twin carb setup

[Sheriff]

Am in process of fitting twin carbs to my standard motor.  For time being will be using standard exhaust manifold. When I removed the standard inlet manifold, the hotbox below it has plenty of soot etc.  The flap is seized shut (well must only be almost shut) and the spring gone.  What is the usual practice for dealing with this.  I was thinking of making up a plate to bolt on and filling the void and sealing it with muffler putty.  Has anyone previous experience with this or a better idea.  Thanks, Mike.

[Rod]

Mike,

You must have read my mind as I was going to post this as well. The flap is to deflect warm air up to the base of the carby to assist when the motor is cold. When the temp gets up to speed it the flap acts like a thermostat and closes and directs all air out the manifold.

I have been looking at mine and the flap doesn't direct air to the carby(s) and still have got the spring present/ My question is how important is the functioning of this valve. Will the motor run much better when cold if I unseaze the valve? Am I wise just to leave this valve seazed in the position its in?

Rod

[Sheriff]

Rod, obviously mine has been running almost closed for many years, I've owned it for over 20 and to my knowledge the spring never worked.  Have never had any problems, but I do live in the best State in the Country, Sunny Qld, where chokes are obsolete , though I wish it was a little less sunny and a lot wetter these last couple of years.     Cheers, Mike.

[mcl1959]

The majority I have seen don't work and it doesn't seem to make much difference.  Probably the reason why the red motor was changed to water heating.

Ken

[RET]

The majority I have seen don't work and it doesn't seem to make much difference.

The first part of that statement is certainly correct, but the second half will get Geoff (Gertie) going.  He's the leading advocate of the functioning flapper-valve When they work, you only need the choke for about as long as it takes to back out of the driveway.  Probably less vital in Queensland, to be sure, but they can make a big difference in the colder climes...

Generally they get gummed up and won't flap properly.  Rather than trying to free the vane and breaking the spring, the trick is to give it a liberal dose of CRC or WD40, and then get two small hammers and gently tap either side of the hot-box until it frees up.

Whilst I agree that the switch to water-heating meant no moving parts to break down, the original flapper-valve design had a fair bit of thought put into it, obviously for a reason.

cheers
RET

[Rod]

Cheers RET & Co,

I think I might have a go at freeing mine up. I live in Ballarat- Say no more.

Rod

[Philby]

G'day Mike,

I'm in the process of fixing a blown head gasket and identified the same problem with my maniflold flap.

I've tried the WD40, hammering and the guy who skimmed my head even dipped the manifolds for me, but it still doesn't move freely.  

All the advice I have been given, is to close the flap about 3/4 of the way and carry on as normal.  I'm in Canberra so there is some use in leaving it partially open.

Cheers and good luck,

Phil  

[Gertie]

The manifold valve definately makes a considerable difference to driveability for the first k or so depending on climate.
The shaft that the valve rotates on has no bearings &  will wear the shaft/manifold hot box & eventually become noisy due to leaking exhaust gas & rattling the valve against the backstop. A bit of oil occasionaly & the fitting of an anti rattle spring will decrease the noise & delay the wear.
I have around 350,000 miles on Gertie & have replaced the manifold 3 times. Each time I had to free up the replacement unit, using kero two hammers gently tapping the shaft & a bit of patience. The end result is worth the effort, especially in winter.
While you are under the bonnet consider a couple of drops of engine oil on the pad in the dizzy shaft under the rotor cap. I found out the hard way & ended up with a seized shaft.
Geoff

[RET]

I found out the hard way & ended up with a seized shaft.

As the actress said to the bishop (or possibly vice versa)

Thanks Geoff for the additional info.  The anti-rattle spring (P/N 7412541) is listed as standard equipment for grey motors from FE engine number L390771 onwards, but unfortunately there's no exploded view of the manifolds to show it.

cheers
RET

[Rod]

RET,
Its interesting that you give the part number and from what engine it was introduced. In the "FE and FC" Series manual (FC section) it makes mention of this. However there is also mention of it in the FE section and a bimetal spring which holds the valve 10 degrees of its seat at 70 degrees F is referred to, not anti rattle. Are they talking about the same thing I wonder?

Other than those manifolds where the spring has broken off, this may help to explain why some manifolds don't have them fitted (early FE or 48-215 / FJ manifolds).

Took your advice along with Gertie and my valve has freed up a treat. Just need patience and perserverence and it does free up. Now to get the motor back together and see how well the valve works in these very cold frosty Ballarat mornings.

Thanks for you help (again).

Rod

[RET]

Rod,

Glad to hear you got it fixed.

The bimetal spring is AKA the thermostat, P/N 1045384, shown in the MPC as item #14 on the Engine L.H. Side view.  This is what makes the valve open and close.  The anti-rattle spring is a later addition, to improve the life of the thing, as Geoff alluded to earlier.

cheers
RET

[Papa Smurf]

You look to be able to buy the heat spring from yankie land if you desire - check this site - http://www.fillingstation.com/

* online catague
* do search of part number FS-141
or description  EXHAUST MANIFOLD HEAT CONTROL SPRIN (no G)

there are lots of other tantalising goodies as well

[Gertie]

The anti rattle spring would be simple to make. It is a straight piece of steel with a bend at one end so as to fit in the slot in the shaft after the thermo spring. It then needs to be adjusted so as to rest on the backstop at normal, preventing the valve from fully closing.
Geoff

[Rod]

Hi all.

I have been able to fabricate as Geoff suggested. Then it came to my attention. The inlet manifold I'm using is for twin Carby's. The heat control valve would be pointless for this set up as its not directed to the base of the carby's. Does this seem right?? or an operational valve still be of use. Any thoughts.

Rod

[EJ_Dave]

You can actually get twin carb manifolds that will bolt to the exhaust manifold to take advantage of the heating valve etc. I just sold mine (not sent yet- don't worry buyer, you know who you are). As I'm in Canberra I often thought that a heated inlet and standard exhaust would be a better bet than extractors and unheated inlet but never got there.

If you don't have an inlet manifold like the one described you'll have to block the hole at the top of the standard exhaust manifold.

Cheers,

Dave

[Rod]

Dave,
This is the manifold I have got. But the carbys are to either side of the hot box. I'm unsure if it would be of benefit like it would be with a single barrel where the heat is directed straight underneath it.

Rod

[EJ_Dave]

Rod,

Maybe not quite as good but I bet it would be a lot better than nothing.

If you live in a cold climate I reckon the advantage in cold driveability would far outweigh the value of the extra power you'd get from extractors once the motor had warmed up. My experience with an unheated manifold in Canberra suggests it's about 10ks before the motor will run properly. You'll actually have more power without extractors over the first 10ks in stop-start driving. Handy with work being 10.1ks from home.

After rigging up a system to suck warm air from over the extractors it only takes 2 ks to run properly and it's probably not as good as a heated manifold.

Cheers,

Dave