3500 Top End Swap Complete

[onefastV6]

I have completed the 3500 Top End Swap on my 2001 Grand Am GT. The swap went pretty well and wasn't too bad as I had everything done in 3 days and 2 trips to the parts store.

There were a few obsticles and changes, but noting too major.

Some of the things I had to do:

1.) The 3500 gasket set (which at this time is only available through GM) uses a gasket now to seal where the LIM and block meet. The 3400 block is not drilled for these new gaskets, so if you want to use them you must drill the block or use a large pile of RTV. I chose to drill the block and had no problems. You will need to drill 4 holes less than 1/4" deep, however make sure to have a vac running and grease the drill bit

The Gasket:


Drilling the Block:


Gasket in Place:


2.) The Coolant Temp Sensor on the 3500 is no located in the side of the rear cylinder head as opposed to on the water neck. This called for a 6" extention to the wiring harness.

3.) The Cam Position Sensor harness had to be extended 6" due to the height difference of the 3500 manifolds.

4.) The Map sensor connector had to be replaced to be switched to the new style connector used on the 3500. The correct pig tail can be found on 98+ Chevy Cavaliers.



5.) The neck on the 3500 Plenum had to be ground significantly, due to the 3400's fuel pressure regulator. An epoxy putty was used to fill spots where the metal became too thin on the 3500 Plenum neck.


I am using the 65mm Throttle Body that is sold by the 60degreev6 Store. The adapter plate for the 3500 plenum was also purchased from the 60degreev6 Store. The adapter plate can also be used with the stock throttle body.

Along with the 3500 Top end I installed TOG headers, so my mod list is as follows:

3500 Heads
3500 LIM
3500 Plenum
65mm TB
TOG Headers
Borla Catback
(I am currently working on tuning via DHP Powrtuner)

I want to especially thank Ben and everyone else who has posted about the 3500 for making this swap possible. I will be getting dyno and track results as soon as I can get everything tuned as I currently have 14 degrees of KR.


Here are more pics of the swap.

[1QUICKHATCH]

so how dose it go? any noticeable gains? congrats on the swap

[onefastV6]

There is a noticable gain, but with the tuning in the state that it is in I have not been able to go much over 1/4 throttle with out getting major amounts of KR. I am working on the tune and I should have the tuning problem addressed soon.

But over all I would say that there is a nice gain, after all headers alone have been dyno proven to add around 18 HP to the wheels. I also know the heads and manifolds not only flow better, but are designed alot better than the 3400 so there is only a gain to be had there aswell.

[El_Diablo]

looks great, like it belongs lol


what ended up being your full parts list?

[SappySE107]

It runs really nice as it is so tuning is going to make it interesting at the track. Its hard to compare to lorenzos now that I thought about it (i told phil that I think lorenzo's is faster in its current condition). It gets up to speed in a hurry but the ride is smooth so its hard for someone that isn't used to the car to compare. It didnt feel a hell of a lot faster to me but then again I didnt realize we were at 60 that fast. Sorta like the BMW I rode in that got up to 60 in a hurry but felt like you just floated there, not like you just took off. Very refined in a way:P

I gotta sleep. His setup is mostly stock other than the valve springs and the port work I did (cleaned up casting flash and polished the exhaust side up and deburred the combustion chamber...nothing major). Plenum is port matched to the 3400 gasket. 3500 plenum gaskets are overly massive so that may be ported again later if he feels like pulling the lower again to open them up the same amount. Not sure if that will help or hurt so I left the lower alone. I used my spare lower to test porting it and only managed to hurt flow in my few attempts so I felt it was best not to open it up and change the shape of the fin/nub that GM cast into the corner on the head/lower intake. Oh, and the heads are decked .020 to help get the compression higher. Stock it would have been 9:1.

[gpse3400]

Congrats on the install!!! I was going to ask you how you delt with the exhaust manifolds and then I saw you were rolling with the TOG's.Which from what I hear do line up correctly. I'm waiting for a ported lower intake From Ben and some full roller rockers I'd like to try out and then I'll be ready at that moment to go out to Indiana for some more DynoTuning.

[onefastV6]

I am hoping that Ben can come up with something for the rockers as well. Which shouldn't be a problem now that he 2 test engines to work with.

What sucks for me is that trying to dyno tune OBD2 is about a pointless venture, as the computer must relearn the fuel trims after they are reset. I am hoping that I can get rid of all my KR on the street so my next dyno pulls show the true gains of my mods.

[AaronGTR]

Wondering how you arrived at the 9:1 compression ratio with 3500 heads on 3400 block? Did you cc the combustion chambers? Reason I ask is the 3400 is supposed to be 9.5:1 and 3500 is 9.8:1 and they have the same stroke, so how does the 3500 heads give so low a compression on a 3400? I thought the difference was in the volume of the dish on the 3500 pistons. You'd have to gain a heck of a lot of volume in the head to lose over a half point of compression wouldn't you? Doesn't sound right to me.


Anyway, milling .020 isn't going to gain that much compression back so wouldn't the loss of compression cut into any power gains from improved flow of the heads?

[SappySE107]

Stock 3500 combustion chamber measures 32.4cc.

[AaronGTR]

Ok. Doesn't tell me much. Whats the 3400 cc? Just wondering how we arrived at those numbers. If it's correct this could be a good swap to do for boosted guys that want to drop their compression.

[SappySE107]

28.4 or 28.6. I forget. I ran it through a calculator online that gave me 9.6:1 to start and 9.0 afterwards. There is a thread around here I started trying to figure out the numbers to input into the calculator. All the numbers are there.

[AaronGTR]

Ok, I'll see if I can find it.

Thats something else that doesn't quite add up though. The GM service info sheet I have for my '00 3400 says compression ratio is 9.6:1, but on the GM media online site the furthest back I can find 3400 specs is 2002 and it says 9.5:1. Did they change something there or just fudge the numbers up? That could make figuring comp changes even harder using 3500 heads on earlier or later 3400's.

[SappySE107]

Go by measurements, not GM paperwork. GM has a lot of typos so their information should always be checked and compared. Compression ratio is 9.6:1 from my measurements. I just ordered a degree wheel and a stand for my dial indicator. Ill have pricing tomorrow for some extensions and then ill get all the measurements we need (cam and compression).

[SappySE107]

Ok, i came up with 9.59:1 for the 3100 and 9.46:1 for the 3400. 3400 piston has 30.6cc vs the 3100 28.6cc. 3400 is 9.5:1 rounded basically and the 3100 is 9.6:1 rounded.

[onefastV6]

When I ran the calculator I came up with 9:1 for the stock 3500 heads and 9.1:1 or 9.2:1 with the heads Milled .020 (I can't remember if Ben said the combustion chamber measured 30.7 or 31.7 after they were milled.)