jcolman
Well-Known Member
I assume so since I just had it tuned
How much "shake" at idle is acceptable?
- Thread starter jcolman
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Starts right up because it's FI. Heck my wifes new Buick doesn't run perfectly smooth the first few min. They are set to run lean. If your FI program allows it, richen it up during the warm up period. (as long as it runs ok when it is warm.
jcolman
Well-Known Member
It runs quite well when warm. But I don't think it should be shaking like this when I first start it up. Actually, there are times when I'll notice some engine shake after it's warmed up but not like this.
Then you probably don't have a vacuum leak, spark, timing, or mechanical issue. Heck even my old Holley Pro Jection 4 had a adjustment to richen up the choke for cold start. There's a reason why carburetor chokes have thermostats that open the choke slowly. Cold start engines don't go from choke to full lean immediately.
Rat Bastid
Dunamis Metron
I’m not familiar with your EFI set up, but as general rule if you are lean at a cold idle it will backfire and pop and bang. If it’s rich it will shake like a dog shitting softballs.
I’m not saying you are rich at cold start, but I would suppose that it’s easy to get into the fuel table and have a look.
It could slow in timing too.
I’m not saying you are rich at cold start, but I would suppose that it’s easy to get into the fuel table and have a look.
It could slow in timing too.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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So your 340 is injected?
If it had a carb I could make it idle at 550 no problem.
With a manual trans , you sorta got to get the idle down, so you can drive slowly. 1100 rpm with 3.23s and a 2.66 low is 10.2mph, Which sucks, cuz you gotta slip the clutch a long ways out.
An idle of 550 would cut your minimum speed in half.
But I guarantee that you cannot make it idle at 550, and still drive it, with hi-stall timing, because it will get to bucking like a wild horse. You would need to get the timing down to ~5*, to kill the low-rpm power.
On another note; is that cam a solid-lifter cam? Or why is it so noisy.
If yes it is, I would recheck the lash, on account of maybe a couple of valves are too tight.
You might be able to get a better handle on her, by doing a compression test.
A 262 advertised cam is pretty tame, smaller even than the factory cam and with about the same overlap. The factory 340s idled on 5* just fine.
If it had a carb I could make it idle at 550 no problem.
With a manual trans , you sorta got to get the idle down, so you can drive slowly. 1100 rpm with 3.23s and a 2.66 low is 10.2mph, Which sucks, cuz you gotta slip the clutch a long ways out.
An idle of 550 would cut your minimum speed in half.
But I guarantee that you cannot make it idle at 550, and still drive it, with hi-stall timing, because it will get to bucking like a wild horse. You would need to get the timing down to ~5*, to kill the low-rpm power.
On another note; is that cam a solid-lifter cam? Or why is it so noisy.
If yes it is, I would recheck the lash, on account of maybe a couple of valves are too tight.
You might be able to get a better handle on her, by doing a compression test.
A 262 advertised cam is pretty tame, smaller even than the factory cam and with about the same overlap. The factory 340s idled on 5* just fine.
Lot's of un answered questions.
jcolman
Well-Known Member
Yes, EFI. You're absolutely right that I have to slip the clutch to drive it. I've got 3:23 gears and even at 900 rpm (where the idle is currently set) I have to feather the clutch when starting out. The cam is hydraulic. It's always been a "noisy" motor due in part to the mechanical fan. I've never tried to adjust the valve drive train so that could be contributing to the noise but I always assumed that a hydraulic lifters shouldn't need adjusting.
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262 duration/490 lift?
262 adv duration?
262 @ 050?
490 lift...........with 1.5 rockers?
It could not be a flat tappet cam with 262 adv duration & 1.5 rockers, even if the Mopar 904 lobes were used. It could be a roller cam, but such a short duration cam in a roller is unusual.
If it is a FT cam, then the specs provided are questionable. It may be that the cam is larger than thought & it just has a lumpy idle as a result, not necessarily a problem with the engine [ other than it may need further tuning ].
