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MG MGB GT V8 Factory Originals Technical - Hotwire efi on factory MG V8

Hi all,

A while ago I bought myself a full Hotwire injection system to replace my twin HIF 6 setup, as fitted to my factory original MG B GT V8.
The plenum chamber was skimmed (through the bottom thread of the stepper motor), the trumpet base and the trumpets were shortened (kept just clean of the threads). After that I skimmed the rest to ease the contact with the fuel rail.
I even skimmed the top part of the plenum; all the "ridges" are off now.
The engine is fitted as low as it gets: the r/h manifold is more or less clear of the inner wing, cannot be lowered any further.
The crossbrace from the bonnet is placed further forward, so it is well clear of the plenum chamber.

Still there is a problem. All is fitted, but the bonnet will not shut. It will close to the first click, after that I can push a bit, but I can't shut it. The front of the plenum chamber is touching the bonnet!
Basically I am wondering what to do now. Any suggestions? Where to take of more material (if any, and if possible?).

Frank
Frank de Groot

Block hugger headers? Had you considered running RV8 style headers? I bet you could get the engine a little lower if you went that route and eliminated the rubbing issues. You could try using a rubber mallet and "ovaling" the fuel rail so you can skim the trumpet stack a little more and get things lower.

Just a few ideas,
Justin
Justin

'The engine is fitted as low as it gets' ............ then you have a thin left hand engine mount - a la RV8 and an BV8 sump with no gap over the crossmember ?
Roger

I don't have a unit to look at but, can you slice-off the offending (I presume), front-corner of the plenum and weld a flat patch over the resulting opening to get more bonnet clearance?
Marc Judson

I don't have a unit to look at but, can you slice-off the offending (I presume), front-corner of the plenum and weld a flat patch over the resulting opening to get sufficent bonnet clearance?
Marc Judson

Frank,

I have a '77 roadster with the Rover hot wire efi fitted under a standard hood (bonnet) using block hugger headers without rubbing. I understand that the manifold was 'skimmed' and the trumpets shortened. The plenum looks stock and does not have the ribs 'skimmed' off. Sorry I don't know the dimensions specifically but the total was about 38 mm. Fuel rail is close but clears. Anyway, it can be done. Good luck.
Edd Weninger

The manifolds are blockhuggers. The sump is indeed the B V8 thing.
There is some space between the blockhuggers and the lefthand wing. Might go and see if thinner mount will fit there.
The idea of cutting of the front offending corner of the plenum is something I might try as well. First I am going to try the r/h engine mount.
Ovalizing the fuel rail is something I will try if everything else fails.

Frank
Frank de Groot

Frank
I can not get the plenum chamber under an RV8 bonnet without the thin L/H mounting and yes the blockhugger is close to the main spar.

Cost aside - the RV8 bonnet receives a lot of attention and could be a plus.

....but then I am not prejudiced..

Roger
Roger

Frank,
If the throttle part of the plenum cover (with water pre-heater removed)is not virtually on top of the LHS Tappet cover you should be able to get some more off the plenum assembly.
I'm not too sure exactly what you've done so I'll decribe what I did and you can pick from that what you like (of course).
I took 16 mm off the bottom of the trumpet tray and 12mm off the top of the same tray. Then took 5mm from the trumpet cover. This gave 33mm and put the throttle part of the cover (with water pre-heater removed)virtually on top of the LHS Tappet cover. I don't know how much you've taken off the trumpet cover and you will have to take this into account as 33 to 34 mm total is all you will get unless you get stuck into the tappet/valve cover (you might be able to remove the ridges. As a guide, the bottom most of the steppermotor threads is about 6 mm in.
In other words if you've taken 8mm off the cover then take 3mm less from either the top or bottom of the trumpet tray, your choice. Keep in mind that if you take 16mm from the bottom there isn't much metal left to locate the trumpets. I used a high grade sovent proof silicon ('grey' grade) to make sure they stayed put. Also although there is certainly sufficient thread to hold the cover onto the top of the tray, you can't afford to overtighten those bolts.
You will need to have the three vaccum take off points on the RHS of the trumpet tray completly welded up/filled, as you must remove the "bumps" on the bottom of the tray. This puts the trumpet tray right on top of the fuel rail (hence the need to remove the bumps). I enlarged and retapped one of the stepper motor mounting bolt holes (RHS top) and screwed in a long threaded vaccum hose take off for the brakes (ie effectivly a hollow Bolt).
I also had to carefully file off the corner of the pressure regulator bracket on the fuel rail (located on the LHS), but you might not have a problem if the regulator is located on the RHS on your set up.
This gave me at least 1cm bonnet clearance , however my motor is located a little higher (aprox 0.75cm) and further back(about 20mm).
Good luck.
Peter

Stepper motorbolt sub' should read LHS top
Peter

I have covered several methods on my website..

http://www.mgbv8.co.uk/fuelinjection.htm

I took 33mm off the centre stack only and left the plenum with standard volume. Using early P6 rocker covers I have about 5mm clearance with water pre-heater removed.
Nick Smallwood

Frank,

My plenium and trumpet base are trimmed down until the inlet just clears the rocker covers.I have P6 (identical to V8GT)rocker covers, these may be lower than SD1's. I have also removed the fins on the plenium, rounded of the edges, and trimmed the front Allen bolts and there is now plenty of room under an RV8 bonnet (I've even fitted sound-proofing and it doesn't rub).

The problem might not be the top of the plenium , prior to shortening, mine touched on the extreme front (Allen bolt heads) and inlet pipe (the rubber tube was right up against the bonnet.

I ended up crawling underneath with a torch and a video camera, it wasn't very sucessful however.

