Weber Stack Length

[Yuji]

I'm planning to puchase Weber carb soon for my GTD. Recently I was introduced Performance Parts Warehouse thru Red Line Weber as the distributor of Weber carb for me to contact. Performance Parts Warehouse recommend 48IDF as more streetable and easy to tune/maintain and most likely I'll go for this kit. Now, my question is whether standard 2" stack or alminum 5" stack? Is there sufficient clearance even install 5" stack? Could someone who use 48IDF for 302SB let me know your stack length? Appreciate your suggestion!

[Neal]

Mushi mushi, Yuji!

IDFs are slightly taller than IDAs. My IDAs have 2" spun aluminum stacks. I suspect 2" on IDFs will be close to maximum height for the rear carbs. I'd suggest you go with the 2" stacks.

Sorry, I didn't have a picture with the rear clip and window on.

[Yuji]

Thanks Neal! OK, I'll go for 2" stack.

[Tim Kay]

Yuji,

I have a set velocity stacks that measure 3" (top to bottom) on 48 IDF's. The very rear most stack slightly touched my rear window. Although, this could depend on where your motor is placed, I believe my motor sits about an 1" higher than some due to my Renault trans. Other tran's, i.e. porshe, ZF, allow the motor to sit a bit lower.

One note: under quick exceleration I get a lot of gas resdue sprayed on the rear window. A bit annoying.

(Hersh, this pic is one of the stacks I purchased and referenced in another thread yesterday)

[Iron Sheik]

Yuji Son,

As Neal mentioned, 2" is probably best. I also have a GTD and with 2", I can actually see behind me!!

[Hershal Byrd]

Neal,
I had IDF's and they sure looked much shorter than the IDA's . I think it's the other way around.. [img]/ubbthreads/images/graemlins/confused.gif[/img] [img]/ubbthreads/images/graemlins/smile.gif[/img]

Hersh [img]/ubbthreads/images/graemlins/smile.gif[/img]

[Frank Catt]

Hersh is right, IDAs are considerably taller than IDFs. The problems are that you cannot adequately use IDAs on a standard height GTD engine set up ( I met Fred from Belgium today in the UK, he has a smashed glass rear window to prove it! ) IDFs have some rather nasty characturistics on a GT40, if run on a more than stock engine, and will have considerable "stand off" (blow back of neat liquid fuel) from the tops of the carbs which can cause fires in the carbs, I have seen lots of IDF sets burning nicely. I did a lot of experimentation with IDFs to try to improve performance and reduce fuel stand off, one of which was reasonably successful. This entailed making extended venturi tubes to reach the same height level as the inlet trumpets, using improved radiused edged trumpets to get a smoother air flow into the carbs. Using mesh covers over the trumpets may look OK and in theory stop any ingress of debris, but the result is a very poor air flow, increased richness which if dialled out by the jets just kills high rev performance. The real answer is to lower the engine and use IDAs, which is what you will find on all UK track use cars running Webers. If you are just a road cruiser with a stock cam and compression, no revs over 5K, then it may work, but not for me ! Frank

[Yuji]

Mmmmm, lower the engine seems not be minor project for me, Frank. [img]/ubbthreads/images/graemlins/blush.gif[/img] Looks better to revisit the project.

[hcar]

Got to look at these
http://www.twminduction.com/v8_kits/302.html

[Fred/Belgium]

I agree with Frank.If you use IDAs on a standard GTD, you will have two options:

1.Lower the engine (I did'nt and finally broke my rear glass) and potentially air intake discrepancies by carb intake.
2.Put a rear window with an opening above the carbs(ie perplex window).

But boy, the noise of the Weber really outperform the exhaust noise when driving...and the look!!!...forget about the rear vision unless you had a big airfilter before(I mean you do not look only in the rear mirror for the traffic)... [img]/ubbthreads/images/graemlins/cool.gif[/img] [img]/ubbthreads/images/graemlins/cool.gif[/img] [img]/ubbthreads/images/graemlins/tongue.gif[/img]

And finally:make sure you have a local expert on Webers before you decide on this option!Once it is tuned,its ok for a long period.

It was a fameous investment to be honnest but its worth another car!!!

Fred

[David Briggs]

I am running IDF's w/2" stack on my 347, they work just fine. I also am using K & N air filters so there is no fuel standoff problem. I like 'em, they work great and sound right.

[Frank Catt]

Fred, I have just installed Weber IDAs into Martin Weigolds car , the top of rear most trumpet is 95mm (4inches) below the glass rear deck window, photos if you want them, (You showed me that the rear trumpet on your car touched the glass and had broken it! )Frank

[Frank Catt]

Fred, Picture added

[Frank Catt]

Another pic

[Fred/Belgium]

Frank,
I assume you lowered the engine?If so with how much and how?
Martins Weber set up looks great!
Tx
Rgds
Fred

[Frank Catt]

Fred, this is done useing the new rear chassis section developed for our new GT40 replica. The chassis is designed so that older chassis can be updated by the simple expediant of cutting off the rear chaasis at the end of the sill sections and replacing with the new piece, just four weld points and its done, although new lowered engine mounts are also needed. Frank

[Yuji]

Frank,
I wish I were there in continent so that I could ask your help!

[David Morton]

Yuji,
I fitted IDA48'S in my GTD and the engine was only partially lowered. The rear carbs would have impacted the glass but Hugh Absolem at Diamond Racing reduced the pipes on the rearmost carbs marginally and then Tony Dunne retuned them. They run without any problems. I'll dig out a photo of it and email it to you. [img]/ubbthreads/images/graemlins/wink.gif[/img] It can be done.....
I'm coming to Narita shortly as well.
Dave M

[Yuji]

Thanks David. Will check the PM. Lookinng forward seeing you in Tokyo! [img]/ubbthreads/images/graemlins/smile.gif[/img]