A few 3.0 questions

[A Quiet Boom]

During my 2.0 to 3.0 conversion I decided I wanted to maintain my current gauges so I removed the senders from the 2.0 for installation in the 3.0. I noticed that on the 2.0 the sender mounts near the bellhousing where the oil pressure switch is installed on the 3.0. On the 3.0 the sender is mounted to the oil line near the fan, I mounted mine here. Anyway with the 2.0 I got regular pressures (10psi per 1000rpms) but with the sender mounted where it is on the 3.0 my pressure is pegged at over 140. Does anyone know why this is? Should I try mounting it where the (unused) switch is?

My other question pertains to the 3.0 distributer with it's vacuum advance/retard function. Does this distributer have a mechanical advance as well? When 3.0's are converted to carbs and the vacuum lines are not connected what typically is done with the distributer? My plans are to eventually take the distributer out and remove or lock out both advance units and then use an MSD timing computer to control timing, this will allow me to set and adjust the curve to my liking and I already have the timing computer since I used to use it on my drag car for street driving.

I haven't set the timing with a light yet because in my brillance I completely forgot to put a positive connection in the engine bay for hooking up my light, but I could tell from the way it started and drove that the timing was way to far advanced so I timed it the old fashioned way, by feel. I'll put a light on it tommorrow though, I'm think somewhere in the range of 32-36 degrees for total timing and about 10-12 at idle. Does this sound right?

[emcon5]

I don't know the answer to the oil pressure question, except to say that the pressure sender needs to match the guage.

It does have mechanical advance.

I can't remember what year your engine is from, but the timing specs from the Bentley book are as follows:

78-79, 5º ±2º BTDC@ 950 RPM, vacuume hose connected, with max advance 26º ±2º BTDC @6000rpm, vacuume hose disconnected

80-83. 5º ±2º BTDC@ 950 RPM, vacuume hose disconnected, with max advance 21º ±2º BTDC @6000rpm, vacuume hose disconnected

I think as long as you work it so your max advance is ~26º you should be fine.

As to hooking up a timing light, do you have a fuse panel in the engine bay? I hook the the + wire to the fuse block, and the ground to the rear engine mount bolt.

Hope this helps,

Tom

[RazorRacer]

I'm pretty sure that my 78SC is supposed to be tested at 6000 rpm with vacuum hose connected. Can you verify the dis-connected statement?

[A Quiet Boom]

Thanks emcon5,

My car is a 912 converted to a 2.0/6 by the previous owner. I completely rewired the engine bay and there isn't a fuse block back there (never was). Im going to just run a connection to the starter and attached to an isolated post for hooking up my timing light. Anyway, I was reading the instructions on my MSD programmable timing computer and I'm gonna just hook it up, I remember really liking it when I had it on my race car, it also includes a start retard function which makes starting the car easier. All I have to do is lock the mechanical advance and remove the vacuum advance to do this. This unit give me complete control over the timing curve and even has a connection for a timing retard chip which is normally used as a high speed retard to gain a few more MPH in drag racing but is also useful to retard the timing in the event of bad gasoline. As for the oil pressure, the sender does match the gauge, I took it of the 2.0 but it installs in a different location on the 3.0 and the reading is wrong for some reason unless 140+ PSI at idle is normal for a 3.0 LOL

[Jim Sims]

Look for an open or high resistance (corroded) connection in the oil pressure sender wire. Jim

[A Quiet Boom]

Originally posted by Jim Sims
Look for an open or high resistance (corroded) connection in the oil pressure sender wire. Jim

Thanks Jim, I'll check that. It's possible I have a bad connection since I redid all the wires, I could have messed up one of them. If that fails I'm going to remove the sender and test it with air pressure and a good air regulator and gauge. I wonder if it's not grounding to the block properly since i did use teflon tape on it but I would think the threads would have contacted metal. It's really an odd sender for a Porsche (I think) because it has 1/8 npt threads on it. I'm starting to wonder if the numerical gauge isn't an aftermarket upgrade by the PO.

[Jim Sims]

There's a thread on the oil sender threads. Do a search in this 911 board with Oil AND sender and under the name: cegerer

I'd post the link but this browser I'm using won't do it properly! Jim

[A Quiet Boom]

Ok I found the thread and I understand what they are talking about etc. but what I still am confused about is sender location. Should I remove the oil pressure switch which I'm not using (back of block near firewall) and put the sender there, this is where it was installed on the 2.0. The 3.0's original sender was installed in the oil line to the right of the fan housing. I drilled and tapped the base of the old sender to accept the 2.0's sender. I could certainly plug this hole and move the sender to the back of the block but my limited knowledge of hydraulics tells me that the pressure should be nearly the same in both locations as it should be anywhere on the pressure side of the system.

[CamB]

I don't know if this helps...

