[Tigers] Radiator Cap

Wed Aug 18 12:05:36 MDT 2021

 Joe, I've had two failures with those Scott Drake caps.   They were about 10 years apart.    Both failed soon after installation.    The 10 year gap was because I had forgotten that the first one failed and then 10 years later I bought another and it also failed.    Ended up finding an NOS cap and that solved the problem.
Both Scott Drake caps were allowing coolant to puke out after short drives.   Dimensions looked identical.   Your results may vary.  Just keep an eye on it.

Doug

    On Wednesday, August 18, 2021, 10:21:47 AM PDT, Joe Brown <jbbrown1980 at gmail.com> wrote:  

 I have an update on my quest to find a radiator cap.  I wound up ordering a Scott Drake Mustang cap from CJ Pony Parts and it fits really well.  And since my temp gauge was always pegged out really high I installed a mechanical temp gauge from Summit on my Edelbrock intake.  After idling for about 20 minutes the temp never got over 190.  Now I need to take it out for a long drive and see how it does.
Thanks for all of the info from everybody.
Thanks,Joe Brown
On Thu, Jul 29, 2021 at 9:35 AM Ron Fraser <rfraser at bluefrog.com> wrote:

Jim 

                Thank you for the pictures.

It appears I have the MOPAR 5220487 Filler cap – good to know.

This also indicates that any 522xxxx number in the Parts List is a Chrysler part number – excellent.

Ron Fraser

From: jimdamelio <jimdamelio at verizon.net> 
Sent: Wednesday, July 28, 2021 8:11 PM
To: Joe Brown <jbbrown1980 at gmail.com>; Ron Fraser <rfraser at bluefrog.com>
Cc: Tigers Den <Tigers at autox.team.net>
Subject: Re: [Tigers] Radiator Cap

Attached are pictures of the 9lb cap 5220487, 13lb cap 1224818 and a 13lb chrome Motorcraft cap.  The 9lb cap measures 1" from inside base to tip of plunger while both 13lb caps measure 1-1/8". 

Jim D

Sent from my Galaxy

-------- Original message --------

From: Joe Brown via Tigers <tigers at autox.team.net> 

Date: 7/28/21 6:49 PM (GMT-05:00) 

To: Ron Fraser <rfraser at bluefrog.com> 

Cc: Tigers Den <Tigers at autox.team.net> 

Subject: Re: [Tigers] Radiator Cap 

Just to add to my confusion I took a look at the Tiger Parts List Supplement (pub number 6601131) and I'm guessing this only covers the Tigers up to  B382001521 because it only shows the 1224725 header tank and Ron has  Parts List 6601334 which show two more tanks.    Parts List  6601131  says the 9 lb. cap is for "later" cars and the 13 lb. cap is for "earlier" cars.  This seems to contradict what is in TBON.  Is it possible that some of the earliest cars had 13 lb. caps and then they went to 9 lb. caps until they changes the header tanks?

The Rootes part number for the 9 lb. cap is 5220487 and when I Google that number I can see that is also a Mopar part number from back in the day.  All of the usual sources want to cross this over to a 13 lb. cap.  I did find a 9 lb. cap made by Motorad but I can't find what the stem length is.  I guess I will have to go down to the different part stores and look at what they have.  

Sunbeam Specialties has three different caps for sale but they are for Alpines, not Tigers.  I asked Rick if any of them would work for the Tiger and he said the pressure rating was too low.  

Ron, the G630 cap pulls up as a match for some older Land Rovers but I'm only finding used ones.

If anybody has recently purchased a new cap that is working fine please let me know what you got.

Thanks,

Joe Brown

On Tue, Jul 27, 2021 at 8:40 PM Joe Brown <jbbrown1980 at gmail.com> wrote:

I pulled out my copy of TBON and he also listed a 9 lb. cap up to B382001521 and 13 lb. after that 

I sent an email to Rick at SS to see if his part number RC5 is the cap you described. It doesn't say it's for the Tiger, it just says it's for the series V.

On Tue, Jul 27, 2021, 8:27 PM Ron Fraser <rfraser at bluefrog.com> wrote:

Parts List 6601334 lists 3 header tanks.

1224725                Header Tank       up to B382001521

5221224                Header Tank       from B382001522 to B382001894

1236126                Header Tank       from B382001895

Graham Vickery sent me a drawing for Header Tank 1224725 and it indicates Filler Cap 9 lbs.

I don’t know if the drawings for the other 2 header tanks are available to see which Filler Cap they indicate.

Ron Fraser

From: Joe Brown <jbbrown1980 at gmail.com> 
Sent: Tuesday, July 27, 2021 7:49 PM
To: Ron Fraser <rfraser at bluefrog.com>
Cc: Tigers Den <Tigers at autox.team.net>
Subject: Re: [Tigers] Radiator Cap

Thanks Ron, the .805" dimension sounds like what I need.

On Tue, Jul 27, 2021, 6:37 PM Ron Fraser <rfraser at bluefrog.com> wrote:

Joe

                I believe I bought my radiator cap from Sunbeam Specialties.

Cap indicates 9 lbs. and G630.

Rubber seal to rubber seal is .805”.

I installed a catch bottle for the header tank overflow.   Catches any overflow which gets sucked back in when the engine cools.

The Parts lists indicates 9 lbs. later cars and 13 lbs. early cars.

Tiger, An Exceptional Motorcar indicates B382001521 as last unit with early header tank and 9 lb. cap – B382001522 1st Tiger with updated header tank and 13 lb. cap.

Well, no really good help there.

I’m thinking 9 lbs. for early cars and 13 lbs. for later cars is correct

Ron  Fraser

From: Tigers <tigers-bounces at autox.team.net> On Behalf Of Joe Brown
Sent: Tuesday, July 27, 2021 6:07 PM
To: Tigers Den <Tigers at autox.team.net>
Subject: [Tigers] Radiator Cap

Hi,

I'm hoping one of you guys can tell me what radiator cap I should be using.  I've tried a cap that was listed as being for a Tiger on Autozone's website but I think the pressure spring part under the cap is too short.  I almost immediately start getting water out of the overflow tube as the engine warms up.  I measured the depth of the expansion tank opening from the top edge to the flange where the spring part of the cap would sit and got .777".  I measured the cap from the big rubber seal just under the cap to the small rubber seal at the end of the spring and got something like .75".  So it looks like I need a cap with a longer spring stem.  

A brand name and part number would be great  And also, what should the pressure rating be?  What I have is 13 lbs.

Thanks,

Joe Brown

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