ignition timing rv8

[barginbucket]

hello to you all,this is my first post,sorry its a bit run of the mill question but here goes,just built a 4.0 litre cross bolt for my sd1,usual bolt on stuff,webber 500,bvh's [41.5/35.5] well big 15 years or so ago lol,kent 224 cam,and mallory unilite and leads,any idea what to set the timing to,have set cam/ign timing as stock[hayneso] but not sure if this is the best thing to do,only done 5oo miles or so,not that impressed with performance,so i'm hoping i've done something wrong
any feedback would be topbombing,thanks for your time

[Richard]

Sounds like a reasonable starting point. What makes you suspect the timing in particular?

[barginbucket]

hi richard,well i kept seeing different figures quoted for the rv8 and was'nt sure what it should be with this spec,its one of the easier things to change and can make all the difference,again not sure about cam/timing shall ask,thanks for your interest

[IanT]

Boring stock answer, but always the first thing to check:
Make sure the zero degree mark on your pulley actually corresponds to TDC on cyl #1. They can be well out of alignment.

[barginbucket]

thanks for your reply,luckily i remembered that on the rebuild,but will double check,cheers

[Paul B]

thanks for your reply,luckily i remembered that on the rebuild,but will double check,cheers

Ignition timing should be as much as your motor will take without pinking under hard throttle, usually between 30 and 36 btdc.

[racer]

[quote="Paul B
Ignition timing should be as much as your motor will take without pinking under hard throttle, usually between 30 and 36 btdc.[/quote]

Wow..I hope you mean total timing. The LR/Rover V8 distributors arrive mechanically advanced 28 degrees. That makes your 30-36 read 2-8.

Bargin,

If your engine is new..and it has done only 500 miles, don't expect much of it (espcially on a 3.5 to 4.0 swap). Your mileage will be bad in that period, your oil consumption high and your cylinder compression likely lousy.

Give the thing a chance! The most logical system I have seen is to change the oil after it first warms up first time. Then, with a LR, keep it under 3000 rpm for the first 500 miles, change the oil again and then add 100 rpm every 100 miles. (On a light sportscar, it should be pushed more than that as the problem is the lack of load makes it take longer for the rings to seat unless treated more aggressively.) If it doesn't happen early, the effect of the cylinder honing lessens and it can take an immense distance 'til the engine is finally happy.

Your compression and performance will improve past 5000 miles.

I am assuming you have dialed in the cam correctly to cylinder #1. There is a competitor in a division one below mine. Nice guy. He wanted to move up a division and spend a fortune on the engine, cooling and exhaust with a local "engine" expert to do so. New 4.0, wild heads, great cam, haltech management, stainless headers, ally rad..the works. Cost him close to 10K.

He gave them the car with 168 bhp at the rear wheels and it came back with 96bhp..a real dog. In the 4 months before he came to see me, he had it up for sale. It had been checked every way from centre by the engine expert and he was told all was right.

They had degreed the cam in to cylinder #2. 31 degrees off. Then got it running smoothly after they dished the pistons to clear the valves. (I haven't and won't tell him about that).

I removed and reinstalled the cam correctly and the thing is now producing 216 bhp at the rear wheels, or so I have been told excitedly). That one will undoubtedly get me into heaven.

Timing is easy. After you have 1000 miles on the engine, put a timing light on the car and see where the timing is. Mark it with one of those white markers. Then loosen the dizzy just enough to be able to turn it and go find a mild hill. Heat up the car, head for a lonely hill, put it into 4th at 20-30 mph and floor it. If it doesn't ping, advance your timing a bit and do it again. Keep doing that until it pings. Then retard it just a tiny bit until it stops. Go home, use the timing light again to see where you are now, and make another mark.

That's it.

racer

[Paul B]

Ignition timing should be as much as your motor will take without pinking under hard throttle, usually between 30 and 36 btdc.

Wow..I hope you mean total timing. The LR/Rover V8 distributors arrive mechanically advanced 28 degrees. That makes your 30-36 read 2-8.

That's the only timing that really means anything; how far advanced your spark is BTDC. All done without vac advance connected of course.

How do you mean: "the LR/Rover V8 distributors arrive mechanically advanced 28 degrees". Is that built in mechanical advance? I found on my SD1 mechanical advance it only gave about 18 degrees. So, 6 degrees at idle turned into barely 24 full advance at 4000rpm. This is, apparently, a known fault from the factory: http://www.seight.com/ignition.html

[barginbucket]

Thanks for that advice fellas,will let you know how i get on,have dialed in the cam on no1 cylinder but timed it up the same as the stock cam,looking forward to adjusting ign/timing soon,again top bombing site

[racer]

Ignition timing should....usually between 30 and 36 btdc
That's the only timing that really means anything;

[Wow..I hope you mean total timing.

That's the only timing that really means anything

No argument but you put it in an odd way. Most people would simply look at their manual and their timing marks and go.. 6 BTDC at 600 rpm. They take the base point for granted, which assumes that the unit is in stock form and still has its stock advance.

From your findings, it seems that your springs need replacement and its curve recalibrated.

racer

[Paul B]

No argument but you put it in an odd way. Most people would simply look at their manual and their timing marks and go.. 6 BTDC at 600 rpm. They take the base point for granted, which assumes that the unit is in stock form and still has its stock advance.

From your findings, it seems that your springs need replacement and its curve recalibrated.

racer

I'm not sure it's so odd. You don't state ignition advance in relation to what is stock, you state it from TDC. Thus 36 degrees ignition advance is just that: 36 degrees BTDC, regardless of what the book says or what it was originally. More a difference in terminology I guess.

I bought new springs for my old dizzy from Real Steel, and it turns out they give three sets, of different tensions, originally from GM, so you could fine tune the curve. I modified the mechanical advance stop inside too, ground about 0.040" off it, so I got a true 36BTDC at 4000rpm with 6 at idle, instead of the old 24 degrees at 4000.