Author Topic: SRM Pressure Relief Valve  (Read 4209 times)

Offline A10Boy

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SRM Pressure Relief Valve
« on: 19.10. 2009 15:10 »
Anyone found this with their PRVs ?

I bought one at the Stafford Show on saturday and it wont screw into the cases, it starts but binds up. I measured the thread diameter of the old and new and the SRM one is about 0.025 wider which is a significant difference.

The geezer at SRM said it cant be wrong mate, its CNC, he blamed my cases !! Anyway, I sent it back and wait their verdict.
Regards

Andy

1960 A10 - Black Golden Flash
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Online chaterlea25

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Re: SRM Pressure Relief Valve
« Reply #1 on: 19.10. 2009 21:57 »
HI Andy,
Yes I had the same problem,
They told me to expect that it would be tight going in as apparently original ones varied quite a bit
and also the threads may be distorted in the casing as well
I used some antiseize on the threads and worked it back and forth a bit until it fitted
Cleaned it all off fitted the PRV and hav'nt looked at it since *smile* *smile*
Cheers
John
1961 Super Rocket
1963 RGS (ongoing)

Offline A10Boy

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Re: SRM Pressure Relief Valve
« Reply #2 on: 20.10. 2009 19:55 »
I tried that a bit but mine seems too far from the correct size to fit. There's no way I'm going to force it and risk cracking the cases. I will stay with the old ball type unless they can ease the thread on their widget.

I don't know too much about thread British Standards or tolerances but their CNC must be at the top of the size range.
Regards

Andy

1960 A10 - Black Golden Flash
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Offline rocket man

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Re: SRM Pressure Relief Valve
« Reply #3 on: 20.10. 2009 20:50 »
hi i got one and had no problems took old one out put new one in
maybe your threads are a bit worn 

Offline Josh Cox

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Re: SRM Pressure Relief Valve
« Reply #4 on: 21.10. 2009 05:39 »
A10Boy,

I have just installed a new SRM unit also, the thread was tight, it was my cases.

Borrowed the correct tap from a friend , and ran it through the thread, fit the new unit into the case nicely.

The one thing I am quickly learning is that all threads need cleaning with a tap/die before fitting new nuts and bolts.
Black 1953 Golden Flash Plunger

Offline A10Boy

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Re: SRM Pressure Relief Valve
« Reply #5 on: 21.10. 2009 19:58 »
I'll try that. Did you do it on a complete engine or with the cases stripped ?

Cheers

Andy
Regards

Andy

1960 A10 - Black Golden Flash
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1974 Kawasaki Z1a
Yam XJR 1300

Offline Josh Cox

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Re: SRM Pressure Relief Valve
« Reply #6 on: 21.10. 2009 23:57 »
Stripped, I would not do it to a complete engine, unless you can be completely sure where the mess will go.
Black 1953 Golden Flash Plunger

Offline alanp

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Re: SRM Pressure Relief Valve
« Reply #7 on: 22.10. 2009 16:52 »
What actually is the thread spec.?
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Online orabanda

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Re: SRM Pressure Relief Valve
« Reply #8 on: 23.10. 2009 02:10 »
7/8" x 16TPI.

Tracey Tools have the tap.

Regards,

Richard

Offline A10Boy

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Re: SRM Pressure Relief Valve
« Reply #9 on: 23.10. 2009 15:37 »
Is that a definate ?
Regards

Andy

1960 A10 - Black Golden Flash
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Offline Josh Cox

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Re: SRM Pressure Relief Valve
« Reply #10 on: 23.10. 2009 19:38 »
A10boy, it was Richards tap that fixed my cases, so yes.
Black 1953 Golden Flash Plunger

Offline 1660bob

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Re: SRM Pressure Relief Valve
« Reply #11 on: 31.10. 2009 19:34 »
yep, me too-bought one this week, goes in 1/4 turn and stops dead.  Out with the mike, O/D is, as mentioned above o.025"larger than the old one.The old relief valve is admittedly quite slack in the cases, perhaps in an effort to address this SRM have backed off the die a bit , but methinks a tad too much!!! Bob `C`

Offline nigeldtr

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Re: SRM Pressure Relief Valve
« Reply #12 on: 01.11. 2009 17:42 »
I bought one from SRM a couple of months ago, went in fine but the release was far too high to my mind, it opened at 70 to 80 psi, my old one opened at 50, which I consider perfectly adequate. As per all the earlier discussions, if the valve is not opening, ie when the engine gets hot and oil thins, then the cam gets less oil. From my perspective let it stay open a little longer while the oil warms up and keep to the original valve.

Regards

Nigel
1951 Golden Flash (engine now rebuilt) 1953 M21 a pain to start and 1961 GF that is turning into a black hole!

Offline alanp

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Re: SRM Pressure Relief Valve
« Reply #13 on: 02.11. 2009 09:08 »
Nigel, in your 25 Sep 09 different thread on this subject, Manorman said that he was able to remove some washers under the spring to get the SRM valve pressure back down to normal, if this is possible to carry out, the question then remains as to whether SRM's plunger instead of BSA's ball is better.
My PRV hexagons are chewed up and I was going to replace it with an SRM unit to tidy up that area and upgrade to the plunger type at the same time. Any thoughts anyone on why the plunger is used by SRM over the old ball, since it must be more expensive to produce?
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Online bsa-bill

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Re: SRM Pressure Relief Valve
« Reply #14 on: 02.11. 2009 09:27 »
HI Alanp - go here for more info         http://www.a7a10.net/BSA/oilrelief.htm

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco