It's all in the timing!

[FuzzFace2]

Good to hear! This thread is helping me plan my attack!

Sorry to say there is no easy way to recurve our distributors.

Plot it, pull it and make a change, put it back in, test & plot curve, repeat till its right.

I have 1 more spring swap, test and plot curve and if ok then move on to the vacuum side of the advance.

Again as a test only as I still have that spring change, I adjusted the can 1 turn back CW for a total of 7 turns CCW from stop. Vacuum hooked up

I have a vary slight ping and not all the time.

Still a little sluggish off the line but throttle response is good when cruising.

I would say if the spring swap dose not work I will go back the the springs I have now ( MSD blue & factory heavy spring) bring the timing from 14° BTDC to 16° BTDC and see what I get.

I don't want to bring the timing up just yet as all my testing has been at 14° and has been starting pretty good.

Dave ----

I have not forgotten this just have not had the time or the weather was not good to swap car / truck around to do the last spring swap & testing.

I am getting a little more pinging and kind of hard figure why?

I have not changed anything and it has been cooler out and the AFR meter has been reading rick when pinging.

I do have the vacuum advance hooked up and going to turn it CCW a turn or 2 to see if that will hold off the pinging till I can get back on this.

Dave ----

[Gary Lewis]

I have not forgotten this just have not had the time or the weather was not good to swap car / truck around to do the last spring swap & testing.

I am getting a little more pinging and kind of hard figure why?

I have not changed anything and it has been cooler out and the AFR meter has been reading rick when pinging.

I do have the vacuum advance hooked up and going to turn it CCW a turn or 2 to see if that will hold off the pinging till I can get back on this.

Dave ----

The colder inlet air packs things in tighter, sorta like raising the compression ratio. (One of the reasons I'm insulating the inlet system on Big Blue.) If you were on the very edge that might have pushed you over. But backing off a couple of turns will probably help.

[FuzzFace2]

The colder inlet air packs things in tighter, sorta like raising the compression ratio. (One of the reasons I'm insulating the inlet system on Big Blue.) If you were on the very edge that might have pushed you over. But backing off a couple of turns will probably help.

Well that makes sense.

Yes it was on the edge before guess it got pushed over

I looked into having the snorkel flapper work but the vacuum motor is no good.

I found out you can get this so will look into it at some point.

Dave ----

[Gary Lewis]

The colder inlet air packs things in tighter, sorta like raising the compression ratio. (One of the reasons I'm insulating the inlet system on Big Blue.) If you were on the very edge that might have pushed you over. But backing off a couple of turns will probably help.

Well that makes sense.

Yes it was on the edge before guess it got pushed over

I looked into having the snorkel flapper work but the vacuum motor is no good.

I found out you can get this so will look into it at some point.

Dave ----

Getting the door to close might help. But in cold weather you'll still have pretty cool air going into the carb depending on the sensor you use:

[FuzzFace2]

Getting the door to close might help. But in cold weather you'll still have pretty cool air going into the carb depending on the sensor you use:

Well after driving the truck for about a month and most of that with the vacuum advance hooked up a week or 2 ago I had a little pinging so I did a little adjusting of the vacuum advance and no pinging.

It was high 70's today and next week getting into the low 80's so going to do a little more driving but I cant see changing the spring to a lighter one as I am pretty sure I would have pinging even with out the vacuum hooked up.

So it looks like where its at now is where it will stay.

I know I have the timing set at 14* BTDC and would have to re-read my posts to see what springs I used but I want to say the 2 heavy springs so the weights start late but it works.

Dave ----

[Gary Lewis]

Well after driving the truck for about a month and most of that with the vacuum advance hooked up a week or 2 ago I had a little pinging so I did a little adjusting of the vacuum advance and no pinging.

It was high 70's today and next week getting into the low 80's so going to do a little more driving but I cant see changing the spring to a lighter one as I am pretty sure I would have pinging even with out the vacuum hooked up.

So it looks like where its at now is where it will stay.

I know I have the timing set at 14* BTDC and would have to re-read my posts to see what springs I used but I want to say the 2 heavy springs so the weights start late but it works.

Dave ----

Glad it is working. Right on the edge of pinging but w/o pinging is as good as you can do.

[FuzzFace2]

Glad it is working. Right on the edge of pinging but w/o pinging is as good as you can do.

