I had been planning to swap an LT1 and later stroke it. HOWEVER; I can't get the idea of a 6.6 TPI out of my head. My concerns are:
1) Third gens run hot-would a griffin alum. radiatior, edelbrock water pump, fan switch, 170 deg. thermo., and properly programmed custom prom allow ample cooling on the notoriously warm 400 block?
2) My plan of action is Vortec Heads w/good porting & 2.00" & 1.55" valves, 1.6 GMPP Rocker arms, Eagle H Beam Rods, 10-10.5:1 Ross or SRP Forged Pistons, Roller Timing Chain, SDPC Vortec/TPI base (port matched), ASM runners, 52mm T.B., Ram Air, Relocated IAT. Jacobs Ignition, 1 3/4" Headers (probably Hooker full-length), Magnaflow 3" exhaust w/cutouts, 24 or 30 lb/hr SVO injectors. Home-made ram air, ported MAF sensor, and AFPR.
*I'd use either the GMPP HOT valvetrain kit or a ZZ9 cam (what's your take on these?). And most importantly-a custom PROM. Just for helpful info-I have a 3.70 gear, will be using T56, and occasional 200 horse shot of the silly juice (only when deemed necessary) My car is an 89 IROC and has T-Tops and all the buttons. I have'nt weighed it, but my car is a little heavier than stock due to addition of SFC's and STB and small stereo upgrade. What kind of numbers can I expect out of this (flywheel, rear-wheel, 1/8 mi & 1/4 mi times)? I intend to use the vortec heads and TPI system described due to stock appearance, however other suggestions are welcome. Sorry so long, but really wanted to be as accurate as possible. Thanks. Dwain Brammer

 

Personal opinion, go with the TPI. They look sweet. If you do go with the TPI setup on a 406 your going to need at least a 58mm throttle body and either a Mini Ram or Super Ram. A 406 needs more air than the original setup can give it, even with aftermarket runners and a ported plenum and base. A 383 is about the biggest you can go with the original setup. That's what I'm going to be putting in my 89" Bird. Hope this helps.

 

Thanks James. Anymore experts please let me know. Whatever I do I want to stick with the Long Runner Setup and cast iron heads so that it looks stock enough to bet runs on. No super rams or mini-rams. Anyone who has experience with this set-up please drop me a line. Thanks. Draino

 

Well, I have a Super ram base, SLP runners and matched plenum with the stock 48mm TB sitting on top of my 406 currently. The motor runs strong up to 4000rpm then it falls flat on it's face(as suspected . The rest of the Super ram system will find it's way on to the motor this winter along with a 58mm TB.
As for cooling, I am using a Griffin rad. with a Stewart water pump and a 160 thermo. The car runs extremely cool on the highway and on a really hot day sitting in traffic it will approach 220 but drops like a stone as soon as the car starts moving again. I also have aluminum heads with 10.5:1 compression.
Hope some of that helps.

James

 

The only thing I question is your choice of heads.Here's why:you said that you want the 406 to appear as a stock 350, the vortec heads are centerbolt but they only have 4 intake bolts per side vs. 6 per side on a stock 350(dead giveaway tht someting isn't right),also you will have to buy new valves,screw in studs,elongate the pushrod holes when using 1.6 rockers,and pay for all the machine work.A better choice might be Sportsman II heads which will except the center bolt valve covers and are available anywhere for $700 to $800,or an aftermarket centerbolt head(paint them black).
Don't get me wrong,I like vortec heads,especially if your building a semi-hot 350.It's just that they kind of lose their cost advantag if you have to spend $$$$ so that they can support a really strong motor.

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92 GTA(only 226 made)ort matched sportsman heads with 2.05 valves,64 cc,milled .015,.028 head gaskets,port matched Accel runners,port matched plenum,port matched edelbrock intake,flow matched injectors,jet hot headers and 2.5" mandrel bent exhaust,Flowmaster muffler,underdrive pulleys,slp cam,1.6 rockers,slp cold air induction,52mm throttlebody,performance resource custom chip,Dyna module,Screamin Demon coil,Accel 8.8 wires,Bosch platinum plugs,timing at 10 degrees,tb bypass,relocated map sensor,shift kit,Fairbanks billet servo,pump vane kit & 2400 stall,Torque converter lockup switch,3.42 posi with welded axle tubes,Zexel Torsen HD diff.,Summit rearend girdle,solid pinion spacer,& alloy axles.Boxed panhard bar,lakewood lca's & edelbrock strut tower brace,Jeg's torque arm,Jegs welded in subframe connecters.Performance friction pads,turbo slotted front rotors,stainless braid brake lines.Roh ZT 17x8.5 front wheels with 255/40ZR/17 tires. 17x9.5 rear wheels with 275/40ZR/17's on the street.Hoosier 26x9.5 slicks on the strip.

 

I'd use the Vortec TPI manifold (soon avail. from Scoggin-Dickey) which will eliminate the cost of machining the heads to adapt to TPI. I can drill and tap the heads for screw in studs & elongate the pushrod holes myself. I think that the Sportsman's would be too big for a TPI (IMO). I would probably port them myself (I've thought about it and with TPI, I really wouldn't want to have too much port work done). The cost for springs, retainers and larger valves would, machine work for slightly milling them and a good valve job would be the only good extra. They should be alot better than L98 heads and cost around the same amount.

 

Tom Keliher has sportsman 2 heads on his car,& I have a really nice set of them on my car,runs very strong!

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92 GTA(only 226 made)ort matched sportsman heads with 2.05 valves,64 cc,milled .015,.028 head gaskets,port matched Accel runners,port matched plenum,port matched edelbrock intake,flow matched injectors,jet hot headers and 2.5" mandrel bent exhaust,Flowmaster muffler,underdrive pulleys,slp cam,1.6 rockers,slp cold air induction,52mm throttlebody,performance resource custom chip,Dyna module,Screamin Demon coil,Accel 8.8 wires,Bosch platinum plugs,timing at 10 degrees,tb bypass,relocated map sensor,shift kit,Fairbanks billet servo,pump vane kit & 2400 stall,Torque converter lockup switch,3.42 posi with welded axle tubes,Zexel Torsen HD diff.,Summit rearend girdle,solid pinion spacer,& alloy axles.Boxed panhard bar,lakewood lca's & edelbrock strut tower brace,Jeg's torque arm,Jegs welded in subframe connecters.Performance friction pads,turbo slotted front rotors,stainless braid brake lines.Roh ZT 17x8.5 front wheels with 255/40ZR/17 tires. 17x9.5 rear wheels with 275/40ZR/17's on the street.Hoosier 26x9.5 slicks on the strip.