What should I expect from this JE 3.5 engine?

crayefish · Post by **crayefish** » Sat Oct 17, 2009 12:05 am

kiwicar wrote:take it to Mark adams and spend alot of money on a rolling road trying to solve it before getting pi$$ed off with EFI generally and bin it for a Holley spending yet more money setting it up and still have dubious part throttle responce, bin the whole lot now and fit a Holley saving all the money on the Mark adams sort out.
Mike

Or get one of those stone age carbs that david vizard goes on about (the name escapes me, but it is literally like a square metal box) that adjusts itself to any situation... you never have to touch it ever, but you look like a proper towel using one!

JEV8SD1TP · Post by **JEV8SD1TP** » Sat Oct 17, 2009 1:49 pm

crayefish wrote: That probably means you have a race distributer. great for WOT and racing, but rubish for fuel economy etc

Whats WOT?

Whats the idea behind race distributors, and what difference does having a vacuum advance pipe make?

crayefish · Post by **crayefish** » Sat Oct 17, 2009 1:54 pm

WOT is Wide Open Throttle

a vacuum advance does exactly as the name says, it advances the spark under high vacuums. this helps to improve fuel economy at part throttle.

not sure why race distributers dont have a vacuum advance... though it could be due to the fact that they dont actually make a lot of vacuum due to big valve overlaps

JEV8SD1TP · Post by **JEV8SD1TP** » Sat Oct 17, 2009 9:03 pm

kiwicar wrote:The "hotwire" bit is the air flow meter, the ECU is the electronic box that Mark adam's chip (s) plug into, I am recommending the replacment of the electronics box with either a Megasquirt, Extra efi, emerald, Vems, ECU (and at the same time you can bin the air flow meter.
The timng of your cam is mild so overlap is not really likley to be an issue, the duration is the 265/225 bit, 265 degrees between .003" of lift (ie just off the seat) the 225 is the .05 lift duration in crank degrees.
the 20/65/ 25/20 are the timing events , the inlet valve opens (just lifts off the seat) at 20before top dead centre, closes 65 degrees ATDC exhaust opens 25 degrees before bottom dead centre and closes 20 degrees after top dead center, that gives 40 degrees total overlap, but as flow effectivly starts at .05 lift and this timing is 40 degrees less than seat timing then you have a 0 overlap cam as far as flow is concerned.
Best regards
Mike

Thank you Mike for the explanation of the camshaft values.

It would seem as though my options are limited at the moment (cant afford to move away from the flapper efi at the moment) and I will just have to put up with the low speed jerking, or adapt my driving style when driving the car.

JEV8SD1TP · Post by **JEV8SD1TP** » Sat Oct 17, 2009 9:09 pm

Mark wrote:Too much ignition advance can cause the symtoms described, try backing the timing off a couple of degrees and going for a drive.
Assuming the EFI unit does not control the sparks ?

Mark

Tried backing off the timing. The bucking was reduced by retarding the timing, but so was the cars performance and it sounded less impressive. Here's how it sounds at the moment (timing at setting that causes bucking/jerking at low speed 10 degrees BTDC with the distributor that has no vacuum advance)

http://www.youtube.com/watch?v=AebxdICIN_g

I rather like it as it is. With timing retarded it loses sound and performance and you can smell unburnt fuel. Just a real pain to drive in the real world (with other cars on the road, most of them travelling slower).

JEV8SD1TP · Post by **JEV8SD1TP** » Sat Oct 17, 2009 9:13 pm

crayefish wrote:WOT is Wide Open Throttle

a vacuum advance does exactly as the name says, it advances the spark under high vacuums. this helps to improve fuel economy at part throttle.

not sure why race distributers dont have a vacuum advance... though it could be due to the fact that they dont actually make a lot of vacuum due to big valve overlaps

Thanks for the explanation Zander. You've answered another query I've had with the car since I got it.

There are lots of little changes JE have made to the engine that people in SD1 circles have not seen before and leave me puzzled.

