went for the maiden voyage tonight with the new motor.. running way rich.. the carb i have is the holley SA 770 i am new to carbs dont know sheit bout them at all had a buddy over but he wanted me to ask here what u guys thought jets i should mess with.. the plugs are sootty black i guess thats how i would explain them.. other then that i guess i would be all set if i can get the carb tuned.. i did have an oil leak which pisses me right off the front seal i think is leaking a little but we ran it then shut it down it leaked a little then ran it again and it didnt leak so i am not sure i just went out to check and there is a little drip so i am going to check that in the morning.. can i just run GM black silocone around the edge or do i have to tear the front back down and put a new seal in? thanks for all yoru help

 

I remember telling you to put #69 jets in it in an earlier post. Did you do that ?

 

are u talking main jets? is that where i should start nothing else for now just the 69 jets?? how much will that lean it up?? what do they come with stock?? thanks

 

How did you tune it if you didnt even change the jets yet ?!? I've got a 408 which is very close in size to your 406. Try those #69s and maybe a different power valve depending on your vaccum.

 

ok i will try that thanks blackened i will have some up dates probably tommorow or wednesday today is my b-day so not going to do much with i dont think except probably change the plugs lol..

 

hey blackened the local parts store didnt have jets # 69 they had 68 so i am going to try those hopefully in the morning.. i was going to ask u what do u have your fuel pressure set at??? just wondering since we do have a very close motor other then our heads.. and what kindof times have u run with your motor?? i am hoping for mid to high 12's think its fesible?? i hope!!! i want to also thank you for helping me here!!! glad to know i have someone to talk to with some one with a close motor like mine!! talk at u later again thanks

 

#68 jets on mine made it stumble just a little bit. #69 made it just perfect. You could also go to #70, but I wouldn't go any higher then that. I set my pressure at 6psi. There's lots of different opinions on what the best pressure should be at. 6 psi works very well for me. I'm in the low 12s myself. That's because I run stock mustang tires (245s) and have no traction at all for 1st and 2nd gear.

 

allright i will try the 69#'s then.. so it sounds like i should hit the 12 sec mark then thats a good thing.. i have sportsman pro tires that are quite sticky!!! so we will see.. going to set the timing and drive it tommorow i hope and see how it runs!! thanks

 

hey also did u have to mess with the back jets once u put the 69's jets in there? if not cool if u did what did u use/??

 

With those heads and a cam that large I would think mid-12s would be not only possible, but conservative. That thing should pull like a raped ape.

As far as the too-rich condition...... What is your manifold vacuum at idle? I bet it's getting down so low that the power valve in your carb is opening up, massively over-richening your mixture. Most power valves open up around 7" of vacuum. Unless you've got more than that at idle and cruising around town you'll be way too rich. And this certainly describes your symptoms. Power valves with lower opening points are available.

Also, manifold vacuum can be affected by ignition timing. With your distributor I'd set it at 10* initial timing (vacuum advance disconnected). Remember, you need to idle the engine down as low as possible when setting the initial timing so that the centrifugal advance is not kicking in and giving a false reading.

Are you running vacuum advance on the distributor? If so, USE IT! It can make a BIG difference in idle quality, manifold vacuum and performance. Typically you want it connected to a PORTED vacuum source on the carb (one that only supplies vacuum ABOVE idle speed). However, you can experiment with a full vacuum source- it could smooth out the idle and improve manifold vacuum at light throttle- but it could also make the idle unstable if manifold vacuum isn't sufficient to pull the vacuum advance FULLY on (usually 8-9" of vacuum).

 

if this other guy is running 69's i would say you should go smaller. his cam is a bit larger than yours. i would think the 68's would be a good place to start.

 

i am going to take it to the guy that built the motor this week sometime.. sunday i got it running good btu the only way that it would run good is setting the fuel pressure at 2 lbs .. why i dont know.. i am not sure if the gauge is off or what but i know that i drove it and it pulled like nothing i have ever rode in.. it was great!! but it dont make sense that the pressure is so low only thing i can think it the jets are way to big and i need to down size because with the pressure up it loads up terrible.. the timing is set a 10* right now.. and yes i do have a vacum advance.. i thanks u guys for your help!!!

 

also anyone know where i can get a oil dipstick for my 400 block?? i bought a mr g one and it wont fit to big around i have one from a 350 in htere but its to long..
2nd what size power valve should i go with?? and bout how much are they??

 

Power valves are under 10 bucks. Put a vaccum guage on it at idle and see what your idle is. Get a power valve that's about 2 or 3 Hg less then that. For examply... I have about 5 Hg of vaccum at idle and I went with a 2.5 Hg power valve.