Distributor curve

[jpaz]

ok, xlnt.

I would do the following next and leave the vacuum advance plugged for now . My "guess" is that increasing it by 6 degrees might be just a tiny bit too much but the drive and start tests will tel us.

TEST DRIVING

After setting the curve you can do the following test to see if you have too much advance.

Get the engine up to operating temp.

Drive at around 20 mph in second gear for a few seconds then floor the gas pedal as fast as you can until you reach around 30 mph and listen for even the faintest pinging sound coming from the engine . If it pings, you have too much timing for the octane gas you are using . You can either reduce the timing some or use a higher octane . The highest timing level you can run without it pinging and/or running erratic will SAFELY provide the most power.

It may ping in hot weather even if it does not in cold weather . If you find this to be the case, the easiest thing to do is reduce the timing until it stops or try higher octane gas . If it still pings with the highest octane gas, you can reduce the timing then.

If the engine turns over more slowly when it is hot, reduce the timing by 2 degrees and let us know.

JETTING

It may be rich or lean . If you installed new spark plugs, I would remove the front plug from each bank and post photos of them.

Black porcelain is rich.

Nearly white is lean.

Very light tan is typically very good and suggests the jetting is very close if not ideal.

Ok will try that test tomorrow. I did end up setting the initial at 14* BTDC, and went for a drive. Seemed to run pretty good, punched it a few times, didn't hear any pinging. It started right up every time with just the touch of the key.

I did have an issue with my oil sending unit, leaked like a bitch when I got home. No biggie, will fix that tomorrow & try what you said

I did install new plugs, wires, dist. cap & the Blue Thunder intake. I like it! I readjusted carb idle mixture screws for max manifold vacuum b4 test.

I'll pull a plug & check for the tan. Thank's again Barnett!

 

[jpaz]

Ok, I did the 2nd gear, 20-30 mph test with no pinging, did it a few times. B4 I did it, I rechecked timing & initial was at 14* BTDC. It started right up when it was cold, & started up easily after it got to normal operating temp.

I was going to advance distributor 2 more degrees to 16, but I noticed I still have an oil leak. It's not the oil sending unit like I initially thought. It's the damn intake manifold leaking. I re-torque, but I don't think that's the problem. I tried to use just black hi temp RTV on the ends, but I guess I screwed it up. I put a real nice thick bead on the ends, but it's got a leak at the back. After I re-torqued, I tried to put some more RTV on the back to see if I can stop it. I have to wait till later today to start it up again. I doubt this will work, but I guess it's worth a try. I'm bumbed

 

[73pony]

Sucks about the leak. I doubt the dab method will hold or at least prob not for very long.

 

[Don C]

I've never had much luck with dabbing on regular RTV, better luck with the Right Stuff, it seems to stick better. I also use Right Stuff for the end seals, haven't had one fail, yet. Had several leaks using the cork or neoprene end seals, though.

 

[jpaz]

I've never had much luck with dabbing on regular RTV, better luck with the Right Stuff, it seems to stick better. I also use Right Stuff for the end seals, haven't had one fail, yet. Had several leaks using the cork or neoprene end seals, though.

I used the Ultra Black on the ends, sure seems real sticky, but I guess I didn't put enough on. If it still leaks today, which it probably will, I'll give the Right Stuff a try.

 

[jpaz]

I finally got the oil leak to stop! Thank's Don C, I took your advice & got some Right Stuff. I used my camera on my phone to pinpoint the leak. Packed some Right Stuff in where it looked like I had a little gap. Let it set for about a half hour, went for a drive & no leak. Went for another longer one, punched it a few times, came home, still no leaks. It leaked every test drive I did b4 I used the Stuff. Not sure how long this will last, but it was worth trying. It was actually leaking w/previous manifold anyway, so now I know why & what the leak was.

Anyway, back to the timing & distributor testing. I did a few more 2nd gear & floor real quick, no pinging at 14* BTDC. Want to try to advance dist 2* more & see if I get any pinging, but will wait till tomorrow. Thank's to everyone for all the help, I really do appreciate it!

 

[barnett468]

Anyway, back to the timing & distributor testing. I did a few more 2nd gear & floor real quick, no pinging at 14* BTDC. Want to try to advance dist 2* more & see if I get any pinging, but will wait till tomorrow.

xlnt!

