Search found 315 matches

by jagwit
Sun Aug 12, 2018 6:17 am
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

mgcjag wrote:
Sat Aug 11, 2018 7:08 pm
Or maybe you agree with much thats already been said in the subject.... :bigrin:
Quite right Steve, absolutely.
by jagwit
Sat Aug 11, 2018 4:19 pm
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

Another opinion on this matter This article confirms much of what I’m saying. The only area where I would like to get clarity from John Hinckley (the author of the article) is that he refers to idle mixtures as being “lean”: "is that lean mixtures, such as at idle and steady highway cruise, " Idle ...
by jagwit
Wed Aug 01, 2018 3:53 pm
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

After all this, I'm hoping for a glimmer of understanding why Jerome's method is not a good method..... UNLESS.... His engine is configured with a vacuum advance module on the distributor and its vacuum line is connected to MANIFOLD vacuum. Question 8: WHY ???????? Question 8: WHY ???????? So, lets...
by jagwit
Wed Aug 01, 2018 3:21 pm
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

JerryL770 wrote:
Wed Aug 01, 2018 2:38 pm
Crikey!! :oops:

It's gorn right over me now.
Ummm, only saw this after I hit "submit". Clearly I did not succeed. :cry:
by jagwit
Wed Aug 01, 2018 3:19 pm
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

Jerome, this approach is wrong, wrong, wrong and I will make sure to explain WHY (actually I already have :geek: ), specifically on this matter, after questions 7 have been answered and I'm sure the answer will NOT be over your head. Hint: 7.2 relates to this matter... Jerome, if you now read my pr...
by jagwit
Wed Aug 01, 2018 2:30 pm
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

When I retard the engine timing below 12º, idle rpm drops. WHY#7.1? When I advance engine timing to more than 12º, idle speed increases to beyond 800rpm WHY #7.2 Found a few moments.... 7.1 : When you retard timing, the fire starts too late, fire burns nicely by the time the piston is well on its w...
by jagwit
Wed Aug 01, 2018 11:57 am
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

if u don’t have a ported vacuum tapping, manifold vacuum can be used. Thank you Colin. May I add please? For the benefits ported vacuum advance may hold, it certainly is not worth the cost and risk of: - removing the carbs - having them drilled and fitted for ported vacuum (hoping they don't get dr...
by jagwit
Wed Aug 01, 2018 7:26 am
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

Gents, Tomorrow, I'm off the the bush as a volunteer for the "Tour de Tuli" cycling event. I'm coming back on the 7th, so please don't stress if I don't reply in this time. Colin, I don't have time to also address your latest post because I have run out of time. I do believe that my posting above ma...
by jagwit
Wed Aug 01, 2018 7:21 am
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

jagwit I think that Jerrl [ nearly spelt his nme right] raises a very valid observation, plus his honesty is to be applauded Idling the engine............... loosen distibutor clamp then swivel right to left and back again, repaet and repeat until the sweet spot is found !!!! Yes its at idle rpm bu...
by jagwit
Tue Jul 31, 2018 6:54 pm
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

It was my understanding that one way of finding the "proper" timing (adv BTDC - when you don't know the advised figure) was to rotate the dizzy one way and/or the other to find the max rpm position at tickover. In other words, when you advance past this position, the tickover speed will reduce. Whe...
by jagwit
Tue Jul 31, 2018 2:28 pm
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

Question 7: Right we have "our engine" idling nicely at 800RPM with 12ºBTDC. No vacuum retard or vacuum advance connected. I trust you will now keep in mind that this 12ºBTDC is 12º not because this is what is needed at idle, but this is the timing needed when the engine goes from "idle" to full thr...
by jagwit
Tue Jul 31, 2018 2:19 pm
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

When talking about efficiency we maybe need to be clear about what it is that we are trying to be efficient about. E.g.1: If the purpose of a car is to move, at idle (stationary) efficiency is zero or worse, more efficient if u turned yr engine off. Burning petrol to overcome parasitic loads, frict...
by jagwit
Tue Jul 31, 2018 9:21 am
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

Idle speed is the engine rpm when the throttle plates are being held open by the idle adjustment screw? Yes and no. Yes, when the engine is running at 800RPM No when the engine is running at eg 5000RPM (This condition is called "overrun" again requires its own unique fueling and timing. I want to t...
by jagwit
Tue Jul 31, 2018 6:59 am
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

You've lost me. Idle speed is by definition, minimum throttle. Thank you for your question Colin!! You are absolutely correct. But I'm sure that you can see that "idle" at 800rpm and full throttle at 800rpm are two very different engine operating conditions that SHOULD require two very different fu...
by jagwit
Tue Jul 31, 2018 6:28 am
Forum: Technical
Topic: Ported vacuum advance vs manifold vacuum advance
Replies: 43
Views: 668
South Africa

Re: Ported vacuum advance vs manifold vacuum advance

therefore definition of Idle speed Must have reference to throttle position Absolutely correct Robsan! Your comment has also prompted me to include reference to sources of idle air and fuel and spark timing. Will amend the definition. Please keep the suggestions coming!! "Idle" definition rev1: It ...