440 Help Needed

Hello,

I have posted about this car before:

Dialing in a Carter AVS

Its a 70 charger that is using a 440 from a 68 C-body. I was told it was an HP motor originally so I am not to sure if it has to 906 heads or the 915(?) heads from 67. It has the stock rotation assembly with some aftermarket pistons that has that lighting bolt on the piston skirts. It is running the factory iron heads, with iron exhaust manifolds with the factory iron 4 barrel intake. I do know the cam specs:

Comp Cams 21-224-4 (XE274H-10)
Hydraulic valve adjustment
Gross Valve Lift: .488 intake, .491 exhaust
Duration @ .006 tapper lift: 274 intake, 286 exhaust
Valve timing @ .006:
Open: 31 intake BTDC, 77 exhaust BBDC
Close: 63 intake BTDC, 29 exhaust BBDC
These specs are for cam installed at 106.0 intake centerline
Duration @ .050: 230 intake, 236 exhaust
Lobe lift: .3250 intake, .3270 exhaust
Lobe separation: 110.0

I originally had the smaller 440 AVS carb on it and no matter what I did your eyes would water standing next to it. From the thread above it was mentioned that is an indicator that it is running really rich at idle. So I thought it was due to the carb being too small so I got a new holley 750 CFM with vacuum secondaries. it helped a little but not much. I have a member on here helping me with this but he suggested I ask for second opinions.

He mentioned that I need more idle air by pass to help close the throttle blades that was exposing to much of the transfer slots which is why I am getting this eye watering issue. So I tried an idle air by pass and nothing changed. This was done by plugging into the PCV port with a manifold with drilled holes to meter additional air into the engine. Again nothing changed.

So I verified the timing mark on the damper and that is spot on. The ignition is still running points, and the dwell setting is within spec.

I checked out the Holley carb and everything appeared to be working the way it should. however I still need 25 BTDC on initial to even get it to run. So the next step was to do the compression test. I followed the procedure he gave me and came up with these numbers (PSI):

1: 200
3: 190
5: 185
7: 175
2: 200
4: 195
6: 195
8: 175

Now I am being told that these numbers are two high for an iron headed engine to run pump gas. However, I do not know if these high numbers are are the cause of my idling issue.

The engine was rebuilt. it was slightly bored, both the heads and engine were decked. Again I am not to sure on the pistons that are in it, but according to something called the "Wallace Calculator" there is a good chance the compression ratio is over 11.0:1. I do not know the combustion chamber size, so the next plan of action was to remove a head and measure the combustion chambers volume as well as cylinder volume at BDC.

Now does this high compression on an iron headed engine seems like its contributing to my idling issue? am I on the right track? am I missing anything?

I have a 1972 Olds 442 with a 455 and the compression on the cylinders is in the 185-200 PSI range. Runs fine on 93 octane, but you need to carefully tailor the timing curve. I usually like really fast curves with about 20 degrees in the distributor 16 initial and all the timing in by 2200 RPM or so. This engine will not tolerate that on 93 octane fuel. I had to lower the full advance to about 3500 and it works fine.
Either way a high compression ratio will not affect idle quality at all. Have you checked your fuel pressure? What fuel pump are you using? If you have a carb that is running that rich at idle usually you have fuel bypassing your needle and seats and just dribbling out of your primary and/or secondary boosters. A 440 with a 236 @ .050 cam is nothing out of the ordinary and you should not have to open up your idle air passages. With the car idling and the air cleaner off, look at the boosters on the Holley carb and see if you see fuel coming out of the boosters. If you do you have found your problem. What is strange is that this happened with 2 different carbs, which means that there is an inherent problem with the car and that it is most probably not the carbs fault. Too much fuel pressure (anything over 7 PSI on a Holley) will be too much pressure for the needle and seats and they will leak. Only other thing I can think of is just a lot of dirt on the fuel tank that is getting to the needle and seats and just not letting them close.

