This is going to be a slow going build. Going to try and finish up my Astro Van for the year (NA build) and am going to work on this a bit at a time as I go along. It's a 1971 Lemans 4 door post car with a 350 and SM326 3 speed currently. The engine definitely has a knock and it's wounded. Probably buzzed it one too many times or a bit too much timing.

This is what I'm thinking so far:

-Pontiac 350, just an assembled short block right now. I need to check for excess RTV and see what's in there. I need to finish the head porting job the previous owner of the engine started, do a base inspection of the rebuild and put it back together. It has an unknown cam in it. I filled the passages with aluminum since I don't want to have to make a block off plate. keepers and 7/16 BBC rocker studs with poly locks are a real possibility as well.

I need to fabricate a set of headers because the manifolds won't flip on this setup at all. I have flanges and some weld els but would need more parts for sure. Swapping to an SBC would net a huge amount of space and the ability to use flipped manifolds. Tempting...................

I need a flexplate to make this work instead of the flywheel.

Carb:Holley 750 DP I started modding out already. Should probably trade it for a 600 if I can find one.Have a jet kit, jet drills, jet extensions, solid floats and a box of brass set screws to drill and tap the emulsion bleeds for. This would run on a heavily modified stock 4bbl intake with an adapter plate.

Transmission (options):
-Keep stock SM326. If the trans its self isn't cannon fodder the clutch surely would be. Would need parts to swap an SBC on to it.
-TH400 I have sitting in the garage. It's from a Grandville, whatever that was. Stall is probably 1200 or similar. I have a B&M Starshifter for it as well. Would need drive shaft, mybe a few minor things like a kickdown switch and a vacuum line/check setup.
-The 700R4 I pulled from the Astro Van. BWAHAHAHA.....No.

Turbo(s) (options):
-Pair of GN Turbos. Have flanges for inlets not for outlets. Internal WG which is nice. These seem like they may be small even on a lightly modded 350 Pontiac.
-Detroit TMF5502. Everyone says these are slow spooling, so they hear. Never actually seen anyone run one. It's basically an S400 sized frame and 71mm. Would use ATR gates I have laying around with it. Have inlet flange no outlet.
-T66 on center .69 turbine P trim wheel. old school Turbonetics. This seems to small by many but it's actually a darn decent match in my estimation. Would use ATR Gates I have laying around with it. Have flanges for it

Axle:
Absolutely nothing except add 1/2 wheel studs. Maybe. It's an 8.2 which isn't the strongest axle out there but it's also a BOP 8.2 which provides the benefit of bolt in axle shafts which means I probably won't die if it gives up. It has a limited slip in it and is 3.23 gears which is not horrible.

management:
Car currently has a Megasquirt I in it for HEI timing control. I'll also be adding an AEM wide band. Ignition will be a 1981 Pontiac 301 dizzy (computer controlled HEI) that will have an aftermarket coil and hopefully something like an MSD box eventually. I may hack in a Vortec 350 ignition module and coil since supposedly they're really good.

I realize that there's probably some bad ideas in here (notably the dual plane intake and possibly turbo selection.) I would peg this engine to make say 250hp on a darn good day. Compression is gonna be about 7.6:1 if I had to guess.

Fuel system:Going to get a stock GN tank and stick it in. I have a 307M from another build I'll probably use. Should be adequate for a blow through. I want to run a 6 or 8AN line up front. I have an Aeromotive regulator already that I picked up cheap (say $50-75 with the lines and fittings.)


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Got a piece of the fuel system over the weekend. It's a Grand National gas tank. I'm going to use my Astro's old sender as the bits to make a custom sender. I Found this bulkhead fitting on Amazon that goes from 5/16 to 6AN so I figure that's what will get used to hook the fuel pump in. I'm still up in the air on the electrical and the return line as of now but I think that'll be pretty straight forward. I have an old school GSS307 sitting around I plan on using for now as well. I'm thinking 6AN feed line (how much HP am I good for there on a blow through) with a stock feed line as a return.

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The gn turbos should work pretty good. Depends on your goal.
A single gn on a 4.3 is done at 4600 rpm and squeezed hard to 400ish. Two should get you to 5800 and over 700hp.
Look back and see how much the Grenade made on two GNs and it should give you a good ref point.

 

^^^^ This is what I was going to say, except without all the useful information.

 

Sounds like that's the way I'm planning at the moment. It'd save me having to do a crossover pipe which would be a not terrible thing I think.