Mark · Post by **Mark** » Sat Oct 17, 2009 9:59 pm

If it were mine I would fit something like Emerald to run the whole shooting match, that way you can control everything 100%. You can have good timing advance for maximum power and still have it drive smoothly at part throttle.
Not cheap but if you intend to keep the car a good investment.

Mark

CastleMGBV8 · Post by **CastleMGBV8** » Mon Oct 19, 2009 5:38 pm

JE V8

Just a thought, if you have a Mallory dizzy, Red cap would be a guide but you should be able to see a name somewhere. Is it electronic or dual points?

If it is a Mallory and it's a few years old they are notorious for having the advance springs go soft or even failing so your ignition may be advancing off idle more than is desirable.

I would suggest, unless you have a timing gun that can do it and someone to shout out the RPM's taking the car to somewhere they can check the advance curve, if it's advancing too quickly a new pair of springs might just fix it.

Kevin.

92rrrandall · Post by **92rrrandall** » Tue Oct 20, 2009 4:05 am

Having a similar problem with my TR8 regarding the bucking at "1700rpm". I have a brand new 4.0 engine with modified intake, heads, exhaust, Crower 230 cam, Mallory distributor.

I am something of an expert regarding EFI and even make my own chips for the 14CUX system.

My bucking only started a few months ago when I installed the 4.0 short block along with a new clutch and transmission. The intake, 14CUX, cylinder heads, Mallory and exhaust system etc were already being used on the TR8 and fully sorted.

My thinking is that this bucking is caused by my new "standard clutch". Some how the clutch is disengaging momentarily at a certain rpm range under very light engine loads. It is as though the spring in the clutch plate finds it easier to separate from the flywheel than to keep it's grip when you are barely moving at "1700rpm".

There are few choices for RV8 clutches and virtually no info on the ones that are available. It is also no practical to experiment with different clutches due to the time and expense involved in a swap. I suspect that a high performance clutch would not buck at "1700rpm", but there may be other problems to live with if you go with the high performance option.

Randall

crayefish · Post by **crayefish** » Tue Oct 20, 2009 8:37 am

92rrrandall wrote:Having a similar problem with my TR8 regarding the bucking at "1700rpm". I have a brand new 4.0 engine with modified intake, heads, exhaust, Crower 230 cam, Mallory distributor.

I am something of an expert regarding EFI and even make my own chips for the 14CUX system.

My bucking only started a few months ago when I installed the 4.0 short block along with a new clutch and transmission. The intake, 14CUX, cylinder heads, Mallory and exhaust system etc were already being used on the TR8 and fully sorted.

My thinking is that this bucking is caused by my new "standard clutch". Some how the clutch is disengaging momentarily at a certain rpm range under very light engine loads. It is as though the spring in the clutch plate finds it easier to separate from the flywheel than to keep it's grip when you are barely moving at "1700rpm".

There are few choices for RV8 clutches and virtually no info on the ones that are available. It is also no practical to experiment with different clutches due to the time and expense involved in a swap. I suspect that a high performance clutch would not buck at "1700rpm", but there may be other problems to live with if you go with the high performance option.

Randall

There are actually a large number of clutches available for the RV8. AP Racing do about 6 alone... anything from OEM to 380 ft lb rated to cerametallic. And there are a few other makers as well

But yes it is difficult to try lots. Just get the highest rated (within reason) that you can afford.

Ian Anderson · Post by **Ian Anderson** » Tue Oct 20, 2009 11:16 am

92rrrandall wrote:Having a similar problem with my TR8 regarding the bucking at "1700rpm". I have a brand new 4.0 engine with modified intake, heads, exhaust, Crower 230 cam, Mallory distributor.

I am something of an expert regarding EFI and even make my own chips for the 14CUX system.

My bucking only started a few months ago when I installed the 4.0 short block along with a new clutch and transmission. The intake, 14CUX, cylinder heads, Mallory and exhaust system etc were already being used on the TR8 and fully sorted.

My thinking is that this bucking is caused by my new "standard clutch". Some how the clutch is disengaging momentarily at a certain rpm range under very light engine loads. It is as though the spring in the clutch plate finds it easier to separate from the flywheel than to keep it's grip when you are barely moving at "1700rpm".