[1] Piss off the Holley & refit the AVS
[2] Because engine A runs on pump gas, it does not mean that engine B will too.
[3] The 455 Olds has the longest stroke of all the big blocks.
[4] What does that mean? Here is a quote from the Sig Erson cam catalog. Note: this quote is ONLY in the Mopar 440 section, no others. "...beware of too much duration.."

The short stroke of the 440 does not tolerate cam duration very well. Not surprised that it likes 25* init/idle timing & in fact it will probably idle better with 35-40*. You get this by using about 10-20* static & add the rest of the timing by using an adjustable vac adv unit [ Allen Key fully CW ] connected to a MANIFOLD vacuum source to add the remaining timing. Tee-ing into the brake booster fitting is OK for this.
Example, highest idle speed is achieved with 32* idle timing. You could use, say, 15* initial & add 17* via the VA unit. Most adj VA units have a 30* range, so you would have to fabricate a stop to limit the travel of the actuator.
Until you get the idle timing dialled in, you will never get the best performance that the engine/cam/carb are capable of...

Eye watering gas smell. The dist mods ^ need to be done BEFORE touching the carb. Hook up the PCV as the factory had it. Drill a 3/32" hole in each sec throttle blade [ NOT the pri blades ]. With timing sorted as above, get the engine idling correctly. Remove carb & check transfer slot showing below pri blades. Should be 0.040" or less, less preferred. If more than 040, enlarge the holes in 1/64" increments until the gaps is 020-040". It would be a good idea to enlarge the Idle Feed Restriction 0.002".

I ran a 440 Charger as my daily driver for years, it had a Comp Cams 230 degree duration cam @.050 and I had no issues with the Holley 750 4779 DP that I was running, ran 2 different 4 barrel Holleys with no issues and no need to drill anything. Ran a factory cast iron 6 pack intake with the factory Holleys with no need to drill anything and no issues. Ran 18 degrees of static timing and had another 18 in the distributor all in by 2200 RPM's, but this was a 9:1 engine, which the OP's is not, vacuum advance was disconnected. OP already tried to get more air in with an air bypass and nothing changed, so drilling holes on the throttle blades will not make a difference. An additional 6 degrees of cam timing is not going to make a difference. If you put a TON of initial advance, and then add another ton of vacuum advance connected to manifold vacuum on an engine with 200 PSI of cranking compression, you will have a so much detonation off idle that you will have a high probability of damaging pistons and piston rings. I have no idea why Erson would put such a statement on their website, as there are so many variables to timing depending on what specific compression you have, gearing, car weight etc... Any engine that you advance the timing on at idle will idle better. You want something to idle really good, just lock out your distributor advance and put the initial timing at 36-38 degrees, idles like a kitten purring, but it will kill your starters trying to start it on the street when the engine is hot. On my old Road Runner 10.80 bracket car we locked out the distributor advance and just ran it at 38 degrees, idled great at 1200 RPM's even with the 650 lift solid lifter cam, tunnel ram and 2 Holleys. The OP needs to be really careful tailoring how fast of an advance he using.

Also 100% disagree in getting rid of a 750 Holley on a 440 with a 236 cam at .050 and putting a 600 CFM AVS. This makes no sense, the Holley carbs are way more tolerant of big cams and modifications and are way more tunable for high HP big cam engines than an AVS, not to mention that a 600 CFM carb on a modified 440 is woefully small and will kill a ton of power.

Bewy said:

[3] The 455 Olds has the longest stroke of all the big blocks.

Click to expand...

You must of forgot about a 500" Cadillac? It has the longest stroke of any OEM American big block passenger car engine at 4.304"

Tom

Bewy said:

[1] Piss off the Holley & refit the AVS
[2] Because engine A runs on pump gas, it does not mean that engine B will too.
[3] The 455 Olds has the longest stroke of all the big blocks.
[4] What does that mean? Here is a quote from the Sig Erson cam catalog. Note: this quote is ONLY in the Mopar 440 section, no others. "...beware of too much duration.."