I felt from the other spring changes it would of pinged and why I dont want to do the last change.

I need to look into the carb deeper as the AFR is moving all over the place and think it should be a little more steady.

Also I remember when I rebuilt it it was missing something on the needle / rod and hope that is why?

I was given a few carbs, think feed back that I will pull apart to see if they have the missing part.

I also have one of them Ebay carbs but I dont want to use it till I have done everything I can to this carb.

Dave ----

[Gary Lewis]

I felt from the other spring changes it would of pinged and why I dont want to do the last change.

I need to look into the carb deeper as the AFR is moving all over the place and think it should be a little more steady.

Also I remember when I rebuilt it it was missing something on the needle / rod and hope that is why?

I was given a few carbs, think feed back that I will pull apart to see if they have the missing part.

I also have one of them Ebay carbs but I dont want to use it till I have done everything I can to this carb.

Dave ----

I used to think that a carb supplied fairly steady AFR. Not so. Big Blue was all over the map when driving.

I had it tuned so that at 65 MPH and no wind and level ground it would be around 14.5. But let the wind pick up or a little bit of an incline arise and it would go above 15. A little more hill and I'd see 16+ before the needles lifted and the power tips came into play and it would drop to 13+. And that was driving gently.

However, that makes it sound like it was nice and steady with gradual changes. It wasn't. Even the slightest change of throttle sent it up or down quite a bit from ~13 to even 17.

That's a big reason I'm looking forward to EFI. I think getting the AFR to be in the mid-14's on a steady basis is going to help the MPG noticeably.

[FuzzFace2]

I used to think that a carb supplied fairly steady AFR. Not so. Big Blue was all over the map when driving.

I had it tuned so that at 65 MPH and no wind and level ground it would be around 14.5. But let the wind pick up or a little bit of an incline arise and it would go above 15. A little more hill and I'd see 16+ before the needles lifted and the power tips came into play and it would drop to 13+. And that was driving gently.

However, that makes it sound like it was nice and steady with gradual changes. It wasn't. Even the slightest change of throttle sent it up or down quite a bit from ~13 to even 17.

That's a big reason I'm looking forward to EFI. I think getting the AFR to be in the mid-14's on a steady basis is going to help the MPG noticeably.

Well maybe mine is ok as it dose the same thing

It seams if I give it just a little throttle or little hill it dose the same, runs 14's to 15's

But most of the time it is high 12's to mid 13's and that is on flat ground 65 to 70 MPH (70 is the speed limit) in over drive around 1800 RPM.

At 55 MPH not in over drive the RPM is also 1800 but I know I am pushing more air at the higher speed so have to use more fuel right?

On back roads where speed limit is 55 and not in over drive I get the same reading on the AFR gauge so I think the carb has got more MPG in it somewhere I just need to find it

Thanks for the information Gary

Dave ----

[Gary Lewis]

I used to think that a carb supplied fairly steady AFR. Not so. Big Blue was all over the map when driving.

I had it tuned so that at 65 MPH and no wind and level ground it would be around 14.5. But let the wind pick up or a little bit of an incline arise and it would go above 15. A little more hill and I'd see 16+ before the needles lifted and the power tips came into play and it would drop to 13+. And that was driving gently.

However, that makes it sound like it was nice and steady with gradual changes. It wasn't. Even the slightest change of throttle sent it up or down quite a bit from ~13 to even 17.

That's a big reason I'm looking forward to EFI. I think getting the AFR to be in the mid-14's on a steady basis is going to help the MPG noticeably.

Well maybe mine is ok as it dose the same thing

It seams if I give it just a little throttle or little hill it dose the same, runs 14's to 15's

But most of the time it is high 12's to mid 13's and that is on flat ground 65 to 70 MPH (70 is the speed limit) in over drive around 1800 RPM.

At 55 MPH not in over drive the RPM is also 1800 but I know I am pushing more air at the higher speed so have to use more fuel right?

On back roads where speed limit is 55 and not in over drive I get the same reading on the AFR gauge so I think the carb has got more MPG in it somewhere I just need to find it

Thanks for the information Gary

Dave ----

Yes, if you are running high 12's to mid 13's then you do have MPG left in the carb. I'd try to get it to 14 or so on flat ground at 65.