Stripping, Cleaning and Painting Jenvey ITB's-one now painted

As part of my engine tart up i'd like to paint the DTH's, however, i'm concerned that i may do more harm than good if i take them to pieces.

Obviously i wouldn't paint the gasket surfaces and i would avoid painting over any screws etc but can they be taken apart and put back together without the need for any balancing or particularly technical knowledge/assembly?

Any info would be greatly appreciated.
Thanks.

EDIT: just to add, there are a few screws in the top of each body-are the positions of these critical to the setup of the bodies or can they be removed and reassembled without consequence?

 

Just to clarify, can anyone tell me what the circled bits are in this image please. Will their position/screwed in depth have any bearing on anything or are they just there for other applications or uses?



Any general advice on stripping them down is also greatly appreciated.

thanks

 

I'd be quite nervous about stripping them down.

I have a feeling those screws might be something to do with the idle. I'd be loathed to touch the settings.

Is there no way you can achieve the required clean up using a solvent and brake cleaner?

 

unfortunately the plan is to do them black so unless i brush painted them (which would most probably look terrible) i can't see a way of doing it without stripping them.

I 'could' mask them but it would be a pig to do and i doubt it would be anywhere near as good as stripping them.

I'm still trying to find out for definate at the moment but from what i've read so far it appears some have an idle bleed screw so theres a good chance you're right about this.

If thats the case then i don't fancy mucking about with them, i'll have to get them professionally done [:^(]

EDIT: The more i read on these the less i want to touch them

 

Just a quick bump for this as in a bored state i found myself taking them apart

It won't be a total stripdown, just a tart up so i will leave anything that looks like it might affect any settings well alone.

If anyone has any advice or tips then now's the time!

thanks

 

blast clean in a cabinet that uses acrylic beads. once the injectors and ram pipes are removed some careful masking using 3m yr500 "tombstone" tape will protect the rest.

a really good wash in solvent before paint to remove an wandering beads

paint wise epoxy will be best, for both primer and topcoat. it has very high heat resistance and discolours rather than burning and would be factory finish

i`ve done hundreds of aircraft hydraulics and wheels this way, and the occasional gearbox

unfortunately i don`t paint any more

 

thanks for the info tinydubs-definately sounds like the 'right' way to do things

However, in the absence of the good stuff i'll just have to make do with whatever is leftover from previous attempts at this sort of thing!!

 

they are the idle bleed/balance screws... circled red in your picture

 

Them idle bleeds/balance will need setting up again if the ITBs come off..only the larger silver one with the locknut though

You'll need a synchrometer to do it. Ideally you need to check/adjust the idle airflows prior to removal- then you know what to set them to when you refit them.

Some adjustment of the balancer screw between the bodies may be necessary too

 

Thanks guys, that confirms i won't be touching their position. The bodies themselves have been off the head for a while now but will simply removing and refitting them make any big difference to the settings? Nothing has been adjusted or changed so even if they do end up slightly 'out' i can't see it making a huge difference-i've been known to be wrong from time to time though!

As and when the engine goes in and everything else is sorted and working i'll be tempted to get things checked over professionally but for now, as a get me going temporary measure i'll just put them back on with new gaskets.

When things have progressed a little further i'll pop some pics up.

 

If you purchase a synchrometer you can do the basics yourself.

Saves a lot of faff and wasted time at the RR. I'd still check it all on refit even if you haven't adjusted it.

You close all the air bleeds off fully initially. Start the car and use the synchrometer to measure the airflow into each ITB at idle.

Once you have established which body has the least- it's a case of tweaking open the bleeds on the others to level them up. Only needs a small amount

You can use the synchrometer to make sure each pair of bodies are balanced to each other too. The central adjuster between the two sorts that if the adjustment is out one pair of bodies will read considerably different to the others at idle. (each pair of butterflies being held at different angles)

Chris

 

The yellow circle is just where they grubbed the drilling after, no need to pull these, unless you are dipping in caustic soda.

 

10% phosphoric acid solution, brightens alloy and removes the oxides for painting.
i`ve never used caustic soda so i can`t comment.

either way its wash wash and wash again

 

Chris-thanks, i'll look into it when it comes to putting the engine in. Hoping to do so in the summer but time is always tight for me!

Brian-cheers, that's one less thing to worry about!

tiny-after rubbing down one of the bodies by hand, using an acid to prep sounds very appealing! Would it be a case of cleaning it up with the acid, washing it off (with what btw?) then painting? I take it that would provide enough of a 'key' on the surfaces for paint to stick?

 

once rubbed down it should have enough of a key, the bare alloy, is scrubbed with the phosporic acid solution and scotch brite to remove contaminants, 10% concentration is enough, wash with water to neutralise.
degrease and dry before paint
you should paint within 1 hour

maybe i should do a full on sticky for stuff like this

 

Sounds good!

 

I forgot i started this! Never mind, i shall update incase anyone is interested.

In the end time was running short on my holiday and the garage was bloody cold last winter so only one of the bodies got done-turned out ok though and the other has been 90% prepped. I also didn't have the time nor inclination to search out for chemicals or other methods and finishes so i stuck to what i'd done on previous engine components.

Anyway, first thing was to strip them down. Easy peasy.



Although they'd already been given a very quick degrease when i first got the engine it had clearly been a bit of a token effort so i used a bit of bilthamber to shift the restof the grime-good stuff this and has served me well.





After that the 'fun' began.

As i would be painting them i needed to get rid of some of the casting texture. I didn't want to go all out and have them super smooth as it would take forever and it would be very difficult to maintain a good surface with just hands and a dremel-for me anyway!

I did get carried away on the easy bits and smoothed the edge of the flange that meets the head and the one that meets the trumpets.



you can see the shiny smooth flange here.



I also couldn't resist quickly polishing up the brass vac fitting



Although they look quite polished at this stage its only because i'd gone over them with a wheel on the dremel as i did briefly consider the polished look. Fortunately i'm not that much of a glutton for punishment/idiot!

I then quickly rubbed over them again just to be sure they were decently keyed, blew them out thoroughly with an airline and began masking.



I had a bit of 'mare trying to mask some areas with tape so stumbled on the idea of using blu-tac. This turned out to be a master stroke as it could be modelled into area's my clumsy hands just couldn't reach with tape.

With the fiddly work done i got out a can of PJ1 satin black and sprayed until my lungs bled (i did use a mask but not a particularly good one). This stuff, although it smells like no other aerosol i've used, is ideal as it doesn't require primer and goes on very nicely from the can.

So the final result....





Overall i'm pretty pleased-they aren't 100% perfect as there were some strange imperfections in the cast and extra bits of material here and there but i seem to remember Bill B saying these were the development bodies for the DTH Jenveys (?) so i was reluctant to start grinding anything away.

The trumpets have seen better days with numerous little dings here and there but they came up well enough with nothing more than autosol and some good old fashioned elbow grease. Stainless bolts have also since been ordered and fitted so they should look pretty good. Fingers crossed they still work

All i need now are some nice, polished Jenvey or Badger5 logo's Oh, and to do the other one

 

good work

 

looks great

good progress blog !

 

thanks guys

still need to do something with the throttle mech and fuel rails but it will be late summer before i can start on those