Not sexy but part of my build. I made a spreadsheet of stuff I need. I need to make a part of it with required actions listed.

Pontiac 350 QTY on hand
cost projected
Weld Els 1.5” 8 4
30 currently 60
Carb bonnet 1


150
log collector 2” 4


80
GN Turbos 2
CL Purchase 125
wastegates 2 2 built into GN turbos; externals on hand as well X
GN turbo inlet flanges 2 2 Ebay purchase 25
GN turbo outlet flanges 2
may have something suitable to use/make?
40
header flanges 2 2
50
GN gas tank 1 1
75
sender 1 under construction

0
fuel filter 1
Walbro Strainer+line filter
50
Fuel pump 1 1
15
6AN hose TBD


175
6AN bulkhead fitting to 5/16 1
convert in tank to AN fittings for runs
12
valve springs 16 16 Use NOS off of 1973 heads 0
head bolts 1 set 1 set Re-use old head bolts 0
head gaskets 2 2 NOS Felpro 350P gaskets 0
Holley 750 DP core 1 1 Got with Astro van 383 0
holley rebuild kit 4779 1


35
Holley floats/extensions 2 2
32
Holley needle seats 2 2
35
holley jet kit 1 1


Bypass FPR 1 1 CL purchase Aeromotive 13202 50
holley inlet fittings 8AN 2


25
10 ORB to 6AN 2


25
8 ORB to 8AN 2 2 came with FPR

8 ORB plug 1 1 came with FPR

8 ORB to 1/8 NPT 1 1 came with FPR

vent tube extension materials



5
#6 tap



3
#6 set screws for carb hole blockoff

Mcmaster Carr

TH400 transmission 1 1 CL purchase 125
TH400 shifter/cable 1 1 CL Purchase B&M Starshifter 50
TH400 shifter install kit 1
check boxes for parts. May have?
32
flexplate 1
Rockauto 30
flexplate bolts 3


12
converter bolts 6


12
cooler lines 2
get line to make?
30
trans cooler 1
use internal? JY extra?
10
vacuum line for TH400 modulator 1
bend up
3
check valve/bleedoff for 400 modulator 1
make/MBC?
5
kick down switch TH400 1
check switches in collection; probably have something
0
drive shaft 1
JY check after trans in
50-225
torque converter 1 1 try to find performance model upgrade

down pipe material various some mandrel bends, straight piping etc.
0-10
intercooler 1 1 big single 3” Ic, optional CL purchase 50
couplers, clamps, etc. various


150
oil return fittings turbo

need bungs welded into pan
20
oil feed fittings turbo

need bungs welded into pan
5
oil/filter



30
ATF



30
shift kit

optional?
30
power valve

check rebuild kit for ratings
X
ignition upgrade

MSD box? Vortec module? Aftermarket coil already from 383
?
spark plugs

NGK UR6 (check if Astro plugs compatible)
0-20
ignition control

MS1 200
distributor

CC HEI 81 trans am 30
wires

Accell Super Stock new from swap meet 20












Gen 2 engine:




forged std bore TRW 350P slugs 8 8


tomahawk rods 8



bearing and gasket kit 1



cam shaft/lifters 1



valve springs 16



Valves (+.2) 16



pushords 16



7/16 rocker studs 16



poly locks 16

 

Well that seemed to butcher the formatting. I'll try to upload it somewhere and add a link.

 

Screenshot it and paste it to word or excel or whatever then you can save as jpeg and post that.

 

Google Drive Doc. Easy enough.

 

I found the outlets for these accidentally today. I ordered up some Walker ball sockets and I accidentally got the wrong size for the socket part. Looking at the ball part I decided to see how it looks on my GN Turbos. It seems to fit perfectly, I just need some spring bolts to get it mounted. The part is Walker 41723. It seems as if I have the basis for my down pipes now.

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Not much to report but I wanted to record a PN for my reference. S13017 by Precision Fuel Pumps fits a Walbro GSS307 fuel pump with the big inlet. The application is a 93 Chevy Corsica. I'm surprised they still have any demand at all for parts from one.

 

So I got one of these little fellas (ICT PN AN861-06-31A) and I'm thinking that's going to be my ticket to getting the plumbing in. Am I on the wrong path here or is 6AN feed good enough for this part? I'll post a few more legit pics when I get a bit more towards a sender. I'm going to graft a left over Astro Van sender to fit into a GN gas tank. Should be utterly horrible or work awesome not entirely sure of what way that will go.


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I think it'll do just fine.