Printable Version of Topic

Posted by: Lavanaut Jun 3 2008, 11:49 AM

I'm wondering what the differences are, and in general (flame suit on) which is "better"? More specifically, what would be the benefits/drawbacks in changing from IDTP-->IDAs? For what it's worth, this isn't something I'm considering doing, it's something that's already been done on a factory /6 I'm looking at. I have the opportunity to purchase the IDTPs in addition to or as a replacement for the IDAs, but have been told the engine is running very, very well with the IDAs. I like the originality idea of sticking with the stock carbs, but don't want to sacrifice performance or the convenience of a more modern, more fully developed product *if* that's what the IDAs constititute.

Basically I don't know shit about carbs. Yet. Any and all feedback (opinions even!) would be appreciated.

Thanks all



edit: Replaced "40s" verbiage with "IDFs" in an attempt at clarity
re-edit: Replaced "IDF" verbiage with "IDA", since that's what they actually are

Posted by: SirAndy Jun 3 2008, 11:54 AM

Carbs suck!

Posted by: Lavanaut Jun 3 2008, 12:15 PM

Posted by: sixnotfour Jun 3 2008, 02:15 PM

if its a six, its either IDTP or IDA or IDS

IDTP's have a step on the mixture screw.

Posted by: Lavanaut Jun 3 2008, 02:28 PM

Yes, they're IDTPs. I wasn't positive if it was IDTP or just TP. Thanks for clarifying.

Posted by: SLITS Jun 3 2008, 02:29 PM

Well, Foist .... I do not know nor never have heard of a triple throat IDF.

911 engines (including 914/6) were equipped with Weber 40 IDA 3Cs, 40 IDAP 3Cs, 40 IDS 3Cs and 40 IDT 3Cs. This is not to mention the Solexs and Zeniths.

And I don't know the differences between IDA / IDAP / IDS / IDT.

From the information I have at hand, they are all the same.

AND .... carbatooters for a street engine really SUCK; I am a dyed in the wool FI man. If I want to hear the engine suckin' air, I take the airbox cover/filter off.

Damnit Jeff

Posted by: Lavanaut Jun 3 2008, 02:35 PM

That's good to know, thanks Ron. I'll check back with the seller.

I'm not necessarily pro-carb or anything here fellas, it's just that WOW, finding a stock injected factory Six is TOUGH!

Posted by: sixnotfour Jun 3 2008, 02:37 PM

slits do you want the rod ?

Posted by: SLITS Jun 3 2008, 02:45 PM

A 5 cylinder 3.0 may leak a tad bit of oil. Just got your message and I will get back to you in short order.

Posted by: SLITS Jun 3 2008, 02:51 PM

No such thing ... but ... a conversion does. You take the carbatooter 12-17 mpg; I'll take the 22 - 27 mpg with FI.

Posted by: Lavanaut Jun 3 2008, 03:42 PM

Ron, you were correct, the carbs on the car I'm looking at are 40 IDA 3Cs. I've changed the topic title to reflect that fact.

Now...anyone out there able to compare the two for me at all...?

Thanks

ps: Hey sixnotfour, if you're gonna give Slits the rod please do so in private...

Posted by: 6freak Jun 3 2008, 03:49 PM

WEBERS RULE IF TUNED PROPER ....we need a screw driver happy face

Posted by: sixnotfour Jun 3 2008, 03:50 PM

not giving , he's buyin.

IDA's wider range of idle mixture adjustment. (no step, full taper)


since your looking for #'s matching you might as well have the correct carbs on hand.

Posted by: Lavanaut Jun 3 2008, 03:54 PM

Cool thanks. Can you translate that for me a little bit? Meaning, given those facts, how does that affect tune-ability, performance, ease of use, etc, when comparing the two?

Posted by: sixnotfour Jun 3 2008, 04:00 PM

Depends on the motor build , stock no difference.
ask why he changed em ?

Posted by: brant Jun 3 2008, 04:10 PM

factory 6's were all carbed
the difference would be the number on the outside of the carb are just not right for a number matching car

I wouldn't think there would be any difference in performance
and even the numbers not matching should really produce no difference either
I suppose in a full pro concours maybe....

but for practical purposes... no difference

I don't know the minute differences between the T and A

I do know the IDS carbs had an auxillary enrichment circuit for high rpm
they only made that carb for 2 years (and none on 914's obviously)
even that is a minute difference, but one could argue it is a performance difference at least.

from a realistic view:
my guess is that the original T carbs were getting worn out, and since they cost 1k to have rebuilt propperly, it was cheaper for the owner at that point to put on a set of IDA's than to rebuild them.. its the throttle shafts that wear and no rebuild/self kit addresses that issue. your choices are between 800-1400 to have it professionally addressed.

brant

Posted by: Lavanaut Jun 3 2008, 04:12 PM

Hmm ok. As for the motor, from my understanding it was very recently rebuilt to stock specs but "L" pistons were used. The seller is not the person responsible for the swap-out, but when I asked him, he commented that in general the IDTPs were somewhat of a step down from the IDAs. For what it's worth the seller is a 911 guy, so that may be no more than his opinion.

