250 build tunning and stuff

Do I need to go get a longer hose for the vacuum gauge? lol I did some driving after getting the vacuum at 9. Car idles at 13.9-14.8 after driving it around now. Cruising it will hold 14.5 good, but once you give it some gass below 2300rpm it will run lean to 17 and make its way to 14s.

I have not gotten to do wot as of yet, due to all of this rain. I will soon though and give y'all the readings.

One thing that I notice is that when I come to a stop it will idle down to 700-800 rpm and act like it wants to die, but once I give it a little gas it goes back to 1000 and stays there. I think this happens when the fan kicks on and there is a load on the alternator. Should I raise the rpms to comp for that load?
 
Man I can not get that engine to run at 700rpm.
At 1050 it's at 14* it's At 34* at 2500. Idk if I should raise the timing or not. I just figured for the street 34 total at 2500 should be good. I've read to try and advance it to the highest vacuum and then dial it back one or two to help prevent detonation. Idk if I should do that as it seams to run fine in that timing with no pinging at all.

I have not changed the power valve yet.
 
69stang_250":2nsxrg4i said:
Man I can not get that engine to run at 700rpm.
At 1050 it's at 14* it's At 34* at 2500. Idk if I should raise the timing or not. I just figured for the street 34 total at 2500 should be good. I've read to try and advance it to the highest vacuum and then dial it back one or two to help prevent detonation. Idk if I should do that as it seams to run fine in that timing with no pinging at all.

I have not changed the power valve yet.
You are right that the timing should not be more that 34* total.
However you can move the initial around now for best idle and stop light response, figure out what that setting is and then limit the mechanical advance so you can have more initial (if that is what it needs) and still not have more that 34* total.
 
So should I hook up the vacuum gauge and adjust the initial timing off of the vacuum numbers I get?
Honestly getting the rpms up and setting the total timing it was running a lot better than it was when I set it at 10 and we were having problems keeping it running and we couldn't get it to idle down below 1300.
 
Best way to set initial is keep advancing it a couple degrees at a time. sHUT ENGINE DOWN then start it again add a couple more degrees repeat until the starter will barely turn the engine over. Back off about 5* from that setting. At that point initial timing should be within + or - 1 or 2* of best setting.

As for begining jetting Often I START WITH a PV plug or a 2.5 Just to keep the confusion of it opening during setting up the main jetting.

Also plug up the vacuum advance while setting initial and testing out different total advance settings.

Your PV is possibly opening at idle if you havent replaced it already. Most typ part stors are not going to have power valves. I use Quick Fuel power valves if possible they are or were cheaper and stronger than the holley ones. Since Holley bought up Quick Fuel thing might be a bit different now.
 
Ok so I sat stepped back over the weekend and did a little reading on bills past replies to me and some web research. I pulled the carb off this morning and reset the idle transfer slot to .030, turned all four corner idle screws 1 1/2 turns out, and checked the secondary blades to be sure they were completely closed. checked every nut and bolt to be sure they were tight on the intake and I installed the carb again. Hooked up the vacuumgauge and plugged the ported vacuum on the carb leaving the distributor vacuum disconnected. Went to start the car and I could not keep it running. Loosened the distributor and had to advance it to keep it a 600rpm. It would not hold any higher than 650rpm. I killed it and tuned the idle screws in half a turn, idle jumped up to 730 rpm and it would stay running. I turned all four screws in completely and then out half a turn and 1/8 more. The car would then crank and run smoothly at 1150rpms. And I was getting 10 inches of vacuum and a lot better throttal response than I had been getting plus the AF ratio was hanging steady between 13.9 and 14.5. Now when I checked the timing it was way off in left field than what it had been. My light was reading 30* at 1150 rpms. That does not sound right to me and has me questioning if my gun is off or something or if the rebuilt balancer is slipping. But anyways, I figured I would see how far I could get the timing to advance before I heard pinging or anything and since I am having a hard time beleaving my gun i went off the vacuum gauge. I got up to 15 inches of vacuum and backed it off to 13, as I have read that's an old technique used.
It idles awesome and better than it was and the throttle response is even better and the is no hesitation or anything when you hit the throttle now.

With all of that I am a little worried about the timing right now though. What do you guys think I need to do? I know for a fact that I can't run it up and set the total timing to 34 and expect it to run. What do you guys think I should do?
I am thinking about taking it out for a drive, but I don't know if I want to just yet.
 
Remove spark plug #1 and with a thin screw driver do your best to get the piston at TDC.
You can usually feel the piston dwell at TDC.
Then check the balancer to see if it is close.
 
