Race set up for an Aceca Bristol

[AcecaRacer]

OK guys -
   Great dialog on the spark plugs.
   
   Now, how about race prepping?
   
   I am currently readying my recently purchased Aceca with a mildly race prepped D2 motor for the season. I am new to this motor and would appreciate any advice on how to set it up correctly:
   
   - Plugs
   - Electronic ignition
   - Carbs (currently have solex's without the accelerator pumps)
   - Brake pads
   - Brake fluid
   - Gearbox fluid
   - Diff fluid
   - Engine oil
   - Anything else I should know?
   
   All input appreciated as always....
   
   Cheers,
   Rob

[pls01]

Rob,
   I don't race my Ace but have tuned it up a bit.
   
   Plugs: I got one of the longer reach plugs, but didn't get around to checking it in the head.  I think its going to bottom out because the head is not tapped through.  I use the 6 heat range as noted befor
   
   Ignition: I put in a positive ground Pertronix.  It gives a little better spark and eliminates the point problems.  Downside is the ignition can't be static timed to get it close after distributor work.  Timing is done dynamically with a strobe, some where about 50 degrees BTDC @ 3000 rpm.
   
   Carbs: Solex with accelerator pump.  120 main jet and 190 air correction.  The book main is a 125, but the plugs are a little dark
   
   Brake pads: stock
   
   Brake fluid: DOT 4, If I was racing, a dual master cylinder set-up would be a priority.
   
   Gearbox: SAE 30 non-detergent
   
   Diff: SAE 90 hypoid
   
   Engine Oil:  Shell Rotella 15w-40
   
   Anti-roll bars and stiffer springs are useful on the track, but I took them off BEX375 for street use.  I have the specs and drawings for these parts.
   
   You asked about cams.  The stock cam has these specs  Lift 0.202, Duration @ 0.05 lift 193 degress, Lobe centers 110 degrees, Timing Intake ATDC 110.   The Bristol sport cam is 0.209, 212, 110 and 110.  My Isky cam is .236, 230, 110 and 108.  Stock valve spring don't work with the high lift Isky cam.
   
   Peter

[Jim A]

I am not familiar with the Pertronix system, but 50 degrees BTDC is by far the furthest advance I've ever heard of.

[pls01]

Rob,
   Yes, 50 BTDC at 3000 RPM.  I have a hard time believing it also.  At first, I thought doing something wrong, but I've been working with points and timing lights for close to 40 years and recheck everything.  Then I thought the marks must be off.  I rebuilt the engine several years ago and calibrated everthing with my degree wheel but didn't find anything wrong.  Actually, the original timing marks are very accurate  It's about 50.  Less than that and power drops off and the engine runs hot.  More and power starts dropping, but it never knocks.
   
   My centrifugal advance is a bit useless.  I need to get new springs and recurve it.  I set timing at 3000 RPM because the centrifugal advance is all in and not bouncing around.  I get a stable reading.
   
   Most other engines like about 30-35 degrees advance at 3000.  I just figure this a quirk of the Bristol.
   Peter

[Jim A]

I think 50 degrees BTDC is not quite half-way up on the compression stroke.
   Maybe that is the penalty paid for having the plug so deep in the head (that untapped section).
   I don't mean to be argumentative, but that figure just strikes me as counterintuitive.

[pls01]

No argument... I agree it is counterintuitive.
   I tried everything and couldn't believe it either.  Sometimes experience gets in the way. I'd set the timing at 35BTDC @ 3000 and tell myself it's right. The engine would run poorly. I'd give in and advance the timing to about 50.
   The manual has a method that was used before timing lights were widely available.  It produces about the same result.  I like using the light since readings are recordable and repeatable.
   50 may not be as bad as it seems.  Piston position is not linear to crank angle.  And yes, slow ignition, flame propogation and pressure rise requires more advance.
   Peter

[Jim A]

I was hoping to get back on and correct my post of yesterday.
   I think your point of linear vs angle is valid.  In any case 50 degrees would be 3/4 up the compression stroke, not 1/2.  This makes the case amazing, not incredible.
   I wish I still had a Bristol to experiment on!

