3500 swap questions

[IsaacHayes]

Ah so you are going with stiffer springs? Going to boost or cam it then?

[PCGUY112887]

Yes.

3900 adapter with 75mm throttle body from the Northstar

Cam (was suggested a 1393 grind for a DD)

External Crank Trigger

Custom Pushrods

COMP Cams Springs

Anyone have any info about getting this TB to work? As far as the IAC goes and the linkage. I know someone has done it/was going to and I can bolt it to the manifold with the 3900 adapter so it must be possible.

[IsaacHayes]

Tuning will be hell with that TB I bet. Will the 3900 adapter work on the 3500?

[Joseph Upson]

Yes.

3900 adapter with 75mm throttle body from the Northstar

Cam (was suggested a 1393 grind for a DD)

External Crank Trigger

Custom Pushrods

COMP Cams Springs

Anyone have any info about getting this TB to work? As far as the IAC goes and the linkage. I know someone has done it/was going to and I can bolt it to the manifold with the 3900 adapter so it must be possible.

As someone has already aluded to, the Northstar throttle body will probably be overkill and may create problems without making an adjustment to slow the throttle opening rate. It's so large that you probably will reach full throttle air flow before the throttle is fully open as well as have difficulty taking off smoothly from a stop.

I started converting the 3500 TB to manual and got as far as installing an arm on it for the linkage but I had so much to do between mating up the 6 spd tranny and still having to add IAC & TPS to the TB that I took the easy way out and went with the parts you are contemplating however when it's finished on the stand the 3900 is going in its place.

I don't believe the TB plate is interchangeable across the 3900 & 3500, I'm not sure but I recall trying to mount my 3500 TB to the 3900 plate and it didn't match up, it's been a while.

[PCGUY112887]

CNCGuy is the one that told me that it would bolt onto the 3500, it has holes for both.

I agree that it COULD cause issues, but I don't believe it will be as bad as some think. People upgrade throttle bodies all of the time and they never have huge issues.

[Superdave]

why do you need such a large TB? 75mm is way overkill...


IMO the TCE 65mm is plenty, i'm having NO problems with it on my 3500. (and it looks good too )

[PCGUY112887]

Cost. $375 vs $100 after adapters.

I still don't see how 75mm is overkill. People put the 62mm TB on the 3100 which has a 52mm TB stock, that's 10mm bigger as well.

[Joseph Upson]

Cost. $375 vs $100 after adapters.

I still don't see how 75mm is overkill. People put the 62mm TB on the 3100 which has a 52mm TB stock, that's 10mm bigger as well.

The potential problem is with airflow per degree of throttle angle. If the flow area is to great at throttle opening you will have a response more characteristic of aggressive acceleration even when you are trying to pull off smoothly.

In other words your moderate throttle application may have less resolution so that it feels like you are jumping off from a standing start as opposed to pulling off due to the inability to easily allow a small enough amount of air into the engine when pulling off from a stand still.

Kind of like a performance clutch that grabs immediately on engagement giving you a jolt instead of a stocker that tends to slide into the engagement without snapping your neck.

[PCGUY112887]

I understand that part, and some tuning should help it... but I just couldn't see it being THAT bad, especially as soon as you got used to it.

I mean if it's real bad I can always turn around and sell the TB and buy a 65mm one, but before I can even try the 75mm I need to know about IAC and linkage. There is no cruise control place on the TB and I am unsure if the stock throttle cable will hook up to the arm on the 75mm.

The IAC on the 75mm TB is dumped into an opening above the throttle plate. On the 3900 adapter, this area appears to just be blocked off so I don't quite see how it is supposed to work even on a 3900.

[Superdave]

I understand that part, and some tuning should help it... but I just couldn't see it being THAT bad, especially as soon as you got used to it.

I mean if it's real bad I can always turn around and sell the TB and buy a 65mm one, but before I can even try the 75mm I need to know about IAC and linkage. There is no cruise control place on the TB and I am unsure if the stock throttle cable will hook up to the arm on the 75mm.

The IAC on the 75mm TB is dumped into an opening above the throttle plate. On the 3900 adapter, this area appears to just be blocked off so I don't quite see how it is supposed to work even on a 3900.

even more reasons to go with the TCE one


Look at that, IAC, TPS, hook up for the cruse controll etc... Although i'm using a different throttle linkage now.. i didn't like the metal one.




Joeseph is right, that 75mm is going to be very on/off feeling. I'm sure you could port the opening of the plenum to 70mm no problem, 75 is going to take forever. you'll have to hog out the actual neck as well to get it to flow right...

[Joseph Upson]

You'll have to do a little carving on the adaptor plate for IAC flow which shouldn't be a big problem using a dremel tool.

The 5.3L throttlebody is a better option I believe than the Northstar because the linkage is on the opposite side.

[IsaacHayes]

I'm using a 56mm unit and carved the TB it'self for the IAC, to make it look and work like the 52mm unit since the TB adapter doesn't have a notch for the air flow.

If you want cheap and can deal with messing with an IAC setup then get a ford 5.0L throttle body for cheap off ebay. You could get one for like $10 and it bolts up to the plenum with just a little drilling on the bolt hole. No adapter needed. Then you just gotta figure out the linkage and IAC. They are 65mm.

The 75mm is just physically too big. It will be flowing max air flow before it's anywhere near all the way open. I guess it doesn't matter if you are going to drag race the car, but other than that a 65mm unit would be better.

[PCGUY112887]

Maybe I will just go with the TCE one so I have cruise control and such. I hate to use a stock 65mm size though, I wish there was like a 70mm TCE one.

I can save ~$80 just by installing my own linkage on it. Once I get my linkage on it, everything just works like the stock 3100 correct? No needing to mess with IAC passages or anything?

Also I had a question about LIM tapping. I know I have read that people have to tap their lower intake manifold for the hard coolant lines (I thin) becuase older engines use a screw type, and new engines use a push type.... well I was taking the LIM off and injectors and everything off the 3500 today and I really see no reason why I can't leave the 3500 hard coolant lines on there and tap nothing. All coolant lines run to the exact same spots as my 3100 does, just stick my soft hoses on and rad hoses and I should be good to go? I don't understand what needs tapped or why the hard coolant line even needs to be changed.

[PCGUY112887]

Anything about the LIM?

Also had a question about the crank pully. I got a Harmonic Balancer puller and that won't work. Am I going to have to use a claw type puller or what?

[SappySE107]

You can use the press fit line if you want. It really doesn't matter so long as it can hook up to your setup.

You need the puller with the right bolts to thread into the pulley. The jaw type will just tear the outside ring off.