To Regulate or Not to Regulate

[MN69Grande 203]

So I'm running a 347 10.2 compression, GT-40x heads, with a Holley 4150 650 cfm Vacuum sec.  I was reading a lot of tuning guides on the wild ole interwebs and they said it was good idea to use a fuel pressure regulator to keep the pressure around 6 lbs.  I've got a Holley Mech pump that does 6.5 - 8.  I seems pretty constant at 7 or above. Holley says the needles in a 4150 will handle up to 9 lbs I think - but then in some of their own videos they say try to stay around 6 lbs.  So I guess my question is to all the tuning wizards out there.  Is it worth running a regulator?  

 

The car had been running rich or lean for a while depending on what jets I was using up front.  I was using the old plug reading method but It seemed I just couldn't get it right.  So I put in an Wide band in 2 weeks ago and found I was running super rich at idle.  So I reset the timing a couple degrees (more advanced now at 15 vs 12), increased the Idle 150 RMP From 800/400 park/drive to 950/550, adjusted the float level 1 turn, and turned the idle screws in one turn each.

 

Now the readings are where I want them at idle.  Just slightly rich like 14-14.5.  I still have to go for some test drives to see if I need to re-jet again.  But I do notice the AFR bouncing around a bit and was wondering if this might be do to the fuel pressure moving up or down, or if that was just the way carbs generally run.  At steady RPMs the bounce is .4 I guess, but as I go into or off the throttle it will jump up or down 1.5 points on the gauge.

 

Oh and I guess and semi-related question.  I originally used a vacuum gauge to set the idle-mixture screw, but then changed it based on the AFR.  Do you think changing from Max Vacuum as the tuning guides say to use to get a better AFR will cause issues?

[jholmes217 65]

I use a regulator with a Carter pump that supposedly a regulator was needed on.  My car was shooting fuel through the vent tubes with 8 psi of fuel pressure.  I set my fuel pressure to 5 psi and runs great.  No more gas spraying around in the engine compartment is a definite plus.

[barnett468 418]

your idle is too high and it sounds like you have a stock stall converter . you need a higher stall converter.

[MN69Grande 203]

your idle is too high and it sounds like you have a stock stall converter . you need a higher stall converter.

 

The idle is high.  I was just running it a bit high to get it good and hot since I wasn't going drive it - not sure why I mentioned it in the post.  It runs fine at 700 rpm too so I'll drop it again to that tomorrow and go for a spin.  The Stall converter is 2600-2800 B&M and it doesn't pull to much on me when stopped.  Before I had a 1800 converter on there and it was a bit of a fight.  Anyway I'm just trying to figure out if it's worth the effort to put a fuel regulator on there.  

 

I think the biggest issue was the float adjustment, when I first pulled the fuel level site plug it gushed a bit.  The mechanic who tuned the carb last obviously didn't start with what is step 1 on all the guides I've seen.

[barnett468 418]

your rpm should not drop to 400 when you put an auto trans in gear if you have a 2400 rpm stall converter.

 

set the gas level so it is just below the hole at idle or immediaely after turning the engine off.

[1969_Mach1 333]

Instead of going through the trouble of a fuel pressure regulator, both Carter and Edelbrock have high volume mechanical fuel pumps that don't need a regulator.  Might be easier to change the fuel pump than add a pressure regulator.  I've never used a wide band O2.  Maybe I am stuck in old school thinking.  Sounds like you have a fairly aggressive cam.  I think using the O2 readings to set the idle A/F mixture will be misleading.  At 14:1 or 14.5:1 at idle you are very likely too lean.  An idle that is too too lean can also cause a need for higher idle speeds to keep the engine running when you put it into gear.  Try adjusting the idle A/F mixture by ear or with a tachometer.  Also, when you are done make certain the primary throttle plates are not open too far at idle.  If so, the secondaries will need to be opened a little more, then you can close the primaries some.

 

If you have an aggressive cam with a lot of valve overlap, the exhaust will always smell rich.