Actually, here's pretty much what I know about the motor at this point, "The original motor was rebuilt by Gary Dielacher of GD Racing in San Bruno, CA and has less than 5,000 on it. The PO told me that they used early '67/'68 911 2.0L pistons which have a higher compression than the stock T pistons"

I guess it need not be a secret, http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=300230283747&ssPageName=ADME:B:EF:MOTORS:1123 I'm looking at...

Posted by: Lavanaut Jun 3 2008, 04:18 PM

I actually do know this, my earlier comment was intended as sly humor..but obviously didn't work too well. Should know better.

The rest of your info is good to know, thanks. What would a good set of IDTP carbs go for do you think? I'd assume they'd need to be rebuilt.

Posted by: Lavanaut Jun 3 2008, 04:20 PM

Actually Brant, to comment further ~ that's exactly what I wanted to know. "no performance difference". I'm just trying to decide if I should opt to have the IDTPs rebuilt and put those on the car, or leave the IDAs. I'm aware of the desirability of these cars when fully stock, but that's another topic.

Thanks again

Posted by: Lavanaut Jun 4 2008, 12:05 PM

I ended up passing on the car. Thanks though for the feedback all. Oh yes, and for the opinions as well.

Posted by: SLITS Jun 4 2008, 12:23 PM

'68 T engine .. 110 HP / 157 ft/lb .. 8.6:1 ... 32/32 ports ... 42/38 valves ... 40 IDT

'68 L engine .. 130 HP / 175 ft/lb .. 9.0:1 ... 32/32 ports ... 39/35 valves ...40 IDA & 40 IDAP

Posted by: 6freak Jun 4 2008, 01:52 PM

golf course .....Florida car the man just payed 12k ...wanna bet on it..wheels been changed out and some one said cars arent investments

Posted by: Lavanaut Jun 4 2008, 02:00 PM

Yes it's the same car, no secret there.

Posted by: bfrymire Jun 4 2008, 11:55 PM

Forgive me for somewhat hijacking the thread....

If you prefer FI, which one is the best to use??? I have a carb'd 2.7 and I would love to move to FI. Just which one and where to get it.

Public or PM is fine, to avoid further hijacking...



-- brett

Posted by: J P Stein Jun 5 2008, 07:09 AM

Jeff Gamroth at Rothsport. The best cost money.....bout the same as 2 new PMO carb set-ups.

Posted by: SLITS Jun 5 2008, 08:17 AM

Just use the stock CIS system. Once everything is right .. it's right. Turn key and go AND it is very reliable. Maybe you lose 15 hp from carbs, but I can still get a $400 ticket in short order.

And if you are in love with the sound of carbs suckin' air, take the airbox cover off ... you'll hear plenty of sucking.

Posted by: J P Stein Jun 5 2008, 11:49 AM

Yeah, find yourself a archaic 30 year old CIS system & stick that on your car.....you'll love it.

Posted by: SLITS Jun 5 2008, 12:11 PM

Well JP, I have brought 4 of them back to life in the last 2 months with nothing but compressed air and carb cleaner.

If you consider CIS archaic, what the hell do you consider carburetors?

Posted by: brant Jun 5 2008, 02:17 PM

popcorn smiley....

Posted by: Root_Werks Jun 5 2008, 02:31 PM

CIS is a very simple metering system for engines and have very few wearing parts about them.

Posted by: J P Stein Jun 5 2008, 06:33 PM

For anyone interested in high performance engines.....
The factory CIS on a 3.0L with standard exhaust makes 180 hp in USA form.
Gamroth's EFI makes 260 hp with all stock internals & a better exhaust.
A hi-po 2.8L Ax engine that I know of made 10 more hp (285 hp) & 30 ft/lbs more torque when using the same EFI over using carbs. All at the flywheel.

My home built 2.7L AX motor makes 198 hp & 190 ft/lbs *at the wheels* using carbs.

Stuff CIS.

Posted by: SLITS Jun 5 2008, 06:44 PM

And a Subie WRXSti Turbo made 394 at the wheels.

Your point?

Posted by: J P Stein Jun 5 2008, 08:03 PM

I guess the point is you can't stay on it and are not worth talking to.

Posted by: Rusty Jun 5 2008, 08:20 PM

Well, I see that someone pumped your regular dose of sunshine up your beehind, JP. Same as ever, huh?

I seem to remember that Gint had a beautiful set of IDA3Cs. I did a quick search, but can't find the pictures or where he had them done.

Posted by: SLITS Jun 6 2008, 12:14 AM

Damn, insulted by a parking lot racer. I don't think I'll ever get over it.

Posted by: LvSteveH Jun 6 2008, 03:51 AM

It's almost as bad as being out wrestled by a realtor

Posted by: Root_Werks Jun 6 2008, 08:37 AM

I am running old Zeniths on my 2.5 right now and they seem to produce a lot of power for the engine. With gas going to hit $5 soon and $6-7 next summer, it's tempting to convert over to FI if nothing else to go from 20mpg to hopefully something more like 25-28mpg.

Posted by: J P Stein Jun 6 2008, 10:06 AM

Yes, it's coming. The cars-as-toys culture is headed for oblivion....at least the driving part. This includes most all "recreational vehicles"...land, sea, or air.