now it's time to fine tune it (Holley carb mainly)....HELP!

[Anonymous]

OK, I think I've finally figured out the timing issues, now I want to dial her in a bit more. Now, the quesitons:

- in what order should things be done: timing, mixture, idle speed
- using a vac gauge on the carb to set mixture...which vac port do I use? I'm supposed to back the mixture screw out until I hit my highest vac point right? Leave it there?
- I've got a Holley 2300 500CFm carb on my OZ2502V head. What kind of jetting should I be looking at using? I have no idea what jets are in it now (stock)...do you?

 

[Anonymous]

almost forgot...i have to adjust the float level as well right...when does that need to be done in reference to the rest of the stuff?

 

[Anonymous]

Well start with timing, then you adjust the carb. TO adjust the carb it is kinda a back and forth type thing this is how I have tuned mine for 5 or 6 years and I have never had a problem. Just remember rich is better than lean, but lean = more power (to a point.).

 

[Anonymous]

Where's ya at with it now Bryce?

 

[wsa111]

Bryce, your 500 cfm comes with 73 jets, try 71's & set the float level where the fuel just trickles from the sight plug. Set your idle speed 25 rpm above where you want it, then turn the mixture screws in to get a 25 rpm lean drop between both idle mixture screws. This method will give you the best miliage & prevent a stinking over rich idle mixture. Road test & if you have a surge at highway speeds go up to a 72 jet, if no surge try a 70 jet. If you then get a surge go back up 1 jet size.
If you have access to an air fuel ratio tester that is the other best tuning tool.
Keep us informed. william

 

[Anonymous]

ok, i got the float level right after pulling the float bowl off to change the powervalve. I went with a 65 PV. That ok with 20HG of vac at idle?

BOTH MIXTURE SCREWS?!! Um, uhoh. Are you sure there are two on the 2300 2BBL?! I've been tinkering with the ONE on the choke side of the carb...there is another somwhere?!

I'll try dropping in 71's this weekend. What exactly do you mean by a "surge" at highway speeds?

I've also been reading some of your old posts on carb tuning. You talk of cam and pump changes, etc. If I buy the beer, will you come over and teach me everything you know!? Do you have any recommendations for such changes on my setup? I've got really poor acceleration, but at 2500rpm, she seems to have some guts.

I don't have access to an A/F meter and can't really afford to spring for a decent one. It's just me and my vac gauge! :roll:

 

[Anonymous]

IDLE MIXTURE SCREWS: ONE EACH SIDE
I am not usually that stupid or blind!

 

[CobraSix]

For me, it's usually a back and forth thing.

Set the timing first though, the do the carb. I like to get the idle speed close so I can better set the timing and then reset the idle, then reset the timing, until there is little to no need to change.

Don't feel bad. It took me a week to find the 3rd vacuum port on the back side of my Holley. Man that through me for a loop. I checked all over for vacuum leaks. Had a huge one...and it was a 3/8" PCV port...hehe

SLade

 

[Anonymous]

OK, i found and adjusted the other idle screw preety close anyway.

Now I am totally confused. I pulled the plug off of the manifold vaccum port at the base of the carb to hook my vac gauge up and the idle went up and smoothed out a lot. I'm sorry? I thought that a major vac leak like that would do the opposite? I hooked the vac gauge up to that port and its jumping all over the place (with the lope of the idle). I tried hooking the DSII up to that port, reset the timing a bit to take into account the immediate advance in the timing, and drove it there. It really smoothed everything out, but the acceleration was not really any better.

Opening that port was like feeding more air to the motor causing it to run better, but shouldn't that have been TOO much air? OR was that just compensating for WAY OVER RICHness? maybe something is screwey and the mixture is way to rich to begin with and adding that extra air, balanced it out. Maybe by switching to the 65 powervalve from the 50 that was in there caused this?? That was a question not a statement.

So, what do I do? man I hate carbs.

 

[Anonymous]

The P/V's flow the same amount, they just open at different "'s You are not getting any extra fuel from the P/V until vacuum falling below it's rating causes it to open.

 

[Anonymous]

right, but if my vac is as erratic as it seems jumping above and below 6.5 (the new PV rating), then it WOULD be flooding it, right?

I'm going to go out and get as many readings on as many things as i can.

 

[wsa111]

