5K Reving Problem

[ke20 king]

So heres the Dyno run I did today.. As you can see its running heaps rich, where do I start?? Any suggestions.

 

 

[ke20 king]

So heres the Dyno run I did today.. As you can see its running heaps rich, where do I start?? Any suggestions.

 

 

[ke20 king]

File attached

[GJM85]

Looks lean to start and richens rapidly. You need find out what jets sizes you have. Then set a base tune, which is the basic starting setting. Being individual runners every cylinder can require an individual setting. So use your spark plugs to determine rich or lean. Black plug is rich, white pug is lean, powderish grey/brown is good.

Start with getting your idle right because the idle circuit will affect the entire rev range.

 

At least weber jets are easy enough to get.

Edited August 25, 2012 by GJM85

[altezzaclub]

What did the dyno guy say??

 

As Gav says, far too rich as the revs go up. The KE70 will hold about 14.0-14.7 going up a hill with the foot hard down, although I can get it richer if I boot it quickly and it goes to 11-12 to 1 for a second or two.

 

See what Google comes up with for jetting the 40s as a start point.

[ke20 king]

I thought I was going to get more out of the Dyno guy.... He did say that I should be running lower than 120 main jets. He also said we need to start of by getting the AFR right then go from there (i.e see if it still bogs down ...)

 

My webers have the following spec.

 

32 chokes, 135 main jets, F47 Emulsion tubes, 160 air correctors, idle jets 59F21.

 

I know I gotta reduce the main jets - I'm thinking of soldering and drilling at this stage and seeing what it does through the rev range..

 

Another guy from the web (similar set up - 5K) is running the following: 32 chokes; 120 main jets; F7 emulsions; 170 air correctors; 45F9 idle jets. Is it just worth running the same stuff as a base?

 

Also, anymore light with respect to my cam anyone.. I know its small, is it worth changing it??

[altezzaclub]

Ok, you definately have it richer than his- more fuel AND less air going in. The problem with DCOEs is the vast range of variables you end up playing with. The best thing you could find is some old guy in a garage with a box full of Weber jets that you can borrow until you sort out which ones you want to buy. PM anyone on here if you read a build with DCOEs and see what setup they run and if they have spare jets you can try.

 

What cam grind is it? It probably doesn't matter, you can jet the Webers to run with any cam.

[ke20 king]

Cam specs were previously posted.

 

I will play around with the jets to start with and go from there.. Will let you all know how I go.

[ke20 king]

I checked my cam by looking at when the rocker puts pressure on the inlet valve (cylinder 1) and it was reading like80- 90Degrees! Did I check it right? below cam specs says should be dialled in at 40 degrees? How many degrees does one tooth throw out ?

 

[Evan G]

http://xtremecarzone.com.au/index.php?showtopic=805

 

 

i went by this, by far the easiest and simplest

[altezzaclub]

Yeah, that is the ideal Evan... However, when the motor is in the car and been used....

 

KE20 King, the cam turns at half the speed of the crank, so if you read 80deg on the crank that is 40deg on the cam, & you were probably in the ballpark, depending on how they wrote their specs.

[JDMJared]

I doubt a STD fuel pump would keep up with twins. I don't know 100% because I've never been game to try.

Just a FYI; the stock mechanical fuel pump has never been a problem on my hot 4k with twin 42's.

[ke20 king]

So I dropped 110 main jets (I had 135) reved out like a normal motor ! This is how the plugs looked after a drive - Does it look lean?

[Trev]

Looks like it is running normal.

[altezzaclub]

Here's a handful from the Altezza after a run up the big hill outside Tamworth. I had the fuel mixture display from the KE70 in the Altezza that day and it stuck on 14.5-14.7 all the way.