• The Roadster Factory Recovery Fund - Friends, as you may have heard, The Roadster Factory, a respected British Car Parts business in PA, suffered a total loss in a fire on Christmas Day. Read about it, discuss or ask questions >> HERE. The Triumph Register of America is sponsoring a fund raiser to help TRF get back on their feet. If you can help, vist >> their GoFundMe page.
  • Hey there Guest!
    If you enjoy BCF and find our forum a useful resource, if you appreciate not having ads pop up all over the place and you want to ensure we can stay online - Please consider supporting with an "optional" low-cost annual subscription.
    **Upgrade Now**
    (PS: Subscribers don't see this UGLY banner)
Tips
Tips

About alternator bracket and cylnder block interface on BN1

matt78

Senior Member
Offline
Hello.

I'm trying to replace my old dynamo by an alternator (AH Spares' kit), but I'm in a fix when it comes to fitting the new alternator bracket on the cylinder block.
In fact, I discovered that one (or maybe several !) previous "mechanics" had modified the 4 fixation holes :
- filled in the rear one with some solder (don't know why... maybe after a failed attempt to deepen it, and water flowing out ?),
- drilled a new one in front of it,
- oversized the second hole (the stud's diameter is bigger),
- maybe after having broken the stud inside the 3rd one, left it as is and put another one but screwed on 2 threads only...
- last but not least, broke the stud inside the 4th hole (the front one), w/o replacing it.
Believe it or not, the old dynamo still manage to stay on the engine - but for how long?

Therefore, I want to have the 4 holes (of course of a larger diameter) drilled in the right position, BUT having noticed that they are on the top of the water gallery, I guess that they must not be too deep, in order to avoid any water leak nor any other joke...

Could somebody tell me what is the maximum length allowed for these holes ? What are the potential mistakes that should be avoided ? Any additional advice welcome :eek:

Thank you in advance for your replies.

Matt
 
OP
M

matt78

Senior Member
Offline
Can you modify the holes in the bracket to match the block instead of trying to repair the block?
No, because the bracket is already drilled and there isn't anymore space to create new one.
Additionally, only two of the current threaded holes in the block are usable...
 

Healey Nut

Luke Skywalker
Country flag
Offline
Weld over the holes in the new bracket and re-drill them to suit you "modified" block .
Repairing the block correctly would be a very expensive undertaking . Welding cast iron is not easy and has to be done correctly to prevent cracking and total block failure resulting in you owning a heavy boat anchor .
 
OP
M

matt78

Senior Member
Offline
Already thought about that, but the aluminium bracket is very narrow and the holes very close from each other. But, yes, this would be the best way...
Thank you.
 

CraigC

Jedi Trainee
Country flag
Offline
Matt, post a picture of the mounting face on the block that shows clearly what has been done. Also post a pic of the new bracket. In the mean time, I have a spare block from which I can get the depth measurement you need.
 
OP
M

matt78

Senior Member
Offline
Ok CraigC, here are some pics.
20160516_112106_resized.jpg20160516_112149_resized.jpg

Could you please tell me what is the "nominal" depth measurement you found ?
 

CraigC

Jedi Trainee
Country flag
Offline
Boy, someone sure boogered those holes up! If the front 2 holes are still unmodified, I would be extremely careful removing what is left of the studs. Is it just the pic or is there a low area around the oversized stud hole(3rd from front)? I wouldn't be at all surprised if the problems were cause by the use of the wrong studs. The studs appear to be 5/16" BSF (22 threads per inch). Approximately .400" of stud is threaded into the block and total stud length is 1.28".

As for the depth of the holes, I was a bit surprised. I even pulled the triangular cover off the front of the block ahead of the generator mounting pad to confirm what I found. Both of the holes that are closest to the edge of the head are drilled straight through into the coolant gallery. The two outer holes are drilled to .665" for the front hole and .725" for the rear hole. This is more than enough for the amount of stud that I found threaded into block.

Unless you regularly find yourself making repairs like this, I would suggest you enlist the help of a skilled machinist. You cant afford to make any mistakes. The IDEAL repair would involve a totally stripped engine and a large vertical mill. This would ensure that all holes are drilled perfectly perpendicular to the mounting surface and perfectly inline with the crankshaft centerline in order to keep the pulley alignment correct. A good machinist should be able to make a satisfactory repair in situ, with care taken to save the two front holes for alignment purposes for location and repair of the rear holes.
 

roscoe

Jedi Knight
Silver
Country flag
Offline
Matt,
Sorry I'm no help in offering the best solution but would you mind letting me know where you got your mounting bracket? I've been looking at the alternator I will eventually install and procrastinating over fabricating my own mount bracket. Thanks.

