Lotus Elan

Warmed Up Stromberg Head

PostPost by: david.g.chapman » Mon May 24, 2004 5:49 pm

I am in the process of getting my Stromberg cylinder head new valves, seats guides etc, and also having sprint cams and big inlet valves fitted.

This should hopefully increase the power to 125-130 bhp from the 115 bhp standard, even though I have a low compression head.

Do I need to change the needles in the carbs, or will the carbs compensate for the extra intake flow in their constant depression mode? I have B1Y needles at the moment.

Dave Chapman.
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PostPost by: elan_fan » Mon May 24, 2004 6:43 pm

If you have an SE engine which yours must be if you are quoting the 115 bhp output then check carefully as you should already have a high compression head and D profile i.e. sprint cams. there is a stamp on a raised part of the casting in the well at the front of the head and yours should be H for high compression. You can also make a quick check on your cams, they should have two rings on the circumference of the boss at the sprocket end to denote D profile. The correct needle is B2AR floating. If you want to go the whole hog QED does a nice fuel injection kit for the stromberg head.

regards Mark ;)
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PostPost by: patrics » Mon May 24, 2004 7:46 pm

Mark,
I think you will be okay with either B1Y or 2BAR just make sure you use the adjustable type piston assembly. I got a 130 bhp out of mine but that was with L2 cams
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PostPost by: steveww » Mon May 24, 2004 8:48 pm

What other mods did you have done to the engine as well as the L2 cams?

L2 is pretty wild 0.354 lift 302 duration with 49/73 I am surprised that the high duration works with the Strombergs, that is a big overlap through one carb :o Must be very lumpy at low rpm

I am also surprised that the normal B1Y needle worked, did you do any mods at all to the carbs?

I was thinking of going with the Holbay cams with my Stromberg: 0.389 lift 288 duration 34/74

I think there are a few Stromberg drivers who would be interested in the details.
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PostPost by: david.g.chapman » Tue May 25, 2004 9:27 am

I quoted 115 bhp without thinking. My engine was a federal type - number I21300, converted back from federal spec to UK spec. There is no letter marked on the head, and the cams only had one ring - so we are probably only talking about 105 bhp as the baseline?

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PostPost by: types26/36 » Tue May 25, 2004 10:42 am

Steve,
My specs for the L2 cam are : 46/70/70/46 Duration 296degrees lift .345"
It is a fast road cam and is quite tractable as I have used it.

The L1 cam which is a rally/race cam with 46/78/70/50 timing, duration 304 degrees, lift .410" (but requires work to the head) is not so tractable but still driveable, I have them in my S2.
I have only used them with webers and have no experience with Stromburgs.
rgds Brian
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PostPost by: david.g.chapman » Fri May 28, 2004 11:53 am

Thanks for all of your inputs.

I will stick to my B1Ys for now, although I can only adjust the mixture by taking the top of the carbs off and repositioning the needle in the air piston assembly.

My engine is running slightly rich at the moment with the needle shoulder in the recommended position i.e. level with the base of the piston. It might be OK with the new head... I will tinker.

Dave Chapman.
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PostPost by: patrics » Fri Jun 04, 2004 5:02 pm

Sorry Steveww for not replying,
With L2 cams the engine is not lumpy at all but it did have a slight flat spot very low down which I could get over by advancing the timing but then it tended to run on a bit. The flat spot wasn't really much of a problem and the car is / was still on points - car is completely stripped at the moment. I have the power and torque curve that I could post. The carbs were new off a V12 jag (same as Elan) just had to drill a few holes for the choke etc I also blocked off all the emission stuff - temp compensator and by-pass valve.
The head was gas flowed and I think the valves were bigger - if not then the seats were.
The only problem with the L2 cams was that they came in with such a bang that I couldn't resist driving it flat out all the time! If I was choosing cams again I would listen to others on the list with more experience.
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