engine and drivetrain PLEASE help me select a distributor

[jdeitch]

I'm restoring a de-smogged 1974 2002. It currently has the original de-smogged engine in it. I have installed a Weber progressive 32/36 carb (Using stock air cleaner with a JAM adapter) and a IE tube header, otherwise it is stock. This engine will be used as a daily driver. The distributor is currently the vacuum advance AND retard dizzy that smog equipped cars came with.

I will save the mechanical advance dizzy for the twin 40 DCOE engine to come in the near future. For this daily driver I would like to convert to a single vacuum advance ONLY dizzy but I'm not sure which one to use. I have included a pic of the various dizzys and their specs. I will install electronic points.

Based on specs alone, the JFU4 0 231 169 007 or 0 231 170 214 look to be the best choices.

Please share your experience/knowledge.

[FunkyLaneO]

your 74 should have a vacuum retard only distributor in it, sounds like the one in there is from a 75 or 76.

[1453aalapapa]

if you go here, you will find that most are no longer available

http://www.bosch-automotive-catalog.com/public/catalog/products?p_p_id=BoschWSRP&p_p_lifecycle=0&p_p_state=normal&p_p_mode=view&p_p_col_id=column-1&p_p_col_count=1&_BoschWSRP_wsrp-navigationalState=%2FWFS%2FAAGLOBAL-AA-Catalog-Site%2Fen_US%2F-%2FEUR%2FViewSearchProduct-Start%3Bpgid%3DD41D8CD98F00B204E9800998ECF8GCb4NNHA%3Bsid%3D9yyoG206f013ECMnE2Uk4WKxPBLL26YElOw%3D%3FSelectedMenuItem%3DSearchProduct&_BoschWSRP_proxyportlet-remoteInvocation=true

[PatAllen]

if i where you id use the current one you have, dont connect the retard hose, leave the nipple empty/free air. connect the advance one to the base of the weber carb. readjust timing for best performance before knock.

http://www.bmw2002faq.com/component/option,com_forum/Itemid,50/page,download/id,57699/

[jdeitch]

if you go here, you will find that most are no longer available

I will acquire one used and recondition it.

[1453aalapapa]

if you go here, you will find that most are no longer available

I will acquire one used and recondition it.

how bout just get any one, and send it to these guys. they can recurve it to whatever

http://advanceddistributors.com/

[PatAllen]

if you go here, you will find that most are no longer available

I will acquire one used and recondition it.

why not keeping the actual one ? other than the dual vacuum unit it is not much different than any other for low CR motors.

[Paul7002]

Why Not use the mechanical advance dizzy? I don't think you need to save that for dual side-draft, hi-perf cars. I have been running one on my car - 38/38, 9.3 c.r. otherwise stock motor for 7-8 years now with no probs. Got it from Max

[PatAllen]

Why Not use the mechanical advance dizzy? I don't think you need to save that for dual side-draft, hi-perf cars. I have been running one on my car - 38/38, 9.3 c.r. otherwise stock motor for 7-8 years now with no probs. Got it from Max

because the timing curve is not "optimal" for a desmoged 74 low CR motor. he will loose performance by doing so, his actual dual vac one is better suited for that low cr motor, even with no vacuum lines connected a all.

[jdeitch]

I restore cars as a business/hobby and I've been involved in the debate over machanical vs vacuum advance dizzys many times. A vacuum advance dizzy is best for performance and economy. IMHO

Here is a great article from a V8 site. Take a minute to read. Very informative.

http://www.pro-touring.com/showthread.php?29320-Mechanical-advance-vs.-vacuum-advance-article

Here is an old, but excellent article regarding the beloved 2002.

http://www.bimmers.com/02/upgrades/engine.html

The advance/retard dizzy I currently have installed needs the relays and vacuum switches that were part of the removed smog equipment to function properly, and thus my quest for a vacuum advance only dizzy.

Thanks for your input thus far. Keep it coming.

[PatAllen]

The advance/retard dizzy I currently have installed needs the relays and vacuum switches that were part of the removed smog equipment to function properly, and thus my quest for a vacuum advance only dizzy.

This statement is highly arguable.

It doesnt need them anymore, just connect the advance port to the base of the carb. you will get exact same result as any other vac advance only dizzy. The timing curve are very similar among all thoses.

As far as i know all other vac advance only dizzy where working on solenoids too. There was vac advance only when engine was cold, for EMISSION PURPOSES, not performance. Only vac retard where connected directly to the base of the carb.

A vacuum advance dizzy is best for performance and economy. IMHO

exactly what i said above.

[jdeitch]

The advance/retard dizzy I currently have installed needs the relays and vacuum switches that were part of the removed smog equipment to function properly, and thus my quest for a vacuum advance only dizzy.

This statement is highly arguable.

It doesnt need them anymore, just connect the advance port to the base of the carb. you will get exact same result as any other vac advance only dizzy. The timing curve are very similar among all thoses.

As far as i know all other vac advance only dizzy where working on solenoids too. There was vac advance only when engine was cold, for EMISSION PURPOSES, not performance. Only vac retard where connected directly to the base of the carb.

A vacuum advance dizzy is best for performance and economy. IMHO

exactly what i said above.

The dizzy I currently have is not listed in the chart I attached. I currently have a JFUD4 0 231 181 011.

From my undertanding, the relays controlled/varied the advance/retard based on engine temp. These smog engines were timed while the dizzy was being retarded. So the total advance is actually amount of retard PLUS the advance amount. Starting from zero (no vacuum retard) and only using the vacuum advance would not yeild many degrees of advance. MAKE SENSE?

[PatAllen]

MAKE SENSE?

no, the inards of the dizzy is mechanicaly the same, regardless of the type of vacuum units used. just reset your timing without the retard, and use only the advance portion of the vac unit and you will be all set. you can trust me. try it !!

dont forget there is still a centrifugal advance in there.

[jdeitch]

MAKE SENSE?

no, the inards of the dizzy is mechanicaly the same, regardless of the type of vacuum units used. just reset your timing without the retard, and use only the advance portion of the vac unit and you will be all set. you can trust me. try it !!

dont forget there is still a centrifugal advance in there.

I will shurely give it a try. How would recommend I time the setup I mentioned above? Initial timing? Vacuum hose off or on?

[PatAllen]

MAKE SENSE?

no, the inards of the dizzy is mechanicaly the same, regardless of the type of vacuum units used. just reset your timing without the retard, and use only the advance portion of the vac unit and you will be all set. you can trust me. try it !!

dont forget there is still a centrifugal advance in there.

I will shurely give it a try. How would recommend I time the setup I mentioned above? Initial timing? Vacuum hose off or on?

at this point factory timing procedure wont do it well and is VERY relative...

if it where me, i would time it to get highest possible idle when hot, then back-off 2-4 degrees. vacuum can be left connected to the weber carb since at idle there isnt any vacuum there, vacuum apears on this port only when the throtle plate is opened 2-3mm and more. you might want to make sure there is no vacuum there at idle. if there is any the carb is out of adjustements, or you used the wrong port, some has a EGR port (if we talk about weber 32/36, Toyota and jeep retrofits and some others iirc has the egr vac port driled out right next to the advance port !!)

then i would fine tune and listen for any ping at wot. if there is no ping then try advance it a litle and feel any performance increase, if there is ping back-off timing 2-3 degrees. not realy scientific but other than a dyno, this is the procedure to get the most performance possible, assuming the afr is fine at wot (12-13:1 air/fuel ratio).

hth.