I'm using Clive Wheatley's cast alloy engine mountings, with standard V8 rubbers ( I refused to pay the extortionate price of the thinner RV8 ones)

Lots of people don't like the RV8 bonnet but mine fitted reasonably well and the 'hump' is not so intrusive from the driver's view, and it's virtually invisible to the car in front.(if you don't believe have a look at the cars (including mine) on the V8 register pages).

Mike
Michael barnfather

I followed Nick's steps (as per Rog P's instructions). Thanks for the website Nick; I just couldn't find it again. Should remember to bookmark it.
Peter - removing the vacuum take ofs is one way of getting it lower. This evening I am going to see how it fits now that I've reduced some more of the chambers offending side.
Mike - you are very right with your comment on the allen bolts. These first touched. I will try the reshaped plenum without bolt. After that grind bolts down. The radiator top hose is one of the next problems. It is said that the Hotwire outlet will do, with the addition of a Range Rover top hose. I am not too sure however, and if I do not succed I will put the normal (original) GT V8 elbow on with something like a Kenlowe switch. First try and get the assembly under the bonnet.
I still refuse to give up my bonnet! Not until I have tried everything to get it to fit.

Frank
Frank de Groot

What's so strange here is my motor with hotwire efi fits under the bonnet without any bulges, and without shaving the ribs off the top of the injection. I think maybe there's a better motor mount that you could be using to get the system under your hood. In my case, I used the motor mounts from one of the state side v8 specialists, and machined the bottom of my trumpet stack by 19.05mm and it all fits under. There's a HUGE discrepancy between your height reduction and mine, and mine still fits.

Justin
Justin

No bonnet bulges for me either!Ban the bulge.
Hang in there Frank, you'll do it.
Peter

Frank,

Mountings look like the answer......there must be thinner rubbers available,.... and maybe the engine brackets could be modified......my cast alloy ones could have been ground down a bit I guess......keep at it.

Mike
Michael barnfather

Frank
All said and done - if it doesn't fit, e-mail - I will 'find' you another half cm.
Roger
Roger

Frank,

Rimmer's latest catalogue shows 3 different round engine mounting rubbers.....and they all appear to be different thicknesses......it might be worthwhile ringing them and getting dimensions.

Mike
Michael barnfather

I just returned from my car, and it seems indeed that it will take another mounting rubber. I am not sure if that will lower the block, but it will sure solve the problem I have with the manifolds: one touches the r/h inner wing, the other has some space.

Frank
Frank de Groot

About the RV8 mounting rubbers:
- where can I obtain them (no problem with ordering in the US or the UK)
- is it only necessary for the l/h engine mount, or should I do both?
- Rimmer Bros told me they don't do these rubbers.

Frank
Frank de Groot

Frank

Brown and Gammons for the RV8 rubber (it quite pricey at about £40). You only want the left hand (right is same thickness as MGB anyway).

Geoff
Geoff Richmond

(right is same thickness as MGB anyway).
Beware -- the 1800 mount droops very quickly
Rog
Roger

Around april last year both of the mounting rubbers were replaced. It will be interesting to see how they are; I have not driven that many miles with the car.

Frank
Frank de Groot

Frank,

I am replacing the steering rack, went under the car yesterday, and I have only a little room between the crossmember and sump....,certainly less than 2cm....is your engine as low as this ?

mike
Michael barnfather

Frank,
I think Justin has hit the nail on the head for you. As I recall you have an original V8 car. The motor mounts in the US, not the rubber but the actual brackets, are not the same as you have. Over here D&D and Glenn Towery offer a set that move the motor back and down. If you are still having problems you may want to try these instead. One problem from this would then be the trany shofter location.

Regards,
Mike



Mike

Frank,
I think that Michael Barnfather makes an excellent observation...the clearance between crossmember and sump is the key and will tell you where you should be focusing your efforts?
I spoke with Clive Wheatley before buying his engine mounts and rubbers (which are "sided"...different thicknesses). Clive doesn't have a web site but you can get his details from the V8 Register site...
http://www.v8register.net/subpages/clivewV8offers.htm Pete
Pete Green

Plus my crossmember is off a rubber bumper car....(with the spacers).....I guess the chrome bumper crossmember might even touch the bottom of the sump.

Mike
Michael barnfather

My car is/was an American.(ironic, my car is more traveled than I am!) The top of the engine mount brackets on the rails are level with the top of the rail, given the position of the steering rack shaft I would imagine that they would all be in much the same location.
The steering rack not the cross member was/is the main problem, being a little close to the bottom pulley, and much higher than the crossmember. After that the actual width of the motor would be the next impediment,as in fitting rubber mounts plus engine brackets plus engine in between the brackets on the rails. The sump/crossmember is the least problem.

You're going to have to weld up those vacuum takes offs I think Frank.

40 pounds seems a little expensive for rubber mounts. Local guys (MG workshops) sell them for $20 to $30 australian dollars each (current exchange rate 2.6 $ for pounds). They are a feww mm thinner and feel much harder than the old rubber bumper MG ones.
Peter

I have a factory G.T. at the shop right now & yes the motor mts. sit the motor up much higher were it will be a problem to put the E.F.I. on top of the motor to close the hood. I have put F.I. on 5, B V-8s & no scoops on the hood & the hood closes!!!! I set the motor DOWN as low as it can go, with the steel motor mts. I have a chrome bumper G.T. with stock crossmember & the alu. hood that has a 1/2" less bow in the hood!!! & the hood closes. Frank, you have done all you can to the e.f.i. now look at the steel mts. & yes the factory V-8 is right hand drive.
Glenn Towery

This thread was discussed between 28/04/2003 and 08/05/2003

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