The short stroke of the 440 does not tolerate cam duration very well. Not surprised that it likes 25* init/idle timing & in fact it will probably idle better with 35-40*. You get this by using about 10-20* static & add the rest of the timing by using an adjustable vac adv unit [ Allen Key fully CW ] connected to a MANIFOLD vacuum source to add the remaining timing. Tee-ing into the brake booster fitting is OK for this.
Example, highest idle speed is achieved with 32* idle timing. You could use, say, 15* initial & add 17* via the VA unit. Most adj VA units have a 30* range, so you would have to fabricate a stop to limit the travel of the actuator.
Until you get the idle timing dialled in, you will never get the best performance that the engine/cam/carb are capable of...

Eye watering gas smell. The dist mods ^ need to be done BEFORE touching the carb. Hook up the PCV as the factory had it. Drill a 3/32" hole in each sec throttle blade [ NOT the pri blades ]. With timing sorted as above, get the engine idling correctly. Remove carb & check transfer slot showing below pri blades. Should be 0.040" or less, less preferred. If more than 040, enlarge the holes in 1/64" increments until the gaps is 020-040". It would be a good idea to enlarge the Idle Feed Restriction 0.002".

Click to expand...

I am aware of getting the distributor timing done before messing with the carb. The issue is that the car will not idle with less than 25 deg BTDC and either because of that or due to the carb, the transfer slots are opened up well past the .040" you mention. I have tried the idle air by pass by adding more air in through the PCV port on the carb and no changed happened.

HSDemon said:

I ran a 440 Charger as my daily driver for years, it had a Comp Cams 230 degree duration cam @.050 and I had no issues with the Holley 750 4779 DP that I was running, ran 2 different 4 barrel Holleys with no issues and no need to drill anything. Ran a factory cast iron 6 pack intake with the factory Holleys with no need to drill anything and no issues. Ran 18 degrees of static timing and had another 18 in the distributor all in by 2200 RPM's, but this was a 9:1 engine, which the OP's is not, vacuum advance was disconnected. OP already tried to get more air in with an air bypass and nothing changed, so drilling holes on the throttle blades will not make a difference. An additional 6 degrees of cam timing is not going to make a difference. If you put a TON of initial advance, and then add another ton of vacuum advance connected to manifold vacuum on an engine with 200 PSI of cranking compression, you will have a so much detonation off idle that you will have a high probability of damaging pistons and piston rings. I have no idea why Erson would put such a statement on their website, as there are so many variables to timing depending on what specific compression you have, gearing, car weight etc... Any engine that you advance the timing on at idle will idle better. You want something to idle really good, just lock out your distributor advance and put the initial timing at 36-38 degrees, idles like a kitten purring, but it will kill your starters trying to start it on the street when the engine is hot. On my old Road Runner 10.80 bracket car we locked out the distributor advance and just ran it at 38 degrees, idled great at 1200 RPM's even with the 650 lift solid lifter cam, tunnel ram and 2 Holleys. The OP needs to be really careful tailoring how fast of an advance he using.

Also 100% disagree in getting rid of a 750 Holley on a 440 with a 236 cam at .050 and putting a 600 CFM AVS. This makes no sense, the Holley carbs are way more tolerant of big cams and modifications and are way more tunable for high HP big cam engines than an AVS, not to mention that a 600 CFM carb on a modified 440 is woefully small and will kill a ton of power.

Click to expand...

I am aware this is not that radical of a cam, which is why I am stumped. Could this idling issue and the high compression be two separate issues? Could this timing issue being something along the lines of "rotor phasing"?

I did find a picture of the pistons we used in this car:



I am not to sure if this helps or adds in confusion, but I appreciate any and all help.

carfreak6970 said:

I am aware of getting the distributor timing done before messing with the carb. The issue is that the car will not idle with less than 25 deg BTDC and either because of that or due to the carb, the transfer slots are opened up well past the .040" you mention. I have tried the idle air by pass by adding more air in through the PCV port on the carb and no changed happened.