There are few choices for RV8 clutches and virtually no info on the ones that are available. It is also no practical to experiment with different clutches due to the time and expense involved in a swap. I suspect that a high performance clutch would not buck at "1700rpm", but there may be other problems to live with if you go with the high performance option.

Randall

Very Interesting that you make your own chips

As I am plagued with this issue I would certainly be interested in something that is plug and play

I have also done a lot of reading around the subject and the kangaroo would appear to be mainly down to lean low throttle mixture along with the refresh rate of the "brain" of the 14CUX which cucles and adjusts only once about every 2 seconds and that is about the time it decides that the last adjustment was way out and then eithe seriously over or under fuels causing the kangaroo

I do not believe your clutch could cause this as in a steady low throttle drive you clutch would be transmitting power and unless you are getting crazy amount of slip could not cause this

You could get clutch judder on take off if something is not aligned correctly / or not machined correctly - or if your clutch is a race type set up where it's operation becomes like an on off switch with no slip

Ian

adarmo · Post by **adarmo** » Tue Oct 20, 2009 2:17 pm

Perhaps I'm stating the bloody obvious...

But why not call JE and ask him ?

92rrrandall · Post by **92rrrandall** » Tue Oct 20, 2009 3:26 pm

Unfortunately I am no expert on clutches and AP Racing would add more expense and logistics. Just thought I would throw the clutch idea out there. Do not remember having this bucking problem before the new block/clutch/trans went in.

The idea that the AF ratio could be wrong under certain conditions is possible. Especially since I have also done some machining on the air flow meter. Will just have to try and be more scientific and determine every possible factor that may contribute to the problem.

Also earlier in this thread someone mentioned that the mallory springs tend to get weaker. Already I am somewhat aggressive with the timing of my ignition. Maybe a little too much advance with a little too lean AF ratio is causing it.

Randall

crayefish · Post by **crayefish** » Tue Oct 20, 2009 3:47 pm

92rrrandall wrote:Unfortunately I am no expert on clutches and AP Racing would add more expense and logistics. Just thought I would throw the clutch idea out there. Do not remember having this bucking problem before the new block/clutch/trans went in.

The idea that the AF ratio could be wrong under certain conditions is possible. Especially since I have also done some machining on the air flow meter. Will just have to try and be more scientific and determine every possible factor that may contribute to the problem.

Also earlier in this thread someone mentioned that the mallory springs tend to get weaker. Already I am somewhat aggressive with the timing of my ignition. Maybe a little too much advance with a little too lean AF ratio is causing it.

Randall

For much less the cost of taking it to places to be examined or new clutches and all that stuff, you could buy (or borrow if possible) a cheap as chips twni SU manifold with carbs and pop that on. if the problem goes, then its your efi. if it still stays, then its either the spark or the clutch

kiwicar · Post by **kiwicar** » Tue Oct 20, 2009 4:20 pm

" For much less the cost of taking it to places to be examined or new clutches and all that stuff, you could buy (or borrow if possible) a cheap as chips twni SU manifold with carbs and pop that on. if the problem goes, then its your efi. if it still stays, then its either the spark or the clutch"

I don't see how this stands a chance of helping at all, sticking on a pair of 25 year old worn out carbs that have needles in for a probably standard engine (and a 3.5 at that) will hardly have a cat in hells chance of giving the right mixture. SUs set up incorrectly are as capable as anything else of making an engine run like a dog. If you mean to then to spend I don't know how long setting it up to run on the SUs why not spend the time sorting out the injection, sorry I just don't get the thinking

.
Can I again suggest that before you go chasing any more red herrings (like the clutch to name one) you borrow a AFR meter (inovate LC1 for instance) and a laptop and log the engine as it is while you drive it, I will bet it is as Ian and I have both said that the ECU you have is running the mixture way too lean then as Ian has pointed out over richening it to compensate when you accelerate (as I said in my first post I could get my RR to do this and it was compleetly standard). If you change to a decent mapable ECU now you will save youself alot of time money and grief in the long run and have a car that is a pleasure to drive not a chore.
Mike