weber 38/38 prefer 32/36

Tweety · Post by **Tweety** » Thu Jun 11, 2015 8:21 pm

As it reads. My fully rebuilt ea81 engine with torquey cam. I expected a drop of 2-3 mpg and got a drop of around 7-8mpg.

This is too much to bare for a retired couple wanting some fun on a trike.

If anyone owns a weber 32/36 in good nick wanting to swap for my new new 38 give me a yell on 0438360934.

Its a good carb just a little thirsty.
Tony

Subydoug · Post by **Subydoug** » Fri Jun 12, 2015 6:28 pm

Il have a chat with Paul for you Tweety. I would give you my old carby but theres a little bit of toing and froing with Paul about putting it on a mpfi ea82 block for Wayno. If he doesnt want it you can have it.

Regards

Doug

steptoe · Post by **steptoe** » Sat Jun 13, 2015 8:56 am

Tony, I wonder if the fuel guzzle is due to the 'made for efi' inlet manifold and worth trying to swap the new carb onto plain jain carby inlet manifold ? Fitting the same spfi inlet to mine has resulted in a 10% drop in fuel miles or kilometres, then a retune to try recover what I lost in economy, an now rarely get my 540 km to 65 litres. Did this week and it involve 100km cruising at 115kph which usually causes guzzle figures

Subydoug · Post by **Subydoug** » Sat Jun 13, 2015 10:49 am

Block of wood behind the pedal for you Jonno! Harder of tweety as theres no Pedal...hmmm Electric shocker when over 60% throttle for more then 10 seconds!

Regards

Doug

Tweety · Post by **Tweety** » Sat Jun 13, 2015 12:13 pm

Thanks Jonno, did think of that for a minute or two. Lets face it, with a 32/36 carb there is a lot of driving time when the first throat only on a 32/36 would be in use. I had a long time thinking about this when on my trip this week from Strathbogie to Donald (around 340 kms one way) country driving. Everytime I'd ride through a town I'd be on the small throat. Everytime when cruising and behind a caravan/truck at say 80kph, I'd be on the small throat only. It just makes sense to me to go the way of the 32/36. I'd have the option of the small manifold (I have the old one) if the 32/36 doesnt perform well.

4 years or so ago when the ea81 first went into the trike I had a 32/36 and achieved 27 mpg minimum and 34mpg maximum. yes it was on the stock manifold. Now I'm getting around 19 minimum and 23 maximum. As for the benefits of the 38 yes, take off is really good but I can sacrifice some for economy.

Doug- am more than pleased to accept that offer if it comes around soon- thankyou. I have a guy willing to part with one of 3 carbs so see how I go

Tweety · Post by **Tweety** » Sat Jun 13, 2015 5:42 pm

guys, I did some checking of the timing today. Remember I dont have a flywheel with timing marks on it. I wont change it because it was adjusted for maximum hp on the dyno. I have a permanent steel pointer marking the point at idle.

The crank pulley is 367mm circumference meaning one degree is a little over one mm. the pointer is 13mm from the crankcase halves. meaning timing is 13.25 degrees. At high revs the pulley mark is 15mm further on or 28mm from the crankcase halves. This adds up to just under 29 degrees from TDC full advance.

Tweety · Post by **Tweety** » Sun Jun 14, 2015 12:12 am

For Jonno, Re: your suggestion (valid) that the SPFI manifold might cause less velocity of the intake gases.

To quote General Disorder "It can be done - I've put plenty of EA82 SPFI manifolds on EA81's and I know of a couple people that have put the EA82 carb manifold's on as well. Not saying there won't be any modifications needed but it can and has been done.

GD "

Was on thread http://www.ultimatesubaru.org/forum/top ... a81-block/

another interesting thread on ea81-2 manifold swap http://www.angelfire.com/crazy/bushy5552/weber1.html

I've read up a fair bit on this topic. Seems the threads elsewhere relate to huge manifolds replacing stock ones. Thats where it is common that owners lose power. I dont think the return to the ea81 manifold is worthwhile. The carbie adapter I had made up has an angle on it straightening the carbie up. This wouldnt be on the ea81 manifold as the mounts are far narrower. It is something I'll take into account after the 32/36 is put on and if the economy is still poor. Good of you looking outside that square mate.