Jump to content

What's the timing supposed to be?


FridgeFreezer
 Share

Recommended Posts

I recently fitted a new dizzy to Dad's RR - it's a stock 87 EFi, however the dizzy is an earlier points one from a carb model but with an Aldon Ignitor in it. It runs OK but the timing is a bit off (too advanced I think) - since the old one was knackered I couldn't compare old and new with any accuracy (plus somehow the timing marks are obscured by mud :unsure: ) so just set it at about 8 degrees BTDC at idle which it seems sort-of-happy with.

I've checked the Haynes Book Of Lies and it talks about static & dynamic and gives wildly varying values for different engines/model years/dizzies plus I think some of it is pre-unleaded <_<

So, can anyone tell me in plain English what to set the flippin' thing to, or if it's just a "knack" then roughly how to judge it... I'm this close to just bunging MegaJolt on it and having done! :rolleyes:

Link to comment
Share on other sites

Your dad's Range Rover is on petrol, isn't it? 8o is correct for idling speed on the hotwire engines - I've a vague idea it was only 6o on ealier (carb?) engines. I've no idea about setting up proper clockwork though - only had dealings with the equally evil electronic jobbies.

At least with the electronic dizzies they'll tolerate a much higher idling advance - I used to run 13o at idle with the dizzy, to get decent performance on LPG. Lumpy idle on petrol, but it was okay.

Link to comment
Share on other sites

Your dad's Range Rover is on petrol, isn't it? 8o is correct for idling speed on the hotwire engines

Is that with vacuum connected or not? Haynes says: :rtfm:

Points system: 5 to 7o BTDC static at idle

4 to 8o ATDC dynamic at idle

June 84 to 86 - 6o BTDC static, 6o BTDC dynamic

87 EFi: TDC +/-1o static or dynamic

87 Carb: 6o BTDC static or dynamic at idle but with vac pipe off

88-9 hotwire: 6o BTDC dynamic with vac pipe off

I thought static was "engine off" but this quotes static-at-idle :unsure: My brain hurts! :wacko:

Link to comment
Share on other sites

Is that with vacuum connected or not? Haynes says: :rtfm:

Points system: 5 to 7o BTDC static at idle

4 to 8o ATDC dynamic at idle

June 84 to 86 - 6o BTDC static, 6o BTDC dynamic

87 EFi: TDC +/-1o static or dynamic

87 Carb: 6o BTDC static or dynamic at idle but with vac pipe off

88-9 hotwire: 6o BTDC dynamic with vac pipe off

I thought static was "engine off" but this quotes static-at-idle :unsure: My brain hurts! :wacko:

Ah Yes, the joy of "Mix n Match" V8 Parts.

TBH if it doesn't pink then I would say "Near Enough" if it does then try 6 degrees, also see what the advance is at say 3000 rpm, dizzys had softer curves in points ones, with the EFI Cam etc things are going to be odd :blink:

I would suggest 6-8 degrees BTDC for me, vac off at tickover say 700-800 rpm ish

Nige

Link to comment
Share on other sites

Often simplest to set by road test.

Accelerate hard in 4th from about 30. If the engine pinks (rattling sound) then retard slightly. If it doesn't advance instead. Keep doing this until it just pinks ever so slightly.

Check the pointer position with a strobe at idle so you can reset when necessary.

Link to comment
Share on other sites

There are many different dizzy’s for the V8 :rolleyes: ………depends on the market ………

The only real differences are the weight and in some cases the springs …….

The RV8 has a design , safe max advance of 28 degres BTDC @ 3750 rpm

The max advance on any engine is down really to the combustion chamber shape …….. IIRC the RV8 is a wedge so therefore something in the order of 34 degrees is the absolute max.

So …….. to set the base timing figure ………..

Either,

1)...........pull the dizzy and strip down to the weights (5 minute job) ……… take a note of the number stamped on the weights …………multiply this number by 2 (think about how an engine / dizzy works) and then subtract this from 28……

example …….. weights are stamped 11

28 – (2 x 11) = 6 ……………. Therefore set the static timing to 6 degrees….

Here is a further example …………. The weights in my dizzy (although now redundant) are stamped 14…..

28 – (2 x 14) = 0 …………. Set the timing at TDC

I can assure that any over 3 degrees advanced and that engine would pink.

2) Another method ……… often used by tuners……….. is to replicate the crank pulley marks yup to about 30 degrees (34 on an tuned engine) ………. Then using a good quality timing light, run the engine up to 4000 rpm and set the timing at 28/ 30 degrees …… this automatically sets the static timing.

The terms Static and dynamic are not quite used correctly. Static timing is more akin to the older points dizzy’s and the static figure is used to set the points opening with a bulb ………… dynamic is when the engine is running and we use a strobe to align the timing marks …………. But essentially the advance at tickover with the vacuum disconnected is the same as the static figure.

Funnily enough an 87 3.5 EFI has a static figure of TDC @ 600 rpm (see example above !) ………3 to 8 degrees at 1200 rpm ………….18 – 22 degrees @ 2200 rpm ……… and 22 to 28 degrees @ 3200 rpm ………….. but all this assumes you have the correct dizzy

John ……… give me a call …….. mobile number in PM

:)

Ian

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy