ok i currently have a complete 400 small block, and i was planning on building a nice motor for my iroc, but heres a few things i have been thinking about,

would it be cheaper and better to build a 87+ roller cam 383 ??

would it be easier to keep cool than the 400?

i was thinking about aluminum vette heads ported and w/ large valves.

i also would like to reuse a TPI system that is siamesed from the plenum until about 5 inches into the base, what motor would respond better to this ???

I will be using a t-56 6 speed and a 4.11 geared 9-bolt.

I know they are both very similiar setups but what are the pros and cons of each??

thanks Matt

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87 IROC-z 305 TPI
Borg Warner T-5 fresh rebuild
10-bolt 3.73 Richmond gears rebuilt GM posi,
formerly BW 9-bolt w/3.45 gears(broke it)
Ported Plenum and Runners Homemade AFPR
ACCEL 8.8 wires, High output coil,and cap & rotor
Bosch platinum + 4 plugs
Ram Air w/ K&N filters,
MAF sensor screens removed, TB coolant bypass
Polyurethane tranny and torque arm mounts
No Cat, Dynomax Headers & catback w/custom tips
K&N oil filter,Mobil 1 synth,Factory Oil Cooler, Futura GLS Super Sport tires 265/50/15 rear and 235/60/15 front mounted on 86 monte carlo SS rims.

406 siamesed TPI in progress

 

I can think of approximately 33 good reasons to build a 406 as compared to a 383, for which the 383 has no corresponding good answer.

The only advantage to buiding a 383 would be if you already had a roller 350 block with all its roller stuff intact. To put a roller setup in a 400 you simply would use what is now called the "retrofit" roller system, which is what I have in mine.

Sounds to me like, if you already have the 400 short block, there's no reason to build anything else.

Those heads should be OK.

My opinion would be to forget TPI and put something with some actual flow potential on it, such as a carb, or if you really want to stay with EFI, a Miniram or a Pro Ram. That will be especially true with the trans and gear combo you propose: at any speed above about 10 mph a 400 will be out of its power band with TPI on it and those gears behind it.

400s are no harder to keep cool than any other small blocks. I had mine for over a decade and 135,000 miles in my 83 with the stock radiator for a later model (lighter), stock electric fan, & stock fan switch, running the A/C continuously 5 months out of the year in a place with 95° & 95% RH weather all summer long.

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"So many Mustangs, so little time..."
ICON Motorsports

 

instead of a siamesed TPI how about a retrofitted LT1 intake?? would that be a better idea for the 406?

------------------
87 IROC-z 305 TPI
Borg Warner T-5 fresh rebuild
10-bolt 3.73 Richmond gears rebuilt GM posi,
formerly BW 9-bolt w/3.45 gears(broke it)
Ported Plenum and Runners Homemade AFPR
ACCEL 8.8 wires, High output coil,and cap & rotor
Bosch platinum + 4 plugs
Ram Air w/ K&N filters,
MAF sensor screens removed, TB coolant bypass
Polyurethane tranny and torque arm mounts
No Cat, Dynomax Headers & catback w/custom tips
K&N oil filter,Mobil 1 synth,Factory Oil Cooler, Futura GLS Super Sport tires 265/50/15 rear and 235/60/15 front mounted on 86 monte carlo SS rims.

406 siamesed TPI in progress