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> Fresh 2.7, doesn't want to wake up
930cabman
post May 8 2024, 05:23 PM
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My /6 conversion is going on 3 years as it seems as many do. I had a local old school reputable shop build the stock 2.7, case was done at Ollies, .... should be a great engine. Finally trying to get her barking, but just won't take hold. While cranking she wants to start, but when I release the starter, she conks out. We have a spark (not real significant), timing is close, carbs appear ok.

Is it possible the valves or maybe rings are not sealing because the engine sat for about 2 years?
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Superhawk996
post May 8 2024, 05:29 PM
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Fuel
Compression
Spark

Something is missing or not in the right order. Go back and re verify your assumptions.

Use starting fluid if necessary. Carbs may not be working on idle jets.
Spark should be strong. Verify battery, coil, and timing


Now for the potentially bad news - verify compression. Leak down if necessary. Not sure who assembled but very easy to screw up cam timing on a 911 engine.
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technicalninja
post May 8 2024, 05:36 PM
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Run a compression test. If low add 1/2 oz of ATF/WD40/ither light oil. Retest.
Better? Spin till it stops pushing lubricant out plug holes and re-try.

Most of the time I do my initial start on carb spray/ether (I use B12).
It's harder to do with ITBs but a little 1/2 second squirt down each barrel should run for 10+ seconds.

If your comp test is way low check valve clearance before ripping it back apart.

You can help valve sealing with a leak down test and bonking the valves.
This works on used, nasty engines.
Shouldn't be necessary on fresh lapped valves.

The only thing that long term storage of a freshly rebuilt engine might effect is the valve springs that have been sitting "compressed". It should only be two of them on a 6 and I would bet BIG money that three years wouldn't hurt them at all.
30 years might...

This does mean clean dry storage. Humid conditions might trash one in three years.
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mepstein
post May 8 2024, 05:46 PM
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Don’t panic, it’s usually something simple.

We were having issues with a “noise” from a 993 engine that had been sitting for a while. Ran through all sorts of scenarios. Finally saw a spark plug that was removed to do a leak down. Replaced plug and it ran perfectly.
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nditiz1
post May 8 2024, 06:49 PM
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Can you confirm fuel is getting down the throats when pumping?
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flyer86d
post May 9 2024, 05:05 AM
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I had the same issue with the 2.7 that I put together for my 68 911. I did all of the compression, spark, fuel verification. There were two issues. I was trying to run the 2.7 without a CDI box and fuel pressure was too high. I thought, they used to sell these cars with Weber carbs new and they started and ran nicely. I went back to the initial settings for the Weber’s including low speed mixture and ultimately fuel pressure at 3 psi. I installed an MSD 6A ignition. It then started, idled and took throttle nicely. That MSD does pack quite a wallop when I tried to put a loose plug wire back on even using insulated pliers.

Charlie
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930cabman
post May 9 2024, 05:47 AM
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QUOTE(nditiz1 @ May 8 2024, 06:49 PM) *

Can you confirm fuel is getting down the throats when pumping?


Yes, I am getting a good squirt, but have not measured the amount of fuel. Where is a tiny graduated vial available to measure this.
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Luke M
post May 9 2024, 05:54 AM
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QUOTE(930cabman @ May 9 2024, 04:47 AM) *

QUOTE(nditiz1 @ May 8 2024, 06:49 PM) *

Can you confirm fuel is getting down the throats when pumping?


Yes, I am getting a good squirt, but have not measured the amount of fuel. Where is a tiny graduated vial available to measure this.





Hi John,

Check out partsklassik.

https://www.partsklassik.com/p-3813-float-l...arburetors.aspx

I believe they are closed until May 12th.
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930cabman
post May 9 2024, 05:56 AM
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QUOTE(flyer86d @ May 9 2024, 05:05 AM) *

I had the same issue with the 2.7 that I put together for my 68 911. I did all of the compression, spark, fuel verification. There were two issues. I was trying to run the 2.7 without a CDI box and fuel pressure was too high. I thought, they used to sell these cars with Weber carbs new and they started and ran nicely. I went back to the initial settings for the Weber’s including low speed mixture and ultimately fuel pressure at 3 psi. I installed an MSD 6A ignition. It then started, idled and took throttle nicely. That MSD does pack quite a wallop when I tried to put a loose plug wire back on even using insulated pliers.

Charlie


I picked up the MSD box and their coil a couple weeks ago, but then a hip replacement followed by internal bleeding has slowed me down a bit. I also was trying to run her with a (good) coil and points. A Pertronix is also on the way.

Where did you mount the MSD box?

Thank you all
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930cabman
post May 9 2024, 06:01 AM
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QUOTE(Superhawk996 @ May 8 2024, 05:29 PM) *

Fuel
Compression
Spark

Something is missing or not in the right order. Go back and re verify your assumptions.

Use starting fluid if necessary. Carbs may not be working on idle jets.
Spark should be strong. Verify battery, coil, and timing


Now for the potentially bad news - verify compression. Leak down if necessary. Not sure who assembled but very easy to screw up cam timing on a 911 engine.


A well known local 911 racer built the engine, I would say near 0 for a fault internally.

And yes, with fuel, compression and spark all coming together correctly is one of the reasons we wake in the morning.

