Well, I've been reading different builds for a while now, trying to decide which way I should go.

My starting point is a rebuilt 400 about 10k miles ago. Was done when I bought the truck. Runs great, super oil pressure, supposed to have strait up timing but I can't confirm it. Has full 2" dual exhaust, stainless steel from the stock manifolds to the rear bumper. I'm figuring this exhaust will suit my needs, perhaps just adding an x pipe or some sort of crossover in it which it doesn't have now. Other than that, it's bone stock (carb, intake, ignition, cam, etc)

So, what I'm looking for is to add more power and torque. I still use it as a truck and have a 928S for performance fun Won't be used for mudding or racing down the road. I have been collecting parts, edelbrock intake and 600 carb, and um, that's it. Should I change the ignition? Cam choice seems the 255 will be what I want, but my biggest question is, should I go with Aussie heads, Tim's pistons, or not bother? The bottom end is really good and if pistons would make a great difference, I'd do them. If just Aussie heads would make almost as big a difference, I'd rather do those since that would involve much less work for me. If my induction choice plus that cam or another one (better suited) would be not much difference from doing heads or pistons, I'd skip doing anything to the bottom end. You see where I'm going? Money isn't really an issue, but I like doing my own work and don't have a lot of time to spend tearing down the engine if it's not going to net me a lot more power/torque.

Basically, how much difference does the Aussie head and or TMI piston make on a mild 400 with the Edelbrock intake, carb and a 255 cam? Anyone else go through this process? Is there a better cam for use with the stock heads and pistons? Sorry for the long winded post!

 

Do you really want to lock yourself into expensive racing gas ? The heads or pistons or both together will do that.

 

Really? Nope, don't want that for sure! Pump gas only. So I guess heads or pistons aren't necessary for boosting my torque and some hp? Do you think the 255 is the right cam, or is there a better one to run with the edel int/carb and stock exh manifolds w/dual exhaust?

 

Anyone recommend a cam other than the 255?

 

i know your happy with your exhaust system but thats where you need to go to gain some torque and its noticable power/torque with a exhaust upgrade, headers. just doing some bolt on upgrades and keep it simple.

 

Comp cams 265DEH

 

Tim makes pistons for whatever head you choose to use. Best bet is to talk to him about the head/piston combo before you buy. He'll give you the best advice and can give you real world numbers.

 

Thanks for all the replies. I'm getting more confused though? Seems that one of the best ways to boost power and torque is by raising compression, but I didn't think Tim's pistons or the Aussie heads would necessitate special fuel, rather premium pump gas at most? Digging even more it seems the stock cam isn't really bad at all, when matched with higher compression, 4V and free flowing exhaust. Anyone here run a combo like that?

 

just putting on the aussie heads wont need better fuel or potentially even tims pistons as you can get pistons to match the general compression depending on your head. you obviously didnt rebuild it as you are wondering about the timing etc. These engines started out with woeful compression around 8 to 8.5 max and depending on the year worse cams and timing. Even rebuilding it with a better cam and timing gear probably helped a lot. I am running aussie heads withe 4V valves (valves a mistake but was talked into it by a chevy head expert) and intake ports matched to the gaskets. Tims pistons approx 9.5 to 1 and no problem with pinging on pump gas and not stupid high stuff either 98 octane max. 265deh cam and new 3 position timing set. The intake and carb is an easy arvo job so that would be well worth the effort first up seeing you already have them and the engine already feels alright. 4V is all about revs and upper level HP. Torque is helped a lot with air velocity. Smaller ports and valves (see where I blew it!!) within reason and appropriate header and carby size (both not too big) very important. I am running dual fuel here in aussie but it is set up more primarily for LPG (propane) so I have a slightly bigger carb and manifold than really needed. Holley streetmaster low rise single plane and a Holley 725 vac sec. Dual exhausts but standard cast manifolds. Have a set of headers that need cutting and shutting in there but have not found the inclination. goes pretty well but havent tried tuning out right until I fit the headers as I will have to do it again probably LOL. Fitted a vac gauge and in gear (auto) at idle 10-11" and at highway speeds approx 17+". the single plane and headers dont do it a lot of help down low even though it's RPM range is from idle to 5500. once the old thing is up and moving (72 galaxie with tall 2.7 rear axle) 2000rpm and up it flys, you just have to hang on ha ha. Changes gear with foot flat at 4500rpm and I have had it up to 5500 briefly being stupid. your problem and a possibly good one is that it goes well already, you just dont really know what the PO did. good luck

 

Well that's good news! I was hoping I could literally refresh a set of stock aussie heads, bolt them on with my edel manifold and 600 carb, and have a noticeable difference. Like I said, not looking for the best 400 build, just "more" of what I consider a really nice, under appreciated motor. What it should have been, stock, know what I mean?

I'll look into those heads. Is there any place in particular to pick up a complete pair? I'm in Canada, so shipping will likely suck a bit, but life's like that sometimes, lol.

 

without appropriate pistons you will not get the full benefit of the heads but they shoud still raise the compression somewhat. If you are feeling really keen rip one head off and check a piston and chamber and make sure you have a good idea whats in there. No idea about where to get the heads as I am aussie and they are everywhere, but that wont help you LOL. T meyer does them I think (??) check his web site.

 

Here's what I had done to my engine after machining:
408 cid
TMeyer 9.3:1 pistons
CompCam 255 DEH
Cloye timing set
Edelbrock 400 Performer intake-1406 Carb
1 5/8" headers w/dual 2.5" exhaust
Stock OEM heads with roller rockers
OEM Distributer
Premium pump gas

Here is the dyno report:

 

What???? Good Lord! That's huge power for what seems very reasonable upgrades. So you went with the pistons instead of the heads, eh? I wonder what the results would be like with using the heads and the stock pistons. Doesn't that give around 9.0:1? Those numbers are way higher than I expected

 

I think the stock pistons were about 8:1. I went with the stock heads because they work really well for street performance and produce very good torque which is what should be a priority for any street engine.
The way to get performance out of an engine is the machining and assembly process just as much as the components that are used. You'll get alot better power out of an engine where the cylinders are sealing the way they should. Anyway you go it's going to cost, so you might as well get it right the first time around.

 

Dont fall into the trap of mis-interpreting the way the HP is presented back in the day. It was lucky to be 200hp the way they measured it in the 70's and on. The SAE method does things like simulate or test the engine with a fan, alternator, AC etc as it would be on the road, so if you were comparing engines/cars it supposedly should be more even. The fact the engine was probably putting out somewhere over 200, the jump isnt so massive. Very noticeable and useful, but not massive. Mind you it in this case it is well over 300hp so that would be very nice!!