[AcecaRacer]

Thanks very much for your posts.  Very helpful. Would love to hear from anyone else who has a racing Aceca.  I know there aren't many of us!

[Aceca289]

Here is a link to an Aceca that was campaigned quite a bit about 7-10 years ago. I remember an article that Alastair wrote in an edition of AC Action (March 2000) about one of his La Carrera Panamericana runs. Based on the article, this guy really liked to drive his Aceca hard and enjoyed the experience. Does anyone know if he is still a member of the ACOC and runs his Aceca on Rallies anymore?
   
   http://www.alastaircaldwell.com/cars_acAceca.shtml
   
   Looks like I answered my own question. Looks like he came in 1st in class and 6th overall in a Rally in Iceland in 2008. This guy sure likes to travel!
   
   http://www.alastaircaldwell.com/2008_iceland.shtml

[shep]

Hi All, I've been racing Cobras and Aces for the last 25 years and have learned a few tricks along the way. I'm sure the basics are the same for an Aceca as they are for an Ace.
   In my experience if you are serious about winning, engines come come completely rebuilt and shrink wrapped on a pallet! They need to have good strong torque and above all be reliable. Who was it said? "To finish first, first you gotta finish!" I get Steve Stanton here in UK to rebuild mine and don't touch them except change oil plugs and points every 6 hours of racing. That's normally about mid season.
   The next most important topic is suspension. I had springs made up which were 25% uprated and slightly shorter to give one and a half degrees of negative camber front and rear. I adjust the ride height with aluminium blocks between the spring and the spring tower on the chassis to give about one inch lower at the front. I made up some brackets and mounted anti-roll (sway) bars front and rear.
   Tyres are normally specified for the class of racing but I tend to run them on the hard side to start, and then measure the tyre temps outside centre and inside of each tyre immediately I come in. If the centre is hotter they are too hard, cooler is too soft. Easy as that!
   My Ace still runs the standard Bishop Cam steering which works OK. The Cobras are better with rack and pinion, but the Ace is never pointing where you want to go so it's less important. The same goes for brakes. I still run drums all round and use them as little as possible. Front discs would be an improvement, but if you look at the 2009 ACOC Goodwood Sprint results, the drums beat all the Cobras!
   To be able to drive at the limit you need to be comfortable, so spend some time finding a good seat position. I use the Ace seat and take out the base cushion to sit on the aluminium. It works for me and lowers my centre of gravity. Pedals need to be adjusted for reach so they work together for blipping on the downchange. I feel safer with a head hoop roll over bar and 4 point harness so normally fit them.
   Other than that, it's all down to the nut behind the wheel!
   
   Have fun and enjoy learning. Andy.

[AcecaRacer]

Andy -
   
   Great info.  Very helpful and appreciated.
   First race this weekend at Laguna Seca.
   I will keep all posted!
   
   Cheers,
   Rob

[nikbj68]

Best of luck at Laguna Seca, and PLEASE make sure someone is armed with a camera so we can see you in action!!!
   (or even better, get them to post videos on Youtube!!!)
   
   Keep it 'shiny side up'!
   Nik.
   [:D]

[AcecaRacer]

Had an outstanding weekend at Laguna Seca.  I  must say that the Aceca did very well.  Had some great duels with a Merc 190 and 2 hopped up TR-3's among others.
   I enjoyed a very diverse class of competitors as well.  Nothing like running flat out on the straight between turn 4 and 5 and seeing two Gullwings bearing down on me!!! I had everything from 120 Jags and 356 Porsches to a Siata 300.
   
   As soon as I figure out how to add pictures I will post a nother note!
   
   -Rob

[Aceca289]

Rob,
   
   Sounds like fun!  I wish I could have made it down from Santa Rosa to Laguna Seca last weekend to see an Aceca in action.  Are you going to make it up to the Sonoma Historic Motorsport Festival at Infineon Raceway on June 5/6? Hope to see you out at the track sometime soon.
   
   John
   AEX521

[AcecaRacer]

Hi John,
   
   Yes, I will be at the Sonoma Historics at Infineon.  I am also contemplating being at the CSRG event at Thunderhill in 2 weeks.
   
   I will keep in touch!
   
   Rob