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MG MGB GT V8 Factory Originals Technical - Earth strap locations
Where do you recommend as mounting points for engine and gearbox earth straps, and how many should I fit.
I read somewhere you can't over earth an engine.
|I used a 24 inch grounding cable from NAPA. One end goes to one of the unused holes on the end of the cylinder head (on mine, it's a 3/8-16 bolt hole) and the other end is under one of the steering rack bolts. You only need one good ground.|
I just finished my V8 conversion. I had forgotten to put the ground cable on it and the first time I tried to start it, the plasic on the accelerator cable started smoking (it was the only ground it had). Once I put the ground cable on, it fired right up.
Broken Arrow, Oklahoma
All else being equal, I prefer the ground strap to be physically close to the starter, like on one of the starter mounting bolts. I like the strap to be fairly big... similar in size to your battery cable. They should be gauged big enough to easily carry the whole load of the starter. They're usually braided cable for two reasons: braided cable is more resistant to fatigue and also it dampens radio frequency interference. Sometimes the hardest part is finding/making a good mechanical connection to the body. All that current has to find its way back to the battery!
You are right. It is not possible to "overearth" a car.
Most car makers use one strap since it is the minimum needed to get the job done.
Personally I have always added two extra to the usual single factory fitted item. One as close to the starter as possible and one at the end of the transmission since there is usually a bolt or two in a suitable location close to the body and the run of cable is normally very short.
Welding cable is my first choice and remember to earth to the untreated / unpainted metal of the body to get a good ground.
Use electrically conductive grease (available from electronics places) to stop corrosion and a decent nut and bolt assembly make a sound connection.
Erratic earth problems are a real pain to try and trace and rectify.
if one is fitted from the rear end of the engine (rh cylinder head/engine cradle hookup)to one of the mounting bolts of the breake/cluch cyl. unit and another one at the rear mount of the gearbox to the crossmember, there is nothing more to do.
Those that came with the SD1 engine in serial trim work very well!
... are there more news upon your projet...?
|R.S. Ralph Siebenhaar|
|As a follow on to this, i have been trying to find a supplier of braided cable in the UK, not having any luck, anyone know of a supplier?|
|http://www.vehicle-wiring-products.co.uk/ is one but there are many others.|
|Consider adding a ground from the head to either the block or to the body. A cause of high load misfire is poor earthing betwen the head and block. Yeah, i know they have 8-10 bolts holding them to the block.|
|Thanks everyone, Graham - Halfords do the braided ones in various lengths.|
Ralph - the project is progressing, the welding is done and mostly filled and primed, brakes and suspensions all done, getting nervous about spraying the engine bay myself.
Also have a bit of body rust treatment to do.
Got a lubricant sealed lower steering UJ from Flaming River the states, after soem advice on the group - slimline and very nice (had to pay the post office 22 quid to get it out of customs!), getting it all aligned though is a pain. A local engineering shop only charged me 35 quid for the required machining on the pinion. I will be doing a wooden dowel mock up tomorrow.
I think the engine needs to go back in and out again for another test fit. Tricky to move the car with no steering rack!
Even though I welded in a rubber bumper steering cone I may still need to shim the rack up a few mm. for rh engine mount clearance, I don't really want to grind away any more than I already have. We'll see.
I will update my web site project page on the next week or so with some photos.
Time is turning into a real issue now, still the weather is warm.
Take care all,
|Thanks Liam, got them from a friend i saw in the pub last night, nearly there now had the engine turning over today and plenty of oil coming up to the top, a couple of hours to that Burble..........|
Needed a boost after all the obsticles, and got it.
|If you have a dual terminal battery, or maybe even if you do not, one very effective ground is to run a heavy cable directly from the battery to the tailshaft extension of the transmission. This is about the most direct connection possible and will drop the resistance in the starter circuit enough that you may have noticeably easier starting. Then a lightweight ground either from the battery to the body or from the engine block to the body will easily handle any other electrical loads. I use cables made for trucks, usually 2 gage or larger. For longer runs they are more effective.|
|Good tip, Jim. Thanks.|
This thread was discussed between 11/07/2006 and 19/07/2006
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