I am sitting here looking at a pair of ICT manifolds
I cant help but wonder if there would be a benefit to extend the manifolds when fitting them to a bug or Bus?
Something like adding a 2inch spacer between the carb and manifold.
this isnt aimed at a specific engine, but as we all know, an ICT engine isnt going to be street eater.
Lets not get into the shape of the offset ICT manifold.
The manifolds themselves seem too short to feed two cylinders and to build up momentum within the tract.
any thoughts or anyone done something like this before?
Modifying ICT manifolds?
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Re: Modifying ICT manifolds?
As a Kadron guy, I have wondered if increasing the area under the throttle plate would smooth out the idle some by decreasing the charge stealing effect. Can't say that I have tried it myself, but would really like you to publish your results, if you should give it a try.
- Marc
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Re: Modifying ICT manifolds?
Back in the `80s Berg offered a dual Solex PDSIT setup that came with cast steel manifolds which looked like those on a `67 Type III, only longer (I believe they came from the Brazilian Puma sports car). IIRC the ICTs' bolt flange is nearly identical; I think I have a pair around here somewhere, I'll try to find them tomorrow and confirm that ICTs will fit.
http://images.thesamba.com/vw/classifie ... 315816.jpg
http://www.geneberg.com/cat.php?cPath=8_585
http://images.thesamba.com/vw/classifie ... 315816.jpg
http://www.geneberg.com/cat.php?cPath=8_585
- Piledriver
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Re: Modifying ICT manifolds?
Marc, was it you that suggested putting a larger plenum under the ICT/Kadss to reduce>eliminate the idle charge stealing effect?
If they are the steel manifolds, it would be ~easy to add a 6" or so bit of 2" steel pipe (horizontally) w/capped ends as a plenum of decent size with some tuning potential. (one could vary the length if anyone thought that could help)
The Corvairs with dual singles used an offset log manifold to even things out.
(easier as it was a /6) but the example worked.
If they are the steel manifolds, it would be ~easy to add a 6" or so bit of 2" steel pipe (horizontally) w/capped ends as a plenum of decent size with some tuning potential. (one could vary the length if anyone thought that could help)
The Corvairs with dual singles used an offset log manifold to even things out.
(easier as it was a /6) but the example worked.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
- Tony Z
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Re: Modifying ICT manifolds?
I am looking at the CB offset manifold and it seems very biased towards one port.
however, unlike on the 6 cylinder, I dont see how this offset can help things. On one side of the engine, this "direct shot" port leads but on the other head it lags. So it must have been made this way to keep things simple. I think with a fair bit of porting you can improve things by grinding away obstructions into the "covered" port.
I honestly didnt think of adding a plenum with the intention of gaining volume under the carb, but more thought about adding length to the manifold as an aid to reduce port robbing. I'd think that A/F comin past the butterfly will be going straight down the one port and then have to transition over rapidly and sharply to feed the other port. But if the carb sat higher, the A/F could have time to bias itself to the other port as the valves open.
Then to add to the issue, when looking at the way the carb fits onto the manifold, you see that on one side of the engine, the butterfly biases air away from the crankshaft into the "bowl" of the manifold, which I think might help this charge robbing effect and even out distribution. But on the other side of the engine, the butterfly biases air towards the crankshaft and this air is the diverted towards the material shielding the one port instead of into a form of plenum.
Are you understanding what I am saying?
however, unlike on the 6 cylinder, I dont see how this offset can help things. On one side of the engine, this "direct shot" port leads but on the other head it lags. So it must have been made this way to keep things simple. I think with a fair bit of porting you can improve things by grinding away obstructions into the "covered" port.
I honestly didnt think of adding a plenum with the intention of gaining volume under the carb, but more thought about adding length to the manifold as an aid to reduce port robbing. I'd think that A/F comin past the butterfly will be going straight down the one port and then have to transition over rapidly and sharply to feed the other port. But if the carb sat higher, the A/F could have time to bias itself to the other port as the valves open.
Then to add to the issue, when looking at the way the carb fits onto the manifold, you see that on one side of the engine, the butterfly biases air away from the crankshaft into the "bowl" of the manifold, which I think might help this charge robbing effect and even out distribution. But on the other side of the engine, the butterfly biases air towards the crankshaft and this air is the diverted towards the material shielding the one port instead of into a form of plenum.
Are you understanding what I am saying?
- Marc
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Re: Modifying ICT manifolds?
I understand completely, but am unaware of any testing that's been done to confirm that there's a real-world advantage. Presumably when they made the taller PDSIT manifolds for the Puma they felt they were better than the short ones used on Type IIIs, but for all I know it was strictly for appearance's sake or to make the linkage design better for the upright engine. The H40/44EIS Solex "Kadrons" have the same throttle-plate issue (since the carb wasn't initially designed for ACVW applications there're no LH & RH versions) and I haven't heard of anyone losing any sleep over it.
I'd be leery of going TOO large on an added plenum as it could introduce driveability issues at the low end - at least until at full operating temperature.
I didn't locate my tall PDSIT manifolds, but I compared the stock `67 III ones to 34ICT manifolds and the stud spacing is ~59mm on the PDSIT, ~64mm on the ICT...so while you can't bolt PDSITs onto the ICT manifolds (without some whittlin'), the elongated holes in the ICT carbs' mounting flanges will allow the opposite - so a set of the Puma manifolds would be a viable option if you can find some (last set I saw on theSamba were $100)
32PDSIT shown with ICT manifold:

34ICT on `67 III manifold:

I'd be leery of going TOO large on an added plenum as it could introduce driveability issues at the low end - at least until at full operating temperature.
I didn't locate my tall PDSIT manifolds, but I compared the stock `67 III ones to 34ICT manifolds and the stud spacing is ~59mm on the PDSIT, ~64mm on the ICT...so while you can't bolt PDSITs onto the ICT manifolds (without some whittlin'), the elongated holes in the ICT carbs' mounting flanges will allow the opposite - so a set of the Puma manifolds would be a viable option if you can find some (last set I saw on theSamba were $100)
32PDSIT shown with ICT manifold:

34ICT on `67 III manifold:

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Re: Modifying ICT manifolds?
I can tell you this does work. A friend had a stock 1600 with the exception of a single QP 1&3/8" exh, 009, and Kadrons. Since we have to pass smog testing, this car would never pass due to idling on 2 cylinders. I took the Al manifolds off and cut out the wall between the two runners all the way to within 1/2" from the bottom. Once installed, the car instantly idled on all 4, and breezed through smog testing.Buggsy wrote:As a Kadron guy, I have wondered if increasing the area under the throttle plate would smooth out the idle some by decreasing the charge stealing effect. Can't say that I have tried it myself, but would really like you to publish your results, if you should give it a try.
- Tony Z
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Re: Modifying ICT manifolds?
I recently bought a baywindow panel van and if things go well, I'll be testing the ICTs on it sometime in 2015.
In the mean time if I get the chance, I'll make up two extensions, probably 1" and 2".
Hopefully I wont have to make up my own linkage to get this to work... but once my new garage is up and running, this shouldnt be too much of an issue.
In the mean time if I get the chance, I'll make up two extensions, probably 1" and 2".
Hopefully I wont have to make up my own linkage to get this to work... but once my new garage is up and running, this shouldnt be too much of an issue.
- GoMopar440
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Re: Modifying ICT manifolds?
I know this is an old post but I'm working on a similar project for my rail and am hoping someone might still know/remember the details. I have a set of the short T3 PDSIT manifolds I'm trying to make work with a pair of 34PICT-3 carbs on my stockish 1600DP engine (1.5" 4-1 header w/QP and a 009 on it now, but I have a 034 for it). I've gotten the mating of the carb to the intake issue figured out with a little help from my Bridgeport mill. My question concerns the slot cut in the manifolds that was mentioned it this post. Specifically, how wide was the cut out between the runners inside the manifold?Bruce2 wrote:I can tell you this does work. A friend had a stock 1600 with the exception of a single QP 1&3/8" exh, 009, and Kadrons. Since we have to pass smog testing, this car would never pass due to idling on 2 cylinders. I took the Al manifolds off and cut out the wall between the two runners all the way to within 1/2" from the bottom. Once installed, the car instantly idled on all 4, and breezed through smog testing.Buggsy wrote:As a Kadron guy, I have wondered if increasing the area under the throttle plate would smooth out the idle some by decreasing the charge stealing effect. Can't say that I have tried it myself, but would really like you to publish your results, if you should give it a try.
Home made rail (street legal), 1600 DP, 34PICT-3, T3 brakes, 4-1 glass-pack exhaust, 31's in back and 7.00x15's up front. Link to build thread: viewtopic.php?f=28&t=147561&p=1227553#p1227553
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Re: Modifying ICT manifolds?
As big as you can go without breaking through the wall to the outside. The Kadron manifolds I did allowed making the new plenum at least 1" wide at it's narrowest. You want the maximum volume plenum you can make.
- Tony Z
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Re: Modifying ICT manifolds?
Coming back to the original topic.
I wasnt 100% happy with the ICTs so I put in IDFs and sold the ICTs.
They ran great, make no mistake, but I dont like the idea of reaching into a fuel bowl to change jets, and that in a bus with no access from the top - too much effort when I have IDFs on the shelf...
I wasnt 100% happy with the ICTs so I put in IDFs and sold the ICTs.
They ran great, make no mistake, but I dont like the idea of reaching into a fuel bowl to change jets, and that in a bus with no access from the top - too much effort when I have IDFs on the shelf...