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GOHER007

Petronix in distributor

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Dear Lotus community thanks for your help.....i changed a petronix unit with a petronix unit (foolish of me)......but thereafter the boost, the pick up is not the same....i remember the revs at idle use to be higher than what they are now at 7-8000......timming is correct.....changed the spark plug wires.......before the petronix swap the turbo gauge will jump nicely to 3-4-5 in third gear...but now only 3...and i dont want to push it....i know something is a miss..................Any helpfull hints or suggestions from the seasoned would be of great help Thank you again

Taking that distributor out again will give me polio of the arms this time around-)))

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Thanks MC....This is a fedral s3 turbo...Do they come with ecu units...i thought they came in Stevens esprits......i will spend a few hours again today to troubleshoot (few hours))) few years morelike it

Thank you

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Because the petronix is running on the coil, and there are not enough ohms running to the coil, perhaps is partially resposible. i was told that it may need 12 oms to be supple (or even a diffrent coil?)

How pethatic of me not to have a voltometer on hand........weekend will tell.

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i forgot to post how i got the timming right on the s3 as follow

You can always do it the "old fashioned" way. Pull #1 plug, stick a straw in and rotate the flywheel. At TDC after the intake valve closes you should see a TDC mark and a timing mark. Or you can make your own with chalk.

David Teitelbaum

Just checked my s3 as my s2 is somewhere else

large marks every 10

small in between at the 5s

10 degrees = 25mm of circumference (or an inch if you into that sort of thing)

mine is numbered TDC and every 10 degrees to 30

no marks after TDC and never have seen on any Lotus

__________________

Thanks to both of you. I even have a dial indicator with extensions I could rig up to make sure of TDC if I want to get real scientific, but I think a straw will work just as well for this application

petersracing - ouch, I though you were going to say that about no ATC marks as there is a red paint mark on the mark I thought was 10 degrees ATC (true TDC). Unless I read the manual wrong, under 1000 rpm timing s/b at TDC. Car was (and is) set at 10 degrees advance at idle. Vacuum advance not used with the Delortos. I tried true TDC at idle and it did not like it at all. Mechanical advance is working fine (just ten degrees off across the board).

Not sure there is detonation risk on a non-turbo car, but I can't think of any reason to have the timing advanced that much. Previous owner told my pal it was set up for gymkhana in the 80's and that he (PO) tuned it for colder weather. That cold weather tuning may be the reason for the advance? Don't know, but I am not comfortable leaving it there.

Our S2 is the federal motor (low comp) that has been changed from Strombergs to Dellorto too. 10 degrees BTDC at idle is pretty close, we just closed off the vacuum retard too. Nothing but antique american iron is going to stand TDC timing id suspect. I think you must be mistaken on the manual but Ive put in a phone call to where the car (and its manual) are to check. We set it recently to 22 BTDC at 4000RPM (ie full mechanical advance) but there is a little variation on the total mech advance between the ROW and the federal cars. If by colder he meant really cold then I'm afraid no experience from here will be relevant

I looked at the book. It is utterly confusing, but I think what it is trying to say is that TDC is 0 degrees and that the static (or idle) timing is 8 degrees BTDC. Depending on what distributor or tune it has it might have different centrifugal timing. I'd set the static and then buzz it up to the end of the timing curve (6k) and see what you get but it should be in the high 20s. If it is a road car I'd just tweak it for driveability. If it will be run hard then its off to dyno. The ultimate authority is Tim Engel who is on this board as Esprit2 as he has seen all these variations a hundred times.

You can always set it up @ 8 at idle and then do what we used to call "Power Tuning". You would play with the advance till you noticed pinging and then back off a few degrees. This is very "hairy" ie, close to the edge. It will be affected by the fuel (age and type) and atmospheric pressure. You do not want sustained detonation, you will melt the pistons. You can also play with the advance curve by messing with the weights and springs. Typically you want to get as much advance in as fast as you can. This will also affect the carburetor tuning so you will have to mess with that at the same time. It can get complicated. What most will want is to be able to burn the stuff they pass off as gasoline with good drivability and fuel economy without worrying about detonation. Means staying on the rich side of Stoch and not over-advancing the timing with enough advance to get good economy yet still run well hot and cold. Factory settings were never meant for the cr-p they pump at the gas station these days to be used in carbureted cars. You will have to adjust a little in any case off spec. Usually towards the richer side. And probably less total advance.

David Teitelbaum

QUESTION

Several Lotus Esprit turbo owners have confirmed that there is a discrepancy between crank "0" deg mark on the front crankshaft pulley and fly-wheel TDC mark on some 1986-88 US Federal cars.

Can you please offer an explanation and which mark is correct?

C.G. - USA

ANSWER

There is a previous article in the knowledge-base which explains this manufacturing error and checking method.

The fundamental question to this problems is - which timing mark is correct, the front crankshaft pulley or flywheel?

To begin with you have to assume both are incorrect.

To determine which timing mark is correct, the initial task is to check and determine the true TDC piston position.

There are two ways of doing this and installing a mechanical stop (modified spark-plug and protruding bolt thread) is the easier.

A spark-plug can be suitably modified by first removing the insulator material and electrode.

Next step is to drill and tap the plug body to accept a convenient bolt size of 3/8"UNC x 3" (75mm) long.

The fully threaded bolt can then be screwed in from the top of the plug to allow 3/4" (19mm) of thread to protrude from the nose.

The plug can then be gently screwed into No.1 spark-plug hole, the engine carefully turned clockwise and anti-clockwise whilst noting the points where the crank stops turning.

The mid-point between the two mechanical stop points is true Top Dead Centre (TDC).

This procedure should be repeated on both the crankshaft pulley and flywheel to determine which set of markings are correct.

Its also wise to check the camshaft timing after determining the true TDC timing mark.

If the cylinder head has ever been skimmed whilst being serviced, it will retard the cam timing (on both cams and you will lose power)

Adjusting the cam timing to the correct MOP (Maximum Opening Point) is the cheapest horse-power you will ever realise from an engine.

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When using Pertronix pick up, it is necessary to replace the Lucas coil with 3 ohm Pertronix coil. I prefer epoxy filled-they last longer.

 

The crankshaft mark trumps other markings.

Edited by MrDangerUS

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