Injector Heat sheilds

[2strokesmoke]

Hi Guys,
While replacing injector heat sheilds, I noticed that the heat sheilds had visably different sized orifices.
So,I measured the orifice sizes and found quite a variation. I would have thought this to be a critical  dimension,possibly effecting spray pattern ?
Old heat sheild orifice dia = one @ 0.198"
                                     three @ 0.212"

New heat sheild orifice dia = two @ 0.214"
(purchased from Autohaus)    two @ 0.218"

Should I be concearned with this ?

Another question:
First a little history:
I have an 82 caddy,with a 1.6NA.
Replaced timing belt,tensioner(used dial indicator)
Set pump timing to .98"
Starts instantly-ran great.
Then IP front seal started leaking.
I resealed the IP
Did the Gov Mod
Did the advance mod (removed the thick washer)
truck sat for a week,before I had the time to put it back together.I had all injectors capped and all fittings on IP capped,while it was apart.
Put everything backtogether and timed at .98" agian..and tripple checked timing.
It still starts instantly,but runs really bad,for the first 1 or 2 minutes.It actually feels like the engine is "bucking"..not just "missing".
There is NO air in the fuel lines..at all. The symptom feels different as well. I have had air in the lines before...and that feels more like "missing"..until the air purges out.
This feels more harsh..like "bucking".
Once the engine runs (smokey while "bucking") for a couple of minutes,then the engine smooths out. I have to keep my foot on the gas pedal,to keep it running,for the first few minutes as well. When the engine is running, I can hear something "clacking". It is more noticable,as the engine warm up. This is a mechanical 1.6NA and never made this sound before.
Do you think ,maybe something got into one of the injectors,while I had it apart ?
I figured that might explain the "clacking" and smokey starts.
Would it also cause the "bucking" ?
I have never encountered this before.
(glow plugs were replaced recently as well)
Any help,would be greatly appreciated.
Thanks in advance,Mike

[rabbitman]

It could be a bad injector, to see which is the culprit, idle the engine and loosen and then tighten them one by one. If the problem is an injector the clacking will go away when the bad one is loosened.

That's weird about the shields though I don't think it would change the spray pattern at all.

What color is the smoke?

[745 turbogreasel]

Maybe torquing the injector mashes the washer, closing up the hole a bit?

Any chance your pump is 180 off time?

[2strokesmoke]

Thanks for your help.
I pretty confident,the pump is timed correctly ,as I locked the cam and did  paint mark the correct IP lock pin hole on sprocket-before disassembly.(so I wouldn't be 180 out upon IP installation)
I never thought of the heat sheild crushing,upon torque.That sounds like a good explaination,for different orifice sizes.
I haven't tested for a bad injector yet. I will have to turn up the idle speed,just to keep it running,while cold.
I tried searching for- Injector pressure or pop tester- but had no luck. I would like to fabricate a pop tester,so I can calibrate and clean/check these injectors.They are rebuilt injectors,which came with the truck.*(in a box-I installed them)*
Does anyone have the thread,for the do-it-yourself- pop tester ?
Thanks agian !
Mike

[745 turbogreasel]

http://www.vwdiesel.net/forum/index.php?topic=2828.0

[Vincent Waldon]

That sounds like a good explaination,for different orifice sizes.

The other thing to keep in mind is that the size of the hole in the heat shield is many orders of magnitude bigger than the nozzle orifice size, and the heat shield hole is in pretty close proximity to the nozzle opening.





To use a terrible analogy:  if a football team is fanning out of a limo parked in an airplane hanger onto the football field... does it matter if the hanger doors are 100 feet wide or 101 feet wide?! 

[zukgod1]

That is a COOL pic!!  Saved!!!

That sounds like a good explaination,for different orifice sizes.

The other thing to keep in mind is that the size of the hole in the heat shield is many orders of magnitude bigger than the nozzle orifice size, and the heat shield hole is in pretty close proximity to the nozzle opening.





To use a terrible analogy:  if a football team is fanning out of a limo parked in an airplane hanger onto the football field... does it matter if the hanger doors are 100 feet wide or 101 feet wide?!