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SU's or Weber/mikuni


grannyknot

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I am planning my build of an L28 3.07 stroker with most of the bells and whistles and I will have to decide soon on either SU's or Weber/Mikuni's. This will be a street driven car with some track/autocross.

I have read a lot of the archived threads and basically it comes down to the SU camp saying that SU's can handle all the air needs of an L28 and therefore triple weber/mikuni's aren't needed. The Weber/Mikuni guys saying there is lots more HP hidden that the triples bring out. So who is right?

I am not in either camp at the moment but I would like to see the numbers, SU's are simple and easily maintained, triples look good and sound AWESOME but I don't want to spend $1500 - 1800 for great induction sound.

Can anyone point me to a thread or site that can help me decide?

Thanks,

Chris

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If you are going to drive the car on the street, I would stick with the side draft options. I know that the Weber guys are going to pitch a bitch, but when was looking to rid myself of the flat tops I did a bunch of searching and based my decision this way.

Finding #1, My motors specs, stock 240, would be a cool looking waste of $1500 to $2000 bucks.

Finding #2, There were like 3 to 1 people out there with Webers looking for technical advice VS the SU owners.

Finding #3, There are like 10 to 1 people out there running SU's on street cars over webers, and that means SU parts and advice were plentiful and cheap.

I went with the round tops, and aside from a vapor lock issue that I recently solved, I have had zero serious issues that I couldn't solve on my own. In my OPINION, the $1000 I saved over the Mikuni's gave much more bang for the buck when looking at the overall performance of the car. But I would still love to have a set on my Lil Girl....................

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Unless you are racing the car regularly, you are probably better of with round tops. There is no question that you will get more power from the triples (not just from air flow but from fuel delivery as well) but from what I have read there seems to be endless fiddling with jets and adjustments to get them set up.

Also, that performance comes at a price- like going from 20 mpg to 13.

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I was having a conversation last night with an MG owner friend of mine who is running a set of Mikunis on his car, and long story short, he is scared to death about the 15% ethanol mandate coming down the pike, He thinks that it will make the car unstreetable, i.e. race fuel only.

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Is 15% ethanol going to work any better in SUs? I don't know that it isn't possible to set them up for E15, but it seems like they would need bigger jets. E10 is already a pain.

Anyway, back to the original subject: I am convinced that if you are going to go to the trouble of building or buying a stroker you may as well go "whole hog" as the locals say and go to a crank sensor ignition system and modern fuel injection. Triples were the hot ticket back in the day, but there are a lot better ways to make power now.

Having two SUs to balance and setup is already a pain. Why would you want to make life even harder? I also strongly suspect that SUs aren't going to have all the power you want on a 3L+ stroker. (just a subjective guess...)

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What head and block are you planning on stroking? Give us some details on your plan so we can assist in guiding you a little better. Get ready to spend some $$! This is going to leave a mark on your wallet!

Oh yea - almost forgot - tell us how you drive your car currently - are you tracking it - weekend mountain cruiser - race car? That's going to be a lot of engine.........

Edited by Travel'n Man
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I'm an SU fan.......plenty of power throughout the power band....."0" problems. Everyone I know that owns sidedraft carbs are constantly changing this or that....fuel leaks etc. My SU's in my modified L28's run to redline in every gear.....w/o the constant attention to linkage, air/fuel ratios etc. Believe me, the SU's are very exhilarating! Sorry Mitchell.....

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I just put Webers on my 260. Read my write up under S30 carburetors: Triple Weber Install. They are pricey but no where near the monsterous finicky things some have made them out to be. You just need to understand how they work and what needs adjusting...once. They will add considerable HP to your engine. I've run round tops SU's for years and these triples blow them away. The Webers offer way more tuning capabilities if you want to "track/autocross". There are other threads on this subject. Lots of good writeups with problems and solutions.

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I've got to agree with Rocket Dog - install them - set them - forget them. Triples are a blast and not near the PITA that folks have made them out to be. I'll bet that most folks that have challenges either are not using a high quality refurbished units or they have not taken the correct setup installs, or some goofball sandblasted them. I will not go back to SU's (I've got them on a shelf in my garage - cause that is the best place for them).

The main thing that you will miss with SU's is the true torque and horsepower of your engine (however you build it) - I've had both in the exact same car with the exact same engine build - my Mikuni set up wins every time hands down. Not a doubt in my mind at all - sorry Guy......

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I think Travelnman asked the single more important question here.

How are you going to use the car? That is the key. Also, there is another option not listed..in terms of expense... they go:

SU's refurbed

SU's bored and modified for more flow

Triple Webers/Mikunis

If you do not want to go with the 1600 dollar triple setup, you can spend more than the 680 dollar SU setup and get a modified SU from Ztherapy that can flow a HECK of a lot more than standard SU's.

Give that a thought.

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I have been running Mikuni's on a 1971 240Z for the past year or so. Once I got them tuned they have stayed tuned. They fire right up and run smoothly every time. The only issue I have is a fuel smell in my garage if I shut the car down hot without opening the hood. I like triples enough that I'm in the process of refurbishing an old set of Webbers for my 1973 240Z. SU's are great. Very reliable and simple. Triples can be just as reliable but not as simple...just more fun.

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