Lotus Elan

Cam choice for Stromberg head

PostPost by: 661 » Sat Feb 24, 2018 10:48 am

Following on from Rohan's comment in another thread:

Why a Stromberg head did not "work" when tuned is probably related more to the cam selection and carb tuning than to the flow divider itself. The Stromberg heads will tolerate a long duration cam much worse than a Weber head

I have a stroked and bored twin cam with a Stromberg head. I honestly can't recall the cappacity as it was late eigthies when it was rebuilt, but believe 1760 cc comes to mind
It is fully balanced and goes really well. It has 'D' cams and on the dyno at the time produced 126hp (which seemed like an appropriate number!)
But, if a chap wanted a bit more excitment in his life, is there an easy way to steal 20 more hp or so? I appreciate the needling on the carbs might need fettling if I change things, but what experience do we have ad is it really worth thinking of when there are a plethora of other things I could be doing to it?
Graeme
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PostPost by: david.g.chapman » Sat Feb 24, 2018 4:49 pm

I have a stromberg head in my +2 running CPL2 cams on a suggestion from an engine builder. As I did not know any better at the time I went ahead and got them fitted.

My engine runs OK, but I believe from what I know now that there are better cams out there.

Again from what I have picked up from this forum, the limit for a 1558cc engine on strombergs is about 130bhp. So with your higher displacement you might get what you are asking for.

So the factors that could give you more are

1. a higher compression ratio - 11.5 to 1?
2. A free flowing large bore exhaust
3. Porting work on the inlet and exhaust ports
4. Then pick the right needle to cope with what should be an increased air flow - hopefully!

Dave Chapman.
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PostPost by: 661 » Sat Feb 24, 2018 7:23 pm

david.g.chapman wrote:I have a stromberg head in my +2 running CPL2 cams on a suggestion from an engine builder. As I did not know any better at the time I went ahead and got them fitted.

My engine runs OK, but I believe from what I know now that there are better cams out there.

Again from what I have picked up from this forum, the limit for a 1558cc engine on strombergs is about 130bhp. So with your higher displacement you might get what you are asking for.

So the factors that could give you more are

1. a higher compression ratio - 11.5 to 1?
2. A free flowing large bore exhaust
3. Porting work on the inlet and exhaust ports
4. Then pick the right needle to cope with what should be an increased air flow - hopefully!

Dave Chapman.


Thanks Dave,
Advice from 'The Family'! I'm honoured.
I have a big bore exhaust
I bought it from a tiny outfit opposite the entrance to Brands which has long since gone, but it sounds like it does the bizz!
I'll have to try to find the original build spec , but 10.5:1 rings a bell
Graeme
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