440 combo opinions

[thrillbilly]

Wow, that took awhile.  But I have some updates.

Installed fuel pressure gage.  Runs between 6-8 psi steadily, idle, cruise, and WOT.   After looking through some of my notes and watching my A/F ratio gage at WOT, there is a big lean spot from partial to WOT, goes into the 17's, not good.  So I skipped ahead, (I know, I know) and went to the 850 mechanical secondary, with the Mopar carb adapter.  Huge difference, A/F steady high 12's, low 13's at WOT, no bogs, just instant throttle response.  It really, really runs great. 

I also removed the PCV system and went to open breathers.  After doing some reading, I didn't know that could cause detonation.  I haven't experienced any since the changes, but it hasn't been hot outside yet, which is usually when I have that happen.

I have found a shop very close to my house that has a dyno.    Great guy owns the place, mostly works on late model LS stuff, but I'm going to run the car on it in the next few weeks.  I guess I'll know for sure what it has then.  I'll post numbers ASAP.

[myk]

How does an open breather cause detonation?

[thrillbilly]

Open breathers don't cause detonation, PCV valves do.

[BSB67]

and went to the 850 mechanical secondary, with the Mopar carb adapter.  .

850 DP, good choice.  Which one did you get?

Why a carb adapter?  Do you mean throttle arm bracket?

[thrillbilly]

A Mighty Demon.  Yes, the throttle arm bracket, the brain is not working today 

The throttle arm bracket does goof up where the stock throttle cable lines up in the cable bracket from the intake.  I had to pull it back so that I am getting WOT, and it's about halfway out of the bracket.  What's the fix there?  I'm afraid it's not going to stay there.

[XH29N0G]

Open breathers don't cause detonation, PCV valves do.

Is it the oil coming in through the PCV valve that causes detonation? 

[thrillbilly]

From what I understand the oil mist coming into the combustion chamber burns hotter than the air/fuel mix?

[myk]

From what I understand the oil mist coming into the combustion chamber burns hotter than the air/fuel mix?

I didn't know that.  Should we all switch to open breathers?

[1974dodgecharger]

Never heard of pcv causing detonation 

[BSB67]

Never heard of pcv causing detonation 

PCV valve don't cause detonation, oil in the combustion chamber will.  If there is that much oil coming from your PCV valve, you have another problem.

[XH29N0G]

That is the same as I have read, the oil mist can contribute to detonation, but that active evacuation of the crankcase is beneficial for the engine (maybe keep the oil cleaner?).

Some use evacuation systems that scavenge crankcase gases with the exhaust (e.g., http://www.summitracing.com/search/part-type/crankcase-evacuation-systems).  
Others put an oil catch can in line with the PCV valve.  I read on another forum of others adapting a OEM style Mopar breather (with the host end) so they can plug the PCV valve into it and filter the gases before going back to the crankcase.

I have seen a few posts on this forum from people evacuate to the exhaust or just run breathers because they do not want the exhaust gases in their intakes for running at the track.  Maybe they will add to this discussion.

(I see a fair amount of oil come out the crankcase on my engine, and I just decided to try the last approach (the mopar breather plumbed in line).  My guess is that will not make a difference I will notice, but if it does, I will let you know.  I also have a small amount of oil on plugs from the 4 rear most cylinders (but not on the 4 forward cylinders which I suspect may be related to the PCV drawing gases into the back of the manifold.  I will see if that changes, but need to drive for a few weeks/months first.)

[firefighter3931]

A Mighty Demon.  Yes, the throttle arm bracket, the brain is not working today 

The throttle arm bracket does goof up where the stock throttle cable lines up in the cable bracket from the intake.  I had to pull it back so that I am getting WOT, and it's about halfway out of the bracket.  What's the fix there?  I'm afraid it's not going to stay there.

With a high rise intake the AR Engineering brackets are the best option. I've used this one with a Performer RPM, Street Dominator and now a Mopar M1 single plane. Worked flawlessly on all of them. I have a factory slant 6 cable which is longer than the stock 440 cable and it works great. The bracket is adjustable so you can get the cable paralell with the carb lever. 

http://www.manciniracing.com/man440en.html

Return spring & bracket

http://www.manciniracing.com/tarespbrben.html


Good to hear it's running much better. Seems like the old carb was the issue. Hopefully the Chassis dyno numbers show a nice improvement. 


