30 replies to this topic

[bikewiz]

1293 A+ 276 cam HIF6 LCB RC40 ss DTM twin box 65d electronic dist. what are the pros and cons of running or not running the vacuum advance? I know most of the race guys don't run vacuum advance. Or should I change to a better dizzy with a different curve to suit the engine better?

[dklawson]

What you elect to install for a distributor depends on what your expectations are for the car and your budget.  What are your plans?

[KernowCooper]

I have a BV Head 10.2 CR HIF 44 and a 276 cam and run a Aldon Yellow with vacuum advance. Racers dont use vacuum advance because A on wide open throttle there is no vacuum and its a economy device which on a light throttle with weak mixture which needs more advance to burn and it increases light throttle torque.

 

If its a car used on the Road it needs vacuum advance to be at its best, test it yourself remove your vac pipe and block it from sucking air and drive it, they dont feel as nice on light throttle or crusing and you'll loose appprox 5mpg+

 

Have you got any head mods to get the best out of your cam ? if so then a Aldon Yellow will be a better curve for your engine with vacuum advance

 

I'll say it again if its a Road Car It Needs Vacuum Advance

Edited by KernowCooper, 20 October 2014 - 12:18 AM.

[bikewiz]

What you elect to install for a distributor depends on what your expectations are for the car and your budget.  What are your plans?

Doug I'd like it more "driveable" it runs fine but I think it advances too much causing it to knock (over here) pink (over there) obviously on part throttle put your foot down and it goes fine. I've got the timing set at 4 degrees at idle.

[KernowCooper]

4degs at idle is not enough but most likely where you have to run to avoid pinking as your advance curve is not correct for your modified engine, change to a Aldon yellow and I'm running 12degs at 1000rpm, you'll notice a difference

Edited by KernowCooper, 20 October 2014 - 12:23 AM.

[bikewiz]

4degs at idle is not enough but most likely where you have to run to avoid pinking as your advance curve is not correct for your modified engine, change to a Aldon yellow and I'm running 12degs at 1000rpm, you'll notice a difference

I may give it a go. It runs pretty good but I'm sure it can run better. The Aldon is a bit pricey but I haven't spent any money on the car in a while.

[dklawson]

As Dave said, 4 degrees is good for getting an engine started but almost certainly not enough for good running.  However, you said that the engine knocks and pings under load which suggests that the mechanical advance comes on quickly, easily, and is perhaps full-on too early.  

 

I have not priced Aldon distributors.  If you decide to buy one, shop around in the U.K.  Any U.S. vendor such as MM is going have a substantial mark up on the price.

 

I suggest an alternative. Contact Jeff at Advanced Distributors.  Discuss with him the state of build your engine and tell him your distributor model number (5 digits marked on the side).  He can rebuild and recurve your distributor for you if you.  His work is not cheap but I have yet to hear of anyone who is not satisfied with the results.  

 

http://www.advanceddistributors.com/

[jaydee]

Race engines dont use vacuum advance since they're designed to work on full throttle only.

At part throttle is necessary to alter the advance to cope with the different fuelling (leaner, so needs more advance to burn) and this is done by an unit (mechanical or electronic) that works on vacuum.

Running a street engine with no vacuum controlled advance is hopeless.

[bikewiz]

As Dave said, 4 degrees is good for getting an engine started but almost certainly not enough for good running.  However, you said that the engine knocks and pings under load which suggests that the mechanical advance comes on quickly, easily, and is perhaps full-on too early.  

 

I have not priced Aldon distributors.  If you decide to buy one, shop around in the U.K.  Any U.S. vendor such as MM is going have a substantial mark up on the price.

 

I suggest an alternative. Contact Jeff at Advanced Distributors.  Discuss with him the state of build your engine and tell him your distributor model number (5 digits marked on the side).  He can rebuild and recurve your distributor for you if you.  His work is not cheap but I have yet to hear of anyone who is not satisfied with the results.  

 

http://www.advanceddistributors.com/

Doug it appears an Aldon Yellow costs around $200 + shipping Jeff charges anywhere from $130-200 for rebuild/recurve  the only thing with a rebuild is I'll be without the distributor for 4-5 weeks. I may buy an Aldon and see how it works I can then send out the original to see if it can better.

[KernowCooper]

Thats a lot of Money H&H Ignitions do a recurve here for less than £50 in P&P and I have used them before top bloke and 2/3 days turn around.

[bikewiz]

Thats a lot of Money H&H Ignitions do a recurve here for less than £50 in P&P and I have used them before top bloke and 2/3 days turn around.

Dave with shipping to the UK it would probably be close to the same 50GBP is around $80 insured DHL would be + - $30 each way. I'm leaning toward getting an Aldon and see what happens it may be all I need to do.

[KernowCooper]

I have one in mine and it is spot on no pinking  and the vac advanve unit gives excellent smooth crusing and no pinking.

[ACDodd]

Hmmm, I feel a mag article coming on.......

[carbon]

AC - a technical article about optimising distributors for modified fast road engines would be just great, this gets my vote

[carbon]

 

What you elect to install for a distributor depends on what your expectations are for the car and your budget.  What are your plans?

Doug I'd like it more "driveable" it runs fine but I think it advances too much causing it to knock (over here) pink (over there) obviously on part throttle put your foot down and it goes fine. I've got the timing set at 4 degrees at idle.

 

Agree with Kernow Cooper, for a modified 1275 with MD276 would expect to be more like 14 - 18 degrees at idle.

 

What octane fuel are you running on? And how much mechanical advance does your 65D give.