262 adv duration?
262 @ 050?
490 lift...........with 1.5 rockers?
It could not be a flat tappet cam with 262 adv duration & 1.5 rockers, even if the Mopar 904 lobes were used. It could be a roller cam, but such a short duration cam in a roller is unusual.
If it is a FT cam, then the specs provided are questionable. It may be that the cam is larger than thought & it just has a lumpy idle as a result, not necessarily a problem with the engine [ other than it may need further tuning ].
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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It's hard for me to imagine only .490 lift on a [email protected]....
so I went with a 262 advertised which would be about right for a stout .490 lift. which would then be something like a [email protected]
=================
Here is what I would try;
I would;
Prove the TDC mark on the balancer, and prove the ECU knows where TDC is
Set the minimum coolant temp to 180* or so.
Set your hot idle speed to 700@ 10* Idle-advance +/-2*.
Make sure the O2 is in OPEN loop until the coolant temp is within 10 degrees of the stat rating, or like 150*F minimum.
If it won't idle, at 10*, 700, and 180*F; something is wrong; Fix this before moving on.
The problem is probably in the AFR setting, but could be several other things like; a too tight valve lash, tight rings, running too cool, vacuum leaks, a dead cylinder, bad cam, Cam out of time, uneven cylinder pressure, etc. But the point is that if all related things are working , then it will idle ALL day on 10*@700. Assuming a 262 Advertised cam, it will idle all day on less.
Your cold engine will like timing of say 25 to 30 degrees for say 60 to 90 seconds, and if you have an Idle-speed motor, crank it up to 1000rpm, for say 30 seconds, then step it down to eventually land at 700 at say 2 to 3 minutes.The AIS motor must then stay there until the next cold start. With a manual trans, you cannot have it hunting .
Then, as the temp comes up to normal, dial the timing back in steps to also land on 10* by 2.5 to 3.0 minutes.
Keep your eye on the fueling, but if the engine is misfiring, forget what the O2 is telling you, it will be lying.
When the O2 comes on line; Kill the cold-start/warm-up program. Now;
program your Warm-Idle timing to 10*+/-2 @700.Give the ECU some room to let the idle wander, else the AIS will want to make changes, and that would be bad if you are just idling along in first gear.
Program your power-timing to start no sooner than 1000 for the manual trans. This will allow you to dink around the parking lot, up to 8 mph, without getting into the dreaded rocking horse action. Then;
Bring the power-timing in fast to hit 28* by 2800. Then slow it down to hit 34* by 3400. Now road test it.... under power of course.
First; the full-load WOT at 3400 and up. I would use Third gear to give me time to listen, and if you hear or feel detonation, observe when and where and make changes as required, to the power-timing map. If the road speed gets too high with those 3.23s, just use Second gear.
Secondly; to the sub-3400 zone, and I would use Second gear, the gear you will be spending a whole lotta time in, with those 3.23s. Work it from the top down in 400rpm steps, from roll-ons to WOT. Make changes to the Power-Timing as may be required, commensurate with a decent AFR.
I'm gonna go out on a limb and say this timing curve is dead safe on 91gas, so you will not get any detonation. Depending on your cylinder pressure, you may be able to downgrade the gas later.
Now fill in your load maps.
You want about 52 to 56* for steady-state cruising, at ~2600 with your 3.23s which should get you about 65mph.
Now; your 262cam is gonna PowerPeak at around 4800. You can still rev it until the valves float, but I suggest a WOT shift rpm, with the 4-speed, of ~5200 to maybe 5400tops. I highly recommend a rev-limiter for the manual trans.
But; your bottom end from 700 to 2800 is gonna start out a lil sluggish, and this is because I set the Idle-timing to 10* to tame the engine for slow-roadspeed puttering, and freedom from bad low-rpm manners. To get the power back, you simply program the timing back in, step by step, beginning at about 1200.
