that the engine has a problem so you should be OK.

To answer your other questions.

Yes you will need a remote filter set up as per the factory V8's V8 Conversions normally have them in stock.

Re the Front cover, space is very tight and most earlier conversions have use the P6 or better the SD1 front cover with a P6 water pump and P6 front crank pulley.

There are obvious advantages in using the 4.0 front cover in that you have the crank driven oil pump, and do not have to modify the distributor body to maintain drive to the early type oil pumps as with the P6/SD1 front covers.

Your main problem is probably going to be finding room for the serpentine type pulleys and possibly the height of the front cover and water pump which why Rover used the earlier set up in the RV8, you will need to measure it all very carefully, a MGC bonnet may provide more height clearance at the front. You may be able to remove any redundant pulleys to give more space.

V8 Conversion have locator brackets which move the anti roll bar forward to improve clearance.

Re the gems, easiest way is to swap to a 3.9 Plenum.

You mentioned swapping to a rubber bumper crossmember which I wouldn't recommend, as to get the correct ride height at the front you are forced into using 1 1/2" shorter springs which reduces the suspension travel and can make the front end somewhat harsh with increased risk of bottoming out.

I would stay with the chrome bumper crossmember and modify the pinion shaft with an additional UJ down by the rack, you have got to do the bulkhead mods to install the cone and UJ from rubber bumper car anyway and having a UJ at the rack end solves the usual alignment problems, a friend has this set up on his roadster and I've never been able to get my steering as light and precise as his.

Do you intend to modify the engine, for road use only, using a pair of stage 1 heads can yield an additional 30 + BHP and make for a much more lively and free revving engine even without a change of cam, a decent road cam could find you another 20 BHP

I can point you in the right direction to source good quality tuning parts a reasonable prices if required.

Regards,

Kevin Jackson.


Picture shows factory set up with a SD1 front cover P6 pump remote take off for oil filter and P6 alternator cradle for smaller dimensionally alternator. and P6 style front pulley.



Edited 1 time(s). Last edit at 09/02/2009 07:26AM by castlesid.

Kevin,

One other point I forgot to mention, if the engine came out of an automatic gear box car then the trigger ring for the ignition will be lost when you convert to a manual flywheel unless you can find a manual flywheel for a 4/0 or 4.6 if they exist also R/R flywheels are extremely heavy and not what you want with a sports car.

Easier to get a SD1 flywheel and then fit a trigger wheel to the rear of the front pulley and trigger the ECU from there which will be simple if you decide to use a Megasquiret ECU, all parts are readily available.

Kevin.

PS I do have a spare SD1 flywheel and clutch assembly which has only done a 1000 miles.

Quote:

Have any others machined the plenum to fit under an RV8 hood?

This part is easier to clamp to the table of a milling machine... you can take some meat off both the top and bottom surface.




(photos from this article)

I've never understood why someone would swap to a rubber bumper crossmember either. In addition to the points KevinJ made, it also seems to me that the shortened springs required to get ride height back to chrome-bumper height would cause bump/roll steer problems.

There are lots and lots of nifty tricks in our How It Was Done section. For example, if you're not set on retaining the MGB steering column, one trick I really like is moving the upper steering u-joint to the interior side of the firewall as done routinely by Ted Lathrop [1] [2] and also by James Bowler. [1] [2]

Curtis, do you have any idea where James got his spherical bearing (part number would be phenomenal)? This might also be a great replacement for the stock TR7 bearing which is failure prone.

Jim

I don't know... but James is pretty easy to reach. He might even have a spare handy that he'd sell.

I have a 4.0 with the transitional front cover- gerator oil pump, reverse rotation water pump, but WITH a dizzy. This is installed in a 1978 body with a 1971 front cross member, with a stock hood. I am using a 4.2 plenham, same as a 3.9, that has been shortened in 3 places, base, trumpet section, and top.

This required a slight relocation of the steering rack to clear, and spacers under the sway bar. Curtis can probably point you to pictures on the V8 News site.

Jim Stuart
1966 MGB 4.0

1974 MBGBT Buick 300

Thanks for the advice so far.

Are we saying that the front cover on 4.0V8 is a non starter? Is this due to the length or oil filter location?

Ideally I would like to use the coil pack and EFI set up as the ecu does all the work.
The question I have is -
1. Does it fit in the engine bay and will it foul anything. I know that the RV8 uses the cranked roll bar which may help.
2. The plenum is square and may need more milling work to fit, but would a MGC or RV8 bonnet fit/ help.( not sure which bonnet is taller?)

Most conversions with the 4.0/ 4.6 engine that I have seen use the carb or older hot wire system off the Range Rover.

This is the dilemma I now have, Hot wire EFI, carb& dizzy or hopefully the complete GEMS kit.

Nothing is easy but that’s the whole point of doing this and not a Kit Car.

Kevin,

"Are we saying that the front cover on 4.0V8 is a non starter? Is this due to the length or oil filter location?"

No thats not the problem as with any front cover you will need the remote filter set up.