Bryce, do everything slade & myself said in previous posts.
If by pulling the manifold vacuum hose off & your engine smoothes out your idle is way too rich.
Make sure your initial advance is set with no vacuum source hooked to the vacuum advance canister. When you set your timing do it at the lowest rpm the engine will run, or do it with then fuel clamped off to the carb & crank the engine with the starter then set your initial advance to 10-14 degrees??I need to know what cam you have in your engine? & how many degrees you have in your distributor. To make a long story short you need about 38 degrees total advance , this may cause you to check the total advance over 3500 rpms, again with the vacuum advance disconnected. Then hook up the hose from the vacuum canister to either the manifold vacuum port or the other port which gives you vacuum advance when you crack the throttle. use the port which gives you the higher rpm at idle. Set your idle speed adjustment screw to say 750 rpms in drive, or if its a stick use 800-850. Then screw in your idle mixture screws to produce a 25 rpm lead drop. You may have to reset your idle speed screw several times to achieve the correct results.
What are your cam specs @ .050 & your camshaft centerline. Better yet what cam do you have in your engine??
This about the limit that can be done on line.
If you still have a problem you need to take your vehicle to a tech with the knowledge of older vehicles before computer experience.
Keep us informed. & advise me what camshaft you have?
the 6.5 power valve is fine.
If you have a camshaft with a 110 centerline & over 214 degrees @ .050 you may need a looser converter if you have an automatic trans.
The only time you need a vacuum guage is a final check of vacuum @ idle in drive or neutral, but use the 25 rpm lean drop with your idle mixture screws. This will give you a final idle mixture on the lean edge but not enough to cause a rough idle. You just want to use the guage to make sure the reading is above your power valve. Good luck William

 

[Anonymous]

before I post what I am about to write, I appologize for wasting so much brain power on my own stupidity.

With that said...

all problems (other than a tranny leak) have been solved.

#6 cylinder rockers were OFF. Broken cap screw. Push rods off. Etc. FORTUNATELY, no bent push rods or lifter damage as far as I can tell.

Replaced cap screw, readjusted all valves, and viola.

bat out of hell.

I'm of course going to continue to tune and tweak to get performance to where I want it with jetting, pump cam, etc, but my #1 concern is WHY!?

Why have I now broken 2 cap screws in my full rollers from Yella Terra? The cap screws were torqued to specs and the valves were adjusted according to instructions.

After fixing this, my vaccuum steadied out perfectly. I have the DSII on the manifold port for now, because I don't think the mechanical advance in the DSII is working. I had my wife slowly rev the motor from 900rpm idle through to 3000rpm and i had almost no advance.

 

[addo]

I suspect the answer to your searching question lies in their (Y/T's) technical page. Some part of the travel is impeded.

 

[Anonymous]

I am not familiar with Yella Terra but their website says;

Shaft type
(1.65) ST2014
*requires Cleveland lifters and 9.130" pushrods

Glad you found the problem.

 

[Anonymous]

I bought the whole kit a kaboodle from Mike at FSPP. I'm certain that he knows what parts need what components. He did have trouble getting hold of the right push rods, but that was just a vendor delay issue.

Hey Mike, wanna chime in if yer around? You did set me up with the right lifters and rods right?

 

[wsa111]

Bryce, your centrifigul advance should be fully in by 2700-3000 rpms if you have any kind of camshaft in your engine. The stock stiff distributor springs will not give you enough advance at lower rpm's just when you need it. Weaker springs are available from summit or if a local tuner has a sun distributor machine & has the knowledge to custom tune you an aggressive curve.
I still have to know your camshaft specs & compression ratio & cranking compression to give you an educated answer on line without having the vehicle for my personal attention. Don't give up you are getting close. William

 

[Anonymous]

Thanks William. That's what I need to know! Here are the cam specs:

CSC-264-DHS
264/274
214/224
.450/.450
.480/.480
.495/.495
110*
1600-5200

http://cquesttechnologies.com/fspp/camshafts.asp?cat=21

right from Mike's new website (gorgeous new site isn't it? wonder who built that for him! )

Ratio should be 9.7:1 based on the compression calculator

I'm not sure of the cranking compression. Don't have a checker-thingy-ma-bob.

 

[addo]

When the vacuum gauge was fluctuating, you might have considered a compression test. But - just to draw a parallel - you are expecting of yourself to achieve diagnosis and results that may befit a person with years of formal training and hands-on experience. It is often an unrealistic ideal. I sometimes wonder if there are dental or medical forums like this... "OK, I've got the molar out but can't fully stitch the gum. What to do?" Look back at the leaps and bounds you have made, and take some enjoyment from there also.

It sounds as though the pushrods are either too short or too long. Examination of the rocker arms will reveal some marking that helps determine which is the case. The rocker length pertains to Aussie 250 blocks and can probably be ignored. Similarly, Clevo lifters are the possibly most common in our aftermarket. All the HT-900 series will work.

The diagnosis will be interesting!

 

[Anonymous]

Thanks for the reality check ADDO! I do expect a lot of my self in contrast to my skill level. I'm a fast study and I absorb what I read and learn quite quickly...hence the reason I ask so many freakin questions!

Believe me, leaps and bounds are an understatement! I went from having some experience opening a head and tinkering there, to rebuilding a tricky and fairly rare motor combo form the ground up! And now...it runs!!

LOL!

I'm not done asking quesitons, and I'm not done thanking everyone who takes the time to help educate those of us who need it.

Everyone here rocks.

In regards to the push rods, I'll need Mike to chime in if possible on this. He would know best as he had to practically drive to the vendor and beat him with an oak tree to get them!! I could always undo my newly tuned setup to measure one I guess, but I don't have a micrometer (or anything better than a tape measure for that matter ) and I'd hate to open it back up just yet!