Carbed 914 Problem Options

[microsa]

I am doing some work on the 914 that I built and sold last year and have run
into something that has me stumped.
The car:
2056cc
WebbCam #86 grind (I think)
IDF 44s
Stock valves w/heavy duty springs (bus I think)
Carbs matched to intake, intake matched to heads, no porting, just 'cleaned
up'.
050 Dizzy w/electronic ignition (Compufire)
Taylor wires
Bosch Copper Plugs (new set)
MSD 6AL
Facet Fuel pump
Facet Pressure Regulator (set at 2psi)
Car has been running great for the past two years, then at last months
autocross, it started acting as if it was running into a rev limiter (goes
'soft') at about 5500 rpm instead of at the 6500 rpm 'pill' in the MSD box.
I first tried removing the pill which should remove any MSD induced rev
limit. Problem was still there. Checked all wiring and all looked fine, even
screwed in a new set of plugs at the autocross. Still fall on it's face at
5500 or so. Below 5500 the car is flawless.
Fast forward to this week. Took the MSD box out of the system, problem still
there and I noticed that it seemed to be intermittent; sometime it would rev
to 6500 the next time it would only go to 5500. Next I removed the CompuFire
and installed a new set of points. Problem still there. Installed new cap
and wires, no change. I next checked all the fuel filters (one before the
pump, one before the regulator) all clean, but I replaced them anyway. No
change in performance, still goes soft. Took the tops off the carbs to check
float bowls; all clean and levels are correct. Removed and cleaned all the
main and idle jets. I installed a new fuel pressure regulator and fuel pump.
No change. The car idles great and runs great up to 5500 rpm or so.
The odd thing is it feels exactly like a soft rev limiter.

Ideas?

TIA

Mike Allen
San Antonio, TX

[rhodyguy]

try turning the fuel presure up to 3.5 - 4 lbs.

k

[Joe Ricard]

QUOTE (rhodyguy @ Mar 8 2005, 04:28 PM)

try turning the fuel presure up to 3.5 - 4 lbs. k

(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif) 2 PSI is about a pound too low. you are running out of gas. I also would change fuel filter to ensure good flow.

When I put the air/fuel ratio meter in my car I was able to pin down just what was going on with my carbs.

Very similar set up by the way. cept I have dual valve springs 86b cam. My 44 IDF's like a 55 idle 135 main gas with 180 air correction. 3 PSI regulated by a holley unit.
I can hold it wide open and watch the ratio get to 12.5 to 1. runs on idle jets around 15 or 16 to 1 but this all depends on air temp, Humidity, time of day and if I have my 914club hat on or not.

[SLITS]

Look at the jets and make sure they are not loose (or anything else for that matter). Just did a car that would start and idle, but would not accelerate....jets were not tight.

[URY914]

Here's a WAG.

What about your lifters? Are they wearing out? There is a bunch of soft ones out there, which may not allow you to rev it up.

Paul (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

[nine14cats]

This sounds very similar to my car. Car would run out of "gas" at 5500 RPM. It was the fuel delivery to my engine. It wasn't my MSD 6AL or the carbs dirty. I had the fuel pressure at 3.5 or 4. I put in a new fuel pump and everything was fine.

For me anyway.... (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

Bill P.

[Brett W]

Could be valve float on tired valve springs. If you haven't done a valve adjust lately your should and check everything while you are in there.

[SpecialK]

Since it seems to be "intermittent", do you suppose that there might be something afoul (sticking) with the mechanical advance in your 050? Sounds like you pretty well covered all of the other possibilities.

[SGB]

the K is right. My 050 lost all it's go. Turned out it wasn't advancing at all.

[Type 4]

Blow out the fuel line in the tunnel. You may have a blockage.

[microsa]

This car was running fine and this happened all at once. Lifters and springs came from Webb and have less than 8K on them. Of course that doesn't mean they aren't bad. Peter Hinkle wrote this and I had heard of this happening to people running MSD boxes and coils in the past:

Mike, you didn't mention the rotor. If you have a rotor going out, it will do
EXACTLY what you describe and the thing may not look bad. I have seen this
many times with ah 050 and an MSD. Mike, I bet you almost ANYTHING that if you didn't change the rotor, that is the problem, what will happen is that even if you change everything else, it won't change the problem. Then, if you continue to drive the car, the rotor will eventually EXPLODE. I mean really blow up. As soon as you said "soft limiter" I knew what you meant. Change it. I would almost bet on it.../peter

I also check the screen filters that are in the fuel supply inlet area of the carbs (forgot about them) and they did have some trash in them, but I don't think that they were clogged. Added new inline filters and left them out anyway. I'll try it tomorrow and pick up another 050 rotor also. The advance seems to be fine.

I will try it first without a new rotor to see what I get. If there is no change I'll toss in a new one and see.

[microsa]

Well, this is what I've done as of noon, CST:

The advance is all in by 1500 rpm so I don't think that is the problem. I
installed a new rotor a little while ago, no change. What ever happened, it happened all
at once. This car was running STRONG till this happened. It still runs
strong up to 5500 or so. The whole engine goes flat, not just one side.
Feels exactly like a MSD soft touch rev limiter, but the MSD box is no
longer in the system. I'll check valve clearance after it cools down, but
the motor is quiet so I can't imagine the valve clearance has opened up.
Hard to imagine valve springs as it seems to be affecting all 4 cylinders.

Once again here is all that I have replaced:
cap
rotor
points
plugs
all fuel filters

These actions have been taken:
idle,main and emulsion tubes have been removed and cleaned
timing has been checked
Taylor wire set has be ohm tested o.k.
advance mechanism in dizzy (050) has been checked for operation, appears to
be free and all in by 1500 rpm.
float levels checked
float bowl clean
fuel pressure steady at 2.5 lbs. (tried all the way from 1.5 to 4.0 lbs, no
change)

What am I missing? I checked with the astro-physics people, we are not
experiencing any unusually high sun-spot activity!

Mike Allen
Stumped in San Antonio

[Root_Werks]

QUOTE (Brett W @ Mar 8 2005, 06:10 PM)

Could be valve float on tired valve springs. If you haven't done a valve adjust lately your should and check everything while you are in there.

(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif) If you have tired springs, this could be your problem. I guess it could be a number of things, but don't rule this one out.