I am aware this is not that radical of a cam, which is why I am stumped. Could this idling issue and the high compression be two separate issues? Could this timing issue being something along the lines of "rotor phasing"?

I did find a picture of the pistons we used in this car:

View attachment 1715971195

I am not to sure if this helps or adds in confusion, but I appreciate any and all help.

Click to expand...

If you drilled holes in the throttle blades and it didn’t get the blades closed then drill the holes bigger. You have to get the throttle blades closed. Then you have to clean up the idle circuit. I need to read all the thread again, but I wouldn’t touch anything until the throttle is shut and you have cleaned up the idle circuit

OP how did you verify top dead center?

carfreak6970 said:

I am aware of getting the distributor timing done before messing with the carb. The issue is that the car will not idle with less than 25 deg BTDC and either because of that or due to the carb, the transfer slots are opened up well past the .040" you mention. I have tried the idle air by pass by adding more air in through the PCV port on the carb and no changed happened.



I am aware this is not that radical of a cam, which is why I am stumped. Could this idling issue and the high compression be two separate issues? Could this timing issue being something along the lines of "rotor phasing"?

I did find a picture of the pistons we used in this car:

View attachment 1715971195

I am not to sure if this helps or adds in confusion, but I appreciate any and all help.

Click to expand...

compression with that piston falls between 10:1 and 9.5:1 depending on head cc.

TT5.9mag said:

OP how did you verify top dead center?

Click to expand...

With a piston stop. On the number one piston I rotated the piston up until it hit the piston stop. I marked the damper. I then reverse the rotation of the crank and marked the damper when the piston again hit the piston. My timing mark was exactly in the center of those two lines.

fishmens67 said:

compression with that piston falls between 10:1 and 9.5:1 depending on head cc.

Click to expand...

Well good to know... I do not know head cc. I do know the heads and block were decked, however I do not know how much of those components were machined, nor do I know the casting numbers of the head off the top of my head.

Rat Bastid said:

If you drilled holes in the throttle blades and it didn’t get the blades closed then drill the holes bigger. You have to get the throttle blades closed. Then you have to clean up the idle circuit. I need to read all the thread again, but I wouldn’t touch anything until the throttle is shut and you have cleaned up the idle circuit

Click to expand...

I did not drill into the throttle blades. I was told if I plumb into the PCV port of the carb Id achieve the same thing. I made a manifold that had multiple small holes drilled into it. as it was running I tried to expose more and more to see if I could expose less of the transfer slots and nothing changed.

carfreak6970 said:

I did not drill into the throttle blades. I was told if I plumb into the PCV port of the carb Id achieve the same thing. I made a manifold that had multiple small holes drilled into it. as it was running I tried to expose more and more to see if I could expose less of the transfer slots and nothing changed.

Click to expand...

If we are talking about the Holley then drill some holes in the throttle blades. Start at about .080ish and see what you get. If you don’t have 4 corner idle just do the primaries.

You need to get the throttle shut. Otherwise nothing you do will fix it.

Has the vacuum at idle been checked yet?

A two corner idle carb might be a bit finicky with a 230@.050 cam....... with exhaust manifolds.

No way in the world a 3.75 stroke with that compression should need 25 degrees to run properly at idle with a @230 cam. Two carbs, same problem. How does it run going down the road? What do the plugs look like?

Any chance your right side manifold has a stuck closed heat riser?

