Beginner tunning questions.

Fresh 466
.005 in the hole
fully ported A429's 2.25/ 1.76
CJ stealth
Tiny cam Magnum 270 224/224
2" four hole
750 holley with proform body and base plate
2" headers
AR3934 plugs
Digital 6 w/ blaster 2 coil

That's about it. This is in my mud truck

It runs, to me, pretty good now. I'm not really looking for much more power. Just want it a little closer to right.
Plugs now look pretty rich. Black at the bottom of insulator. Blackish tan on the end. I'll get some pictures later this week.

I was planning on running it like it is, but some folks looked at my plugs and said I could definately pull some fuel out of it. Said being too rich might pull the tops of the pistons off???

Just having nothing other than the plugs to go by, where sholud I start? One size down on primary and secondary? Just primary? just secondary?

Do you have any chassis dynos inyour area?

Nope. Small town.

have you thought about leaving the fuel were its at .... and add in some timing

Give some more info. What are you running? As in jets, initial and total timing? What fuel?

Are you restricted to 750cfm per class rules?
Also need to know what jet size you are running now and what's your altitude i.e. 900 feet above sea level or ???

750 Is just what i have right now. As soon as I can scrape up some funds I'm going with something bigger. Planning on a QF950.

Dizzy is locked out. Have ran it at 32, 35, and 38. But all in different pits. Couldn't really tell a lot of difference. Only thing I'm sure of is at 32 the converter stalled to 3000 before pushing through the breaks, where as at 38 it wanted to push through at around 2600-2700.

6.5 primary, plug secondary. 72 front 80 rear

Running on 93 with Nos Race octane boost mixed 6oz/5gal. Can't run actual race gas because of the classes.

300' above sea level.

Thanks for the help folks.

Phantasea466 wrote:Are you restricted to 750cfm per class rules?
Also need to know what jet size you are running now and what's your altitude i.e. 900 feet above sea level or ???

how much timing are you running with your a429's?

I don't want to send you away from this site. But I will suggest finding a chart to read your plugs. There is more to it than the color. The "ring" on the electrode and the pattern on the ground strap are important in figuring out what you need in fuel or timing. Not sure if I could see it well enough if you put up a pic.

Shift points and trap rpm? I'm thinking you are going in the right direction with a larger carb, as a too small carb can cause a rich condition to be present. Are you limited to a single plane manifold? Can you run a dommie?

I have been to almost every site on the net about reading plugs, 2 things I have found:
1)Some sites I read contradict others. Makes it hard to believe one or the other.
2)Plugs don't always fit the pictures I have to compare to. I have a hard time seeing the color change on the ground strap and I'm not sure I have ever seen the ring on my electrode.


I leave in second and shift into 3rd within 20-30 feet. c6, 205, 5.38 gears, and 38.5's I know it's too much gear, but its what I've got.
Pulls hard to 5800-6000 and stays.
I'm happy with that though because it still has stock rods.

I could run a single plane and a dommie. I just don't have the funds right now.

Thanks for the help
If I need to I can post more specs???

I'm betting that if you had a vac guage in the cab when you are pulling through the traps @ 6000 you will find that you are pulling considerable vacuum. Get a bigger carb and the motor is going to rev easier and higher. Those heads if they are properly ported have a lot more potential than a 750 cfm carb is going to feed.

That sure would make tuning easier. Proper parts for the combo. By the way, there is a good plug reading thread in this same section.

Funny you just said that. I was just talking to my buddy, told him its his duty to hold and watch the vacuum guage this weekend. The heads look pretty good. To me anyway. The exhaust floors were welded up flat and the roofs raised. On a side note, I had them flowed but my engine guy only had a 4" bore fixture. They flowed 199 at .600 and 330 at .600. Any way to guess what they would have flowed on a 4.39 bore?

As far as a bigger carb turning higher, I'm a little scared to turn it much higher.

I'm about to check out that thread.

Would it be easier to tune if I pulled out the power valve and square jetted. What kind of issues might I run into?

If it's a race only truck I'd ditch the pv's it take one more problem off the table. Probably up the jets 6-8 if you do.