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Old 03-12-2020, 04:02 PM   #1
spock345
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Default Emissions and NA performance mods

I am currently feeling out options for upping the power in my 240. I am not looking for a 200hp+ car. Just to squeeze what I can out of this engine with stock parts and maybe a bit of machining and programming. I could strap my +T parts back on the car but being in California smog is a pain in the ass. I also have the means to build a nice NA car and chip the computers once I can find my chip programmer. I also probably wouldn't have to worry about destroying my M47. Ultimately though it all comes back to smog.

Currently I am running an A cam advanced 3 degrees, AC delete, Electric fan, 3.73 rear gearing, and an IPD sport exhaust. Soon it will be getting an EZK chip.

How would shaving the head 0.040", a bit of porting, and a more aggressive cam effect emissions? I have read some threads saying that they pass fine but others that express worry about more aggressive cams.
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Old 03-12-2020, 04:10 PM   #2
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Define "decent"
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Old 03-12-2020, 04:13 PM   #3
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Decent wasn't the right word for what I meant. More aggressive than an A cam.
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Old 03-12-2020, 05:03 PM   #4
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You should be fine if the catalytic converter is up to snuff. Raising the idle speed also helps.

Kyle (klr142) has a decent cam in his dd and it passes the PDX sniffer test... though I think he run larger valve clearances to get it through smog (reducing the cams duration).
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Old 03-12-2020, 05:27 PM   #5
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I ran an H cam with flat top pistons for years in a B23. 10.5 ish to 1 compression. Header, 2 1/2" exhaust. No cat (no smog checks in my area). 2 deg advanced. 40# injectors from a Ford 460 (blue tops). Idle was a little lumpy till warmed up. Would keep up with my intercooled 84 GLT.
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Old 03-12-2020, 05:29 PM   #6
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Well I am due to replace the cat anyway. It barely squeaked by on NOX last time. I have narrowed it down to the 30 year old cat.

I am mostly worried about what shaving the head will do as that feels like a point of no return. The goal is the low 10.3-ish to 1.

At this point I am debating between a V, VX, or K cam. With the overlap I am guessing a K will probably hurt emissions the most.

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Old 03-12-2020, 05:59 PM   #7
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With shaving the head, and one of those cams.... you’ll be completely fine.
I run a shaved head with a B cam and passed Oregon DEQ with flying colors, even with a 30yo cat. That was without doing an oil change, spark plugs, or anything.
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Old 03-12-2020, 06:56 PM   #8
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Upping compression ration will very likely bring up the level of NOx under load. Only very active/new cat can clean that up. Do they do dyno or just idle/2500 test where you are? Because mods will affect thing differently depending on type of test.
Overlap will likely bring up CO at idle and low RPM. Also HC at idle because of incomplete combustion.

Running K-cam on K-jet with Lambda I had a closed throttle switch wired into ECU to put it into open loop at idle. The CO would be still lower than running closed loop.

K-cam on K-jet with no Lambda: car passed emission part of test on the dyno just fine even without a working Catalytic converter and air injection pump. Probably because allowable levels for a '76 were pretty high. Ran CO around 1.5% IIRC.

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Old 03-12-2020, 07:35 PM   #9
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Quote:
Originally Posted by PCH View Post
Upping compression ration will very likely bring up the level of NOx under load. Only very active/new cat can clean that up. Do they do dyno or just idle/2500 test where you are? Because mods will affect thing differently depending on type of test.
Overlap will likely bring up CO at idle and low RPM. Also HC at idle because of incomplete combustion.

Running K-cam on K-jet with Lambda I had a closed throttle switch wired into ECU to put it into open loop at idle. The CO would be still lower than running closed loop.

K-cam on K-jet with no Lambda: car passed emission part of test on the dyno just fine even without a working Catalytic converter and air injection pump. Probably because allowable levels for a '76 were pretty high. Ran CO around 1.5% IIRC.
Up here they do the dyno test if they don't fail you on the visual for having crimp connectors used to repair the wiring harness. It is rather easy to tell from the lumpy starting that LH2.4 has some difficulty with the A cam. The two I am mostly considering are the V and VX due to the lower overlap and higher lift. Hopefully those would play nicer with 2.4. The K would be nice but probably expensive and a bit more crazy than I am feeling right now, but it one popped up in front of me I would take it.

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Old 03-12-2020, 08:09 PM   #10
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K with m47 would be nice, what rear gear ratio?
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Old 03-12-2020, 08:42 PM   #11
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The car used to be automatic so it has a 3.73 rear end. It gets moving pretty well.

