set up to 48 IDA..

[Tom G.]

Hi guys,
i make often experiments so now i think about to change my carbs from 40 DRLA to 48 IDA only for racing , for street i want to take my 40DRLA, in a 1951ccm engine...But the fact is, i have tuned 043er heads with stock Valves (35,5x32)...I have good results on the 1/4mile with 15,8s with the 40 DRLA...
And next season i don´t wanna change engine parts like heads , because of less time etc...
So my question is: Does it have an effect to my current engine specification to change to IDAs?

I changes these season to 1,25 rockers and Mallory hifire ignition...

Current specification:
- schleicher 324° cam, 0,378"  lift at the cam
- stock heads 043, ported
- 9,3:1
- 1 5/8" A1 sidewinder
- 90,5x76
- 40 DRLA, 34 vents,148 main, 180 air,60 idle
At which rpms does it fact to have IDAs?? And they look so nice 
I want only know hart facts, what can i expect on performance..i know about some guys, how take 48 IDFs, 48 DRLA with 37,38 vents etc on 35,5 intake valves...
So lets talk about..
Bye
Tom

[Zach Gomulka]

With your engine I think the 40s will work best. If you put big valves in the heads then the IDAs will make a big difference!

[alex d]

- schleicher 324° cam, 0,378"  lift at the cam

isn't that  A LOT of duration? it sounds like a ratio rocker cam, do you have 1,4s?

[Tom G.]

No,
it is a german cam with a lot of duration!! Engle, buck pack etc take lower duration, but more lift...so different ways...So the schleicher cam is nearly the same like eagle cams...
Tom

[alex d]

IMHO you could use 1,25 rockers with that cam to gain some lift at the valve, then you could take some use of the IDAs...

[Fastbrit]

In my opinion, you are ultimately wasting your time staying with such small valves. You need a minimum of 40 x 35.5 to make it worth using the IDAs. You say you don't want to make other changes because of time, but it would be better to wait and have your heads modified or buy some new heads than try to make this combination work. 

[Tom G.]

hi,
is there no other method without change the heads, to get more rpm or more horsepower at higher rpms..? I will change my valvesprings to harder remmele ones and take titan retainers...
And my 40 drla with 34 vents...i have the opinion, that they hold the system down...so are the 40 DRLA the optimum for this combination? Which max. rpm is possible with HD scat/bug pack valves springs..??

Ok thanks for your opinion
bye
Tom

[TiDi]

In my opinion, you are ultimately wasting your time staying with such small valves. You need a minimum of 40 x 35.5 to make it worth using the IDAs. You say you don't want to make other changes because of time, but it would be better to wait and have your heads modified or buy some new heads than try to make this combination work. 

I have a 1776 with Magnum 044 heads and 40x35,5 inox valves (127.7 Hp - 111.1 Hp @ wheel)
Which is the best configuration for the IDAs??

Thanx TD

[Tom G.]

In my opinion, you are ultimately wasting your time staying with such small valves. You need a minimum of 40 x 35.5 to make it worth using the IDAs. You say you don't want to make other changes because of time, but it would be better to wait and have your heads modified or buy some new heads than try to make this combination work. 

I have a 1776 with Magnum 044 heads and 40x35,5 inox valves (127.7 Hp - 111.1 Hp @ wheel)
Which is the best configuration for the IDAs??

Thanx TD

a friend of mine had a 1914ccm with 42x37..he had changed from 40 idf to 48 ida (37 vents) and the it was awesome the difference in performance...He made with 48 IDA 131 HP..With 40 IDF it was nearly 15 HP less...
So it does work...
Bye
Tom

[alex d]

a friend of mine had a 1914ccm with 42x37..he had changed from 40 idf to 48 ida (37 vents) and the it was awesome the difference in performance...He made with 48 IDA 131 HP..With 40 IDF it was nearly 15 HP less...
So it does work...
Bye
Tom

your heads are way milder than your friends' , you need head flow to go with the bigger carbs, in fact without changing carbs I bet you would notice quite a difference swapping heads for something bigger.

[Andi/DFL]

this corresponds my experiences. switching from 40IDF to 48IDA made no noticable difference in performance for my engine (small valves, small engine, small anything...), but it didn't get worse, either. so I kept the IDAs, 'cause they look and sound better :-)

[ESH]

...I kept the IDAs, 'cause they look and sound better...

Can't say fairer than that really! Though maybe it's time to do something with the motor?

[Andi/DFL]

Can't say fairer than that really! Though maybe it's time to do something with the motor?

thank you, more salt for my wounds please :-))

[Rasser]

In my opinion, you are ultimately wasting your time staying with such small valves. You need a minimum of 40 x 35.5 to make it worth using the IDAs. You say you don't want to make other changes because of time, but it would be better to wait and have your heads modified or buy some new heads than try to make this combination work. 

I have a 1776 with Magnum 044 heads and 40x35,5 inox valves (127.7 Hp - 111.1 Hp @ wheel)
Which is the best configuration for the IDAs??

Thanx TD

a friend of mine had a 1914ccm with 42x37..he had changed from 40 idf to 48 ida (37 vents) and the it was awesome the difference in performance...He made with 48 IDA 131 HP..With 40 IDF it was nearly 15 HP less...
So it does work...
Bye
Tom

My old 1914 made 147hp  using 40mm dellortos (36mm vents).......       what venturis did you have in your 40idf´s ?

[Tom G.]

Thanks Guys all for your replies..I will waiting for bigger heads :-)
Bye
Tom