The jet in your picture is talking to me - it is definitely not unmolested! The reason that it might be different is that in many, many cases, jets are reamed to a new, larger size. People do that because it is sometimes easier than locating/buying specific replacements. I've taken 140 mains out of a car that were factory stamped 105s, and I've seen many, many cars with modified jet sizes - even different ones from cylinder to cylinder. I use jet drills if needed to clean up a used set to a certain size, but I've always preferred to use jets with factory markings - less confusion! It would really help if you could come up with a set of small drill bits and a caliper/micrometer to measure them with.

Yes, the upper rocker covers are aka as the intake valve covers... A factory manual (and probably a Bentley manual) will show exactly how to set up a dial indicator and measure cam timing (no disassembly required - we just want to know what you've got in there!).

What sort of drill bits do I need? I have a micrometer (vernier caliper I think it's called). How do I go about measuring? I don't know what 110 refers to... http://forums.pelicanparts.com/support/smileys/sad2.gif

I'll read up on the cam check procedure. I have 101 projects, rebuilding the 911 engine, performance handbook, haynes and one more. I think I'll find something in there. I think this part is secondary though. I'm not concerned that they've changed the vitals of the engine. But you never know.

I'm sorry! "110" is 1.1mm, "180" is 1.8mm, and ".55" idle is .55mm. When I mention drill bits I mean that you should measure the part (using either a vernier caliper or micrometer) that fits into the drill chuck. After you verify a drill's size, you can use it like a go/no-go gauge. For instance, if you find a drill bit that measures 1.1mm, and it passes cleanly through the jet orifice, but a 1.15mm drill will not, it's safe to assume that you have a "110" jet. Of course, you only want to use drill bits that are in good condition, an older bit that's chewed up from years of use can damage the orifice of the jet. Also, never force a drill bit into a jet!

About your cams, that's helpful in determining emulsion tube type. For instance, if you have T cams you'd want to use F2 tubes. if you had S cams you'd want to use F3s. F26s should be OK for E cams, but when attempting to get a car running just right, it never hurts to know that both cams are timed correctly as well!

I had a quick look through my library but couldn't find a comprehensive description of what I want to do, ie to see what cams are on my car.

I take out the upper valve covers and then what? Is a dial indicator tool a must or can I do it without one? I understand I'm not looking for precision here, just to make sure that my valves are opening at the specific degrees off TDC that E-cams are supposed to. Right?

Great info here...

Pete inspired me


Background;
2.7
E-cams
PMO, 34 vents, 55 idles
NGK BPR5ES
2.5 turns
Runs ok, but slightly rich

Carbs set up pretty good so fouling is not a problem. I know it's not really great as I monitor EGTs, but it runs good enough and the car needs other work priority wise. I ran it like this x-country and another hike into the Smoky Mts.

So now it recently became time to spend some time tuning carbs as I await up-grade parts to come in. I'm flaky to set car up for another one of my rides so it'll give me something to do.
My EGT's were ok but there was more on the table. EGT is combustion heat. Heat, within reason, is power.
I turn 2.5 turns of the idles down to 2 turns and test ride. EGTs too hot and BPR5ES shows very lean mix.
I try 2.25 turns. EGTs where I want them but BPR5ES still shows lean and enough popping under 3k to be a pia.
I start thinking. If I turn idles rich then my EGTs will cool but I can't live with the popping or lean plugs.
3 days later I'm still thinking of a solution and remember what Pete said about plugs in his general info of setting up carbs. BPR7ES is cooler than my 5's so I'll give it a try and experment while I'm still trying to figure this out.

