SMELLY - De-camming for de-smelling ?

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morgan
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SMELLY - De-camming for de-smelling ?

Post by morgan »

Just an idle (sic) curiosity question.

I'm getting seriously tired of the smell from my car at idle. It makes your eyes water. Its embarrassing at traffic lights and my neighbour shouted at me for 'stinking out the neighbourhood'. This makes herself unhappy so the time has come for something to be done...

Only really 2 core culprits as far as I can see.
I can throw money at trying to get it tuned, jetted etc - carb type investigations. (Or switch to sniper EFI and let it sort its life out). But I cant shake the nagging feeling I am wasting my time and the real culprit is the big cam and that the overlap will mean it stinks whatever I do. Perhaps when all is said and done it just needs calming down a bit into a more streetable configuration (yes. I know. I know. I was told.) I dont mind spending some to get it sorted but I dont want to throw cash at it only to find that cam is always gonna stink. Isky 292 246/245 lift duration with lift of .336/.505 at lobe/valve.

Engine is exactly as it was in Bob Browns car EXCEPT -
- Ignition is now MSD all in one with stock[ish] curve. No vacuum. 16-18/34 all in at 3K. I dont know what curve Bob had.
- Carb is not the zonking great 885 (!) with fogger plate but is now a Holley street avenger 770.
Anyone happen to know if it stunk in the fire up lane when Bob was running it ?

Whats the thinking chaps ? What do we think is the best way of making this bad boy smell a little less offensively ? I can live with the lumpy profile and the performance is entertaining, but the smell has GOT to go !
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Pete
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Re: SMELLY - De-camming for de-smelling ?

Post by Pete »

Have you considered installing an AFR set up to get to the bottom of what is actually happening and take the guesswork out of it?

In my experience, very very rich and very very lean tend to smell the same...
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morgan
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Re: SMELLY - De-camming for de-smelling ?

Post by morgan »

Not a bad shout. I had thought about it and decided that given I'd have to buy one as part of a sniper kit if I went that way in the future then I'd be doubling up. A quick google suggests however you can get cheap-as-chips-chinese gauge and sensor for ~£35 or UK vendor ones for £200ish.
I'm taking her down to get a probe shoved up her exhaust too over the long weekend which will hopefully give a clue.
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SJH
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Re: SMELLY - De-camming for de-smelling ?

Post by SJH »

If it was mine the first two things I would check are the fuel pressure and the carb float heights. If these are not correct you can get excess fuel dribbling into the carb, and it will be impossible to tune. I also had a friend whose fuel line was getting so hot in the engine bay the pressure from evaporation was affecting the floats in the carb. I would recommend member Jim Smith to investigate/tune the engine, he did mine and it has never run better. His business is near Birmingham.
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Re: SMELLY - De-camming for de-smelling ?

Post by SJH »

SJH wrote: Fri Apr 02, 21 9:56 am If it was mine the first two things I would check are the fuel pressure and the carb float heights. If these are not correct you can get excess fuel dribbling into the carb, and it will be impossible to tune. I also had a friend whose fuel line was getting so hot in the engine bay the pressure from evaporation was affecting the floats in the carb. I would recommend member Jim Smith to investigate/tune the engine, he did mine and it has never run better. His business is near Birmingham.
Also check the float bowl needle valves are moving freely
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Re: SMELLY - De-camming for de-smelling ?

Post by Dave999 »

where did you end up with your ignition timing :) oops opens a can and its full of worm like things.
i just added at one end and removed from the other until the smell went away.

can you get an electronic lean burn dizzy off a 400 engine windybeego... these are locked, no advance what so ever
whack it in at 20 BTDC and see how it goes


i have an AEM UEGO thingy... tune to 12.5- 13 not 14.7

weld a wheel nut off a vintage rover to you exhaust and it will screw right in uses a pre calibrated Bosch lambda wide band sender i.e the calibration resistor is in the plug all comes ready to go.

if you are looking down the bore of your collector put the lambda sensor at 10 or 2 o-clock you don't want it to spark out due to fuel or condensation running down into its GUTS

then its a fat wire loom from there through into the cabin

gauge on dash comes with a 4 or 5 wire pigtail as well as the plug for the sensor.
1 is power 1 is earth and 3 can be used as Gnd RX and TX for logging on a lap top or feeding into your EFI or ignition box to provide lambda input to an ignition or fuel Map if you want

handy little thing. all the magic is hidden in 1 chip inside the gauge

it was cheaper to get than the UK produced stuff (£300+) and has been reliable

https://www.ebay.com/itm/AEM-Electronic ... SwKF1cecWz


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morgan
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Re: SMELLY - De-camming for de-smelling ?

