11 replies to this topic

[DTV Racer]

Hello,

I have been using for hillclimbs and tarmac rallies, it seems forever, a 1293cc Howley engine with 36/29 stage 4 head, Kent 296SP, and a Weber 45DCOE with 38mm chokes, 12:1CR. Engine has always been a dream to drive (even though many fellow racers have accused me for not going to 40mm chokes) and very-very reliable; but competition went ahead, and I am no longer as competitive as I used to be.

I recently purchased a 1430cc short unit with Wossner forged pistons, S rods,etc, and I plan to keep the Howley head and the Weber. I am considering 3 different camshafts, it will be one of them. Either Kent Super Sprint 595, or Med AGSP, or Piper BP300.

My problem is the following: one of the reasons the Howley 1293 engine performed like a dream I believe is that as the 296SP had larger exhaust duration, and that combined with the relatively small head exhaust valve brought flow to balance. The three cams I am considering I believe are all symetrical. Will my new setup work well? What is to be expected powerwise? Do I maybe need to go to larger exhaust valve 30mm or 30.5mm? Will that affect reliability of the head? I am not sure I would like to touch a head that always worked great... And what are your opinions on these camshafts?

Thanks in advance for any input.

Basil

[matt large]

i used the med agsp in my 1380 autograss motor, was an all steel engine but pulled like a train all the way up to 7100rpm, power output was 121@wheels, cant remember torque figure, simon at Morspeed (who used to work at MED) built it, may be worth giving him a shout, work is first class, not far off firing my 1420 twin kam he built,

also used same cam in sisters 1380, slightly different spec made just over 100@wheels but again pulled like a train,

matt

[DTV Racer]

Hi matt,

What valve combination did your head have, and what was the CR?

Thanks,
Basil

[DTV Racer]

Any ideas for a good cam, anybody?

[Artful Dodger]

A special tuning 649 with 1.5:1 rockers:D

The 649 has Exellent qualitys but lacks lift for an out and out racer, which is why the higher lift rockers are necessary reccomended by DV in his book

[86mayfair]

If I remember rightly, the 649 was the lairiest cam that the Works cars used for tarmac rallies
This should give you an idea of how lumpy it is

And what it drives like - albeit in a 1293 with a very light flywheel

[bmcecosse]

I would stick with the kent 296SP - you seemed happy with it! And get the 40mm chokes..........

[DTV Racer]

I can remember the 649 in my previous oselli unit. 1293, 11:1, 649, 2x1,5 SU, great torque due to the cams overlap but not very revy engine, shifted at 7200, output 113bhp. My present Howley unit's output is 121bhp and I shift at 7600, the 296sp is revier than the 649. But guys I have to move ahead, my competition's power/ weight ratio asks for 130+bhp in my case and that's why I bought the 1430 block. Good 1430s make from 135 to 145bhp. Since I am keeping the Howley head with the 36/29 valves I am looking at 135bhp realisticaly. The 1430 is as revy as a 1293 I think, and certainly less revy than the 1380, but torqier. Kent 595 supersprint who is famous for supreme torque due to huge overlap and moderate lift, will it work? The BP300 sounds great idea, but 316 duration is maybe too much for a 1430? The Med agsp most people believe is a staight copy of the works Rover Mini Group A 90's camshaft, as sold by Minisport previously but not any longer. Is it such a miracle cam? Anybody?

[ACDodd]

If you are looling for 135 to 145 bhp then a Kent 310 with 1.5 rockers is where you need to be. 296 is all out of puff at around the 130mark. The 1430 is a lot less revy than a 1293 or a 1380 due to the longer stroke and higher piston speeds. Needs a big in take minimum 37.2mm. Worry less about the exhaust size in a high cr engine. Run 100 to 105 octane minimum and 12.5:1 CR.

AC

[DTV Racer]

Thanks AC, I will go for the large inlets, that's an easy mod as inlet ports are already 1.5" and I will get away with only the larger valve seat cutting. Is the 310sp better than the non sp 310? Is there measurable output difference?

[bmcecosse]

For hill climbing - I would want the wider power band of the 296 rather than a very peaky 310 with 1.5 rockers.....but it's your engine ! If it was a circuit racer - yes the 310 etc would be fine.

[Gulfclubby]

Don't forget the longer stroke of the 1430 will likely translate to the engine not being too happy revving too high. Thus I'd also go for something that works well in the lower revs too, you'll have the torque to do it.