Bingo
I maintained my EGT's and BPR7ES looked normal and only an occasional pop around 2.5k rpm in 2nd or 3rd gear. 4th and 5th gear at 3k, 3.5k, 4k rpm, etc were perfect. A customer would probably complain about the occasional low rpm pop but after 4 60 mile highway rides I'm keeping my present set-up.


so.. in my case.
Start with BPR5ES and keep leaning till these plugs show white on the porcelin with low rpm popping. Make sure plugs are relatively clean or clean them for next test. Turn idles down very slightly. [Sherwood always brings up how small amount of turns have an impact so I figure guys know that already]. When you find that lean white porcelin edge where this happens install BPR7ES. If I was using BPR7ES from the beginning it would be to much cleaning.


thx Pete

Great stuff Ron,
I like your EGT set up.
I don't like the price for new aviation type instruments.
Is there a more reasonable alternative? Maybe something under $1,000?
I looked at the instrument site and the gauges seem to have many features I really don't need.
Thanks,

Great stuff Ron,

I'm real happy with the 7ES, etc. It seems that it's the right plug and idle turns. Time will tell.



I like your EGT set up.

It's a dream toy with carbs. I can tell which idle is fully clogged or partially clogged. If it's a partial I can drive it home conservatively without burning anything. If it's totally clogged the EGT isn't hot, it's completely dead. Other info just solves the mysteries of what's happening to E-tubes, mains, transition, accelerator volume, etc.




I don't like the price for new aviation type instruments.

You're right. $ could be invested in the car with more logic.




Is there a more reasonable alternative? Maybe something under $1,000?

Not sure? My thoughts are that an analog is ok but not accurate enough to fine tune with. You need a digital numerical. The number will be bouncing around but you can get the envelope reading with it.

6 EGT probes are not completely necessary for tuning if you turn the idles the same amount. I can't comment on Webers besides reading in a Weber manual to turn them all the same turns. In my case with the PMOs with all turned the same only one cylinder was slightly off from the other 5. It wasn't enough to be noticable and wouldn't show on a plug reading.

If you could find a single probe digital EGT that would be great. You'd have 90% of the tuning help. If I couldn't find one I'd call the EGT mfg's and tell them what you want and see what they say. It's one thing to be on a dyno and another to tune in the real world.


and if you do connect with a single digital it'll take you awhile to understand what the numerical means. It's not as easy as just reading a number. For instance is that high EGT reading because it's lean or it's rich and the unburnt gas is still lighting off past the exhaust valve at the probe? ect etc

Ron,
Thanks for the quick and concise response. Great info as always.

Ronin: Thank you, I'm glad to hear that my comments were helpful! I'm not familiar with PMOs (of course I know Richard well, and knew about his project from the start, but I sold my shop before he had them ready to go) but the rules should be similar to Webers. Today it's all about the gasoline, and hotter plugs don't always produce good results. It seems that there is a need for a better balance between mixture and spark plug heat range than in the old days. I remember when we had to start going one heat range hotter (on cars with Webers or MFI) than our usual application (say a W6DC instead of a W5DC), sometimes two heat ranges to find that balance between good running characteristics and plug longevity. It can get a bit tricky on some models, it's good that you found an improvement. BTW, I became a fan of exhaust gas temp sensors/gauges after melting a set of very expensive pistons in my E/P 914!

not familiar with PMOs... should be similar to Webers.

Yep.. same 3 circuits but with extreme accuracy.
At equal idle mix settings the EGT differential among all 6 is in the range of high end FI at 60-75 deg F. Even when fully on the mains at 4.5-4.8k rpm in 5th gear for 20 miles in Nevada it's accurate. Equal power at all 6 cylinders is nice.





Today it's all about the gasoline, and hotter plugs don't always produce good results.

I can only say that I am now dialing idles in for power. I have confidence in the carbs on how they deal with various conditions after running them around the country a bit rich . Now EGT's 1,350-1,375F for the idle circuit. I need a plug to deal with that.

The mains will stay the same. They don't fully dominate till 3.8k and run around 1,325F.

For entertainment I have at least 3 sets of BPR9ES and maybe 1 set of BPR8ES.




It seems that there is a need for a better balance between mixture and spark plug heat range than in the old days.

Maybe one way to tune is to have a particular heat range and tune carbs to that plug Or to tune carbs first and then find your heat range...





It can get a bit tricky on some models, it's good that you found an improvement.

I was inspired