340 build No POWER need help w tune

-
340Duster247

340Duster247

Well-Known Member
Joined
Dec 5, 2012
Messages
833
Reaction score
141
Location
Calgary
Ok so I've already spoken to some of you guys about this problem in the race forum and still have no luck. So thought I would start a new thread over here.

I've just had a new engine built and installed and here are my specs.

Balanced 340 .40 over. ( just over 10:1 compression ) KB hypo
Eddy RPM heads
Eddy air gap intake
Comp mother thumpr cam. .497/.483
Msd digital 6 plus
Msd pro billet dist.
Tti headers
Holley 750 street hp dp
Holley mech fuel pump

727 trans with 2800 stall right now (TCI 3800 SSFighter on order)
8 3/4 w 4.30 gears
315/60/15 mT drag radials.

Now our first problem was timing and carb running way way too rich. Could not get the idle screws to work ( all the way in and die). She acciually revs up when there all the way in. With the poor poor vacum that cam produces so far we switch the power valve to the correct number for the vacum that's being produced (5" at 1000rpm).
Still ran rich.
We then Opened the secondaries to allow for more air and were able to close up the primaries. That helped with the richness and made her idle a lot better. But there is still no change in the idle mix screws.

Now for the timing. Right now I'm running what I've been told from some of you on here. In the distributer using black bushing and light silver and blue springs. And did my inistial timing @ around 26 degrees.

When I take the car out for a test, and from a stand still mash the gas. It is extremely disappointing. Dosent even spin the tires. :(.

What am I doing wrong!
Haha this is my first build with a more radical cam ect. And can't seem to get it right.

Ps have checked every where for vacum leaks.

Is my timing in correct ??
 
sounds like your idle bleeds are plugged, pull the blocks off and blow out the passage
 
I it still runs with the screws
all the way in check for a blown or wrong power valve for a start
 
that thing should scream your new verter will help a lot. did you degree the cam shaft?
 
Where are the throttle blades set? You have to have it set so that only about .020" of the transfer slot is exposed, too.

You will have to pull the carb to check that.

Flip it over and look at the slot that the blades expose as they open. You want it to look like a tiny square to start with, then put it back together.

Turn your screws to 1.5 turns out, and start from there again.
 
Did you degree cam when you built it? What is your timing when all in? You need to do a compression or leak down test. If it was running as rich as you say rings may not have seated.
 
805moparkid said:
what number? also look down the primaries and see if you can see the transfer slot or not, i bet you have the primaries open to much and your into the transfer slots
Click to expand...
HAH!

You're thinking the same thing I am.
 
"New" power valve does not mean "good" power valve.

Should be able to crack open the secondaries with the not-so-obvious screw if the idle slots are out of range
 
805moparkid said:
sounds like your idle bleeds are plugged, pull the blocks off and blow out the passage
Click to expand...

It's a new carb. Have 2 new power valves. A 3.5 and a 2.5 that's in now. Have already adjust the blades for correct transfers lots The only thing I haven't done is drill holes.lol.
Has already been jetted for my altitude
Checked floats. Everything good there

The engine was built from a reputable engine shop. I didn't ask how they degreed the cam.

The car is not driven on street yet. Just have test area down driveway
 
whenever I have a problem its always something stupid (kiss effect) Did you double check the firing order? (I had 5 and 7 swapped last year hahaha)
 
Why not just switch carbs and see if that makes a huge difference??? You did degree your cam right? What's total timing above 2,500 RPM? That's more important than initial timing at idle.

I'll bet that you have multiple issues that need to be addressed, so don't freak out. You'll get them all with patience and persistence.
 
Have you checked the fuel pressure?
Actually verified it at the carb with a gauge.

What fuel pump are you running?
 
First off id do a compression test .Make sure there is nothing wrong mechanically . Also if your ignition is not working properly it will make it seam like its running rich. Maybe swap in a stock ignition just to rule out you msd set up and well check the basics like plugs wires and stuff. if everything else fails its your carb.
 
Fuel pressure is great. Have a gauge installed inline. Brand new holley mech 110 fuel pump.

PVC is new and plugged into correct port.

Fireing order is correct. 100% haha
 
340Duster247 said:
Fuel pressure is great. Have a gauge installed inline. Brand new holley mech 110 fuel pump.

PVC is new and plugged into correct port.

Fireing order is correct. 100% haha
Click to expand...

How much fuel pressure, with the holley 110 you need a regulator.
 
You must log in or register to reply here.
-

Back
Top