Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > 911 Engine Rebuilding Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Aug 2004
Location: Houston, TX
Posts: 895

__________________
Matt
72 911T Targa - Sold

Hang up the cell phone. Put down the Latte. Ignore the kids in the back seat.
Use your blinker when you want to change lanes. AND DRIVE YOUR Fu@#!NG CAR!!
Old 02-07-2006, 12:44 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #21 (permalink)
Registered User
 
Join Date: May 2001
Location: Peoples Republic of Long Beach, NY
Posts: 21,143
Originally posted by kucharskimb

for some reason, the 140's were actually leaner at 3500. i'm going to pull them and see if they are drilled correctly.

------------ maybe cylinder heads became noticably hotter ?

i could probably try to drop the AF down further, but i figure the air will be warming up soon enough...
---------- It's an EGT game. Even a single probe with a digital ga gives great operating info. Analog wouldn't be accurate enough.
50F difference is noticable.

roninlb,
i'd like to email you directly for some questions.

-------- hit profile at the lower tool bar and e-mail me. Put something in the subject header I'll recognize. Sometimes my PMs get screwed up.


Meanwhile.. whatever power your engine is built for is what you have. The game is to have it delivering available opertional power. EGT is a reflection of that power. Adjusting carbs alters the engine's EGT. You just can't add more gas for more power if it cools the EGT below your optimum operating EGT. The optimum operational EGT is a bit richer and cooler than max power. Webers and PMOs seem to be very accurate in delivering equal gas to each combustion chamber. You want all 6 cylinders delivering the same power or the same EGT. .5 air mix turn is a noticable difference. It also upsets keeping all pistons delivering the same power if the screws are turned out a different amount. That's called EGT "differential". It may not be perfect but fine tuning that differential or balance is involved.
__________________
Ronin LB
'77 911s 2.7
PMO E 8.5
SSI Monty
MSD JPI
w x6
Old 02-07-2006, 01:33 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #22 (permalink)
Registered User
 
Join Date: Mar 2003
Location: napier, new zealand
Posts: 29
roninlb - thanks for the info

The distributor is a 0-231-184-001, 4-5 degrees at idle max 35 degrees at 6000rpm.

I am waiting on a pair of SK carb synchronisers before going into the idle mixture and air screws to see where they are set. The shop has previously set up the engine - so time to take matters into my own hands! The step down to 55 idles without any other change has had no noticable effect on the idle etc. The theory would be to run the smallest idle jets i can for economy without affecting transition or having a poor idle, right?

nathan
Old 02-07-2006, 01:51 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #23 (permalink)
Registered User
 
Join Date: May 2001
Location: Peoples Republic of Long Beach, NY
Posts: 21,143
[QUOTE]Originally posted by wirihana

The step down to 55 idles without any other change has had no noticeable effect on the idle etc.
---------- the amount of turns of the mix screw should have a noticeable effect. So do you have them turned out 2 turns? The amount of turns will steer you to larger or smaller idle jets.


The theory would be to run the smallest idle jets i can for economy without affecting transition or having a poor idle, right?
---------- PMOs shouldn't have any transition probs to the mains if the idles are set where there is no off idle to 3k rpm prob. This area just happens to be best fuel economy. Many guys tend to over rich their settings which quickly loads the plugs. Rich is only good to start leaning from. It's better to start rich than to start lean. Over rich cools the combustion chamber and creates a large EGT differential. I'd suggest cleaning the BP5ES if you think you were rich. Dirty plugs may seem ok but screw up your adjusting picture. The main area I worry about is at the porcelin base where it's hard to scrub with a tooth brush and carb cleaner/whatever.


Anyway.. it may be a pain to go thru this adjustment but it's worth it. I went thru adjustments that I knew in advance wouldn't work out just to see the engine's reactions. Different jets, different mix settings, etc. I went thru every NGK plug from BPR5ES to BPR9ES to see the effects.

One sign of good induction is the ability to equalize the piston power in each cylinder thru lower EGT "differential". Fuel Injection accuracy is conventional wisdom superior, in this aspect, over a crude system like carbs. My PMO's accuracy is extraordinary and I can prove it with hard info. PMOs are a dream come true. My game wasn't max rpm hp. I didn't want to change plugs every 100-500mi. I wanted a stable performer in the envelope the engine provided. I wanted settings that are doable in local summers and winters. I wanted it adjustable when I hit 110F desert heat.
btw.. each of my adjustments included a 50-75 hy run for a clearer idea on circumstances in 5th at different rpms.

IMO dynos are great to a limited extent. It's not the last word on what you may want. It's not real world circumstances. Max EGT and power may look good on paper and then blow your engine when it's running under different circumstances.

also set up a signature with imp eng details for a clearer idea for anyone responding.

BTW.. I'm not a pro. I use EGT probes for a look into the combustion universe.

__________________
Ronin LB
'77 911s 2.7
PMO E 8.5
SSI Monty
MSD JPI
w x6
Old 02-07-2006, 03:05 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #24 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 06:14 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2020 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.