[ray1970 88]

Not much help here.

I have never had an A\F meter on a carburetor but i can tell you that with my FI its a bit all over the place unless your at steady throttle

I can only think that with a prehistoric vapor valve it would be harder to get a read.

 

I try to keep in mind that TBI is 30 year old technology in itself..

 

Do we know what the blow off presser is for your stile inlet needle and float?

 

Not shore even where you would find that info?

[Rsmach1 71]

+1 with 1969_Mach1, too much of the transfer slot showing makes idle tuning difficult. I set mine up off the car, and use the secondary plates for minor rpm adjustments.

 

Also if you have put "light" springs in your distributor this can have an effect on the rpm drop from park/neutral into gear. Light springs can cause a small amount of mechanical advance while in Park, then when shifting into gear the advance stops causing a larger rpm drop.

 

Edit; what port do you have the distributor vacuum advance hooked to?

[MN69Grande 203]

+1 with 1969_Mach1, too much of the transfer slot showing makes idle tuning difficult. I set mine up off the car, and use the secondary plates for minor rpm adjustments.

 

Also if you have put "light" springs in your distributor this can have an effect on the rpm drop from park/neutral into gear. Light springs can cause a small amount of mechanical advance while in Park, then when shifting into gear the advance stops causing a larger rpm drop.

 

Edit; what port do you have the distributor vacuum advance hooked to?

 

This is interesting as I was reading about this elsewhere.  Someone did change the springs in the distributor and it was giving me a ton of problems before as one of the springs actually came loose.  It looked like 1 stock spring and 1 light spring from Mr. Gasket.  It hasn't been acting up like it used to but I wonder if your right about the spring being too light.   I'll pull it apart again this weekend and see what it's up too.  I might as well just order a new set of springs at this point.  Do you have any recommends on springs?

 

At the moment I have the Vacuum advance disconnected.  I was planning on connecting to what I think is the ported vacuum at the base of the Carb.  

 

I haven't checked or messed with the transfer slots.

 

I will say I feel I'm getting closer.  The car isn't stumbling off the line like it used too (I think it was bad float adjustment).  I just wish I had more time to work on it.

[MN69Grande 203]

Not much help here.

I have never had an A\F meter on a carburetor but i can tell you that with my FI its a bit all over the place unless your at steady throttle

I can only think that with a prehistoric vapor valve it would be harder to get a read.

 

I try to keep in mind that TBI is 30 year old technology in itself..

 

Do we know what the blow off presser is for your stile inlet needle and float?

 

Not shore even where you would find that info?

 

Yeah the AFR does bonce around a bit and it only on one bank of cylinders, but I've been reading as a range more than trying to hit specific numbers.

[Rsmach1 71]

Hook the vacuum adv to the timed port (metering block on holley's), there is no need to add the additional advance at idle (I just use initial) which is what manifold vacuum (port on holley baseplate) does.

 

As for advance springs I haven't used the Mr Gasket Springs, I typically run stock Springs on the street and am as aggressive as I can be with initial, while dialing back a little with vacuum.

 

To see if the light spring is causing an issue simply replace em with stock, and go from there.

 

Edit; When running higher initial be aware of what the total is.

[barnett468 418]

dont connect the advance until you have zero vacuum at the ported port.

 

one of the advance springs should be slightly loose but it should not fall off.

[MN69Grande 203]

Anyone know a good place to get stock springs?  I don't have the original ones for this distributor and all my searches only come up with the Mr. Gasket springs.  I suppose I could go to the junk yard and pick up a used Distributor to take apart.  

 

As for the advance I should be ok. The guy at ford racing said to run initial at 14-16 and total should be around 32.  I found a few charts that said I could go as high as 36.  So I modified the relutor arm to advance a little over 18 degrees max.  So far that seems to be working.  So as long as I keep the Initial timing below 16 I should be ok.