Jon
 
OP
M

matt78

Senior Member
Offline
@ CraigC : there is no low area, only a different colour on a small zone. Regarding the risks, I fully agree with you : that's why I'm having the job done by a british cars specialist (hope he's good enough :eek:). I will keep you posted about the final result.
@ roscoe : I ordered a kit from AH Spares UK. It already included the bracket, but I think that this one is available separately.
 
Similar threads
Thread starter Title Forum Replies Date
90dog A H Spares Alternator Bracket Austin Healey 53
drooartz General MG Alternator link - adjusting bracket length on MGB? MG 8
AngliaGT Early '74 Midget Water Pump Bolts/Alternator Bracket? Spridgets 1
PatGalvin TR2/3/3A Alternator Bracket for TR3A Triumph 3
philman Wedge tr8 alternator bracket needed Triumph 1
texas_bugeye in a pinch alternator bracket Spridgets 3
R Alternator Bracket MG 4
D It was a loose alternator bracket... Spridgets 2
I MGB Alternator help MG 0
P Alternator Installation Pic Austin Healey 4
P Generator to Alternator Swap Austin Healey 2
W Generator or Alternator? Austin Healey 18
Writer2022 GT6 GT6 MK3 Alternator Problem Triumph 4
K TR2/3/3A Is it time for a new alternator??? Triumph 8
M Smog pump and alternator brackets Spridgets 0
V MGB Never occurred to me that my '66 would be positive ground. Does the presence of an alternator show that it's been converted? MG 22
A General MG 78 MG MIDGET ALTERNATOR SMOKES MG 5
E MGB external alternator regulator MG 2
DrEntropy MGB Generator to alternator swap MG 1
M TR2/3/3A Generator Warning Light on with the Alternator Charging the Battery Triumph 4
K TR2/3/3A Overtightening the alternator belt? Triumph 14
B TR6 Swapped Lucas to GM alternator Triumph 9
M TR6 Alternator Issue for 72 TR6 Triumph 7
K TR2/3/3A Can anyone confirm that if you replace the ammeter with a voltmeter ( generator removed and alternator added) that you...... Triumph 5
K TR2/3/3A British Wiring alternator conversion kit question. Triumph 3
K TR2/3/3A Red ignition light stays on...car has alternator not generator. Triumph 17
K TR2/3/3A TR3 with alternator conversion... red light stays on and low voltage on the voltmeter gauge? Triumph 1
G Spitfire Alternator troubles Triumph 2
jehuie Help...replaced my alternator and now my water pump is leaking. Spridgets 16
TheRealDestrux MGB Unknown connector on alternator MG 6
R TR2/3/3A Amp Gauge-erratic reading after alternator conversion Triumph 39
lilifer_13 Spitfire New alternator doesn't fit - '78 Spit Triumph 2
AUSMHLY Generator to Alternator Swap Austin Healey 20
J TR6 1975 TR6 Alternator Advance/Retard spring(s) Triumph 1
Lin Fan belt for 1275 with alternator Spridgets 4
PAUL161 T-Series Dynamator Alternator conversion. MG 23
P '58 XK150 Dynalite Alternator swap question Jaguar 5
B Delayed charging Lucas alternator Triumph 1
Merlin63Tr4 TR4/4A Alternator or alternator in a generator case? Triumph 4
Walter74 Dynamo to alternator Austin Healey 2
S Stag Lucas 18ACR alternator conversion Triumph 5
Got_All_4 TR5/TR250 Rebuilt Bosch Alternator stops charging Triumph 0
donbmw TR2/3/3A Converted to alternator Triumph 14
R TR2/3/3A generator to alternator Triumph 5
JPSmit Alternator help - please. Spridgets 21
I Bugeye generator/alternator conversion question Spridgets 7
Ripper01 TR6 110A Alternator Triumph 7
F TR2/3/3A I'm stuck... alternator/wiring/starting/? Triumph 2
Sopwith_Camel alternator eater Spridgets 20
longbridgehealey Alternator conversion and tach Austin Healey 9

Similar threads

Top