HKM400

HKM400's 1969 Lotus 7 Series 3

90 posts in this topic

You've got me curious Rookie... I enjoy a good toast but not of the engine variety. I'm actually thinking about what Fliboi has suggested... on my manifold there is a vacuum outlet which I has been blanked off with a bolt, there is also what I believe is a breather coming from the block... should I just loop these with some heater hose so the vacuum circulates? I think the vacuum was used to power assist brakes or something? This will probably make me look like a total moron if I'm wrong haha.

 

Should also state the engine is all good at idle and starts easily with no choke (hasn't been cold recently though). Idle is around 1k which needs to be dropped, sounds pretty lumpy. Only under load does it start shitting its pants. 

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you dont want to hook that vac port to the breather, youll end up hoovering up all your oil. that breather should either go to the air filter, a catch can, or you can do what alot do and put a breather filter on there, but it gets messy and isnt really a best option. 

 

did the engine ever run properly in your ownership? i had issues with my manifolds not sealing against the head causing this issue (vac leak causing it to run lean as rookie said) 

 

do you know if that sidedraught carb is jetted for your engine ?

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Under load is where you will do damage. It is untuned right? Just keep plugging away and get it tuned at a suitable time, but don't drive it until you do.

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i highly recommend a wideband kit. i tuned my car for 6 months by feel. and remarkably did get it pretty close, but came to a point where i was going around in circles, got a wideband, and had it dialed in within the hour. 

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I too recommend a wide band!

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Engine never ran when I bought that car, so pulled it out straight away. It first ran last year after I rebuilt the whole thing, carb was rebuilt by a specialist and he apparently used the correct spec jets for that engine. Plus that carb came on the engine originally... wide band sounds like a good idea at this point and I will get someone to tune it properly... will not be driving it until then, damn thing is an arsonist.  

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I would look at an innovate wideband for a DIY'er , I have an LC1 which has served me well for a number of years. Mine is a bit like this:

 

http://www.ebay.com/itm/Innovate-LC1-Wideband-DB-52mm-Kit-O2-Sensor-BLUE-LC-1-3795-/400862052433

 

the LC2 is slightly different but will do the same job for you, no doubt there are cheaper and more expensive options out there which will be worse/better but this is what has worked for me. 

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i used the innovate kit too. 

 

pulled it out after i tuned, cause the sensors deteriorate when used. not sure when ill use it again, but i cant bring myself to sell it, after it proved its worth in tuning assistance.

 

edit/spam/ will probably bang it back in a bit when i put in the computer to take car of ignition, and i can map the AFRs a bit nicer and possibly refine it further. but dumb muffler shop chopped out the section of pipe with the boss welded in and didnt swap it over  :doubt:

 

tuning is fun

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Yeah innovate lc2 works fine for me

And leave it in for continuous tuning availability. I would argue that keeping it in the car longer term is fine/ value for money is good keeping it in

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Any idea what setup you've got with the carb at the moment? I am also having tuning issues with mine (weber 40 DCOE on 1600 crossflow), might be able to compare notes. Someone else might have some tips and/or experience too.

 

I've ordered (haven't installed yet) 34mm venturis, 140 mains and 190 air correctors. From advice I've got and researched online it sounds like it might be close at least. Might need to go up to 150 mains and 200 air correctors. Will hopefully find out soon and can have a look at accelerator pump etc.

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I had the carb refurbished by Simon at Palmside and he assembled it with the correct specs- specific to my engine which is the same as yours, 1600 Crossflow, single weber 40. 

I do have a regulator in the fuel line due to the fact that the pump I have may over or under fuel it...

 

Seems my engine just needs some attention from someone who knows more than I do about tuning- which isn't difficult...  

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well if he's got you in the ball park you should be pretty sweet, are there any air leaks, manifold is straight, gaskets healthy ect? if its spitting I believe thats more on the lean side, so checking reg/neadle valve/floats?

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Yeah, Simon seems to know his stuff. I would agree, sounds a lot like you've got an air leak or something somewhere. Could be a poor seal between your manifold and head or carb and manifold. Also make sure you check all your vacuum lines carefully, make sure they are connected properly without any splits or holes etc. 

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I really do need to do a thorough check of the manifold, there will more than likely be an air leak somewhere. Will have a spanner up today and see what eventuates.

This tuning thing will no doubt be never ending, will just have to get used to it! 

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Have you had any breakthroughs with the carbs? I'm getting excited to hear this thing sing!

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I rechecked the seal between the carb and the manifold itself, seems the o rings weren't sealing properly hence the leak. Haven't had a lot of time to try start it again and check if it's fixed any of the issues- put some fuel in it last weekend though so might have a crack today and see how I get on.

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Reg on hold right? If so, couldn't you just get a wof from that guy? No need to take it somewhere else

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Indeed reg on hold so that is the plan- Shouldn't be too many issues...... fingers crossed.

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Good work on the wof!

How did the carb tuning efforts go?

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