[Rsmach1 71]

C5AZ-12192-C (secondary) and C5AZ-12192-F (primary) I believe, check rearcounter.com good way to find obsolete parts. Or call West Coast Classic Cougar. They have stuff not listed in their catalog.

[MN69Grande 203]

C5AZ-12192-C (secondary) and C5AZ-12192-F (primary) I believe, check rearcounter.com good way to find obsolete parts. Or call West Coast Classic Cougar. They have stuff not listed in their catalog.

 

Thanks!  Ordered up a combination of springs.  Funny thing is 10 dollars for 4 springs.  18 dollars shipping!  That was for UPS, USPS, or whoever.  I'm guessing there was a either a not well advertised Min or a steep handling fee.  Oh well.  I'll have some spares in a box just in case now.

[1969_Mach1 333]

Anyone know a good place to get stock springs?  I don't have the original ones for this distributor and all my searches only come up with the Mr. Gasket springs.  I suppose I could go to the junk yard and pick up a used Distributor to take apart.  

 

As for the advance I should be ok. The guy at ford racing said to run initial at 14-16 and total should be around 32.  I found a few charts that said I could go as high as 36.  So I modified the relutor arm to advance a little over 18 degrees max.  So far that seems to be working.  So as long as I keep the Initial timing below 16 I should be ok.

I see a lot of posts mentioning 14-16 deg BTDC initial timing.  I guess my question is with what kind of compression ratio?  The experience I have had with motors that have 10:1 or more CR is that either kick back while cranking starts occurring or detonation on initial start-up occurs when the timing starts getting close to 12 degrees BTDC.

[MN69Grande 203]

I see a lot of posts mentioning 14-16 deg BTDC initial timing.  I guess my question is with what kind of compression ratio?  The experience I have had with motors that have 10:1 or more CR is that either kick back while cranking starts occurring or detonation on initial start-up occurs when the timing starts getting close to 12 degrees BTDC.

 

The Ratio is 10.2:1 I was running at initial time around 11 or 12 (my timing light kind of sucks) and bumped it up to 14/15 over the weekend.  I might move it back now that the carb isn't flooding and see how it runs.  But I'll probably not do anything until I can return the distributor springs to stock.  I don't get a kick back or ping on start, but I do get a little shudder/ kick when I turn it off.  I am running 93 non-oxy so maybe that is helping a little.

[MN69Grande 203]

Just an update for anyone who might be interested.

 

I got a spring from NOS parts.  It was the C5AZ-12192-C.  I also ordered the F spring but a bracket of some kind showed up.  So I swapped the Mr. Gasket Spring out for this one, pulled the idle back to 650 RPM, pulled the timing back to 11/12 degrees, and then reset the idle mixture again.  BOOM the car doesn't drop from 900 RPM to 450 any more when I put it in gear.  Now it's idling at 650 and drops to between 550-600.  I call that a win!

 

I did also put the Holley Fuel regulator in.  The only real difference there was the engine idles more smoothly at the same settings.  I set it to 6lbs the pump alone does 7.5+.  

 

So in conclusion the 2 big issues with the tune

1.) Incorrect springs in the Distributor - well this one came off the shelf of a racers shop so...

2.) Bad float adjustments - slight flooding from the float bowls

[Rsmach1 71]

Sorry about the bad part # the -F is actually an advance weight, I had it written down from years ago as a spring (my bad). The good news is the one spring worked, I had the same 400rpm drop issue when I recurved my dizzy 20+ years ago, and it took me a couple days to finally figure out what was going on. I'm glad it worked out for you.

[MN69Grande 203]

Sorry about the bad part # the -F is actually an advance weight, I had it written down from years ago as a spring (my bad). The good news is the one spring worked, I had the same 400rpm drop issue when I recurved my dizzy 20+ years ago, and it took me a couple days to finally figure out what was going on. I'm glad it worked out for you.

I think your number is right I verified it a couple places.  I think the supplier screwed up.  No big deal.  Thanks for the help.

[Rsmach1 71]

Your welcome.