So, straight up 3500 instead of hybrid?

[Sidewinder]

Awesome thanks

You bought headers for your right? How hard were they to get to fit into the engine bay? I image yours isn't too far off mine in shape and size. Also, what kind of gas mileage does a cammed 3500 get?

[PCGUY112887]

Yes, I bought the S&S headers for the 3400 Grand Am. They fit, but it's CLOSE. What I had to do with the rears was rock the engine forward after I got it in and slide the rear header in, without the flex connected. Then very carefully brought it up (with help of friends tiny hands) and bolted it into the rear head. Then attached the crossover piece. I dropped the engine in with the front headers already on.

It rubs on the firewall a bit, but not enough to be a huge problem. At first it vibrated like crazy against the sub frame while driving, so I had my mechanic take a look at it up on the lift and he decided to put in some spacers on the sub frame to move it away from where the headers were hitting on it.

After that it never hit when going froward, since as the engine rocks back it actually moved away from where it was hitting. But in reverse, it would hit if you hit the gas too hard in reverse. I got some poly dog bone mounts in there now so it doesn't hit nearly as bad since the mounts don't let the engine move.

Right now I am getting about 17MPG mix city/highway. I know I can get more out of it though... my tune is no where near perfect, just haven't had the time. I also don't drive it like a stock car, I drive kinda hard. I put my 3500 to work.

I would encourage you to read through my whole thread, I ran into issues that you will too. Such as the transmission to engine mount on the pass. side of the car, it doesn't quite fit! Had to machine out holes to make them bigger and leave out a bolt. It's been OK so far.

Your AC compressor also won't fit totally, you have to leave out the bottom bolt. It doesn't align with the 3500 oil pan, and you can't use a 3400 pan on a 3500.

As far as heads and manifolds, I ported my own upper and lower intakes. Just gasket matching, took a while with a dremel but I did it. Took a damn good bit of material off, especially off the upper manifold. When I went to gasket match to the heads, I realized that the heads were already exactly the same size as the gaskets so I just left them and put my valve springs on them.

I love helping with a 3500 swap, let me know of anything else your curious about.

[BillS]

I guess I am always doing things too soon.

When I did my Fiero turbo, there were no 3.4s in production (or they were just released, either way, none available used yet) so I went with a 3.2 capacity. At least I gained the benefit of the longer stroke.

When I did my Jamaican MG, the 3.4 was the only game in town (OK, OK - I could have gone with a 3400, but the cast iron head engine out of the Camaro was easier to graft into a front engined car), and the 3500 not yet released.

Now I guess the 3900 is the nice way to go, but if I used that in a project, for darned sure they'd release a 4.2 or something the next month....

[Sidewinder]

Alrighty, that seems to be the general consensus about those headers in W(s) is that they just fit. Once I have the cash for the rest of the exhaust I'm going to get a set and get better motor mounts while I'm at it. Hopefully I can get mine installed without any issues.

On a related note because I'm curious, you can do a 3500 top swap onto a 3100 by over boring by .60 correct? Aside from that what else it needed? How much would this job usually cost? Can this over boring be done safely on a 3100?