New engine is smoky at idle, did I screw up my specifications?

Begle1

Begle1

Active member
Would a constant idle haze be expected with 286210 Mahle pistons and extrude honed 370's (5x~14's)?


The thing has a constant idle haze since rebuilt, has maybe 300 miles on it, hasn't seen over 20 psi of boost pressure yet due to a terrible boost leak.


To the best of what I can tell, my build is as follows:
.020-over 286210 Mahle pistons,
extrude honed 370s that I asked to be matched to the pistons but don't know how I can confirm,
stock-height head gasket,
a milled block with O-rings cut into it (boy I wish I knew how much was milled, but more should make things less likely to smoke, right?)
stock-thickness injector washers,
stock-tuned-up VE injection pump,
timing somewhere about 1 tooth advanced from stock,
some sort of camshaft I'm looking for records of (I wanna say it was a MaxSpool),
 
Last edited:
I'd guess the problem to be the extrude honed nozzles. Nozzle holes should be made with EDM. Try swapping to a quality injector first, easy to rule out if it's not the problem.
 
But these are what all the cool kids were running 15 years ago.

They're supposed to be 5x~14's.
 
I say yes. I would expect the unburnt fuel smoke. I wouldn't blame the extrude hone completely, 370's were smokey out of the box.

Timing one tooth advance from stock. Very old school tech Begle. Back then we thought the haze was normal for a hotrod.
 
Not to derail Begle, but had a similar question myself. My 300k mile stock injectors haze horribly at a cold idle. I figured it was the racked barrels and low pop pressures from worn injectors.

Is there anything serious to worry about with idle haze? Low compression?
 
I know mine will breathe, whistle and make a loosened cap dance. Not like I’m going to rebuild it either way though lol.
 
Well, they still run a long time loose, ha.
My old daily driver had 450k on it, had blowby issues at around 200k after I blew the head gasket.
 
So what injectors can I get that will have the most power potential while still being able to be driven clean?

Any idle smoke is way too much in my opinion, for a daily driver.
 
Begle1 said:
So what injectors can I get that will have the most power potential while still being able to be driven clean?

Any idle smoke is way too much in my opinion, for a daily driver.
Click to expand...



Probably a set of SAC 5x.014’s would do great, without knowing much about your engine and goals.

I played with some 7 hole injectors, but I’d stick to the 5 hole stuff unless someone else with more experience can chime in on that.


Sent from my iPhone using Tapatalk
 
So the difference between 5x14 EDM'd injectors is significant from 5x14 Extrude Honed injectors?
 
extrude honed 370's (5x~14's)?
Click to expand...

My ddp stage 4's from the 05-06 era were allegedly modified 5X14 370's. Cold starts were borderline problematic, haze wasn't always visible but the raw fuel was obvious any time below operating temp. This was on my 96.

Sent from my motorola one vision using Tapatalk
 
Begle1 said:
So the difference between 5x14 EDM'd injectors is significant from 5x14 Extrude Honed injectors?
Click to expand...

Night and day. Not only because of hole size consistency and concentricity, but because with extrude honing you are pushing abrasive paste through the nozzle. This damages the pintle sealing surface. This can cause your nozzle to drip, not have a clean start or stop of injection, or have poor atomization.
 
The 286210 is 17.5:1 out of the box. They have a 43.2cc bowl, and do not match the spray pattern for the marine injector.

The marine piston (286050) had a 52.3cc bowl accepting the 155* spray angle , and I believe are 15.3 15.5 to 1.

If you want a nice runner with a clean idle go with some 215 HP Bosch injectors
+ 20-25% extrude hone. I think the 215 injector nozzle was like 5 x.10 stock
I do wonder about the injector bodies you are running with the VE pump. It depends on what injector line nut size.

On edit:
0433175081 is the part number of the nozzle alone. you could always just buy the nozzles if you have the older bodies, but I don't know how Muai is set up for injection shops.
The complete 215 injector is part #0432133844
 
Last edited:
First gen. 12mm line nut size.

5x12/5x14 VCO 145 degrees or 5x13 micro blind SAC 148 degrees (a bit crisper tip in) would all work well, depending on the air you have.

I'm curious why you didn't install 155 degree marine pistons in your non IC '90.
 
Ah, if the 286210s are 155*, then the 370s "should" work well.

Depending on the builder more than whether they're EDM'd or extrude honed, of course ;-)

OP should fix the boost leak & play around with static timing a bit.

Even on 145 degree IC heads, I never needed to jump a tooth with 155 degree 370s; just a 1/8" to 3/16" timing bump was what it took to get an acceptable warm idle.
 
ofelas said:
5x12/5x14 VCO 145 degrees or 5x13 micro blind SAC 148 degrees (a bit crisper tip in) would all work well, depending on the air you have.

I'm curious why you didn't install 155 degree marine pistons in your non IC '90.
Click to expand...

VCO is an abbreviation hence why it is capitalized, sac should not be capitalized as it is not an abbreviation. And the 5x0.013" micro-blind sac type nozzle is 155° from a marine application. The non-intercooled piston was the right choice here. Personally I would make sure the rings were seated before I got too excited.
 
You must log in or register to reply here.
Back
Top