Sidedraught Soft mount opinions?

Pedey · Post by **Pedey** » Wed Feb 12, 2014 8:52 pm

Hi everyone,

I've had conflicting advice in regards to soft mounts for triple carbs. Some say that they are a bad idea, a recipe for vacuum leaks and not neccissary. But then others, like the guys down at Hitech Motorsport today, said I should be running them.

Would really appreciate some thoughts from people in the know.

Thanks!

Ricky · Post by **Ricky** » Wed Feb 12, 2014 9:07 pm

Hi Peter
Nissan never used them on there L series 6 cylinder engines, Nissan motorsport never used them in racing, BRE never used them and I haven't used them.
They are required on 4 cylinder engines as then tend to suffer major vibration issues when pulling big rev's. They wont hurt your engine you will just spend more time than they are worth maintaining them.

Just my 5 cents worth.

Ricky

Pedey · Post by **Pedey** » Wed Feb 12, 2014 9:17 pm

Ricky wrote:Hi Peter
Nissan never used them on there L series 6 cylinder engines, Nissan motorsport never used them in racing, BRE never used them and I haven't used them.
They are required on 4 cylinder engines as then tend to suffer major vibration issues when pulling big rev's. They wont hurt your engine you will just spend more time than they are worth maintaining them.

Just my 5 cents worth.

Ricky

Hey Ricky,

Absolutely, it was your advice that I followed in the first place and it makes sense to me. So I was a bit confused when Grady told me I needed them! Thought I'd ask around, see what other people thought, though I'd rather not run them as they sound like a pain in the arse.

Did you have a look at my build thread? You might have seen the car didn't quite make it on its maiden voyage. I suspect vapour lock, but again, Grady said highly highly unlikely, so I'm unsure what to think ...

old_datto_fan · Post by **old_datto_fan** » Wed Feb 12, 2014 9:46 pm

Hi Peter,

I haven't run soft mounts on my car and not having them has not been an issue. My engine tuner/dyno man says you don't need them and he has been tuning sidedraught carbs for decades.

Mike

Andy · Post by **Andy** » Wed Feb 12, 2014 11:37 pm

I ran soft mounts when carburetted for no other reason than they were there, the four cylinder thing appears to be correct. I also owned probably the poorest tuned carbuettor setup ever.

However since not running soft mounts with the throttle bodies I have managed to split every weld on an alloy airbox and open up the fixing holes on a fibreglass airbox due to engine harmonics, so there maybe a case for soft mounting not the carbs but maybe to maintain the integrity of an airbox if used.

nzeder · Post by **nzeder** » Thu Feb 13, 2014 9:06 am

As stated Nissan never used soft mounts on the triples installed (be it works or sport options sold over the counter) on the L6 motors. I have never ran them on 3 cars I have had with triples and I will not be running them on the 2 cars I have now.

Andy re your comments - it most likely is not due to engine harmonics but engine movement on the mounts - you have more power engine, well you are getting the power from it now unlike your carb setup so you might not have seen the torque before and now you do

On a L6 I would not run soft mounts but that is just me, Nissan never did so why should I and Nissan spent lots and lots of $$ on R&D - also Prince before them did not use soft mounts on the G6 powered S54B Skyline GTB which were fitted with triple webers from the factory.

Also when you were in Japan how may S30Z and KGC10 with L28 and triples did you see running soft mounts - ahhh...none.

EDIT: Re the maiden voyage - car going fine then died later once cooled down all was good with the world again....I have seen this before on a carb power Mitsubishi Sapporo I had years ago (great road car shame it was written off by a drunk) it was the ignition at fault. Worked fine but then when the car got hot sitting in Auckland traffic it would just die - wait 30 minutes and it would start back up again and drive perfect this only happened twice before I isolated the fault and replaced the ignitor box then never happened again best $15 I ever got from the wrecker (kept the dicky one in the glove box as spare even though it had a fault)

merlin · Post by **merlin** » Thu Feb 13, 2014 9:19 am

I have had my 3X dellorto carbs running for 8 years (standard gasket) and no problems. I had more problems try to find a guy that can tune the carbs. Still looking!!

Pedey · Post by **Pedey** » Thu Feb 13, 2014 10:20 am

No soft mounts it is! Thanks for your opinions everyone, appreciated. I was already of that frame of mind in any case, Grady's comments just threw me.

Interesting point in regards to the fault Mike, might be something to look into. Regardless, I think I need a heat sheild in any case!

Baker93 · Post by **Baker93** » Thu Feb 13, 2014 3:15 pm

I don't run them either and my engine is solidly mounted ! Never a problem. Tell Grady he is dreaming

Though he is right re the vapour lock. It is not your problem. Vapour lock can and does cause difficult starting on our race cars, but I suspect we may have a bit more under bonnet heat than most road driven cars. Alloy air boxes will crack all day long. I have never solved this problem and have given up and moved on. Again as per Ricky's comment, just my 5 cents worth.

nzeder · Post by **nzeder** » Thu Feb 13, 2014 4:26 pm

I think I have 2 or 3 more different dizzy here at home. I need to do a big tidy up. The dizzy you have iirc is like the one I originally sold to Rocky many years ago. Ricky modifed his as per period locking out the vacuum advance plate and replacing the ignitor box on the side so the pickup when straight into an MSD type unit. So if it is ignition there are a few things that can be done to improve things.