400 sbc build need head and ignition advice

[sev85]

Hey guys I have posted before and it has been awhile as everyone knows life happens was in a bad car wreck and just now getting back to being mobile

I use the truck to play in the mud alot but it will see minimal road use in bad weather or occassional cruise or to a show maybe but specs are

I have a 1982 gmc high Sierra. 4 inch lift kit 35x14.50x15 super swamper boggers 1978 400 sbc 509 casting came out of a motor home trans is a th350 stage 1 kit 203 tcase with part time kit gm Corp 10 bolt 3.42 gears in front gm Corp 12 bolt 3.42 gears rear Both open diffs

Motor has stock heads stock bore very mild rv cam has edelbrock rpm air gap intake edelbrock 1406 carb with edelbrock avs thunder 1465 upgrade kit and 7/8s headman headers to a 3 inch collector to a 2 1/2 inch exhaust with flowmaster I believe 40 series mufflers have to double check mufflers

Also running a 2 core triple pass aluminum radiator with dual 3500 cfm electric fans over heating is never a concern at idle runs about 180-200 and about 210 when into hard playing in mud

My questions are I am upgrading to a msd 6a 6200 ignition box and msd distributor and coil or should I do the msd hei setup?

Secondly should I just break down and do the vortec heads or spend the money on aluminum like I want to

Also is there a suggested cam as I want my power band roughly 1000 to 5500 maybe 6000 rpm max? Dont wanna run any higher as for right now I'm staying externally balanced with stock bottom end will look into upgrading the bottom end for more durability later

I would like to be around 400hp and 500ft lb of torque for just a fun driving truck Thats is a torque monster

Any suggestions with part numbers or links is much appreciated also what kind of fuel economy are you getting and what are your personal builds and opinions for what is reliable and works best this thing is just being built to be a fun truck nothing outrageous

[tmoble]

since you asked....

IMO this is the all time best deal in ignition systems:

http://www.summitracing.com/parts/NAL-93440806/

IMO the MSD stuff is way overpriced and not very reliable. Especially, the Ready-to-Quit HEI stuff. This is china sourced and not any better than the $53 Fake HEI pushed by Skip White, the King of all ebay cheap china junk.

did I mention I have my own opinions of this stuff?

[jrcaprai]

These Are the Best Deal for Aluminum Heads Going... they Flow as well as AFR's Unported, and are Inexpensive... 195 CC
http://www.profilerperformance.com/r.../sbc-23-degree

With a 400 you need a Bigger Carb, at least a 750 CFM

Are you going to Go Roller Cam or Stay Flat Tappet?

I would go roller if you have the Budget...

I would do these Cams in this Order.... you need lots of Grunt with Those tires...

http://www.compcams.com/Company/CC/c...?csid=175&sb=2

http://www.compcams.com/Company/CC/c...?csid=166&sb=2

I ran this through Engine analyzer Pro and it Came up with 492 Lbs-ft @ 4000 RPM and 423 HP @ 5500 RPM... It Showed 412 Lbs-Ft at 2500 RPM. with a 750 CFM Carb

[rich weyand]

A fellow on one of the forums put the Dart aluminum heads 127121 on a 400 (IIRC) with a 12-238-2 cam. Camquest simulator gives 403 hp @ 5000 and 485 lbft @2500.

That's hydraulic flat tappet -- not a roller, so no roller conversion to get that.

He also dynamited his TH350. Biggest torque engine GM put a TH350 on from the factory was 410 lbft.

