HELP-crosman 1377 pistol problem

[ggggr]

Got a 1377 pistol which I was told wasnt working. Never had one apart so fancied it. When you pumped it, you could feel the pressure build up and it was ok if you fired it pretty quick but power fell very quick if you left it about 15-20 seconds. Wouldnt hold charge overnight. Stripped it and took valve boddy apart. All thats in it is a piece of tapered plastic(inlet valve?) a small pieced of aluminium,a spring and what looks like a brass adapter for blowing up a football(exhaust valve or what?). Its about inch and a half long and looks like it may have a small o ring where it seats in that half of the pump body. Phoned chambers (no diagram for it and not much for 1300) to order some bits. The plastic piece is longer than the original, About as long as the original and the aluminium piece,so Im assuming it is ment to replace both? The exhaust bit looked nothing like the one in mine so I couldnt fit it. Anyway I put it back together and it was worse. I think the taper on the plastic may be different. Phoned a few places and one of them suggested here!
Any crosman experts? I dont know if Ive got original valve body or not,or whether interchangable. I could do with a small inlet piece( about 1/4 inch long + the exhaust bit) I dont want to spend £25 on a new valve when I should be able to sort it for a few quid.
OVER TO YOU FOR ANY ADVICE OR SPARES THAT WILL DO THE JOB.
Its only going to be a plinker and I may pass it on to my mates lad.

[lightning22]

Pics would be useful.

Rich

[deebee]

Try Steve on here. One of he good guys

http://www.sdcustomdesign.com/index.htm

Dave

[T 20]

Hi ggggr
The long inlet valve you describe is a direct replacement for the short plastic valve and aluminium spacer.It sounds like your exhaust valve may be leaking, this valve has also changed from a brass head with rubber insert to a teflon valve. All the parts diagrams are available to download on Crosman.com customer services, the valves are all available from S D customdesign. The website hotrod 13xx gives good pictures of the differences in the old and new type valves and also shows how to tune these guns. Don't forget to replace the O ring round the middle of the valve as a small cut in this can cause an air leak.
If air is leaking into the pump the inlet valve is faulty, if the leak is into the barrel the exhaust valve is at fault. The angle of the inlet valve has not changed in over 50 years but the valve lengths have changed from gun to gun over the years.
If your inlet valve is leaking it may need lapping in to the valve body, you need some way of turning the inlet valve inside the body. to do this I normally cut a slot on the back of the valve with a hacksaw so that it can be turned with a screwdriver. You need to use a very mild abrasive to lap the valves in, I use CIF or toothpaste (not joking), the valve seat and valve when lapped will be cleaned and pollished and a perfect seal when done. The exhaust valve can be lapped in the same way by rotating it with the valve stem when it's installed in the valve. Wash all the components of the valve assembly with warm water and dry, oil the valves and screw back together and fit into the gun. This should cure the problem, the Crosman valves and pump rely on being clean and oiled to work properly, I always leave the Valve with one pump in it when I put it away. I have never had to buy a new valve after 30 years of owning Crosmans, if you lived nearer I'd sort it out for you, but anymore help you need just ask.
Cheers Mick
PS I've just had to fit a stock to my 1377 as it's doing 750 fps
PPS the first 3 or 4 digits of the serial number of your Crosman are its date of birth

[ggggr]

Thanks for info,people. Just looked at website and the valve stem is the same as mine. Will probably have a go at lapping in( was going to do it before being warned off). Id like to fit a slightly longer barrel as well-about 4 to 6 inches longer. Do they do them for the 1377 and is the breech block in with it or does that pull apart. Thanks once again for help.

[T 20]

14 inch barrels are about 20 quid.
Custom Crosman breaches are about 30 quid.
Best to go for .22 as they are more efficient power wise and easier to load.
You need to drill out the foresight for a longer barrel.
Go steady with the lapping you only need to achieve a light polish.
what age is the gun by the way?
Cheers Mick

[deebee]

Thanks for info,people. Just looked at website and the valve stem is the same as mine. Will probably have a go at lapping in( was going to do it before being warned off). Id like to fit a slightly longer barrel as well-about 4 to 6 inches longer. Do they do them for the 1377 and is the breech block in with it or does that pull apart. Thanks once again for help.

