3500 LIM and coolant sensor question

[mcgavinz26]

Will the 3400 lower intake manifold swap onto the 3500 (LX9) without any clearance issues or other problems? I think it is ok, but wanted to check with this place first. Also, if you do a manifold swap, should you change the lower gasket or can you reuse it?

The 3500 has the coolant sensor in the head, it is 2 wires, and it is a smaller thread size than the 3400 had in the lower intake manifold. I was hoping to use a 3 wire setup (two sensing elements inside a single sensor) for my 3500 swap and was bummed when I realized the threads weren't the same size. Does anyone know of an application where there was a smaller thread size sensor with 3 wires that could work?

My backup plan at this point is to just swap on the 3400 LIM so that it has the sensor housing behind the thermostat (3500 LIM doesn't have one at all).

If anyone cares about the swap, it is an 88 Fiero GT with the Getrag and I'll be controlling it with a Megasquirt ECU. As of yesterday the spec clutch was installed and the engine was bolted to the trans as it sat on the cradle. The engine bay is cleaned and painted. Things are going pretty good so far. Trying to keep the air conditioning too.

[caffeine]

You can drill/tap the LIM manifold for the 3-wire, or buy a modified 3-wire sensor from britishcarconversions that fits the stock 3500 location. The 3400 LIM will not line up with the heads properly IIRC.

[mcgavinz26]

Man I love the interwebs. Thank you very much Mr. Caffeine. Any idea about how good the headers are that they sell there?

I have both manifolds in the garage right now, but they are both installed on blocks. I saw that the 3500 had room to drill and tap, but I wanted to avoid that if possible.

Another nice find yesterday was how the lower AC mounting bolt was just ever so slightly off center and shorter compared to the 3400 compressor I had. I ended up slotting the lower bolt hole on the compressor and stacking two washers. Fits fine now.

Did you keep AC on either of your swaps?

[caffeine]

No I don't really have any need/desire for A/C. My Firebird had it originally but never worked anyway.

[mcgavinz26]

Your temps are probably a little more moderate year round than mine. July and August are pretty rough here and I like taking the cars for cruises more than track days.

Do you know anything about the quality of the headers that company makes? Heard any reviews?

[caffeine]

Haha last August heading back from the track for 200km or so I was dripping sweat by the time I got back I'm sure a lower shift boot would help prevent the exhaust heat from reaching the interior though...
In my fiero I removed the fiberglass insulation in the engine bay and with the sunroof removed in the summer the car is perfect for cruising.

As for the headers, you're probably better off asking on the MG forums since I believe they're designed for MGs. The factory 3500 front manifolds fit great in a fiero though and are good for making decent power. My car dynoed at over 200whp with those manifolds and stock Fiero air cleaner canister, zero engine mods.

[mcgavinz26]

Blame global warming?

Michigan weather just seems so random. This month we've hit 90s, then had frost warnings, then almost back to 90s, and then back to 50s.

Anyways, thanks for the vote to remove that insulation. The threads I've read go back and forth about people saying it was a good idea/bad idea to remove it. Either way, it had to come out because it was so trashed in my car.

As for the manifolds, my plan was to fit the front 3500 in the rear, but the clearance to the trunk looks really close. Do you have any picture of it installed? I might try installing my engine this weekend, but a heads up would be nice.

My plan was to run that one and a 3100 log manifold for the front. I would make a Y pipe right below the rear manifold and then take that right into the muffler. Most of the custom header setups I've seen look so bad and seem like hell on the shifter cables. Plus I'm not trying to go overboard on this swap. I was hoping to have as few custom parts as possible. The more I can replace at a junkyard, the better.

[caffeine]

Two front 3500 manifolds fit perfectly in a fiero. I don't know if you need a cat or not, but if you don't that makes the y-pipe fairly simple. The clearance on the front (firewall side) is close but doesn't hit anything with the engine on stock mounting points

Just be sure to tie up and heat-wrap the wiring that goes through the firewall near where the manifold is. It comes fairly close.