Post by morgan »

Thanks chaps.
Haha - can-o-worms indeed. Timing is reverted to a stock-ish curve on the MSD - 16-18 init with 34 all in by 3000 from memory. Nothing horrible.
Compression is high (10.8) and is on 98oct fuel. Doesnt pink. I have heard it 'spit back' once but thats all.
Engine bay heat is incredible - hot for hours. Stinks. Otherwise runs really nicely !

Half a mind to stick the old massive carb that BobBrown ran back on it and just see if anything changes.

Pete is right of course - dont know what I am chasing.
As far as I can see it could be
- timing (but this should be good)
- Some kind of breakdown in the ignition causing missing sparks (that is a guess)
- Carb stuff.
- Super-loopy-silly-cam (but to be fair, I dont think the cam is THAT extreme - I mean its not double springs or anything).

Not sure it can be much else. :dontknow: The point of the post was really "Am I wasting my time trying to de-smell with a cam like this" ?

A friend has a 68 Chevelle with a 383 stroker SB chevy. He took it to a tuner in Rayleigh (I think) 'atspeedracing' and rated them highly. They had his car several hours and put it on the rollers, took carb off etc. They DOWNGRADED his carb size and jets and the car was transformed - he can outdrag me on the dual carriageway... I am considering taking it there to just get a sensible running opinion. Even if that opinion is 'Yeah, carbs knackered' at least I have something to go on.
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Pete
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Re: SMELLY - De-camming for de-smelling ?

Post by Pete »

Do you have a cam card?

If it is not double springs on the Valves, then I bet it is not as nearly as big as you may think it is.

However, the "Old School" approach was lots over overlap, so you have to rev the Ertha Kitts off it to make real power and it may result in smell.

I think the Full advance is coming in far too late, but a lot depends on how loose you Convertor is....
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Dave999
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Re: SMELLY - De-camming for de-smelling ?

Post by Dave999 »

an efficient motor will advance perfectly well without help from ignition advance

i can't base any advice on anything but my own small motor but my expectations in this area were far too "OEM standard" for the motor i built
and i quietly fought it for three years + wrong plugs, wrong timing.... and should have just asked.... i resented the cost and hated that bloody car :)

its still not right but getting the 7 range NGks with the very shielded nose worked wonders it allowed me to see what i needed to do becasue they just worked all day every day, no fouling up

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morgan
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Re: SMELLY - De-camming for de-smelling ?

Post by morgan »

Thanks. Yes, there are only so many things it can be. As a bag-of-bolts it runs and clearly makes good power (at revs its like falling out of a window!) I just want it to not make the squirrels fall from the trees with fumes when idling.

Good news that cam might not be so wild. Nearest I have to a card is this (picture)

Dave 'resented the cost and hated that Bananarama! car'. Totally get that. :)


I might swap the carb back to race carb just to see. But other than that I think the course of action is to take it somewhere they cam actually measure and analyse what the heck is going on.
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Re: SMELLY - De-camming for de-smelling ?

Post by Pete »

My 6 Pack Bee had a bigger cam in it.

I know many members run bigger cams than that on the street.

Dave Billadeau will be able to give you chapter and verse on that.

I assume the 5 degree Retard was for greater Valve to Piston Clearance but I could be wrong, maybe Bhp / Torque trade off?

I would bring the timing advance in much much earlier, literally once it had fired up.
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morgan
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Re: SMELLY - De-camming for de-smelling ?

Post by morgan »

Good info. Thanks. I tried to get curve readings off the engine before it came out of the Daytona but vendor and I struggled to get reliable readings off it. The answer could well have been in there. C'est la vie.

From memory I am running profile3 now with black bushing. (This gives 18 degrees total mech advance at 3,000rpm).
This allows me to set ~16 initial at startup with 34 all in at 3K.
I have an adjustable vac can, but its disconnected. No point. No vacuum.

There are 3 options to bring this advance in sooner looking at the chart. Some of these will bring in a few degrees at idle sort of speeds.
Can be 34deg all in by 2500, 2000 and 1750 by the looks of it.
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Re: SMELLY - De-camming for de-smelling ?

Post by Pete »

I would want one that looked like the face of the Eiger.

The only reason you have initial timing is so you can crank the motor without ripping the teeth off the ring gear.

In my opinion, you want to get as much timing in as early as possible without causing drag on the convertor - this is where the trade off takes place.

Don't underestimate the Vacuum canisters - they have their uses, but ironically not how they were intended....
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Re: SMELLY - De-camming for de-smelling ?

Post by Pete »

You are really playing with old technology here.

The other fix is to have locked out timing and a programmable and mappable Ignition system.
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Re: SMELLY - De-camming for de-smelling ?

Post by morgan »

Yes. Thought about that (locked, programmable) which can work really nicely with sniper injection too.

Which of course brings me back round to my question in the first place - "Am I wasting my time trying to make this cam not smelly". To which is seems the answer is 'No. Plenty run specs like that without the stink'. Therefore its worth me pursuing a better fuelling/timing solution and not worrying so much about the metal bits.
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