How much would I have to advance the K or V to recover a bit of the lower end? I don't need a ton of torque down but some would be nice.

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Old 03-12-2020, 09:38 PM   #12
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Bosch 4-hole injector upgrade.
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Old 03-13-2020, 12:48 AM   #13
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Quote:
Originally Posted by culberro View Post
You should be fine if the catalytic converter is up to snuff. Raising the idle speed also helps.

Kyle (klr142) has a decent cam in his dd and it passes the PDX sniffer test... though I think he run larger valve clearances to get it through smog (reducing the cams duration).
Pretty sure cali tests are tighter than up there.
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Old 03-13-2020, 11:21 AM   #14
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Quote:
Originally Posted by spock345 View Post
The car used to be automatic so it has a 3.73 rear end. It gets moving pretty well.

How much would I have to advance the K or V to recover a bit of the lower end? I don't need a ton of torque down but some would be nice.
I had the K about 3 degrees advanced. M47 with 3.73 rear. Single muffler turbo style under axle exhaust.
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Old 03-13-2020, 01:08 PM   #15
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Throw a new cat on there and use volcano wrap from the manifold all the way to the cat. Will help quite a bit at passing. Also drive it like you stole and it and don't turn it off before the test to keep the cat toasty. You can also take some of that wrap just for testing days and put it around the cat.
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Old 03-13-2020, 01:10 PM   #16
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My slightly modified ford 300 failed the test here and I replaced the cat and it still failed...then I wrapped everything up and drove it hard and its passed every time since. I used to have a scan of the progression and the numbers before and after the exhaust wrap were significantly different.
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Old 03-13-2020, 03:11 PM   #17
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About wrapping the Cat: part of visual inspection in CA is verifying correct EO# that is engraved on any replacement Cat. So if the tech sees the converter as not original he has to see that number and verify it against EO list.
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Old 03-13-2020, 03:33 PM   #18
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Wrapping the downpipe wouldn't be hard.

They usually have a mirror on a stick to verify the cat EO or part number.
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Old 03-13-2020, 04:03 PM   #19
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I run a V15 n/a cam. Use a chipped ezk only and a simons sport exhaust. I pass emissions every time without issue. As my cat got older it started to get higher nox readings but still passed the last time it was checked. Then I got an exemption and no longer have to inspect or test the car as it's older than 1995.

Changes I would make for a bit more performance.
A lighter flywheel.
The 3.73 rear which you already have.
Shave the head a bit and some flow work.
While the head is off measure the piston height so you can make the engine tight squish.
Maybe go to slightly larger injectos like the 16v ones if I did the head work.

That's all I'd do and then leave it alone and enjoy. If you use the rear axle ratio of the manual cars you'r testing rpms will be lower so you'll have lower emissions. But the 3.73 is a better axle ratio for fun driving.

Last edited by dl242gt; 03-13-2020 at 04:04 PM.. Reason: spelling correctioin
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Old 03-13-2020, 04:31 PM   #20
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Quote:
Originally Posted by dl242gt View Post
I run a V15 n/a cam. Use a chipped ezk only and a simons sport exhaust. I pass emissions every time without issue. As my cat got older it started to get higher nox readings but still passed the last time it was checked. Then I got an exemption and no longer have to inspect or test the car as it's older than 1995.

Changes I would make for a bit more performance.
A lighter flywheel.
The 3.73 rear which you already have.
Shave the head a bit and some flow work.
While the head is off measure the piston height so you can make the engine tight squish.
Maybe go to slightly larger injectos like the 16v ones if I did the head work.

That's all I'd do and then leave it alone and enjoy. If you use the rear axle ratio of the manual cars you'r testing rpms will be lower so you'll have lower emissions. But the 3.73 is a better axle ratio for fun driving.
The V15 cam has been sounding pretty good to me. Is there any easy way to get one of those in the states? If I can't find one of those I am thinking a V or VX.
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Old 03-13-2020, 05:53 PM   #21
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Quote:
Originally Posted by culberro View Post
You should be fine if the catalytic converter is up to snuff. Raising the idle speed also helps.

