Author Topic: left hand conrod  (Read 3023 times)

Offline Rich

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left hand conrod
« on: 25.11. 2011 21:01 »
can anyone identify this part number 67 1160 R4Z?
this is quite urgent for me to know as I may have purchased the wrong type
Thanks
Rich

Online Brian

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Re: left hand conrod
« Reply #1 on: 25.11. 2011 22:09 »
Rich that is a large journal A10 rod.

The only thing that is a little confusing is the 4 in the R4Z. I have two spare sets of rods and one set has R1Z and the other R2Z, both sets are identical. The numbers on the rods are the same for both sides, if it has the oil hole then its a left one.

Offline Rich

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Re: left hand conrod
« Reply #2 on: 26.11. 2011 09:27 »
Thanks for that Brian, I have just purchased two left hand rods one new, one second hand, from ebay, I took the chance they were large journal but only had the small journal spares book.
I take it, it will be ok to use two left hand rods (both with oil hole) in an engine?

Online Brian

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Re: left hand conrod
« Reply #3 on: 26.11. 2011 09:38 »
That I'm not sure about. There has been discussion on the forum before about using two left hand rods. Some seem to think it is ok but personally I wouldnt, I would plug the hole in the right side.

Offline LJ.

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Re: left hand conrod
« Reply #4 on: 26.11. 2011 09:38 »
Quote
I take it, it will be ok to use two left hand rods (both with oil hole) in an engine?

Not really a good idea Rich as this will then allow less oil pressure to the left side, this is the side that usually goes bang when oil starvation occurs. There is more information on this in the forum archives.
Ride Safely Lads! LJ.
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1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline Goldy

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Re: left hand conrod
« Reply #5 on: 26.11. 2011 11:43 »
56 A10 Golden Flash - Restore, ride, relive.                                          
56 C12 BSA project ongoing

Offline Rich

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Re: left hand conrod
« Reply #6 on: 26.11. 2011 12:29 »
many thanks, I have read the post and providing they are both ok, I will block the hole and get the rods the same weight prior to rebuild

Offline trevinoz

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Re: left hand conrod
« Reply #7 on: 26.11. 2011 19:48 »
Didn't the A65 have both rods drilled some time during production?
If so, having both rods drilled on an A7/10 would not matter as they are virtually the same design as the A65.

  Trev.

Offline MG

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Re: left hand conrod
« Reply #8 on: 26.11. 2011 21:44 »
Dunno if this was at the same time, Trev, but the last A65 models used wider gears in the oil pump to improve lubrication.
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Offline jjbsa

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Re: left hand conrod
« Reply #9 on: 30.11. 2011 14:25 »
In the mid 60s I was buying a pair of large journal rods from Eddie Dow's.  They only had the ones with the oil hole in stock and they told me to block the hole in the rod that was to go on the timing side.  I did that.  I have heard of people running pairs of undrilled rods OK. 

Offline kiwipom

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Re: left hand conrod
« Reply #10 on: 30.11. 2011 21:17 »
hi guys, i have read all the posts on this subject. I ordered a set of billet rods from SRM and when i received them i noticed that the hole was not there, i contacted srm and sent the relevent info from my manual and asked for thier opinion. They informed me that the hole was origonaly there to promote oil flow through the sludge trap and was now unnessarsary so i fitted them as per instructions. As a matter of interest where does this sludge come from? is it from unfiltered air or oil? if so once filters are in place no sludge,just my thinking correct me if i am wrong, cheers, Bob
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Offline MG

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Re: left hand conrod
« Reply #11 on: 30.11. 2011 23:47 »
Interesting, I fitted a set of SRM rods in September last year (blimey, where has that year gone???). Back then the lh rod HAD been drilled, although I had to prise a lot of polishing compound and muck out of the hole first...
Here's the complete story: http://www.a7a10.net/forum/index.php/topic,3195.0.html

The sludge comes from unfiltered oil, the idea was to remove it from the oil and deposit it in the sludge trap by centrifugal force.
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Online Brian

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Re: left hand conrod
« Reply #12 on: 01.12. 2011 00:21 »
Only my opinion but if it was me I would be drilling the left rod.

I dont know exactly why BSA did it in the first place but it must have been in response to some problem and they all had the oil hole from then on.

Online KiwiGF

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Re: left hand conrod
« Reply #13 on: 01.12. 2011 07:12 »
I bought billet rods from thunder engineering uk a short while ago and they look identical to SRM rods (they probably ARE SRM rods) and one rod has an oil hole......
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Offline jjbsa

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Re: left hand conrod
« Reply #14 on: 01.12. 2011 12:25 »
Hi Kiwipom,
You photo of the 3 rods is interesting.  The rod on the right, which I take to be the BSA one, has to my way of thinking, an unusual end cap, in that there is lots of clearance around the nut and a rather sharp looking junction between the face the nut seats on and the face parallel to the axis of the bolt.  That junction looks like a stress raiser to me.  All the BSA rods I've ever seen before have had a quite narrow circular section milled recess for the nut, with BSA trying to keep as much metal as possible in that area.  For that reason I have to use a slimmed down socket to deal with those nuts.

While we're talking about con rods, has anyone any experience of the steel Carrillo ones?  Do you need to do a rebalance if you fit them?

JJBSA