Ron

[BSB67]

 I also have a small amount of oil on plugs from the 4 rear most cylinders (but not on the 4 forward cylinders which I suspect may be related to the PCV drawing gases into the back of the manifold.

This is not an uncommon result due to a leaking intake manifold gasket.  Are you using just the pan gasket?

[XH29N0G]

 I also have a small amount of oil on plugs from the 4 rear most cylinders (but not on the 4 forward cylinders which I suspect may be related to the PCV drawing gases into the back of the manifold.

This is not an uncommon result due to a leaking intake manifold gasket.  Are you using just the pan gasket?

Russ,  It could be.  I did not assemble the engine.  From what I can see it has the valley pan plus at least one other gasket  which looks like it is on the manifold side.  To make sure I understand your point, you mean there is a leak from the below the pan.  [To follow up on my last post, I took the car out yesterday and did not see a noticeable change in detonation with the filter.  The one rear plug I pulled yesterday still had a little oil on it (possibly a little less, but still there).  Either means the solution I tried did not work, or the slight amount of oil is coming from somewhere else - like under the valley pan.]

Thrillbilly, I'll be interested to hear more about how it runs too.

[BSB67]

Yes.  I've seen every scenario. One pair, two pair, three pair and all intake runners leaking due to intake sealing issues.  Just saying it could be.   Could be other stuff too.  Removal of the intake and close inspection can separate the leaking valve stem/guide seal from the intake gasket seal.

What intake do you have.

[XH29N0G]

Performer RPM. 

[c00nhunterjoe]

If you think it is pcv pulling oil, pull the hose off the valve and inspect for oil in the hose. If so, you need a better baffle system in the covers or run a catch can.

[thrillbilly]

A Mighty Demon.  Yes, the throttle arm bracket, the brain is not working today 

The throttle arm bracket does goof up where the stock throttle cable lines up in the cable bracket from the intake.  I had to pull it back so that I am getting WOT, and it's about halfway out of the bracket.  What's the fix there?  I'm afraid it's not going to stay there.

With a high rise intake the AR Engineering brackets are the best option. I've used this one with a Performer RPM, Street Dominator and now a Mopar M1 single plane. Worked flawlessly on all of them. I have a factory slant 6 cable which is longer than the stock 440 cable and it works great. The bracket is adjustable so you can get the cable paralell with the carb lever. 

http://www.manciniracing.com/man440en.html

Return spring & bracket

http://www.manciniracing.com/tarespbrben.html


Good to hear it's running much better. Seems like the old carb was the issue. Hopefully the Chassis dyno numbers show a nice improvement. 


Ron

Thanks!!  I ordered one!

[thrillbilly]

I don't know if the pcv is the cause of my detonation, but thought I would pull it off and see.  I'm leaning more towards the carb being the issue.  I'd rather have it on honestly.  I get a whiff of oil sometimes, but I don't see it coming out of the open breather. 

I just replaced the valley pan gasket on mine.  I've had to change it out a few times over the years, eventually I see oil on top of the pan?  I've always just used the pan, no other gaskets.

Just an FYI, I tried to use the Hughes 2 piece pan, and it won't fit with a performer RPM intake.  The RPM is too deep to clear it. 

[thrillbilly]

Finally got to run the car on the dyno.  Made 380 hp and 418 ft lbs of torque @ 6000 rpm.  A/F was right around 13.  I went up a few jet sizes and it seemed to like it.  I am still getting an off idle lean spot if I ease into the throttle.  I don't have any issues if I just flat pedal it.  There is no slack in my accel pump lever, I went up a squirter size, and that did seem to help. 

[XH29N0G]

Finally got to run the car on the dyno.  Made 380 hp and 418 ft lbs of torque @ 6000 rpm.  A/F was right around 13.  I went up a few jet sizes and it seemed to like it.  I am still getting an off idle lean spot if I ease into the throttle.  I don't have any issues if I just flat pedal it.  There is no slack in my accel pump lever, I went up a squirter size, and that did seem to help.  

This sounds like good news.  Do you know if it solved the detonation issue, too?  

I read your statement about a flat pedal (resulting from a lean spot) as you ease in to the throttle from idle, to mean you do not have issues when you romp on it or when you accelerate from a cruise RPM.  This tells me that it is something that happens just as the primary throttle blades begin to open. If you haven't already, make sure you have the floats set correctly because the fuel level plays a role in how gas is drawn through the various circuits in the carburetor.  

