Twin Webers

[KaboomJohn111]

Hi all,

 

Been planning this upgrade for my 83 KE70 (4k-c) for some time

 

I plan to replace the stock intake system, for twin weber carbies

But Since I want a twin setup, I was unsure weather to go with 2x 40 DCOE (weber 151), or 2x 45 DCOE (weber 152G)

 

Currently have Tighe 104 (270 deg)

And Full custom exhaust (2 inch from extractors back, 2 inch resonator (14 inch length body) (sounds great)

The car is my daily, so I want it to be liveable

[altezzaclub]

Twin 40s... If you were going to race it the 45s would be good, but that cam is fine for daily driving.

 

You'll need around 30mm venturis, which is why the 30mm quad bike carbs are an option for 4Ks.

[5KKid]

Agree twin 40's they will be better for a street motor, I have a 270 deg cam and twin 4dcoe Webers with 32mm venturies to match my inlet ports of a 3k bigport head on my 5K now, I had 45's on the motor some years ago and It didn't start making power until up in the last half of the rev range, 45's were the 40's seem to rev quicker,

I can give you the jetting size for twin 40's on my 5k for a starting point if you like I could dig them up for you,

[parrot]

Also agree with above. If you haven't already, get the head ported and shaved for some sensible compression around 10:1. And match port the manifolds

[KaboomJohn111]

Thanks guys

 

Heads Have been ported but not shaved, and will need to get the port matched to the new manifold, btw anyone know where I can get a suitable manifold (That was my other concern)

Will it be necessary to get the head shaved, I though it only necessary if I have a cam grind of 280 deg or higher which then i'd need at least 10.5:1 compression

 

And 5KKid, I'd would be gracious if you can find the jetting size for your 5k, I'm just guessing I'd need a size or so smaller than what you currently have

 

Another question is that can the stock fuel pump be sufficient or need to upgrade that at the same time (Since If I can i would upgrade it at the same time)

 

This is the carbies i'm going for http://www.weberperformance.com.au/product_info.php?cPath=1_9&products_id=2&osCsid=ln1fjtm1s9h4sm6cltd9qmri26

If there are any specs I should request like 30mm venturis, Please let me know

 

Cheers all

Edited October 4, 2016 by KaboomJohn111

[parrot]

Have a read up on compression. Don't overdo it as you will run into problems on a multiuse engine.

 

The standard fuel pump should be sufficient. I ran twin Webers etc in a 2T in my TA 22 Celica for years on the standard fuel pump. Often people like to run an electric pump, but these are moderately expensive, and need to be wired carefully to ensure the pump switches off in the event of a rollover (for example). You also need to be careful about the fuel pressure the electric pump runs at or it may overwhelm the needle and seats and flood your sump with fuel when you turn the pump on.

 

You can set it up with an appropriate pressure pump, fuel pressure regulator etc, mount the pump in the boot near the tank (most electric fuel pumps push rather than suck fuel), wire it properly etc - or just use your stock mechanical pump. I would do the latter.

 

If you search Weber settings, I have a post somewhere with a booklet of recommended chokes/jets put out by warneford from memory. This will at least give you some reasonable starting points, but you would always need to put the car on a dyno to get it right.

 

 

[ke70dave]

I've also not come across a carby fuel pump that isn't annoyingly loud......

[parrot]

Yes. I had a solid state facet pump in a Datsun 1600 (after having flooded the sump and washed the bores with a too high pressure pump). That was rubber mounted to the floor but still made a hell of a racket.

 

Here is a link to the thread with the weber settings: http://www.rollaclub.com/board/topic/61441-weber-settings/page__p__619800__hl__+weber%20+settings#entry619800

[twistie]

I did this with twin delortos off an alfa gtv & a manifold from the US air force base drag club on Guam island.