help with your opinions about cold start of e9 3.0cs engine - VIDEO

[deQuincey]

hi

i would like to hear your opinions about this little video that presents the cold start of a 3.0CS engine original 1971

the process is:

no air filter, carbs syncronised "by ear", engine cold

1- first of all the accelerator is pressed and thus it can be seen that the throtel butterflies close sharp

2- then the ignition is put on without pressing the accelerator

3- the engine revs up at 1700 rpm´s, starts warming up

4- checking of the throtel butterflies that are 3mm open due to the engine vacuum effect

5- after warming up, accel is pressed to reach 900 rpm (really 1000 due to absence of air filter)

click in the photo to see the video



i would appreciate your feelings about what you see and hear, i am not 100% happy with this, so i would like to know if i am being too suspicious or i have to go on with it

thanks and regards

 

[Stevehose]

what don't you like about it? the cold start idle looks good as does the warm idle. seems to be working as it should. I have to pump the accelerator a few times on mine in order to keep it from stalling after it starts cold, then it will do as yours does.

what is the red cannister that looks like an a/c receiver/dryer mounted on the passenger fender? Are you adding a/c or did your car once have it?

 

[deQuincey]

what don't you like about it? the cold start idle looks good as does the warm idle. seems to be working as it should. I have to pump the accelerator a few times on mine in order to keep it from stalling after it starts cold, then it will do as yours does.

what is the red cannister that looks like an a/c receiver/dryer mounted on the passenger fender? Are you adding a/c or did your car once have it?

hi steve,

yes the car starts fantastic ! i do not have to pump the accelerator at all, but: two things are bothering me:

1- the high revs of the cold iddle get higher and higher as the engine warms up, it starts at 1700rpm´s when cold, and it goes up to 2000rpm´s

2- below the engine sound, i can hear a high frequency noise similar to the one that some steel balls would make inside a metallic box, and i can not identify it, also i don´t know if it is normal too

regards

 

[deQuincey]

what is the red cannister that looks like an a/c receiver/dryer mounted on the passenger fender? Are you adding a/c or did your car once have it?

sorry i forgot your second issue: the red cann. belonged to a a/c installation that the car once had, and i am renewing
regards

 

[Stevehose]

1. Are both carb's throttle plates open the same amount when set on the cold idle cam?

2. Are you describing the valve train "tick tick" that is common or is this a new noise after your rebuild?

hi steve,

yes the car starts fantastic ! i do not have to pump the accelerator at all, but: two things are bothering me:

1- the high revs of the cold iddle get higher and higher as the engine warms up, it starts at 1700rpm´s when cold, and it goes up to 2000rpm´s

2- below the engine sound, i can hear a high frequency noise similar to the one that some steel balls would make inside a metallic box, and i can not identify it, also i don´t know if it is normal too

regards

 

[deQuincey]

answers in bold

1. Are both carb's throttle plates open the same amount when set on the cold idle cam?
don´t know, probably i would have to cross check this

2. Are you describing the valve train "tick tick" that is common or is this a new noise after your rebuild?

yes probably is that tick-tick, but it seems louder than never to me, again your opinion, when you hear this engine it seems normal to your records ? it is rather subjective comparing it with yours, of course, but that helps a lot !

thanks again

 

[Stevehose]

Mine ticks a little, difficult to compare by videos, check out you tube for some other running engine vids that feature the valve tick. Maybe others can chime in here regarding the tick noise and its loudness.

yes probably is that tick-tick, but it seems louder than never to me, again your opinion, when you hear this engine it seems normal to your records ? it is rather subjective comparing it with yours, of course, but that helps a lot !

thanks again

 

[61porsche]

Check your valve adjustment. A newly rebuilt head will result in the valves seating a little more and decrease/ increases the clearance.( Or you can check clearances at the cam lobe/ rocker pad but subtract .04mm. if you think that there is a clearance stack up of components due to wear.)

Lower the high speed idle to 1500. This will compensate for the increase in rpm after intital start up. Then you should be at 1700. You can actually go lower if you live in a mild climate. ( MIne's 1200 then goes up; a little less wear.)

When you were in the car..... the connecting throttle rod to the rear raised up slightly. meaning the front carb came on first rather than together. Rod a little loose ( the new nylon bushings) or the back small rod with the thumbwheel needs adjustment. You can only see/do this while pressing the accelerator and NOT by manually pressing the linkage as you did to kickdown the idle to normal. It's a geometry thing.

Looks good though.

 

[Stevehose]

I did the same, I don't like having the engine race high when it first starts, especially after sitting for a while.

Lower the high speed idle to 1500. This will compensate for the increase in rpm after intital start up. Then you should be at 1700. You can actually go lower if you live in a mild climate. ( MIne's 1200 then goes up; a little less wear.)

