grunta

grunta's 67 vc valiant

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so the carter carb i have has a hose connection on top on the accelerator pump , is this just a breather?

 

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Probably something emissions related? Ie a breather to stop fumes escaping.

The aussie spec ones ive had don't have that bit

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yeah i was thinking something like go off to a charcoal canister spec thing.cool as

 

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guesses on how long viton o rings will survive on throttle shaft? , im thinking around a year... or 12 x drives

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1 hour ago, grunta said:

guesses on how long viton o rings will survive on throttle shaft? , im thinking around a year... or 12 x drives

I did wonder about that, depends on what you lube with with I guess.

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magnalube... its a ptfe grease...the best shit.,

good for -40 up to  282 degrees c..

 

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I think it is very unlikely that you are over-carbed with a stock style 2 barrel on a slant 6 and the fact that things are OK at wide open throttle suggests that the carb size is just fine for your engine. 

Maybe try running it with your vac advance disconnected and the port on the carburetor blanked off or even try knocking the timing back a few degrees. Slant 6's make a fair bit of manifold vacuum and at part throttle you will almost certainly be pulling vac advance . This could be contributing to the part throttle problem while at wide open throttle the vac advance shouldn't be active.

Not sure if it will make any difference but it's very easy to try.

 

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Funny you mention that as It did run much smoother when I knocked off the tube and didnt realise ... had a vac leak too and was smoother... initial timing has been played with and im set around 8'btdc and it looks to advance to around the 30-35btdc mark under full throttle ... (thats just in the garage not under load... ) ive been to both exrtrams of initial timing 2-12' and it made little difference .. is it a known problem with the vac advance causing thibgs ljke this because it would make sence with the symptons... ? I will definitely try it... any idea on what the mechanical advance will advance it to by its self? .. .. also went for a massive drive this morning which was choice .. I really dont drive it at all above 1/2 throttle anyway so it really isnt a problem... drove nice tbh

 

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One of my cars in the past I had to block off the vac advance because of light throttle bag-o-dickery,  it would start surging. That had a too lumpy cam though.

 

 

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I know fouling of #6 can be a symptom of timing issues. 6 runs hottest and can be prone to pre-ignition/poor combustion if the timing curve is not correct. Vac advance modifies the mechanical advance curve and if it's pulling too much in the mid range maybe it's contributing to the problem. 

Like cletus I have had to disconnect the vac advance on a modified engine because it just wouldn't run properly with it connected, that engine also carbon fouled #6 and that's actually what prompted me to suggest disconnecting it. 

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