Like this you mean?


http://i235.photobucket.com/albums/e...tomCarbine.jpg

Shoots really well
Dave

[T 20]

Nice one deebee thats just about what I'm making at the moment, Ive just finnished making the pump tube out of stainless steel with a slightly longer stroke. I've also made the flat top adjustable piston from stainless and brass with an O ring seal. I have a Crosman custom breach and 14" .22 barrel ready to fit but I'm having trouble finding a tap for that little screw inside the breach, I may tap it at 3 mm yet, with the original .177 barrel I'm getting 750 fps on 12 pumps. I'm also making a new pump tube and pump for my Crosman 140 rifle at the same time out of the same stainless tube, not because I'm flash mind you its just that I can't seem to blue anything (it always looks crap).
ggggr your Crosman was made in June 1978 I've sent you a PM, hope it helps get you up and running.
Cheers Mick

[deebee]

Mick you're obviously much cleverer than I am! Mine is just bits bolted together!!
The little screw in the breech is a right pain in the arris to get out when your allen key just goes round! RJ Machine who supplied my breech supplies a stainless posidrive with it & that is much better. My home bluing comes out all right normally, but I've never tried to do things that have to remain straight!
Dave

[T 20]

Not cleverer at all, just never looked after my 1377 and it was a bit rusty, so I thought s*d it lets make a proper job of the pump to go with the new barrel and breach. I had to buy 3 metres of stainless tube (minimum order) for the 140 so it seemed a good idea to practice on the 1377 first and use some tube up. I made the flat top piston to see if it made any difference to pumping, it makes lots! By the third shot over the crono the barrel had moved forward inside the breach due to the increase in pressure, it's locktighted in now. I've had the 140 for thirty years and never used it because the pump tube was beyond repair so I'm looking forward to getting it finished now as soon as I've finished the 1377.
Cheers Mick
PS if I can get my secretary (daughter) away from that Wii thing I'll post some pics of the stainless 1377 pump and tube.

[granger]

Mick - try http://modelfixings.co.uk for a suitable tap for the small screw you are having problems with. They tend to supply some mighty small taps, dies, allen screws and keys for modelmaking.
Worth a try,
Dave

(Some interesting and useful info in this thread.)

[T 20]

Hi Dave
Thanks for the info on modelfixings, but my problem is actualy identifying the thread form of the original screw! I had read the thread size on one website and then lost the page, after deebee's post last night I realised it was R J Machines webpage. I still may tap in 3mm metric as this would give a much larger choice of head profiles, I may even change the whole gun to metric threads as this would make life much easier in the future. Most of the places I deal with only supply UNF and UNC fixings as special order only. This is a right pain for me as my car is 37 years old, my motorbike is 43 years old, my fergy tractor is 55 years old and some of my guns are Victorian. Is changing thread forms to be inline with the rest of Europe really progress ?
Thankyou again for your help Dave
All the best Mick

[Jethro]

Crosman 1377 docs:
http://www.crosman.com/2004/pdf/manuals/crosman/1377/

Good forum for all things Crosman:
http://www.network54.com/Forum/275684/

1377 disassembled:
http://i297.photobucket.com/albums/m...sassembled.jpg
(not my picture but from a quite useful Russian site:
http://translate.google.com/translat...24/254657.html)

Cut-away diagram:
http://i297.photobucket.com/albums/m...ayandwhole.jpg
(again, not mine but acquired through the above Crosman site)

And, in case you haven't been there:
http://airgunartisans.com/
pages and pages of modified Crosmans to oggle.

[T 20]

I keep looking at the 14" barrel and custom breach I've bought, and it's occured to me that fitting this setup to a standard length 1322 pump tube would be a bit of a missed opportunity. I actually like the standard Crosman front sight, so why not use the 14" barrel and make a new longer pump tube to suit it. Most people fit a 14" barrel to a 13xx and then fit a barrel weight to it so why not just extend the pump for the extra weight and use the original foresight? If I did this the gun would only be 17.5" long and would still weigh less than a scorpion, with a weaker hammer spring I would have multishot capability at sub 6 ftlb velocities on each pumping.
If anyone has an old 13xx or 22xx as a donor give me a shout as I will need a triger assembly, I'll be a bit busy for a day or two, and I may get my 140 finished one day, but I think this idea is worth having a bash at.
Any comments ?
Cheers Mick

[medalist]

leaking air. my brother oiled the crap out of it well thats the least i know. took her apart cleand her up after 18 years never had a problem until now; and she still leaking. i love my time with my 2 air guns and this sucks. need a good tutor to talk me threw this im hoping. also have a 1377phase 2 she is perfect but wouldent mind increasing fps any tips.