setting up delrin manifolds & PHF on t3

[yackee]

I ran into some issues with installing new PHF30 carbs on my t3. Initially things seemed fine, but after a 60 mile ride the bike started acting strangely, revs wouldn't come down with the clutch pulled. At home I found all the manifold bolts had loosened. I tightened them back up but the bike still won't run reliably, revs still stay high before dropping and then stalling.

I was wondering:

1. how tight do I tighten down the delrin manifolds? I am worried about cracking the plastic.
2. Does anyone use RTV, or should the o-ring be enough? And do I change the o-ring every time I take the manifolds off the cylinder?
3. Does anyone use lock washers under the manifold bolts?

Anything else I should consider? Thanks for any tips.

[SIR REAL ED]

I would install the biggest flat washer you can next to the manifold to get some bearing area.  Then a lock washer and only tighten enough to compress the lock washer.

If it still leaks or loosens up, then I would use some sealant on the o-ring and thread locker on the threads.

[Frenchfrog]

I've had issues with those manifolds and took them off and went with alloy ones.
The main problem I had was the manifold screw threads for fitting vacuum gauges leaked and stripped so I fitted helicoils with an o ring to seal the screws and have a decent thread.
Personally I don't rate the delrins after that.

[Turin]

did you use step studs and lock nuts? That's what i did and have never had an issue.

[Frenchfrog]

yeah but the issue was with the bleed screws on the sides Turin.They leaked .

[Antietam Classic Cycle]

yeah but the issue was with the bleed screws on the sides Turin.They leaked .

They have metal thread inserts in the vacuum ports now.

[Turin]

Wouldn't be the first time I read something wrong... so the bleed screws to the port on the sides of the manifolds are coming loose and causing a vacuum leak? I'd use a dab of Silicone on the threads or just glue them and be done with it. That's just me though.
 

[SIR REAL ED]

yeah but the issue was with the bleed screws on the sides Turin.They leaked .

some would say they... bled...

[yackee]

did you use step studs and lock nuts? That's what i did and have never had an issue.

I used thread-reducing inserts but hadn't thought about reducing studs. That might be the solution.

[yackee]

I've had issues with those manifolds and took them off and went with alloy ones.
The main problem I had was the manifold screw threads for fitting vacuum gauges leaked and stripped so I fitted helicoils with an o ring to seal the screws and have a decent thread.
Personally I don't rate the delrins after that.

Frenchfrog, which alloy versions did you use? I didn't know anything non-plastic was available to mount them to a T3. I still have the stock manifolds.

[Turin]

I got my step studs at ace hardware. I use a little copper RTV on both sides of the gasket.

[Frenchfrog]

They have metal thread inserts in the vacuum ports now.

I helicoiled mine...still have to say ,much to my surprise, the bike runs better with alloy manifolds !!!!

[Frenchfrog]

Frenchfrog, which alloy versions did you use? I didn't know anything non-plastic was available to mount them to a T3. I still have the stock manifolds.

You can use any of the alloy manifolds as long as they match the carb and cylinder intakes.They do need a small bit of porting to match to the heads as a rule but this is not really essential.
The ones I used for T3 heads and then LE Mans heads were from later square head bikes