I just checked it and it is off.
So I noted that when the piston reached the top the mark was at 15-16 degrees. The timing pointer only reads up to 14 and it was a little before 14 when I checked it out of the car.
What is the best way to mark it in case it slips again?
Also, do you think using the vacuum method for timing is a good way to go?
 
Paint a new line on the balancer with white paint or something equivalent.
Vacuum method is a good start but you finish by checking it with drivability.
 
Ok so I got back out there and makes the line again, but i was wrong and i don't think it slipped. The notch lined up where it should have, but I used some model paint that I had to make it more pronounced.
Anyways, the lowest I can get the thing to idle is at 950rpm @ 24* it's a little choppy, but sounds fine and the engine is not bucking all over the place, but vacuum is back down to 9 in. I can bring her up to 1000rpm, but that puts me at about 28*.

I do not get any pinging at all unless it's faint and I can't hear it. One thing to note is I'm using 20 gal of 93 octane and a booster that raises 10 of those gallons to 101. That could be why, but idk.

Just for reference: carb floats are set as center as I can get with it at the angle, .030 transfer slot exposed on the primary side, secondary blades closed, idle screws 5/8 turn out and has the best vacuum and keeps AF ratio 13.8-14.6.
Everything has been checked for vacuum leaks and none found, all ports are covered on the carb, and thats about it for the carb.
Initial timing is at 24* right now, but will go higher and give more vacuum with carb adjustments. I tried to bring total advance to 38 at 2500 rpm, but I can't keep the car running after I set it at that.

I know I need to get the timing set right before the carb will tune properly, but I have no idea which direction to go with the timing.

May primary consern is messing up the engine.
 
I have not touched the idle speed screw at all and from doing some reading I think I may end up opening up the secondaries a little to help with the idle speed so I can lower the timing. Like I said, it's kinda crazy to me that the engine will take almost 30* of initial timing without any pinging and I'm pretty sure if I leave it at that, I will hear it when I go for a drive down the road.

Do any of you guys know any likes or have any references on how much you should open the secondaries if they are needed for idle?
 
Don't mess with the secondary yet
With the vacuum advance line disconnected I need you to drop the idle speed down with the idle speed screw and watch the timing as you do it.
Hopefully the timing will bottom out at some point.
Then run the rpm up and check the total timing. It won't hurt anything with no engine load if the timing is way out there.
This will give you the total mechanical advance.

What I'm trying to get at is the actual mechanical initial timing which you would see at cranking speed or around 600 rpm.
What happens now is the lower the idle goes the lower the timing is so if the rpm drops say at a stop light the engine feels like it wants to die.
Then the engine hesitates as you leave the stop light because the timing drops again with rpm.

The Goal would be to have the real initial timing set at 16 degrees which would be the rock bottom possible, then limit the mechanical advance to 18* (9* at the distributor) so the total timing would be 34*. Bill can do the distributor advance for you if you don't want to.
Then hook the vacuum advance back to the manifold port so the idle timing would be back in the 20s at idle.

Does the vacuum advance have the adjustment screw inside the canister?

The other part of this is (If you haven't already) the power valve needs to be lower before you can do any further carb tuning.

You are trying to tune a 250 six that has a cam with 11 degrees of .050" duration overlap. It will take some work.
 
I am picking up what you are putting down man.
I will get in it tomorrow and see what I can find out. I'm sure I can figure out the timing at 600 rpm.

It does have an adjustable vacuum can. I was reading up on that a few days ago.

I'm confident doing the work as long as I have yalls advice.
 
So I talked to bill and I've gotten the timing figured out.
It is set at 20* initial and then I hooked up the vacuum advance to the manifold vacuum which raised the rpms about 200-300 and then turned the curb idle down between 1100-1200 rpms with 32-34 degrees of vacuum advance. It is idling better and I don't have the drop in rpms that I did with the ported vacuum when I come to a stop sign. I did change the power valve out to a 5.5. Only had a few options at the parts store and that was the next size up from the 4.5 that would have matched my vacuum.

Now when I drive the AF ratio stays in the 13.5-14.5 range mostly in all driving conditions, however it does cruise at 80 on the interstate at around 14.5-16. Give it a little gas and it gets back in the 13s quick.
In first punching the gas gets me in the 11s, but does not stay there very long.

Now the only issue I have is this spot around 2700-3000 that the engine quits pulling for about a half second to a second and then it pulls hard. Kinda like it bogs down just a little and the catches up to its self.

Suggestions?
 
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