johndregg

johndregg

Active Member
Running a 3.5 on twin SU carbs. Up to now it's been running two 35mm mixer plates. It's always felt a bit gutless on lpg, lacks grunt uphill but sits at 65mph returning 4-500klm per 90 litre fill up on a run.
Been reading a lot about blos mixers being the best solution for running lpg through carbs, so I took the plunge and bought a couple.
I fitted them today, basically running them through two elbow pipes into the SU carb mouths.
Followed the instructions supplied and have got the engine running well enough to test drive it. So far it feels strong, it revs more freely than before and has a much deeper tone at the exhaust.
I intend to get it to an lpg specialist for final set up and I will post back here on the results wether good or bad. First impressions are that the engine sounds like it does on petrol, that pfft pfft noise that it had on lpg before is gone. Let's see how it goes.
ae7f822c5d6235e040554870061ef967.jpg
 
Ran into a problem as soon as I took the car out on the open road. It would seem that the old low comp v8 doesn't creat enough vacuum through one bank on its own to fully open the Blos slide. Going to cobble together a junction pipe tomorrow so that both banks are operating through one blos and see how it runs from there.
Still sounds lovely though and is nice to drive until you plant the throttle and it runs out of puff.
 
Nice looking install though...................... I'm about to go over to Blos, most of the research I've done suggests one Blos is plenty for a 3.5 - so your single set up should cure it, plumbing just wont look so cool, good luck and looking forward to your results. [Mine is on a Weber 500 though so a bit different]
 
Yes, I've overdone it with the blos bling. My mistake was to imagine each bank of four cylinders to behave like two separate four cylinder engines, when they actually pump air at half rythmn (compared to an inline motor).
With the next attempt using one blos for all eight cylinders I am expecting better results.
Though the sound of the engine is much throatier already and a part throttle it runs nice.
Ordered all the pipe work and clamps today to make my new intake. Should know by the weekend hopefully.
 
Excellent, should work fine sucking through one Blos. How much were they? From Poland? Where are you ordering your intake bits and bobs? I'm designing a plenum thingy as I object to giving RPI a fortune for their saucepan! but will be needing some ducting etc.
 
Yes, I ordered the blos from Poland, think they worked out at £100 each posted so if I'm selling one next week I think I'll offer it a £75+ p&p. someone can grab a bargain.
I've used the two alloy pipes from the SUs to the Tee piece, then some blue silicon hose to seal these to the tee piece. I will mount the blos to the inlet from the air filter on this Tee piece.
Used ebay to find all the hoses and clamps.
I'd like to make something that put the blos closer to the carbs eventually but I'll see how I get on with this first.
 
That looks good - closer would be better - give me 1st refusal on the Blos if it's going spare, A
 
In your previous thread I mentioned carb balance but what I was also unsure of was whether a single vapouriser would send a balanced delivery. Iwema sell a bullet mixer with 2 LPG feeds. Their setup (on an efi rrc) uses 2 vapourisers :\
 
Right now with one blos for each carb you can see that each bank just doesn't create the vacuum to open the blos all the way. I'm assuming it's the firing pattern having pauses in it if you know what I mean, as a cylinder pumps on one side the next vacuum stroke comes from the other side (have I got this right??).
I'm hoping that running both carbs through one will cure it.
I'm also running on the assumption that my reducer was ok on two mixer plates, so should be ok on this system.
I'm in contact with the seller of the blos mixers and he is trying to help aswell.
If all fails and it's not better than it was before, I can also return to the flat mixer set up. :-/
 
I think your logic makes perfect sense [and a Blos is probably not as sensitive as an SU/Stromburg] so if there is not enough vacumn to fully operate the Blos then it wont.............. Logically you could reduce the size of the inlets pre Blos but then you'd be getting close to being back to square one. Both inlets drawing through one Blos must sort it. As I'm running a Weber my plan is to feed almost directly into the top of the carb, 64 or 70mm inlet then Blos then aircleaner/filter - hopefully I'll have enough vacumn. Did your Blos come with the spare slits? Maybe trying the next weaker one would help? If not then the next richer? Still interested if you have a spare Blos - keep me informed, thanks Ali
 
It didn't come with the spare tubes, but I think the mixture will be ok on the one supplied.
The seller has suggested taping the front up bit by bit to increase vacuum, something I've done in the past to a lambretta air box to richer up the mixture, but if it gets to that stage and there's no performance improvement I will be fitting the mixer plates back.
Positives so far are: Starting, when warm it starts like it's on petrol, no problems and the engine feels free-er, so I'm still hopeful that this will work well.
 
TBH I don't have a clue about Lpg. I understand the blos because it's like a cross between the dellorto carbs I use on two strokes and the su carbs on the landy.
 
I'm no expert, plus the 110 has been unused for over 10 years so I'm as rusty as it is.................. I assume you got yours ready converted? How old is the conversion? The early mixers were mighty basic apparently and hugely restrictive - the one on my 500 is unbelievably restrictive which is why I'm thinking Blos. My concern with them though is that no-one here seems to sell them, can't help wondering why. If you have no luck then maybe a change of mixer is the answer? Anyway will be interested in your results, regards, Ali
 
eb1c8182ccb0f79c764e1d58624a47dd.jpg

This is the set up that I'm currently trying. I had to wait for some pipe work to arrive and that took a few days. Running one Blos through part of the original air intake system.
It now creates enough vacuum to operate fully, the engine revs freely and on the road it will rev out further than on mixer plates.
First impressions are very good.
 
Just did my first start from ice cold on gas, started after just a few seconds instead of the usual cranking for 30 secs then a cough, cranking 10 secs start from before. Progress!
 
1 BLOS is sufficient for the 3.9/4.0 Serp engines, so should be pleanty for a 3.5

Landy056.jpg


This is my old series 3, this is an LPG only machine, no ECU, injectors are in there just to plug the holes. Starts no issue at -5°C.

I'm using an OMVL R90e as feed to the BLOS, and a free flow air filter, no restrictions required to increase the vacuum.

If your prepared to go LPG only then put an EFI manifold on, far less restrictive compaired to breathing through two SU's
 
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