Let's sort out some of the BS here.
- we are talking about a 50+ yr old engine. Who knows if it is original or has been rebuilt with the compression ratio reduced. That could be one explanation for the good idle with 25* BTDC....or it just likes 25*.
- if it 'idled great' with 38* BTDC, why is it that 25* is too much, even with a smaller cam. My 455, with 9.8:1 CR, a long stroke engine, idled best with 32* BTDC with a 235/228* @ 050, 110 LSA cam.
- I ran a custom ground Crower 230/230 @ 050, 108 LSA, HFT cam in my 440. It was an absolute pig on the road, idled rough, came out after two weeks. Similar overlap to the OPs cam.
- 'So much detonation off idle'. Vac goes to zero when you nail it, & 17* of vac adv is NOT a ton of vac adv. MVA [ &/or a lot of initial timing ] cools the engine. A hot engine detonates more easily than a cool engine, so using MVA wards off detonation. Perfect example is my 66 GTO: it left the showroom idling at 26* [ 6* init + 20* MVA ]. 10.75:1 CR. Mild cam 197/212 @ 050, 113 LSA. That would have to be up around 200 psi cranking pressure maybe more, didn't detonate.
- the reason Erson put that note in the catalog is.....because he knew what he was talking about. It is called the rod/stroke ratio. The 440 has one of the highest out of the popular engines, 1.80. Other engines: 318 1.84, 360 1.71, 454 1.53, 350 Chev 1.63, 351C 1.65, 400 C 1.64, 455 Buick 1.69, 455 Olds 1.58, 455 Pont 1.57.
The shorter r/s ratio has the piston accelerating away from TDC faster than a large r/s; this pulls in more air at the start of the intake stroke. Why do stroker combos such as the 383 Chev & 408 Mopar punch above their weight? The only architecture change is the stroke. I only quoted part of Erson. Here is the full quote:
'When ordering a cam to be used in a standard passsenger car chassis with torque flyte trans, beware of too much duration. Although the longer duration cam will make more hp, the loss of torque at low rpm will more than offset the gain at the top end & the ET will suffer.'
- another quote, this one about idle timing. It is in a carb book, not an ign book [ hmmm....] by D. Vizard. "The optimum idle advance is typically 35-40* for a short cammed street engine & [ though not commonly realized ] as much as 50* for a street/strip engine."

tom,
You are correct. I did forget the Cad.

Carfreak,
Another thought about your idling problem. The vac from that cam might be too low to actuate the PCV, which would then act like a large vac leak, needing more fuel [ t\blades open more ] to keep the engine running. Not quite sure what you did with the PCV, but I would plug the carb port for now & try readjusting the idle settings. You may need an adj Wagner PCV or just use a fixed 7/64" orifice.

PRH said:

Has the vacuum at idle been checked yet?

A two corner idle carb might be a bit finicky with a 230@.050 cam....... with exhaust manifolds.

Click to expand...

Yes Idle vacuum is roughly 10-15inHg. It is not really steady as the vacuum sways between those values.

OldmanRick said:

No way in the world a 3.75 stroke with that compression should need 25 degrees to run properly at idle with a @230 cam. Two carbs, same problem. How does it run going down the road? What do the plugs look like?

Any chance your right side manifold has a stuck closed heat riser?

Click to expand...

The car had the heat riser removed and the holes the shaft went through closed off.
It runs okay down the road. It is fairly smooth. It has a 727 going to a 3.55 rear end. It has okay pick up. Pulling away from a dead stop its good, second gear pulls arent what my dad described these cars being. But again he was working off of memories and cars have changed drastically since then.

Originally the plugs were black, appearing to be running rich. Now they did not look like that when I removed them for the compression test. The porcelain had like a red huge to it.

Bewy said:

Carfreak,
Another thought about your idling problem. The vac from that cam might be too low to actuate the PCV, which would then act like a large vac leak, needing more fuel [ t\blades open more ] to keep the engine running. Not quite sure what you did with the PCV, but I would plug the carb port for now & try readjusting the idle settings. You may need an adj Wagner PCV or just use a fixed 7/64" orifice.

Click to expand...

Never thought of that. But the PCV is just plugged into the front port of the carb.

