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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Adjustable Vacuum Advance Distributors

I thought that many of you BBSers would be interested in one of these adjustable distributors. Below is an offer from British Parts Northwest, a excellent and competitively priced supplier of parts for our cars.

Frank Grimaldi

Product and Shipping Special.

The ignition timing and advance will be different for every car. This is why we have come up with an adjustable distributor for the 4-Cylinder BMC cars that use a DM2, 22D4, 23D4, 25D4 or the 45D4 distributor. Our high performance distributor has a performance advance curve dialed into them and the vacuum advance has been removed but the total advance of the distributor is adjustable. For instance your Big Block Triumph TR3 to TR4A with a big bore can’t have a pile of total advance so you most likely would set the total distributor advance between 18 and 20 degrees. But if you have a little 1275 A-Series you will need more in 24 to 26 total advance range. And last for all of you mileage heads out there you can even take your lower compression engine all the way out to 30 degrees of total distributor advance. Here is a link to the two distributors, the first is a point’s style and the second is a fully electric unit. Both function the same in the adjustable advance.

http://www.bpnorthwest.com/.sc/ms/bdd/ee/10389/Distributor%20High%20Performance%20Adjustable%2045D4

http://www.bpnorthwest.com/.sc/ms/bdd/ee/10390/Distributor%20Elec%2E%20High%20Performance%20Adjustable%2045D4%204-Cyl

Also it wouldn’t be a Thanksgiving weekend with out a shipping special, Black Friday for you brave souls. No need to get out in the weather for your British parts, this weekend from now until Monday the 29th of November we will have free shipping to the 48 states with any order totaling $150.00 for in stock items. All you have to do is use the word black in the coupon code box.

Again thank you for your business, and we love seeing all of the postings of your cars on our Facebook page. The pictures of the cars in the snow are great! Keep them coming, seeing the cars that people work on is a kick. Have a safe holiday and if you have any questions about the above specials or about any other parts just reply to this email and we will get it handled for you.

Regards,
British Parts Northwest

Frank Grimaldi

Hmm. So the curve is not adjustable? All engines have to use the same curve? Can't say that I see that working out very well. And I think removing the vacuum advance was a bad idea as well....

Sorry BPNW, but I don't think these are for me....

Thanks for posting this, Frank!
Rob Edwards

Vacuum advance isn't used in 'performance' applications as it greatly complicates finding and achieving the 'ideal' curve for a given engine and fuel. Vacuum advance is used on road cars as it significantly improves cruising economy, as well as sharpening part-throttle acceleration, neither of which are particularly relevant in 'performance' applications. Unfortunately many are suckered into thinking that *any* distributor without a vacuum advance is going to give them more power. This just seems to be an adjustable maximum advance, but that is only a relatively small part of timing, the curve over the rev range is far more important.
PaulH Solihull

Indeed, Paul. I think people see that "race cars" (define that how you will) don't have vacuum advance, therefore for race-car performance, remove the vacuum advance. However, what they don't consider is that a car on the track is at either full throttle or closed throttle most of the time, whereas a street car is at full throttle probably less than 5% of the time and at part throttle 90+%. The two applications are entirely different....
Rob Edwards

Yet another bit of bling sold by parts dealers to the unsuspecting owners who largely do not understand the implications of fitting these parts to their cars.

As well as listing it as an adjustable vacuum advance distributor with NO vacuum advance!

Does Frank work for BPNW? If so this is blatant advertising on this BBS.
Chris at Octarine Services

>Does Frank work for BPNW?

I doubt it -- BPNW is in Oregon and Frank is in South Carolina. They're in opposite "corners" of the country....
Rob Edwards

Dear All, I would have to agree. To dispence with the vacuum advance on a road car is not good news. Read Peter Burgess's chapter in his book Tuning the MGB engine for power and performance under the Ignition chapter. I Use the 123 ignition system made in the Netherlands, great, it is available in non-vacuum advance if any racing boys are going to use it, but has several other buit in advance curves so there is bound to be one for the state of tune of your engine. Did it live up to its name? By golly it did, I was most impressed.
J.M. Doust

This thread was discussed between 27/11/2010 and 06/12/2010

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