Installed LS6/LS2 valve springs on '01+ 3400

[kprofthestrs]

my bigger concern other than just the top end swap is that i will be adding a nitrous system at the same time or with in a week or so of doing the swap and ecu. i will know more once its been on the dyno so i will have a base line to go by when i install the ecm. i have program that does a automatic ve table but its only 8x8 table but it will give me a base ve table to start with to hopefully get it running and i'll go from there weither i try the 28's or go to a 22.5's. just thinking more long term. i do want to do boost sooner than later.

[gectek]

well even running the spark and CAI and 2.5 exhaust(headers too or just cat back, or downpipe back) you would not see much more than the stock 175 hp, and at the wheels thats even less, about 20% is the norm, with a manual i think about 15%, and i dont think the MSD would really add any power due to it just being a stock engine. maybe it will increase throttle response, but the spark is good on the stock engine AFAIK, but maybe it will help out in problem areas. id say the HP is prob right at what you are looking at 170, due to the PCM you are running and the way it runs the engine systems isnt nearly as efficient as the newer OBD II systems.

using the injector calculator on www.witchhunter.com when u put in 170 HP (which i think is being optimistic) at 6 injectors at 80% duty cycle, and the constant at .5, then you get 17 lb per hour injectors, so the 00 and up GA injectors should be more than enough at that is only at 43.5 psi, at 55, which is stock rating for the 00 and up FPR (IIRC) that is only 19.1 lb per hour, that the injectors are putting out and that the engine will need. so even then, if you use the AFPR and the 22.5 injectors, you will still be above what you need and more then enough for the 3500 top end swap

[kprofthestrs]

ok i have not read about a CR loss with the 3500 top end swap. i am all ready using a msd dis-4 with a full swap 3400, 2.5 to 2.25 exhaust,custom CAI, all on a 95 obd 1.5 ecu. as i changed plugs yesterday and found plugs looked more like i was burning lean. i did have a set of 22.5 injectors that came with the 3400 i swapped in. with the sites i have been read about different ecu's on one has a calculator for injector sizing with what hp your wanting to build and at 55psi. for what i have been told guesstimate hp i have now at my stock pressure 22.5 won't be enough. at 55psi the 28lb injector won't be all that much bigger tha what it is telling my i will need, which i believe was 26.5lb. but i will be getting it on a dyno to determin exactly what i have hp wise before i go buying parts i may not need. and the 28 lb injectors were free so who was i to argue.

[gectek]

well i havent heard of anyone needing to upgrade the injectors first, but if you dont need them, you will prob run into a little tuning issues with them, but less than another aftermarket injector, because these are still supposed to be pintle style that have a fine spray pattern like stock so they are good for idle still and atomize great. i would try the 00 and up injectors that are rated at 22.5 first to see if you have any issues, because even though you may need more fuel, with the loss of compressoin you can use less fuel with the increased air flow and not have to worry about detonation. the CR when u use the stock unshaved 3500 heads on the 3400 is about 9.1 or 9.0 and the heads even shaved .020 is about 9.12 CR, so you might not need all the extra fuel, but just my opinion. but yah all that should work, with the spring/valvetrain/seal options that is what superdave did and his turned out ok so far, and also if you are going cammed, then make sure u get an adjustable pushrod checker to make sure you are using the right rod length

[kprofthestrs]

actualy i will be doing the afpr also. i am changing the injectors because i am still running the 95 17-19lb/hr injectors. i will be added nos and an aftermarket programable ecu unit to the vehicle in addition to the 3500 top end. so i will not have to worry about fuel starvation at high rpm's since i do bracket racing with the vehicle. those are the reasons i asked about the valve spring swap for the 3500.

[gectek]

well i dont know as you need to change the injectors yet, i would try the stockers and then an AFPR to up the fuel press at better conditions, but if you see you are running the stock inj. too long, then i would switch

[kprofthestrs]

neither. i am curious if the lsx springs and the comp seats pn 4705-12. and either the 3.1 or 2.2 exhaust? seals will work on the 3500 top end. i will be swapping a 3500 top end on a 00 3400 bottom with 28lb/hr injectors from the 4.2 v6. will this combination work?

[gectek]

ull need a shim under there at least or the spring will eat the alum head up. idk if the 3500 seat will work for that , but it might have the tendency to walk around the valve guide, but first off let me get this right, u wanna use the 3500 seat for your springs, or the 3500 seal on the valve stem?

[rickykline]

on the 3500 you can just cut off the bottom of the seal. the shim part.. thats what im planning on doing

[gectek]

ok in case yall want to know, comp makes a spring seat/spring shim (.060 IIRC) that will work with no probs they are pn 4705-12, but for some reason they arent on the comp site, thats ok, you can find them here and get them even cheaper than the comp website, go to www.sdpc2000.com and enter the pn and thats it, about 32 bucks, not too bad, ill post pics in a new thread when i get the chance

[kprofthestrs]

these parts will actually be applied to a 2000 3400 engine. just curious since im gonna have the 3500 parts if doing the springs before i install all the parts is really gonna be benafical since i will be using chrome moly rods also.

[ForcedFirebird]

With a Gen12 3.1 I acn use the LS2 springs with Toyota seats, ground LS2 shims and my stock seals?
I just discovered (I think, untill I pull the covers) that I broke a spring, which I already knew I was dangerously close to binding the stock exhaust springs with the 1.7RR's and ran them anyways (my own fault). So I'm thinking now of going with a turbo (Delta re-grind) cam, 1.6RR's (already have a set of Crane magnums) and the LS2 springs to help ease the stress a little.

[kprofthestrs]

would changing the springs now before i install the heads onto the vehicle be
more benaficial for higher rpms. i bracket race this vehicle and with the 3500 topend swap i will be adding a 35 shot of nitrous.

[AaronGTR]

with all the talk about the 3400 head and using the ls2/6 springs. what about the 3500 heads the ones based for the 3400 block not the 3900/3500?

probobly gonna swap a 3500 top end and curious to know if the spring swap is needed on the 3500 heads

The spring swap is only needed if switching to a bigger cam, doesn't matter which set of heads it is. The 3500 springs are stiffer than 3400 springs but still not stiff enough for a high lift high duration cam.

[kprofthestrs]

with all the talk about the 3400 head and using the ls2/6 springs. what about the 3500 heads the ones based for the 3400 block not the 3900/3500?

probobly gonna swap a 3500 top end and curious to know if the spring swap is needed on the 3500 heads