That's what I would do.....
after I did a compression test to prove I still had an engine to work with, that it had a working cam, and no vacuum leaks not external nor internal. And while the plugs were out, I would regap them to .045 to work with my Big Yellow Square-Top Accell Super Coil, that zaps mosquitoes from a hundred yards away. Well ok, that bit is an exaggeration; but that coil fires anything, and forever. I just pulled out the plugs of my 367,to do a compression test, that were installed in 1999, and have over 100,000 miles on them. The engine was running just fine on them,
but I changed them out anyway....... lol.
so I went with a 262 advertised which would be about right for a stout .490 lift. which would then be something like a [email protected]
=================
Here is what I would try;
I would;
Prove the TDC mark on the balancer, and prove the ECU knows where TDC is
Set the minimum coolant temp to 180* or so.
Set your hot idle speed to 700@ 10* Idle-advance +/-2*.
Make sure the O2 is in OPEN loop until the coolant temp is within 10 degrees of the stat rating, or like 150*F minimum.
If it won't idle, at 10*, 700, and 180*F; something is wrong; Fix this before moving on.
The problem is probably in the AFR setting, but could be several other things like; a too tight valve lash, tight rings, running too cool, vacuum leaks, a dead cylinder, bad cam, Cam out of time, uneven cylinder pressure, etc. But the point is that if all related things are working , then it will idle ALL day on 10*@700. Assuming a 262 Advertised cam, it will idle all day on less.
Your cold engine will like timing of say 25 to 30 degrees for say 60 to 90 seconds, and if you have an Idle-speed motor, crank it up to 1000rpm, for say 30 seconds, then step it down to eventually land at 700 at say 2 to 3 minutes.The AIS motor must then stay there until the next cold start. With a manual trans, you cannot have it hunting .
Then, as the temp comes up to normal, dial the timing back in steps to also land on 10* by 2.5 to 3.0 minutes.
Keep your eye on the fueling, but if the engine is misfiring, forget what the O2 is telling you, it will be lying.
When the O2 comes on line; Kill the cold-start/warm-up program. Now;
program your Warm-Idle timing to 10*+/-2 @700.Give the ECU some room to let the idle wander, else the AIS will want to make changes, and that would be bad if you are just idling along in first gear.
Program your power-timing to start no sooner than 1000 for the manual trans. This will allow you to dink around the parking lot, up to 8 mph, without getting into the dreaded rocking horse action. Then;
Bring the power-timing in fast to hit 28* by 2800. Then slow it down to hit 34* by 3400. Now road test it.... under power of course.
First; the full-load WOT at 3400 and up. I would use Third gear to give me time to listen, and if you hear or feel detonation, observe when and where and make changes as required, to the power-timing map. If the road speed gets too high with those 3.23s, just use Second gear.
Secondly; to the sub-3400 zone, and I would use Second gear, the gear you will be spending a whole lotta time in, with those 3.23s. Work it from the top down in 400rpm steps, from roll-ons to WOT. Make changes to the Power-Timing as may be required, commensurate with a decent AFR.
I'm gonna go out on a limb and say this timing curve is dead safe on 91gas, so you will not get any detonation. Depending on your cylinder pressure, you may be able to downgrade the gas later.
Now fill in your load maps.
You want about 52 to 56* for steady-state cruising, at ~2600 with your 3.23s which should get you about 65mph.
Now; your 262cam is gonna PowerPeak at around 4800. You can still rev it until the valves float, but I suggest a WOT shift rpm, with the 4-speed, of ~5200 to maybe 5400tops. I highly recommend a rev-limiter for the manual trans.
But; your bottom end from 700 to 2800 is gonna start out a lil sluggish, and this is because I set the Idle-timing to 10* to tame the engine for slow-roadspeed puttering, and freedom from bad low-rpm manners. To get the power back, you simply program the timing back in, step by step, beginning at about 1200.
