Spitfire My Spitfire doesn't have a vacuum advance

[spit71]

I have owned my bright red 1971 Spitfire for about a year. I have had a few ignition issues lately that I won't bore you guys with. However, while looking for distributor parts online I realized that all of the diagrams showed vacuum advances attached. I don't have one.

Now, I think my car runs OK. The top end seems weak, but I don't remember how my 1974 ran all those years ago, and I have owned alot of modern high performance import cars since then. My Triumph certainly doesn't want to rev like my Acura TL or Audi A4, but I don't expect it to.

Would a vacuum advance improve this or would it improve some other performance attribute that I haven't noticed.

My Spitfire is fitted with a Weber down-draft carb and Pertronix ignition. Any advice or experiences with this would be greatly appreciated.

 

[tdskip]

What kind of distributor is it? It should have a stamping on it.

It is possible that has been replaced at some point in the last 37 years....

 

[vettedog72]

It makes a significant difference with the TR6 under street conditions. I don't why it would not be the same for the Spitfire.

 

[spit71]

I'll check. AFAIK most things have been replaced or altered. PO was not a mechanic however (neither am I, really). a lot of little things needed attention when I purchased the car, like the choke wire not connected correctly, mixture super rich, etc. I guess I figured that this got left off at some point and wondered if it was worth replacing.

 

[tdskip]

First make sure you have a plug etc for it - lots of aftermarket parts can be swapped in over the years.

Second - assuming it is there then get the advance fitted. As pointed out above, it can make a substantial difference. I was pretty shocked at how much stronger proper timing made my TR6.

 

[eejay56]

A street car should definitely have the vacuum advance. It adds more advance at lower rpms to aid idle and around town driving. If the timing is advanced to compensate it could affect your top end. Don't expect it to run like a modern high performance car though, a stock US 1500 only produces 53 HP.

 

[guzzul]

A couple of pieces of info would help.

As noted in an earlier post, what is the Lucas model number of the dizzy? Check around your carb for a plugged vacuum line - typically around the throttle area - see anything? To eejay's point, what is the current timing measurement at idle (hot)?

A couple of pics would be good.

 

[foxtrapper]

My Spitfire is fitted with a Weber down-draft carb

And that is frequently why the vacuum advance is disconnected. Folks aren't sure where to connect it on the carburetor, and depending on the distributor, hooking it to the wrong vacuum port produces terrible performance. So many a person simply disconnects it and runs with centrifugal advance only.

 

[RonMacPherson]

If it's the 32/36 you should have a vacuum nipple down around the base plate. This should be ported vacuum. Check to see that there is no vacuum when at idle, but vacuum appears when the throttle is opened. This is where you hook the vacuum advance up.

 

[spit71]

A street car should definitely have the vacuum advance. It adds more advance at lower rpms to aid idle and around town driving. If the timing is advanced to compensate it could affect your top end. Don't expect it to run like a modern high performance car though, a stock US 1500 only produces 53 HP.

Wow, that had not occurred to me. I bet this is exactly what I'm feeling in the car. I did, in fact, advance the timing by ear while the car was idling. I'm sure this compensated for the rough idle and killed the top end.

I will look around over the long weekend and see if I can find the vacuum port and numbers off of the distributer.

I have been distracted lately by the new stereo I installed last week. (I purchased the retrosound from Moss). After the install, I realized that the shifter struck the face of the stereo when put into first gear. I think this says it all about my level of expertise.

 

[tosoutherncars]

I have been distracted lately by the new stereo I installed last week. (I purchased the retrosound from Moss). After the install, I realized that the shifter struck the face of the stereo when put into first gear. I think this says it all about my level of expertise.

Hahaha... thanks, had a good laugh at that... (but I'll try to remember it when installing mine!) Did you find a workaround?

 

[eejay56]

I have to be in 4th gear to put in a cd

 

[IanF]

We have a new dizzy in Robyn's '79. When I was having the running issues with the SU's, I fiddled with the vacuum port on the dizzy... and it doens't seem to do a darned thing... timing advances the same with or without it connected... applying vacuum to the dizzy when the car is running yielded the same result: nada... very strange...

The dizzy on the '73 Volvo is a retard-type and the recommendation from the 1800-gurus is to disconnect it, although for more modified engines they recommend seeking out one of the (rather rare) vacuum advance types that were installed on earlier cars.

Robyn installed a modern flip-down face stereo in the Spit. The shifter doesn't hit the face palte, but does need to be in 2nd or 4th to load a CD.

 

[TR3driver]

We have a new dizzy in Robyn's '79. When I was having the running issues with the SU's, I fiddled with the vacuum port on the dizzy... and it doens't seem to do a darned thing... timing advances the same with or without it connected... applying vacuum to the dizzy when the car is running yielded the same result: nada... very strange...

'New' doesn't always mean 'working'. I've had several dizzies come to me with the linkage jammed or disconnected inside; or of course it's possible the vacuum module is bad.
Whether retard or advance, applying vacuum should definitely move the timing.

 

[tosoutherncars]

Yes... I hate to suggest anything so basic, but sucking on the vacuum fitting should show a visible movement of the advance plate in the dizzy (or it did on my 1500, anyway.)