[sev85]

i really appreciate it guys im only doing the msd because i picked up a old school msd control box thats an original made in usa for 20 bucks and works great i have found the hei upgrades to use it on the hei distributor but wanted tto ask about the new distributors insead

my plan is to do a hydraulic cam with hydraulic lifters and probably 1.5 roller tipped rockers or 1.6 if i absolutely have to other wise im staying with the 1.5 rockers and may not even do the roller tips like i said my plan is to do a mild budget build motor for fun i dont plan to turn super high rpms and i dont plan to make it a daily driver but if the snow gets bad here in kansas i will pull it out to get to where i need to go and i only use the boggers to play offroad otherwise it will have 32s or 33s on a 16 inch rim for street use when it does see it which will be rare

im also probably going to upgrade to a 4.10 or 4.56 gear ratio front and rear and add a true trac locker rear with a selectable locker in the front and possibly later on a selectable locker in the rear but those are later on upgrades

im doing the motor now because is getting ready to hit the machine shop for hot tank cam bearings .030 bore and im shopping for new pistons rods and crank and doing new crank bearings but as for the cam i will be shopping for it as the motor is being freshened up at the machine shop there is nothing wrong with the motor it doesnt smoke or anything but the front and rear main seals went bad and since i gotta pull the motor to replace em why not go ahead and freshen it up and make it the dream motor i have always wanted while its out of the truck

i was gonna try and do the e-street edelbrock efi but is looking like im gonna end up with a 750 cfm carb instead because i would rather spread the money over the whole truck insttead of just a throttle body i like edelbrcok bu it looks like i might end up with a holley because of tthe 4 squirters or possibly a demon

but right now the motor doesnt have any trouble spinning the 35 inch boggers on it now i just want to make it a lil meatier motor and a lil more fun to play with

[sev85]

sorry pc doubled postted

[bmchevy1979]

I don't know if you have looked into it or not but a internally balanced crank isn't to expensive I'm building one for my k5 all internal balance with mild top end upgrades and it should be able to handle 6000 rpm just fine with little effort and with 6in rods they last longer not as much side load on the cylinders

[Tom]

-6000rpm is fine with a stock bottem end. 3.75" stroke x 6000rpm=just under 4000fps piston speed.
-6" rods are an extra expense that is not really worth it IMO. 5.7" rods are a dime a dozen, pistons using them are easy to source, and your not building an engine that the bigger rod will make any difference on.
-I love vortecs but if you have the money then buy the aluminum heads.
-MSD box gives you more benefits then the HEI upgrades

[sev85]

Already got the msd box a msd 6a 6200 series and I planned on staying with the 5.7 rods I want to eventually go internally balanced and all forged internals just depends on budget after machine work gets done to a 406

[crashmod]

Your 400SB sounds like the exact setup that I have in my 82 Camaro. Its basically a stock rebuilt 400 with msd 6al box distributor and coil. Shorty headers with a high rise edelbrock intake with Holley crab. I went with the box over HEI due to I can use the rev limiter chips and keep the rpm's limited if I need to. The heads are actually off of a newer 350 that have been worked over to suit the 400. I'm running a PBM power cam in it that is slightly bigger than an rv cam. Basically you can't go wrong with that setup it has a lot of torque. Probably not a ton of horsepower but enough power to shut the passenger up. Ive actually thought about pulling it and putting it in my 85 k10 but as either a 406 or 377.

[tmoble]

generally need 6" rods for internal balance. longer rod allows bigger counterweight without interference with the bottom of the piston at BDC. there are some cranks advertised as internal balance with 5.7 rods but several I have seen needed additional heavy metal installed to balance.

Need to ask the machine shop to very carefully magnaflux the decks of the block before going any further. Many have small cracks between the head bolt holes and the steam holes. Some of these can be used anyway. The 400 block in my car has a couple of these.

[tmoble]

Tom, you're Mesa? I'm in Glendale near 59th Ave and the 101. Ever get up this way?

[sev85]

Ok than i am probably gonna stay externally balanced and just go 406 with aluminum heads

Crashmod we have slmost the exact setup whats ypur fuel mileage just cruising? Because mine seems to be horrible right now

[crashmod]

Basically horrible as well. I never really averaged it but if I was guessing I would say 8 or less. I do know I can drive it down the road about a half a mile do one burnout and drive back home and it eats about a 1/4 tank of 93. But it puts on one great tire show.