3500 questions

[ForcedFirebird]

1. What is the chamber size on the 3500 heads?

2. Will the 3500 pistons fit a 3400/3.4 bore, and what size dish do they have?

[Joseph Upson]

The pistons won't fit, 3.7 vs 3.62 bore, otherwise they look like 3400 pistons from the top with the typical dish. The cobustion space is slightly larger by about 3 or 4 cc's I believe it was.

[Driver_10]

The pistons won't fit, 3.7 vs 3.62 bore, otherwise they look like 3400 pistons from the top with the typical dish. The cobustion space is slightly larger by about 3 or 4 cc's I believe it was.

That answers the question about the pistons, but whats the size difference between the 3500 3400 head chamber.

(It sound like you only described the piston diameter and dish displacement.)

[SappySE107]

The 3500 head is 32.4cc vs 28.6 for 3400.

[ForcedFirebird]

The CR Calculator lists the 3400 heads at 26.4. If they really are 28.6, then the comp might be bareable with a stock 3.1 bottom end (at 27cc, the CR would be 12.7:1).

The pistons won't fit, 3.7 vs 3.62 bore, otherwise they look like 3400 pistons from the top with the typical dish.

So a .080 over 3400 is a 3500? And what is a "typical dish"? The only 60* that I am aware of that did not have any dish is the 3.4 DOHC with the valve reliefs, and the 2.8 HO with the flat top pistons. My question is HOW MANY cc's are the dish?

[ForcedFirebird]

Sorry, the CRcalculator lists the 3400 heads at 26.4. Ben, did you cc them and find them to be 28.6?

Is it hard to accurately cc them myself? Wouldn't it just be a matter of measuring how much fluid it can hold?

[ForcedFirebird]

Well, another one...

The injector ports on the 3500 heads are different so NONE of the injectors I have laying around are going to work. It doesn't even appear that I can modify the lower to use the old style injectors.

What are the newer style called? Do they come in high flow? I will probably be looking into 65#, or better so I only have to buy them once.

Thanks again.

[Superdave]

i'm using Multech 1 injectors on my 3500, no problems... #32's out of a syclone/typhoon.

[ForcedFirebird]

i'm using Multech 1 injectors on my 3500, no problems... #32's out of a syclone/typhoon.

SY/TY has the same kind of injector port? As you know, the older ones have a lip inside to seat the o-ring and these have a sort of taper instead.

[SappySE107]

Use a gen 3 rail and you can use your injectors. The 3500 rail is akward and uses the little injectors.

[Joseph Upson]

Well, another one...

The injector ports on the 3500 heads are different so NONE of the injectors I have laying around are going to work. It doesn't even appear that I can modify the lower to use the old style injectors.

What are the newer style called? Do they come in high flow? I will probably be looking into 65#, or better so I only have to buy them once.

Thanks again.

Not sure what kind of problem you are refering to regarding the earlier fuel injectors not being able to fit the manifold ports although I haven't tried it as yet. The 3500 injectors are Multec III and about 24lb/hr, I purchased some 30 lb/hr injectors that are Multec I and the short style like the 3500 injectors from the GM 8100 big block to allow use of the 3500 rail. I'm thinking about using the narrow 36 lb/hr injectors I have instead for the 3900 since it will be turbocharged and comes with about 28 lb/hr injectors stock suggesting the 30s might not be enough for double digit boost.

I'll have to use the 3400 rail and block off the regulator end so I can convert it to returnless since I like the idea of one fuel line to the engine and experienced just how much heat is added to the fuel in the return fuel system when my EVAP system clogged and the turbo started pressurizing the tank, when the top came off an unhealthy amount of pretty warm fumes was released.

Using the adjustable regulator with tubes from the 8100 fuel rail I will not need to perform any mods in the tank to make the system returnless, I posted a picture of the regulator in an old thread showing how easy it makes converting the system to returnless. I do intend to install two high flow pumps and a thick power cable to them, because I can hear my pump surge with my turn signal.

[ForcedFirebird]

Use a gen 3 rail and you can use your injectors. The 3500 rail is akward and uses the little injectors.

I have 2 3400 rails (I think they are the same) I bought the 3500 upper from someone who never got around to installing it on his 3400, I'm talking about the way the bottom of the injector mount looks. I haven't tried bolting in the injectors yet, but I'll take a look.

[ForcedFirebird]

Will the Gen2 valve covers fit on 3500 heads, and will Gen2 pushrod guide plates fit? I have found 1.7 roller tip rockers to adapt to work on the 3500 heads, just need to make sure the stud seperation is the same 9if they don't fit, I will make new ones). I was going to use the 3500 roller fulcrums, but like the idea of having adjustable rockers on my hydraulic flat tappets.

Sorry for the noobish questions, but I can save a trip to the yard if someone here has an answer.




Injectors fit fine, the manifold side just looked different from my Gen1.

[86euro]

I personally wouldn't screw with making 1.7s work, especially if they're only roller tip and not a full roller. But that's just my .02

[ForcedFirebird]

I personally wouldn't screw with making 1.7s work, especially if they're only roller tip and not a full roller. But that's just my .02

It's not a matter of making them work, all I need is to buy the adapting studs from Comp (not the first one to do this), the 1.7's are the same dimensions as the 3500 rockers I have now, but they have 3/8's locking nuts and the threads in the heads are 8mm. The studs are so you can use SBC rockers on metric/ASE adapting studs.

BTW: The 3500's are not full rollers either , they are roller fulcrum.