type 4 motor

[Piledriver]

If you have a dual vac can, the vac advance is also a boost retard.
You only connect the vac side, vac retard side of vac can leave open.

[GARRICK.CLARK]

Ok thanks Pile.
I still don't understand why its backfiring as the boost gets to 10 psi and 2/3 throttle.
AFR gauge shows 11.5 at the point of backfire.
No pinging .
I have also turned off the rev limiter as per petronix instructions.
Timing.
Do I keep advancing the timing till it starts pinging ,then refit the boost retard vac can to back down the total.

I'm thinking of fitting an advance stop on the dizzy plate , but allow the plate to move in the opposite direction to retard the timing when I fit the boost retard can. I would then have mechanical advance only and the retard under boost.

I have tried the engine with vac advance and mechanical advance together and under light load it pinged bad, I unplugged the vac can and the ping went away.

[Piledriver]

The Dual vac can does advance and will retard under pressure , the single vac unit cannot, it has a stop the dual does not as the dual is designed to do retard. (just leave the back hose disconnected)
Knock kills engines, if you can hear it at all its already doing damage.

Backfire could be the intake valves not sealing fully or even burping hot ex. gas back into the intake on overlap.
A smallish turbo with high ex. back pressure makes this worse.
More likely the latter esp if your timing is very retarded, but a leakdown/compression test is called for.

A fully programmable ignition is the way to go, CBs black box or a Microsquirt would work, there are other choices.

[GARRICK.CLARK]

I don't think its the valves not sealing as I lapped them in last time it was apart, after the lapping I checked for leaks, all good, low miles since rebuild, I did fit some dual springs to the inlets but not the exhaust, my thinking was that the firing cylinders pushes on the valve head keeping them shut. I could be wrong tho.
Turbo is sized for a 2ltr.
I will do a leak down to check it.
Think I'll try the CB Black Box soon.
For now I'm gunna advance it till it pings under load/boost.
Then fit the retard can, and fit an adjustable bleed valve, setting the boost blowing into the retard can say a couple of psi lower than my max boost pressure for the engine, so the retard doesn't start too soon in the rev range and starts to retard before pinging starts.
Good idea or not.
Thanks Pile.

[Piledriver]

Just make sure you suck and blow on the vacuum side only.
Retard side stays open to atm.

[GARRICK.CLARK]

Well my experiment hasn't worked but engine revealed a couple of things.

1st. Engine doesn't like being retarded by the dual advance/retard canister. So back to mechanical only.
2nd. More total timing stops it backfiring.
3rd.With more total I can now go WOT
BUT more total now makes motor ping. Doesn't ping on slight down hill road.
AFR was at 13.5 at WOT
So I think my only option is put more fuel in at the top end.
Do I need a head temp gauge. maybe the heads are getting too hot.

[Clonebug]

More fuel will help with cooling and therefore you might need to run as rich as 11.5:1 at full boost.
More fuel will also. keep the engine from pinging.
It is better to be on the rich side than too lean especially when testing high boost regions.

[GARRICK.CLARK]

Hi guys, I've been reading about fuel pumps.
My pump is a Facet cube. 1.5 psi-4 psi and 20 gallon per hour.
My Su hs8 doesn't leak with the 4 psi max pressure.

I'm thinking that the 20 gph is too low and the bowl could be running dry which might contribute to my on boost high rev back fire.
I read that draw through turbo vw's need at least 40 gph to run.
thanks for any advice.

[Piledriver]

These work extremely well, and have a built in filter and water separator.
3 meter dry lift. It really, really sucks.
http://www.facet-purolator.com/dura-lift-pumps.php

I use one for a recirculating feeder on my TDi... Massive overkill, but it always has a prime and fires off instantly.
VW didn't figure out they really needed a feeder until 2001... I have a 99.5.

[madmike]

Holley 'Red' pump works too

[GARRICK.CLARK]

thanks for the above guys.
I like the look of both those pumps.
I have an over kill efi pump that I used to use on blow through, if I was to use that with the reg that brings the pressure down from 90 to 3psi and bleeds off excess fuel back to the tank would this be ok. would I still need to boost ref the fpr of leave it at 3psi but with all the gph I would ever need .
Just asking before I pay more money out.

[Piledriver]

The Holley red has a shaft that goes to a motor with little tiny brushes at ATM.
The teflon seal leaks after a season or two... Stupid design, massively cheap build.
(I ran one breifly, and took it apart after it started puking fuel---never again)

A plugged regulator or kinked return line will leave you with max fuel pressure.
A pump with limited pressure capability is strongly suggested for safety reasons.

A lot of setups "work" but are not necessarily a great plan.

[madmike]

Never seen a Reg that will drop 90-3 lbs but if it works ,,use it

[Clonebug]

Boost referencing a stock fuel pump is a reliable and inexpensive option......

[GARRICK.CLARK]

Hi Mike, the reg I have is an fpr014. its for converting fuel injection to carb use.
I've got some figures wrong.
the pump 0 580 254 984 spec is
43 GPH with 70 psi.
The reg can take pressure down from 88psi to 2 psi.