Thanks all
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mb911
post May 9 2024, 06:04 AM
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Ok so I will echo wrong cam timing. A friend bought an engine a few years back from a reputable shop. Got the car running but ran terrible for a year chasing everything. Really not safe to even drive once he got it running. Turned out cam timing. It is very easy to time one cam 180 out. That is where my money is.
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930cabman
post May 9 2024, 06:05 AM
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QUOTE(Luke M @ May 9 2024, 05:54 AM) *

QUOTE(930cabman @ May 9 2024, 04:47 AM) *

QUOTE(nditiz1 @ May 8 2024, 06:49 PM) *

Can you confirm fuel is getting down the throats when pumping?


Yes, I am getting a good squirt, but have not measured the amount of fuel. Where is a tiny graduated vial available to measure this.



Hi John,

Check out partsklassik.

https://www.partsklassik.com/p-3813-float-l...arburetors.aspx

I believe they are closed until May 12th.


Luke, it might be this one" https://www.partsklassik.com/p-2136-carbure...harge-vial.aspx

I was going to contact you, but this project is taking a back seat for another week or so. I need to heal a bit
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Retroracer
post May 9 2024, 08:26 AM
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@930cabman - hope recovery from the health issues goes well.

Fuel/spark/run issues aside - did you turn over the engine (w/spark fuel disabled) to make sure the oil pressure builds nicely? The Dempsey book talks about the technique/need. You may well have done this already, but one less thing to debug before figuring out the 3-dimensional aspect of cams/fuel/spark/running/etc....

- Tony
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gereed75
post May 9 2024, 08:31 AM
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Incorrect fuel level in carbs can result in a no go condition. The sight glass shown in the first link is the way to go Works like a charm.

I think the second one measures the accelerator pump discharge. That is way less critical than setting float level.

Get better
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930cabman
post May 9 2024, 09:37 AM
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QUOTE(Retroracer @ May 9 2024, 08:26 AM) *

@930cabman - hope recovery from the health issues goes well.

Fuel/spark/run issues aside - did you turn over the engine (w/spark fuel disabled) to make sure the oil pressure builds nicely? The Dempsey book talks about the technique/need. You may well have done this already, but one less thing to debug before figuring out the 3-dimensional aspect of cams/fuel/spark/running/etc....

- Tony



Thank you, after almost a week of an internal bleed after a hip replacement, we are on the mend.

Yes, I have an old school oil pressure gauge and have confirmed 20-25 psi while cranking.
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930cabman
post May 9 2024, 09:40 AM
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QUOTE(gereed75 @ May 9 2024, 08:31 AM) *

Incorrect fuel level in carbs can result in a no go condition. The sight glass shown in the first link is the way to go Works like a charm.

I think the second one measures the accelerator pump discharge. That is way less critical than setting float level.

Get better


I can tell everyday is improving, thank you

The Weber 40 IDT float levels appear quite simple with the 18mm and 12.5mm gauges and I am confident with the float levels. I am hoping the addition of a new MSD box, MSD coil and Pertronix trigger will get me over the hump.
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Root_Werks
post May 9 2024, 10:00 AM
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Would certainly do a simple compression test, just to make sure those numbers are good enough to start the engine.

Would agree with most, probably something simple, timing too far or ignition switch cutting power after you let off the start position.

Would really hope the cams are not 180 out. (IMG:style_emoticons/default/sad.gif)
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Superhawk996
post May 9 2024, 01:06 PM
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QUOTE(Root_Werks @ May 9 2024, 12:00 PM) *


Would really hope the cams are not 180 out. (IMG:style_emoticons/default/sad.gif)

Remember 911 cam timing is set via index pin that has a multitude of possible “wrong” positions.

Doesn’t have to be out 180.

It sounds like there are still plenty of other assumptions that need to be verified and hopefully it isn’t cam timing.Attached Image
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930cabman
post May 9 2024, 01:14 PM
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QUOTE(Root_Werks @ May 9 2024, 10:00 AM) *

Would certainly do a simple compression test, just to make sure those numbers are good enough to start the engine.

Would agree with most, probably something simple, timing too far or ignition switch cutting power after you let off the start position.

Would really hope the cams are not 180 out. (IMG:style_emoticons/default/sad.gif)


My engine builder has probably built hundreds of 911 engines, I suspect the fault does not lie with the engine internals.

dumb question: how/why would the power to the coil not be energized after releasing the ignition switch?

Prior to the /6 conversion, she was a running /4. Nothing was changed in the main wiring harness
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mb911
post May 9 2024, 01:17 PM
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QUOTE(930cabman @ May 9 2024, 11:14 AM) *

QUOTE(Root_Werks @ May 9 2024, 10:00 AM) *

Would certainly do a simple compression test, just to make sure those numbers are good enough to start the engine.

Would agree with most, probably something simple, timing too far or ignition switch cutting power after you let off the start position.

Would really hope the cams are not 180 out. (IMG:style_emoticons/default/sad.gif)


My engine builder has probably built hundreds of 911 engines, I suspect the fault does not lie with the engine internals.

dumb question: how/why would the power to the coil not be energized after releasing the ignition switch?



I have built hundreds of aircraft engines and about 20 911 engines. Trust me it can happen but your right to chase down the power issues
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