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 

[Antietam Classic Cycle]

I was never a fan of the Delrin manifolds - I try to avoid plastic anywhere critical on older Guzzis. The clincher for me was when I ordered a pair for a customer and one arrived cracked, brand new in the wrapper. Nope...

[Frenchfrog]

I fell prey to the shtick Antietam  and at that point didn't come across any ally ones

[wirespokes]

I've thought of trying the FI manifolds. Perhaps the 40mm Dellortos could mate up to them? Anyone do that?

Thanks for the word on the Delrin manifolds. I've never been too excited about plastic in that application.

I've wanted to cast aluminum and it doesn't seem too difficult. One of the first projects would be intake manifolds for 36 Dells.

[Turin]

fyi, Stein Dinse and others sell alloy reducer manifolds that taper down to fit a bigger than stock carb. I bought a set for my lemans III.

[wirespokes]

I'd think the stock 36s on a LM3 would be sufficient. Is there much to be gained going larger?

[blackcat]

I had a pair of G&G Delrin manifolds on the 1000S but when I had the heads flowed by Mike Rich he told me to ditch them because they leaked. But I’ve had a pair on the CX for years with no issues and that bike has always run well with those manifolds. And when I purchased the manifolds the stepped screws weren’t available, so I just used the original screws from the OEM manifolds and they’ve never been removed.