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SureStart engines with cracked backplate housings

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SureStart engines with cracked backplate housings Empty SureStart engines with cracked backplate housings

Post  sosam117 Mon Nov 16, 2020 8:07 am

I purchased "three" new in the package SureStart engines.
SureStart engines with cracked backplate housings Surest10

I removed one from the packaging to look it over. Looked nice but seemed tight?
I also purchased "two" of those throttles to replace the straight choke tube.
After I removed the choke tube I noticed where the needle valve is press in being cracked?
I checked the other two and they also have the same problem.
SureStart engines with cracked backplate housings Surest11

Is this going to effect the performance (use) of the engine? Is it a problem that has to be fixed?
Or does it really matter if this is cracked? Will it cause a problem down the road while I use the engine?
Will these cracks then effect how well the choke tube with the throttle will work?
Thanks,
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SureStart engines with cracked backplate housings Empty Re: SureStart engines with cracked backplate housings

Post  balogh Mon Nov 16, 2020 8:40 am

Because of the small amount of false air entering the venturi through the cracks, instead of the throttle tube, it may affect the throttle efficiency (even when the throttle is fully closed, the engine can inhale some air, and may idle instead of stopping..but conventional COX heads are not hot enough to keep a good idle without flame-out, anyway, unless you use hot glow plug in a plug adaptor, and/or retain some heat with an exhaust manifold) .

Other than the risk of getting the spray bar rotated if the NV is over tightened, there is no more risk I could see...this is an inherent problem of almost all SureStarts with the grey horseshoe backplate. I also have a few with the same cracks. In another post  someone mentioned, the material of the grey backplate is not the same flexible delrin as was used for earlier production backplates, but a more brittle material,  therefore the venturi snapped when the spraybar was pushed in in the factory.

I am not sure if there is a reliable glue that would stay in the crack and keep the edges together, especially in a nitro environment. The good thing is that the throttle tube has a lip that slips over the venturi intake, and lends a bit of circular/tangential strength to it that may at least prevent the crack to advance further.
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Post  MauricioB Mon Nov 16, 2020 10:04 am

I have seen that problem on gray plates.
Therefore a while ago I made this solution.
You can even make it long and also place an air valve if it is of your interest.
The aluminum alloy tube is the permanent and definitive solution to this problem that comes from the source.
SureStart engines with cracked backplate housings 20201016
SureStart engines with cracked backplate housings 20201018
SureStart engines with cracked backplate housings 20201017

and if you want you can place an additional air valve RC Plane
SureStart engines with cracked backplate housings 20201019
SureStart engines with cracked backplate housings 20201020
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SureStart engines with cracked backplate housings Empty Re: SureStart engines with cracked backplate housings

Post  MauricioB Mon Nov 16, 2020 10:40 am

You can place the original tube and valve (r / c), but you can also do it as I show you here.
SureStart engines with cracked backplate housings Action10
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Post  davidll1984 Mon Nov 16, 2020 11:14 am

Just litle trick To préserve old new plastiques part use wd40 lube give flexibilité To old plastiques part like wit Kyosho f1 black plastiques part use To spray wd40 on part let it dry and try flex part litle wil flex bether than new y found this using wd40 To lube suspension part of one of m'y 4x4 nitro Monster truck y have one for parts Not used for years Find différence in flex of part used wit wd40 and Not lubricated part from m'y second Not used truck after couple test on difrent part Find useful To spray on Most unused parts complète engines stores in box for years it wil préserve plastiques and save time mony destroying Front suspension arm wil be hard To Find parts for vintage cars and its Not working wit al type of plastiques dont spray on clear Windows parts cox control ligne plane fuselage ok move sticker of the plane after wing flex litle bether spray on befor it crack y like mauricio modification Good way To fix and bether place for its carb mauricio very créative Thumbs Up Airplane
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