 

[Mikes73]

Just remember it is called a timing curve for a reason. To much to soon isn't always a good thing. Just my personal opinion from past builds.

 

[jpaz]

Just remember it is called a timing curve for a reason. To much to soon isn't always a good thing. Just my personal opinion from past builds.

Your right, that's why I'm trying to figure out how the PO had the distributor set up. I've also made a few changes, so trying to get it all balanced. Thank's Mikes73!

 

[jpaz]

Ok, I reset timing yesterday. It was at 15* BTDC, so I went up 2 more degrees to 17. Went for a drive, did the 2nd gear test with no pinging. I pulled #1 plug to check how its burning & no tan color, looked a little wet like its running rich. That was as far as I got last night. Engine does still start right up, it was 80* out and had no start up issues.

I think I may need to reset idle mixture screws?

 

[barnett468]

.

If anything, the more timing you add the leaner it will be . If it was gas on the plug, it should have quickly, or instantly dried up so it may have been oil.

17 is a lot in most cases but if all the tests I suggested tell you that is what it wants and it doesn't ping, then that is what it should be . Sometimes the outer ring on the damper slips a little also which ca cause an inaccurate reading which is one reason its not always best to rely solely upon the numbers you see.

 

[jpaz]

Ok thank's Barnett, I am going to check timing again today. I could also be off a degree, its kinda hard to get a good look at the damper/timing mark.

I adjusted idle mixture screws w/vacuum gauge & max vacuum I could get was 11-12 in. Hg. does that sound about right or is that low?

I was going to post a pic of the plug, but it just looks like its brand new.

 

[barnett468]

i don't remember your cam or compression so I can't comment on the vacuum, but if you have a big cam, your level would definitely be in the ball park.

If the porcelain looks blazing bright white, it is screaming lean. especially if there is no black on the threads and this condition would warrant an increase in the front jet size by at least 2 sizes which is how much I would go.

 

[jpaz]

I don't know cam or compression either. Cam is for sure larger than stock. I'm gonna check a few more plugs.


Pulled another plug, looks same as first one.

 

[Jeff73Mach1]

The method I was taught to read a plug requires you to make a nice hard pull and cut off the ignition, coast to a stop and then pull and check the plug.

Regardless, that looks lean to me.

 

[jpaz]

I think I need to go up a couple sizes.

 

[Jeff73Mach1]

I would tend to agree-2 sizes at a time is generally necessary to see any change. I'd bet one change will get you where you need to be.

 

[jpaz]

Ok, thank's Jeff I'll start there. I just removed the two front jets & they are 70's. Going to get some 72's & see what happens.

 

[barnett468]

exactly what type of carb is it?

ok, yeah it is lean on the mains.

reading plugs is a little different than it used to be due to the differences in gas in gas, and in general, what looked good before would now be a little rich . i can post a bit more info on it later but yeah, go up at least one and no more than two on the mains.

i would also say that if you floor it from a dead stop or from 5 to 10 mph and it has a slightly hesitation before it goes, this is at least partially due to lean jetting in your particular case.

the fact that the end of the threads is black means that it is not lean at all throttle positions and it is highly unlikely you can jet it so the threads won't be that black but it is only a problem if it causes some type of performance issue.

if it has an abnormally nasty sounding idle, it has a fairly big cam like a comp XE274H, and if this is the case, you will benefit from running a multi fire ignition like an msd 6 type box or pertronix III module along with a high voltage coil . i prefer the msd anti vibration coil to their other one.

 

[jpaz]

exactly what type of carb is it?

I am running a Holley 770 Street Avenger

ok, yeah it is lean on the mains.

I'm trying two sizes up from 70's to 72's

reading plugs is a little different than it used to be due to the differences in gas in gas, and in general, what looked good before would now be a little rich . i can post a bit more info on it later but yeah, go up at least one and no more than two on the mains.

i would also say that if you floor it from a dead stop or from 5 to 10 mph and it has a slightly hesitation before it goes, this is at least partially due to lean jetting in your particular case.

the fact that the end of the threads is black means that it is not lean at all throttle positions and it is highly unlikely you can jet it so the threads won't be that black but it is only a problem if it causes some type of performance issue.

if it has an abnormally nasty sounding idle, it has a fairly big cam like a comp XE274H, and if this is the case, you will benefit from running a multi fire ignition like an msd 6 type box or pertronix III module along with a high voltage coil . i prefer the msd anti vibration coil to their other one.