3500 swap questions

[3400-95-Modified]

You can only turn it down a little... too far and yes then you cut into where its bored out for the sensor wires. Notice how in my pic the thread length is very short in comparison to a stock one. Use the thread count for reference as far as how far back I turned it. There is only about 4 threads on there IIRC... After that was done he just trimmed off the old threads to make it look neat.




Mine was a freebie

[wasas9]

black is ground by the way. green to the gauge and yellow to the ECM



Just got a call from my machine shop, apparently the CTS's are very cheaply made.. they broke it


He said he'd pay for another one, i just gotta bring it down.

how much is that costing you dave to have it turned down?

If it's more than 10$ then id say that adaptor i got is a great piece.

[Superdave]

black is ground by the way. green to the gauge and yellow to the ECM



Just got a call from my machine shop, apparently the CTS's are very cheaply made.. they broke it


He said he'd pay for another one, i just gotta bring it down.

[PCGUY112887]

Well I gave it to my uncle (bought a new 3 wire sensor) and he's going to do it tomorrow if he has a die that size.

Hopefully it works, I rather have the dash gauge and the computer seeing the same temp.

[IsaacHayes]

All I know is there is a coolant plug you can take out and put the single wire sensor (3100 94-95) in there. That sensor takes a green wire. Then for the ECM the 2 wire black and yellow wire sensor is used. (The 3500 sensor is 2 wire right? So leave that in place.) You'll just need the right connectors after the single wire sensor. That is if there is a coolant plug like the 3400. IIRC it's on the firewall side of the block.

[PCGUY112887]

No, I am at work right now. If there is one, what would it be near? I doubt a single wire one would even work with the 3100 harness? Which color is for what on the 3100 harness? I'll guess yellow is for the computer, the green is for the dash, and black is +5v

[IsaacHayes]

Might not be the best option either, in case you ever have to replace it, but they should last a long time, but you never know. Did you check out the back of the block for a place to put a single wire gauge cluster temp sender?

[PCGUY112887]

I guess machine shops around here just don't care about small business, none of them seem interested enough to even look at it.

[Superdave]

mine is being threadded to M12x1.25

[PCGUY112887]

That is probably the best option, to have it cut down.

Issue is now... trying to find someone to do it. Uncle is a machinist but I hate asking for crap like this.

Can anyone confirm the 3500 size? M12x1.5? M12x1.25?

[Superdave]

I think I may have to get ahold of wass9... I talked to Carquest today with the number, he called their warehouse, some of the factories they buy from, everything and they say it's a legit part number but no one can get it to me (because no one has it).

Same result as i had....


I took a 3 wire CTS into the machine shop and am having them cut it down and re-thread it for the 3500 head. Hopefully it'll be done very soon.

[PCGUY112887]

I think I may have to get ahold of wass9... I talked to Carquest today with the number, he called their warehouse, some of the factories they buy from, everything and they say it's a legit part number but no one can get it to me (because no one has it).

[IsaacHayes]

So you have the gauges and ECM reading just one sensor and not a 3-wire sensor? I would say that could well be a problem. At least it's a variable I would take out of play before going any further. Disconnect the gauges wire and see if the code goes away. You could PM wass9 and see if he could send you the adapter he got if you can't find one, or put the gauge single wire style sensor in the back of the block in a cooling passage. I've heard of people doing that when swapping a 3400 into a car that had the separate single wire sensor in the head like 94 3100's had for the gauges. Not sure though if the 3500 has one or not to put it there.

[whitelightnin04MC]

Yeah, after seeing yours, I guess i did. It's worked good so far. If I come across another mount or should have to take the front header off for anything, I may do it over. At the time I had nothing to go by, so I just hacked a piece out of it. The guy I bought the headers from cut an entire section out of the mount, all the way across. He sent it with the headers for me to use. After looking at it, I decided that I'd modify my own. Yours looks sturdier than mine, but I think it's plenty strong. As long as all the stress isn't being put on the one bolt that holds the mount to the head, then I'm fine with it.

[PCGUY112887]

DANG you cut a lot out!

I barely had to notch any out on mine... I posted pics of my notch job earlier in this thread.