V8 RPM Signal

[vlad01]

holy shit the first one! on decel its shocking.

Have always hated dizzys with a passion but this makes me angry.

[Holden202T]

whats the big issue, if you didn't have a data log youd never know it was like that ? it works perfectly fine

[vlad01]

trust me I have always known this before ever playing with EFI cars. Used to shit me when trying to time an engine with a timing light but its too jumpy because of timing scatter caused by being mechanically linked to the crank so imprecisely.

[Gareth]

Im with vlad, we ran straight cut gears in our speedway engine years ago and had trouble with what we thought was valve bounce, it turned out to be the fucking cam gear backlash (which wasn't heaps btw) was hurting our ignition system some how, over the shoulder goes the straight cuts and in with stock type helical gears, 1500 more rpm... til valve bounce

[vlad01]

dizzy and carbs are a good hammer target practice.

[VK_3800]

Something's wrong if it won't even hold steady for a timing light.

The output from my V8 with distributor is nowhere near as bad as the other examples - its just as stable as the MAP reading

[vlad01]

volkswagens and fords was the issue lol.

VW use a worm drive off the crank to a floating fuel pump vertical cam shaft and then to a multi shim drive dog. You can turn the rotor a good few deg from the slack and thats as good as they come.

As for ford, they always seem to have tones of shaft play in the dizzy, I've seen in a few cases where the side movement was around 2mm.

Can't say much for holden V8, only ever worked on a 304 dizzy in a torana so it was a no go even getting to the cap. Was seriously thinking the only way to get it out was to remove the engine lol.

I left that with the owner as I wanted nothing to do with it haha.

[Holden202T]

I've seen a lot of end float in dizzys that makes a massive difference even without including the cam chain/gears or anything else like that.

[vlad01]

I've seen a lot of end float in dizzys that makes a massive difference even without including the cam chain/gears or anything else like that.

yes because the gear is helical

[VK_3800]

I'm as guilty as the next guy sometimes but you can't blame the machinery when its done 3 lifetimes of work and is starting to wear out. A lot of people complain about VN-VS Commodores being "unreliable", but most have high kms and haven't even seen an oil change for half their lives - its good engineering that its still running, not bad that it needs a little maintenance!