Bewy said:

Let's sort out some of the BS here.
- we are talking about a 50+ yr old engine. Who knows if it is original or has been rebuilt with the compression ratio reduced. That could be one explanation for the good idle with 25* BTDC....or it just likes 25*.
- if it 'idled great' with 38* BTDC, why is it that 25* is too much, even with a smaller cam. My 455, with 9.8:1 CR, a long stroke engine, idled best with 32* BTDC with a 235/228* @ 050, 110 LSA cam.
- I ran a custom ground Crower 230/230 @ 050, 108 LSA, HFT cam in my 440. It was an absolute pig on the road, idled rough, came out after two weeks. Similar overlap to the OPs cam.
- 'So much detonation off idle'. Vac goes to zero when you nail it, & 17* of vac adv is NOT a ton of vac adv. MVA [ &/or a lot of initial timing ] cools the engine. A hot engine detonates more easily than a cool engine, so using MVA wards off detonation. Perfect example is my 66 GTO: it left the showroom idling at 26* [ 6* init + 20* MVA ]. 10.75:1 CR. Mild cam 197/212 @ 050, 113 LSA. That would have to be up around 200 psi cranking pressure maybe more, didn't detonate.
- the reason Erson put that note in the catalog is.....because he knew what he was talking about. It is called the rod/stroke ratio. The 440 has one of the highest out of the popular engines, 1.80. Other engines: 318 1.84, 360 1.71, 454 1.53, 350 Chev 1.63, 351C 1.65, 400 C 1.64, 455 Buick 1.69, 455 Olds 1.58, 455 Pont 1.57.
The shorter r/s ratio has the piston accelerating away from TDC faster than a large r/s; this pulls in more air at the start of the intake stroke. Why do stroker combos such as the 383 Chev & 408 Mopar punch above their weight? The only architecture change is the stroke. I only quoted part of Erson. Here is the full quote:
'When ordering a cam to be used in a standard passsenger car chassis with torque flyte trans, beware of too much duration. Although the longer duration cam will make more hp, the loss of torque at low rpm will more than offset the gain at the top end & the ET will suffer.'
- another quote, this one about idle timing. It is in a carb book, not an ign book [ hmmm....] by D. Vizard. "The optimum idle advance is typically 35-40* for a short cammed street engine & [ though not commonly realized ] as much as 50* for a street/strip engine."

Click to expand...

It is not the original engine and it has been rebuilt. I am not to sure what the compression ratio is. If it likes 25, then I guess that is okay (?), but what concerns me is that the throttle blades are opened above the .040 recommendation to keep the engine running.

So this was a video I took of the engine running. let me know if this works, first time posting a video to youtube

https://www.youtube.com/shorts/UtFSaPT9PLg

Sounds like it’s got a pretty decent surge. I’d be looking for a vacuum leak first.

What’s the carb part number, and how many turns out are the mixture screws?

My experience has been that the “wandering” idle speed can indicate a lean condition.

If you look down into the primary barrels while it’s idling, is there fuel dribbling out from the boosters?

Float levels have been set/checked?

OldmanRick said:

No way in the world a 3.75 stroke with that compression should need 25 degrees to run properly at idle with a @230 cam.

Click to expand...

carfreak6970 said:

however I still need 25 BTDC on initial to even get it to run.

Click to expand...

carfreak6970 said:

The issue is that the car will not idle with less than 25 deg BTDC

Click to expand...

Just to address some of the previous comments, i never thought the car wouldn't like 25 deg as part of the tuning process, i was responding to carfreak's posts above. I've run cams like that in many short stroke small blocks and even thou they wanted more, they would run cleanly with as little as 12/14 degrees.

I just have a hard time believing this is carb related. Even if the AVS took a dump, that new 750VS should have been able to bolt on and clean it up at idle. With 72ish jets and even a 10.5PV it should idle with the vacuum he has 10/15.

Maybe it's ignition related, who knows? I know the heat riser is gone, but still seams to me like it's acting like a restriction somewhere. Any chance a baffle in one of the mufflers broke loose? Run it up to 2500 r's or so and see if you have even flow out of both tailpipes?

Ok, that's all i got...

I agree that the engine should idle with less than 25* at idle......but it will certainly idle a whole lot better with 25*....& possibly more. Are any of the lifters bottomed out, which would hold the valve open?