That's what I would do.....
after I did a compression test to prove I still had an engine to work with, that it had a working cam, and no vacuum leaks not external nor internal. And while the plugs were out, I would regap them to .045 to work with my Big Yellow Square-Top Accell Super Coil, that zaps mosquitoes from a hundred yards away. Well ok, that bit is an exaggeration; but that coil fires anything, and forever. I just pulled out the plugs of my 367,to do a compression test, that were installed in 1999, and have over 100,000 miles on them. The engine was running just fine on them,
but I changed them out anyway....... lol.
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jos51700
Green Bearing thread connoisseur
I'd take a bottle of windex and individually spray each head pipe. They should all cook that windex off at the same rate. If one gets wet and then dries off, instead of sizzling it off right away, that cylinder is not pulling it's weight.
If it's bouncing header off the Torsion bar, that tends to make me think that the engine mounts aren't up to snuff.
And it's idling a bit too fast.
If it's bouncing header off the Torsion bar, that tends to make me think that the engine mounts aren't up to snuff.
And it's idling a bit too fast.
And the headers are too close to the torsion bars. Any little shake can cause a noise. I agree the mounts could be soft. They may benefit from a shim or washer or two. Sometimes it doesn't take much. As far as the shake? I still think it's fuel mixture during warm up. The op said it runs fine warm.
jos51700
Green Bearing thread connoisseur
That shake can be anything from a shot timing chain to the wrong balancer.
I'd work on making it right, if the motor mounts are weak, replace em. Check timing, check if there is a miss you can't hear, and if that shake is only cold there's nothing to sweat if it goes away when hot
I'd work on making it right, if the motor mounts are weak, replace em. Check timing, check if there is a miss you can't hear, and if that shake is only cold there's nothing to sweat if it goes away when hot
jcolman
Well-Known Member
Thanks guys for taking the time to express your thoughts and advice. Much appreciated!!
I wish I had exact cam specs but I don't. I don't even know if the specs I do have are correct as some of the other specs I got from the guy who finished my car have turned out to be wrong. He was not the original engine builder.
I'm hoping that all that is needed is a motor mount adjustment and/or some fuel map tweaks. I'll post up what the shop finds out.
My recent chassis dyno tune showed that peak HP came in at 5600 rpm and peak torque hit at 3550 rpm if that says anything. As mentioned, the car seems to run well once it's warmed up. With the car in 5th gear, I can cruise at 75 mph turning 2000 rpms and it runs smooth. Above 2000 rpm the engine seems happy and runs strong.
I wish I had exact cam specs but I don't. I don't even know if the specs I do have are correct as some of the other specs I got from the guy who finished my car have turned out to be wrong. He was not the original engine builder.
I'm hoping that all that is needed is a motor mount adjustment and/or some fuel map tweaks. I'll post up what the shop finds out.
My recent chassis dyno tune showed that peak HP came in at 5600 rpm and peak torque hit at 3550 rpm if that says anything. As mentioned, the car seems to run well once it's warmed up. With the car in 5th gear, I can cruise at 75 mph turning 2000 rpms and it runs smooth. Above 2000 rpm the engine seems happy and runs strong.
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Well therein probably lies the answer.
The stock 340 made peak hp & tq @ 5000 & 3200 rpm.
To make peak hp 600 rpm higher would require a longer duration cam, & they often come with a lumpy/rough idle [ included in the price! ].
So you are probably chasing a problem that is 'normal' for the parts combination.
The stock 340 made peak hp & tq @ 5000 & 3200 rpm.
To make peak hp 600 rpm higher would require a longer duration cam, & they often come with a lumpy/rough idle [ included in the price! ].
So you are probably chasing a problem that is 'normal' for the parts combination.
Gator
Mopar or No Car
Well I know in my HiPo 340 with 509 Mopar purple cam along with a 3500 stall if my idle is @ 900 I get a little engine shake so currently my idle is at 1100 with no engine shake
Simple test: Drop a 1406 Edelbrock "Carberator" on it, if the shake goes away you know it is your EFI fuel management system. Try a new Oxygen Sensor and a new set of spark plugs.
Pull a few spark plugs and see how they read.
Pull a few spark plugs and see how they read.
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