This sender here (part number might be 901 741 551 01) is to marry a '69 oil pressure gauge to an SC case. It was ~US$40. I trust my mechanic to have done it "right".

[A Quiet Boom]

Sheesh Cam, your engine have it's own cleaning crew or what? LOL. Anyway that's where I mounted my sender. I took the 3.0 one apart and made and adapter out of it i.e. drilled and tapped it to accept the one that was on the 2.0. I figure I'll check the wiring and the sender tommorrow and if that doesn't work I'll try it in the same location as on the 2.0.

I can't wait to sort out these little details since my first test drive in the car tonight flat out rocked.

[CamB]

Haha - I was thinking as I cropped the picture (of the engine on an engine stand) that it will never look this nice ever again...

Good luck getting the stuff tidied up. If/when Warren sees this, he may be able to post the scans of the factory manual which show the advance curve for your engine.

I have the curves for a 2.7 CIS that someone (maybe Warren?) sent me - see below:

http://forums.pelicanparts.com/uploads/dist curves 184-001.jpg

You should copy one from an SC, I guess (one of the many areas of expertise I am lacking in).

[Jack K]

Cameron

How do you get/keep the engine that clean ??!

[CamB]

It has been completely rebuilt by someone who knows what they are doing. I suspect that is why the case is so clean. The chain tensioner kit provided the chain covers and lines. The muffler strap you see has surface rust, so it isn't perfect

Some bits were on my 2.0T engine (eg the blower assembly) but these were powdercoated or were relatively recently refinished when I bought the car so weren't too dirty. Hell, there is something of everything on there (964 wires etc and he snuck in some braided cable)...

Of course, most fully rebuilt engines look like that.

My wallet is justifyably proud of the outcome:

http://forums.pelicanparts.com/uploads/fuel%20injection%20small.jpg

[Jack K]

Oh, yes .... now that you mention it , it looks terrible!

[Jim Sims]

I'd leave the sender there as there will only be 5 to 10 psi difference (cam tower oil line location pressure will be lower) due to the pressure drop in the oil galley in between. I'd look for the wiring problem as it will still be there if you move the sender. Cheers, Jim

[emcon5]

Originally posted by RazorRacer
I'm pretty sure that my 78SC is supposed to be tested at 6000 rpm with vacuum hose connected. Can you verify the dis-connected statement?

That is what I saw in the Bentley book. I will look again when I get home.

It could be wrong.

Tom

[emcon5]

Originally posted by RazorRacer
I'm pretty sure that my 78SC is supposed to be tested at 6000 rpm with vacuum hose connected. Can you verify the dis-connected statement?

I verified it, Bentley says:
78-79, 5º ±2º BTDC@ 950 RPM, vacuume hose connected, with max advance 26º ±2º BTDC @6000rpm, vacuume hose disconnected

I looked at Haynes book as well, It says the same thing.

Anyone got a 78 spec book?

Tom

[RazorRacer]

Originally posted by emcon5


I verified it, Bentley says:
78-79, 5º ±2º BTDC@ 950 RPM, vacuume hose connected, with max advance 26º ±2º BTDC @6000rpm, vacuume hose disconnected

I looked at Haynes book as well, It says the same thing.

Anyone got a 78 spec book?

Tom

Thanks. I must have gotten confused.

[A Quiet Boom]

Well, I've got the initial timing set at 10 degrees with total coming around 30-34 (hard to tell without degree markings) anyway I've got a bad hestitation on the part throttle to mid throttle transition which seems to get better with less timing. I'm thinking the mechanical advance curve is way wrong for my carbs so I'm going to have to get my timing computer installed sometime this weekend. Other than that and the screwing oil pressure gauge it's running great, starts on the first hit of the key and idles smooth around 800rpms. On throttle power is brutal for an engine this "small". I'm still very impressed with the throttle response of my modified Zeniths especially since I haven't even touched the accelerator pump adjustments yet. Oh well back to tinkering LOL

[A Quiet Boom]

Well I've got my MSD timing computer installed, I locked out the mechanical and vacuum advance on the distributer by welding the plates together. Curve is set with 10 BTDC intial and total timing at 5500 of 30 BTDC. This has greatly helped the part throttle misfiring but I think I need to turn my attention to the accelerator pumps and the main jets at this point. While I'm well versed at tuning Holley carbs new at Zeniths and Webers. Anyone here have any advice on dialing in the transition from part to mid throttle? I'm first going to double check that the carbs are sychronized with the engine warmed up fully. Then check accelerator pump linkage etc. I'm using the steps laid out in Waynes book for sychronizing and adjusting the carbs as well as recommendations from the company I bought the larger venturis from.

BTW I've heard lots of talk about the 901's first gear being the weak link anyone have actual experience with this? I have two spare transmissions so I'm not overly afraid of hurting it, plus over the winter I'm going to install my 915 gearbox (just wish it had 7:32 gears like the 901)