Tech Spam thread - because 1/4" BSP gets 5 hand spans to the jiggawatt

[RUNAMUCK]

So is this a thing, or have I eaten too many blue mushrooms/brown acid?

It seems to me that low compression engines seem to go harder on stale gas. The old 3.5hp side valve kwaka on my kart seemed to go better on shitty gas. And sometimes it seems like my 50 does too. Perhaps the heavy end which us less volatile makes more BTU's

Or am I mistaken?

[tortron]

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[SOHC]

It's true, my old flathead v8 runs better on 2 year old 91, it just runs sweeter, I have the vacuum brake wound right out on the dizzy and it still won't ping

[Steelies]

would lack of ping indicate a slower flame front?

ie, old engine love less volatile gas, and never went well enough to show benefit from the technology-magic contained in fresh gas anyway?

[SOHC]

It has a low compression design, looks of space under the head, and I think it will run on 70 octane happily

[SOHC]

I think it likes a fast flame front as it has to travel all the way from above the exhaust valve and round the corner down into the cylinder

[tortron]

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[SOHC]

I was playing round with an old Norton sidevalve single and it had 2 plug holes, one above the piston and one above the exhaust, the one above the piston has a threaded plug for finding tdc and if you put the sparkplug there it runs like shit

[SOHC]

What is a cheep and easy to find 2bbl down drought carb witch is reasonabley good looking?

[RUNAMUCK]

Single or two stage?

[SOHC]

Single stage is fine, I have x4 holly 94s here but want something else

[RUNAMUCK]

32/36 weber?

[SOHC]

Would a weber Dcoe or Ida carb be expensive? They look alot nicer

[oldrx]

Ida are expensive, empi do a copy green brothers in Tauranga sell me.

Q, 13b headers glowing cherry red after idling at 2000rpm for under 5 mins seems at bit much? Must get temp gauge. Fuel pressure seems high spitting out main jet at idle - could be related. Think I want a more old man spec pump anyway carter way too loud.

[SOHC]

Glowing exhaust usually meens retarded ignition and spitting back can be lean or ignition related, but not sure about a rotor

[kpr]

as above, sounds like timing issue.   probably  slow to rev and down on power also if thats the case.

 

Edit: top fail

[oldrx]

Car not mobile so no seat of pants power data available, timing light next pay day. Dizzy rotor lines up at tdc mid range on base adjustment though, was running 3/4 to max advance when it was heating up. Hard to start with less timing and barely runs. Maybe vac leak causing lean

[Seedy Al]

allllllll righty then

 

Carby Electric fuel pumps.

 

I need to replace my suspected leaking mechanical pump on my crown, looking for some experience here with flow rates and PSI's

 

Factory mechanical pumps 4.2 to 5.4psi

 

Can either get a 1-4 psi pump at 90L per hour,

or 3-7 psi at 120L per hour.

 

Its going on a 2.8liter Toyota 5m (6 cylinder)

 

Peoples thoughts on which choice you would go for?

price is the same so not worried about that. Just worried about getting the bigger one and over powering the float needle, or getting the smaller one and not pumping enough to run the turd.

 

Also I assume its still ok to run the pump off the ignition and not needed a tachometric replay to power the thing?

I under stand there are benefits to safety for the tachometric, but i also dont wanna be cranking the shit out of it when the fuel is trying to prime up after a stint of no use.

 

I have intalled the higher PSi pumps in the past on other vehicles, and not really had a problem, but as I learn more, I constantly start to over think things like this lol

 

Cheers

[tortron]

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[Raizer]

I've been meaning to ask the same question, but for a 2l Mitsubishi.

Mines pumping almost as much oil out the vent as it is fuel down the line.