Kyle (klr142) has a decent cam in his dd and it passes the PDX sniffer test... though I think he run larger valve clearances to get it through smog (reducing the cams duration).
This last time I didn't get it to pass, actually, so now it's registered as a Special Interest vehicle. Sometimes I'd also have to put in E85. That being said, I have a small race cat and a full header with no wrap or coating. The cat cools down too fast and I don't pass at idle. If I raise the rpm for a bit I can watch the cat start working better with a gas analyzer, but as soon as it gets back to idle it isn't good enough anymore. This is with an H cam and a header designed for 175whp+. I did get it to pass years past with the H or a smaller cam in it, but the primary header pipes were smaller with less volume to cool off. I need to get it coated to help keep the heat in there. I also should just get a larger, factory style cat, as it isn't that big of an issue. I also have had big valves with port work. Right now it doesn't have the big valve head with much/any port work, but it still doesn't want to pass with the H cam in. B cam went through emissions testing with flying colors, even with the rest of the setup mostly as it is.

Quote:
Originally Posted by spock345 View Post
Well I am due to replace the cat anyway. It barely squeaked by on NOX last time. I have narrowed it down to the 30 year old cat.

I am mostly worried about what shaving the head will do as that feels like a point of no return. The goal is the low 10.3-ish to 1.

At this point I am debating between a V, VX, or K cam. With the overlap I am guessing a K will probably hurt emissions the most.
If you take .030" off, add a thinner headgasket and slap the K cam in there, it will be a good setup. You might want to adjust the combustion chamber a bit for less possibility of detonation and to help make the compression ratio not be too high for your 91 octane fuel. The stock ignition timing may be too much with just .030" off the head, a .030" or .036" headgasket and the K cam. I wouldn't run anything less than a V cam at the very least, and even likely less than the K cam because the dynamic compression will be high.

I'd get a K cam, slap a thinner headgasket on it, get a nice 3 angle valve job done and shave .030" off(or more, depending if you can tune your ignition timing), maybe open up the combustion chamber around the spark plug's bump, and run it. Set the valve clearances to stock or on the looser side around .018", advance the K cam 3-4 degrees to account for the shorter head and gasket, and it'll be a torque "monster" from 2000rpm on up and should go through emissions testing without issue if the downpipe and cat are stock-ish items, I expect.

Quote:
Originally Posted by PCH View Post
I had the K about 3 degrees advanced. M47 with 3.73 rear. Single muffler turbo style under axle exhaust.
A good recipe for fun, and even more fun if you shave some off of the cylinder head and/or use a thinner headgasket.

Quote:
Originally Posted by dl242gt View Post
I run a V15 n/a cam. Use a chipped ezk only and a simons sport exhaust. I pass emissions every time without issue. As my cat got older it started to get higher nox readings but still passed the last time it was checked. Then I got an exemption and no longer have to inspect or test the car as it's older than 1995.

Changes I would make for a bit more performance.
A lighter flywheel.
The 3.73 rear which you already have.
Shave the head a bit and some flow work.
While the head is off measure the piston height so you can make the engine tight squish.
Maybe go to slightly larger injectos like the 16v ones if I did the head work.

That's all I'd do and then leave it alone and enjoy. If you use the rear axle ratio of the manual cars you'r testing rpms will be lower so you'll have lower emissions. But the 3.73 is a better axle ratio for fun driving.
Agreed with all of this, too. The V15 NA cam will have better idle and emissions than the K cam, with maybe slightly less peak HP, but it'll still be good all around and much better than a V or VX.
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Old 03-13-2020, 05:54 PM   #22
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Old 03-13-2020, 06:08 PM   #23
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BTW I run the V15 at six degrees advanced. With the 3.31 rear I don't mind giving up a bit of top end as Kyle mentioned and the cam advance helps get the car going. If you look at the specs the V15 has the ~lift of the K cam but with the same duration as the B cam. So it's not going to rev out as high as the K.

I bought my cams direct from enem many years ago.
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Old 03-13-2020, 09:28 PM   #24
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Direct port Nitrous do it do it do it

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Old 03-14-2020, 08:35 AM   #25
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I have 0.040" off of my 530 head with a V cam and 3.31s. '91 245 with an M47. Cam is straight up. I can speak from a driveability standpoint that there's no reason to advance the cam, it will gently pull itself out from low rpm/high gear circumstances, no problem. With 3.73s, it would be even less. I also run 87 octane with this combo with no problem. My commute is about 20 miles one way and a near 50/50 split between city and highway and I average just over 23 mpg winter. Took a long road trip up through Maine a couple weeks ago and got about 29. I'm very happy with this cam, I feel it's an improvement over the A I had been using for years.
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