My experience which is only with my car so far has been that the biggest impact on the lean spot just as the throttle is opened is related to the pump lever not just no having slack, but actually sending a healthy amount of gas when touched.  I have my pump lever adjusted even beyond the point where it is slack but not to the point where it can bottom out and stress the pump assembly.
 
Opening up the squirter size also can help by increasing the amount of gas that comes in early, but changing this might also mean that you will want to reevaluate the off cruise and full on throttle transitions.  My guess is that the accelerator pump cam is not the issue and is doing its job by keeping the gas delivery right for romping or tipping in to acceleration from cruise.

I would focus on these first, but also look up information on idle air bleeds (IAB) and idle feed restrictors (IFR).  These affect how the fuel is delivered as the blades move across the transfer slots (from where the idle mixture screws work into cruise conditions and up to the point where the main circuit takes over).  My brain isn't working today, so I can't remember how to explain what to do with these.

It is possible to get the circuits very close when the carb is sized right, but I find that I see changes in summer/winter gas and other variables like warm/cold engine on the A/F that I do not sense with the pedal. (Detonation also seems to change for me with summer/winter gas transitions.)

[thrillbilly]

This sounds like good news.  Do you know if it solved the detonation issue, too?    I've ran it pretty hard and I haven't had any detonation since the carb swap and the removal of PCV.  I'd rather have the PCV valve, so I may try and put it back on to see if that was causing the detonation.

I read your statement about a flat pedal (resulting from a lean spot) as you ease in to the throttle from idle, to mean you do not have issues when you romp on it or when you accelerate from a cruise RPM.  This tells me that it is something that happens just as the primary throttle blades begin to open. If you haven't already, make sure you have the floats set correctly because the fuel level plays a role in how gas is drawn through the various circuits in the carburetor.    Right, if I just floor board it, no stumble, it just takes off.  But if I try to drive like a normal human being would, it wants to stumble under light acceleration from an idle.  I went from a 31 squirter to a 35, it helped, went to a 37 and it made it worse.  The float level is within the hash marks, but are at the high side of the window.

My experience which is only with my car so far has been that the biggest impact on the lean spot just as the throttle is opened is related to the pump lever not just no having slack, but actually sending a healthy amount of gas when touched.  I have my pump lever adjusted even beyond the point where it is slack but not to the point where it can bottom out and stress the pump assembly.
 
Opening up the squirter size also can help by increasing the amount of gas that comes in early, but changing this might also mean that you will want to reevaluate the off cruise and full on throttle transitions.  My guess is that the accelerator pump cam is not the issue and is doing its job by keeping the gas delivery right for romping or tipping in to acceleration from cruise.

I would focus on these first, but also look up information on idle air bleeds (IAB) and idle feed restrictors (IFR).  These affect how the fuel is delivered as the blades move across the transfer slots (from where the idle mixture screws work into cruise conditions and up to the point where the main circuit takes over).  My brain isn't working today, so I can't remember how to explain what to do with these.

It is possible to get the circuits very close when the carb is sized right, but I find that I see changes in summer/winter gas and other variables like warm/cold engine on the A/F that I do not sense with the pedal. (Detonation also seems to change for me with summer/winter gas transitions.)

  Thank you for some good things to look at, appreciate it

[BSB67]

I am still getting an off idle lean spot if I ease into the throttle.  

My experience, this symptom is never due to the squirter.  Open up the two primary idle mixture screws a 1/2 turn, and give it a test drive.  Add 5° initial timing and give it a drive.  Then report back.  These are just tests to see how the car responds to these simple changes, and are not necessarily the long term adjustments.

380 RWHP is quite excellent, IMO

[BSB67]

On a second read, here is what is odd, IMO, about your dyno data.  380 hp @ 6000 rpm..  That rpm seems a little high for the peak power level.  But maybe not. 

Can you post the data?

[thrillbilly]

Sorry,  I guess I meant it was ran up to 6000rpm, not that it peaked at 6000rpm.  I'll have to scan the graph and attach it.  You can see on the graph where it's poopie until around 2500 or so, then picks up and takes off.  Thank you, I'll try those things and report back.