Heat riser spring, is manufactured wrong.

[harmony]

My story starts back in the summer, when my new heat riser spring arrived and I decided to install it.  I have a post on here about the whole episode.  15 minutes after I took it for a test ride the car started to cough and sputter and then finally backfired and then called it quits.  At the time I really didn't suspect the spring, however that was all that I had changed.  Long story short after many hours scratching my head I discovered that the large plug in the intake manifold at the back was missing.  In the meantime I had disconnected the spring and removed it, because the car ran fine without it for a year at least.  

So now in hind sight I think maybe since the spring had kept the flapper valve in the open position, the intake got hot enough to expand a bit and that maybe cause the plug to loosen and work it's way out.  Maybe, just a theory.

 

However, fast forward to a week ago and me having just replacing my intake/exhaust gaskets and I thought I would revisit the spring issue.  After a bit a research and checking out the article here in the resources section I believe, I've come to the conclusion that the spring has been manufactured wrong.  It's wound correctly, so it looks identical to the factory one, as illustrated in the service manual.  However what I think has happened is that the manufacturer flip/flopped the bi metals.  They are on the wrong side or opposite sides so to say as they should be.  When I install it correctly, and heat it up,  the right angle part of the spring that rests up against the stopper pin(under pressure), starts to relax, and nothing happens to the flapper shaft.   Instead of contracting and pulling the flapper shaft in a counterclockwise direction. 

 

During my head scratching research I came across this video, where the guy pretty much says the same thing and demonstrates it.  

https://www.youtube.com/watch?v=EiKVmaRjxlU

The video is kind of drawn out a bit and he's not exactly very good with a camera.  However he makes an interesting observation

So I took his advise and reversed the spring.  Sure enough, it works now.

So what I've done is not only reversed the spring but I reversed that gismo arm inside the back of that counterweight plate.  (I think it's designed to come up against the pin and keep the counter weight at 12 o'clock, or there abouts. Mine had rotted off, due to heat as opposed to heat no doubt and it couldn't be salvaged, so I made a new one).   Now it doesn't even have the chance to go past the centre balance point so it can't possibly go into the open position.  Which is all I really want in the end.  Because my car starts fine without the spring even in cool weather.  My only concern was that that counterweight was free to jump around.  So if I hit a pothole, in theory that jolt could have bounced that weight over to the opposite side and opened the passageway and heated up the intake, fairly easily. 

Some guys take the whole assembly apart and weld that flapper plate in the closed position.  I was not about to risk breaking those 4 long bolts off. ( see the recent post by MikeS about that process) 

So it's a win for me, by just reversing that spring.  I'm curious if anyone else has purchased one of those springs and had the same issue?

 

One more thing, The flapper valve shaft has a little play in it.  Maybe about a 1/16" at the end or even less.  So there is some wear on either the shaft or the bushing, causing a slight exhaust leak.  Not at all noticeable though.   Since I'm going to keep that flapper closed all the time, would it make sense to put a little muffler cement around the shaft where it comes out of the casting?

Edited January 19, 2022 by harmony

[Sniper]

I live in Texas where it is hot almost all the time.  On my 87 Diplomat, I just pulled the flapper out completely, put a long bolt in the holes to close it up, used a nut on the other end, and left it that way.  Not sure if that's an option for you.

[Loren]

What you’re describing happened to me with an electric choke.

You applied electric current and the spring closed the choke instead of opening it.

I fixed it by prying the bi-metal spring off and reversing it on the center shaft.

Then I re-installed the electric choke housing 180 degrees from normal.

You’d think they’d test these things.

[sidevalvepete]

@harmony. Where did you source spring from. I have couple, maybe three, I have acquired over the years. One which I have fitted to my build. Have fired up engine a few times but only short test periods. Seems sort of ok but fine tuning still ahead so I perhaps haven't been affected by this yet or maybe my springs are ok. Will check now.

Interested to hear from others about this  (Thanks Loren for your input)

[harmony]

45 minutes ago, sidevalvepete said:

@harmony. Where did you source spring from. I have couple, maybe three, I have acquired over the years. One which I have fitted to my build. Have fired up engine a few times but only short test periods. Seems sort of ok but fine tuning still ahead so I perhaps haven't been affected by this yet or maybe my springs are ok. Will check now.

Interested to hear from others about this  (Thanks Loren for your input)

I'll have to get back to you on that.  I get my stuff from a few different suppliers, but I'm almost sure who I got it from, but I better check my pile of receipts and make sure, before I throw them under the bus.  However it might be safe to say that the springs probably all come from the same Chinese factory, but they just go out through different doors with different company names on them. 

Interestingly I found an old thread on here, (ironically through google, and not the p15-d24 search engine), from 2015 with the same issue. That spring came from a supplier whom I get a lot of my stuff from, hint hint. 

 

[47Jim]

Keith Barron has the best video I’ve found for installing and testing one of these, I couldn’t have done mine without it.

my kit was from Andy and I guess I was fortunate that the spring operated correctly, you definitely could put it on backwards very easily but the torch test would quickly reveal it.

 I was overzealous in my tack welding and warped the shaft, once I cut that out, just whittled a new one out of a long carriage bolt the same diameter, tested with a torch, had to trim some corners on the plate just a bit, then good to go.

 I don’t know how to link the Keith’s Garage video but it’s easy to find, invaluable for fellas that have yet to do this repair 

[Sniper]

7 minutes ago, 47Jim said:

I don’t know how to link the Keith’s Garage video

 

Right click on the video, copy video URL, paste it here in a reply.

 

 

[harmony]

9 hours ago, Sniper said:

 

Right click on the video, copy video URL, paste it here in a reply.

 

 

Thanks Sniper, As I started to watch the part when Keith brought up the manifold from under the bench , I twisted my head like a puppy dog does at a strange sound.  I'm looking at the counterweight hanging upside down.  I'm thinking how is that even possible?  It should be about 180 degrees from where it is. ???  Then of course it was obvious once he showed the separated flapper plate inside.