 

[deQuincey]

thanks

Check your valve adjustment. A newly rebuilt head will result in the valves seating a little more and decrease/ increases the clearance.( Or you can check clearances at the cam lobe/ rocker pad but subtract .04mm. if you think that there is a clearance stack up of components due to wear.)
it has been re-checked recently, but i will take a look

Lower the high speed idle to 1500. This will compensate for the increase in rpm after intital start up. Then you should be at 1700. You can actually go lower if you live in a mild climate. ( MIne's 1200 then goes up; a little less wear.)
ok, i will go for the process again, it is a PIA to fix that little screw that you can only see when you press full throttle through that tiny hole

When you were in the car..... the connecting throttle rod to the rear raised up slightly. meaning the front carb came on first rather than together. Rod a little loose ( the new nylon bushings) or the back small rod with the thumbwheel needs adjustment. You can only see/do this while pressing the accelerator and NOT by manually pressing the linkage as you did to kickdown the idle to normal. It's a geometry thing.
will recheck this too

Looks good though.

thanks

http://s999.photobucket.com/albums/...desdefriomayo2011contapafiltro02052011257.mp4

 

[Tierfreund]

Kudos! That engine looks, starts and sound fantastic. Having the same setup, I know how difficult it is to get it to behave so well. To get there more or less from scratch on a carb rebuild is very impressive.

The only thing that would warrant some investigation is the slight, damp knocking noise. Doesn´t sound like valve clearance to me (that would be higher in pitch), but since it seems the car was running in a garage, I´d recheck the sound outside as garages can distort the sound.

What I find hepfull in locating the source of such noises is a motor-stethoskope (no kidding, the exist and are very helpfull). I´ve had a similar noise on my M30 (fearing the worst for the main bearings) that turned out to be a loose power steering bracket (wrong length of bolts). Or I´ve heard similar from a bad water pump on a Dodge...


Also Kudos to gentleman by the nick of 61porsche. I agree with all his observations and hints and tips and observations but could never voice them as clearly and logically.
I´d say he´s a very helpful contributor to this forum.

 

[deQuincey]

hi, thanks and question

The only thing that would warrant some investigation is the slight, damp knocking noise. Doesn´t sound like valve clearance to me (that would be higher in pitch), but since it seems the car was running in a garage, I´d recheck the sound outside as garages can distort the sound. probably you are right, not valve clearance, seems to be a noise that modifies with rev´s, so ? any idea ?
it seems to come from a place in the top part of the engine,
the fuel pump is new, but i have lubricated it well before assembly, i checked the rod that pulls the pump and lubricated it also with clean engine oil

What I find hepfull in locating the source of such noises is a motor-stethoskope (no kidding, the exist and are very helpfull)..
any brand or link to find one ?

regards

 

[deQuincey]

engine start with air filter

i have no changed anything yet, but i am posting here the cold start when i closed the air filter on sunday

the engine is started again from cold accel is pushed once before starting and then ignition on without accel pushing

maybe you can hear different noises



thanks and regards

 

[61porsche]

Timing chain noise

Did you change the chain when the valve went? If not, try to guage how loose it may be by prying with a screwdriver by the cam gear. The other possibility is the tensioner and spring for which there are pretty exact measurements in the repair book. The tensioner piston sometimes gets pushed back in slightly.

It's not uncommon to replace the tensioner.

 

[deQuincey]

Did you change the chain when the valve went? If not, try to guage how loose it may be by prying with a screwdriver by the cam gear. The other possibility is the tensioner and spring for which there are pretty exact measurements in the repair book. The tensioner piston sometimes gets pushed back in slightly.

It's not uncommon to replace the tensioner.

hi

no, the chain was not changed as it was said to be in good condition

i have a spare set of the tensioner (piston+spring), but i am afraid of changing it as i do not know if it has a "certain" position

should i open the cap, and pull out the old, and push in the new, and close ?, or do i have to follow any precaution ?
regards

 

[61porsche]

It's worth checking. Sometimes there's wear on the face. But again, the most important part to me is the dimension of the piston which is actully two or more pieces carefully fitted together with an interference fit. When an engine backfires is when the piston compresses more than normal.

It's in the repair manual, but here's some tips:

There will be oil. Take precautions to catch it. The slipper fits the chain up and down so when it comes out you'll see the orientation. There is a good amount of tension when the last thread is undone and like wise you may have to press hard when putting it back together.

 

[Stevehose]

Before you go down the slippery slope and start taking things apart, was this noise present before your fuel pump install?

 

[deQuincey]

Before you go down the slippery slope and start taking things apart, was this noise present before your fuel pump install?

it is an intelligent remark, but unfortunately i do not remember, probably yes

on the other hand, i am really aware of not making any mistake on the assembly of the pump, moreover is not possible to make mistakes provided you have to assembly certain parts that maintain the distances, and so on, the only thing left to your choice is the torque setting, but that can do no harm to the assembly position

 

[Stevehose]

The stethescope is a good idea to pinpoint the area of the noise further, by putting it directly on certain components will help eliminate them from the puzzle:

http://www.amazon.com/MECHANICS-STETHOSCOPE-ENGINE-DIAGNOSTIC-AUTO/dp/B002A1IQ58

it is an intelligent remark, but unfortunately i do not remember, probably yes

on the other hand, i am really aware of not making any mistake on the assembly of the pump, moreover is not possible to make mistakes provided you have to assembly certain parts that maintain the distances, and so on, the only thing left to your choice is the torque setting, but that can do no harm to the assembly position

 

[deQuincey]

last video check please

here you can see the final iddle i got, the rattling sound you can hear i think it is normal valve train sound

the knocking noise has dissapeared with some km drive !

now sounds better, don´t you think so ?

regards