The roll bar can be moved forward with the adaptors from V8 conversions.

The main problem is the depth of the 4.0 front cover with the serpentine belt arrangement which has deeper pulleys.and you only have limited space in the B with the engine in the standard location between the front of the engine and the Radiator and crossmember.

The R/Bumper crossmember does give more room but if I did mine again I would rather notch the crossmember for clearance than use the rubber bumper one.

I don.'t have a dimension for the depth of a 4.0 front cover including crank pulley, if you could measure yours from the front face of the block to the front of the crank pulley that would give us something to work from.

As you are using a chrome bumper shell it may be that you can cut the fire wall back a bit more and set the engine a little further back if necessary but this will entail moving the gearbox crossmember further back as well.

Which gearbox are you intending to use and have you thought about the flywheel and trigger ring problem I mentioned?

Kevin.



Edited 1 time(s). Last edit at 09/03/2009 06:24AM by castlesid.

Kevin,

Thanks for the reply, so it is the pulley set up that will be the issue due to the serpentine belt system?
1.Can a different pulley be used on the crank ie a P6 / Range rover item or custom pulley.
2.Will this affect the engine balance if done?
3.Is there a remote filter option for this engine, I have one already for a 3.9 engine but not seen this done on the 4.0V8?

Re cross member the conversion book said go rubber bumper set up, so after 4 month searching I now have all the bits. The reason for this was that it was easier to fit the engine in with the lack of room available.

I will check the dimensions of the pulley next week when it arrives, keep you posted.

Re gearbox ect. Going to use one of the better suffix LT77 units as I am not going to increase the power beyond 200BHP, been told that it is not worth the extra money for the R380 unit. I don’t mind moving the cross-member back as I need to replace the floor pans, sills ect, ect..... (Oh the rust!)
Looking to obtain a 4.0 Flywheel and then look at the trigger set up (was not aware of this when I first bought the engine)

Its early days on the engine as I have to get the shell up to scratch first, so this is why I am doing my research so I have something to do over the winter months.

Kevin

Jim Stuart wrote:

Quote:

This required a slight relocation of the steering rack to clear, and spacers under the sway bar. Curtis can probably point you to pictures on the V8 News site.

Certainly! This is such a wonderful car: Jim's HIWD Write-up

A few specifically relevant photos:









(Jim can clarify... but I think he went to a different routing of the serpentine belt and a different upper radiator hose installation after this photo was taken.)

Hi Curtis,

Thats fantastic news! So the front cover/ Oil filter will fit. Was there a reason why Jim put the hot wire system on the car and not the GEMS unit?
Kevin mentioned about the Flywheel trigger, is there anything elese that might come up and surprise me with the GEMS system you could think of?

Looks like there is light at the end of the tunel!

Thanks again for that!

Kevin,

If your shell really needs all that work it would probably work out cheaper to find a sound rubber bumper car and convert that.

Theres quite a few coming up on e-bay and £1500 would probably buy you a clean solid car as a base for the conversion.

If you can find a 75/76 with tyhe original type dash with the V8 size gauges you have a much more authentic car as this is basically a V8 shell and you only have to change the rad mounts to the forward position.

Kevin Jackson.

I used the hot wire because I understood how it worked and I could use a distributer. I still have have not figured out the crank fire.

This later front cover has so many advantages with a much better oil pump for starters. Some of the pictures Curtis put up were early in the car's life when it had a carb. I always used the later front cover, but first it was a 215 Buick with a carb, then hot wire, then a 4.0 with hot wire.

Mounting brackets for a GM alternator and a Sanden A/C compressor are available from D & D Fabrications, as are the pulleys.

Kevin,

The front cover in Jims car is what is known as an intermediate cover which has both the late crank driven oil pump and provision for a distributor.

Just done a bit of research and it appears that the 4.0 front cover may be 2"-3" less deep so will make life a bit easier.

When your engine arrives, if you can measure the depth from the front of the block face to the front of the crank pulley, I can compare with mine and see how much space you have.

The 4.0 engine also has a sensor on the front cover for cam position + the trigger wheel on the flywheel, but if you intend to use the Gems ECU you could fit a trigger wheel on the back of the front pulley but it may have to be slightly different than the standard 36-1 wheel used with most aftermarket ECU's

I don't think this will be a major problem and if you contact Trigger Wheels who do rover specific products, i'm sure they will be able to help.

[trigger-wheels.com]

Regards,

Kevin Jackson.

Kevin,

Thanks for looking into this for me. I spotted the dizzy and know that these covers are rare( no chance of these coming up on eBay!). Hope the one fitted will fit.
Looked at RPI engineering and found out that I will need the engine ECU which came with the car as they are engine specific!!! (hope it has not been sold yet)

Engine is hopefully arriving Thursday so will take some measurements.

I will have a look at the auto flywheel and see what it has fitted and how this will fit on a manual flywheel, good web site you sent me.

Keep you posted.

Does any one know which bonnet is taller MGC or RV8?