pontiac?

[messed up c-10]

Well guys if you have been reading on Chevytalk then you know that I'm thinking about droping a pontiac 400 in my truck. What do you guys think should I get the 400 from the salvage yard and build it up over time or try to save up and get the vortec 350 or try to find a Chevy 400 to build up?

[87 STEPPER]

Go with the vortec 350 every thing is going to bolt up and you'll have a lot less headaches and probably spend less money in the long run.

[N2TRUX]

Get a late model Vortec 350, and a conversion manifold so you can run a carb and your done. With a set of 3.73 gears, you will have a sweet running truck. If you want to spend some time and money, convert your truck to the EFI that comes with the Vortec....

[kballan]

Yep, I agree with the others. Go with the 350.

[1FaastC10]

i to ohave thought about dropping a Pontiac 400 in my truck. i've done extensive research on it, and it cant be done without major fabrication on the motor mounts. headers will also be a problem, as there arent any available. an Olds engine might be another to think about, as all you would need is a set of 5.7 Diesel engine mounts, and it would be a bolt in deal.

[Hardrock2]

Hey Jeremy!

Pontiacs literally drop in these trucks.

Years back I pulled a complete 400/400 combo from a crashed '74 Trans Am, and dropped it into an almost new '77 SWB Silverado I had. Originally a puny 305/TH350 truck.

I used the steel cage block mounts from the T/A, and the stock C-10 frame mounts. If I am remembering corectly, I didn't even have to mod the driveshaft, (except swapping the TH400 yolk) as the TH400 sat right where the original did. You will have to slide the X-member back to the TH400 set of holes, though. I used one from a '73, so I had "true dual" exhaust clearance. The wiring is a simple "near plug-in", with only a few wires to lengthen. Throttle cable is a bolt-up, but, if your truck was a TH350, you'll need to get the factory switch and wiring from a TH400 truck. Even the T/A breather AND SHAKER fits under the hood of a pickup!! I used the 4-core T/A radiator, and hoses, with a SBC fan shroud from the truck. lined up perfectly!! P.S. pump from the T/A with the truck lines.
The battery tray from a later ('80) diesel truck moved the battery to the other side. The fuel line is opposite side also, but can be re-routed down the other side of the frame, or crossed under the front of the pan rail with "loop" fasteners, to the other side.
I used the stock exhaust manifolds with duals in the end, but I did try both T/A and GTO headers, but didn't want to bash them.
They needed minor clearancing! I THINK I remember getting the A/C hoses from the diesel, but they may have been from a BB truck, can't remember for sure! It all looked factory GM when it was done.
GM stopped putting Pontiacs in trucks,... in what.......'56,'57?
I just thought...." Hey, it worked good then.................!!!"

NEVER underestimate the power of a PONCHO!! LOL!
The truck looked and sounded stock, but would eat any stock or near stock SBC truck around!!
With a 3:42 Posi out back, the T/A programed 400, a "loose" TH350 converter from a V-6 Buick, and a "mild" Ultradyne cam, it was a pretty fun truck to play with! All while getting the same or better mileage than a small block Chevy.


Mike

[Slonaker]

As I said in your CT thread, I drove a mid 1970s 1/2 ton with a Pontiac 400 in it about 10 years ago, so I know it can be done. The guy who did it was both stupid and lazy (seriously...), so the conversion can't have been too difficult.

On the other hand, I wouldn't bother unless I already had the Pontiac engine on hand.

Slonaker

[Tom]

I have a vortec 350 in my 79, and it is a great platform to start building from. 9.3:1 compresion, roller cam, 4bolt mains usually, vortec heads, and 1pc rear main all stock. Add a XE268 roller cam, shave the heads for 10:1 compression, and put a 750cfm carb on and you'll have a easy 375-400hp.

[sam79]

The vortec 350 would be my choice. Just a small addition to Jeremy's story about dropping in an olds engine. A standard Chevy trans will not fit an olds engine. The bolt pattern of an olds block is different from a Chevy block so for the old you will need a different transmission or some kind of adapter. This I know because my own truck has an olds 350 which I wanted to swap to a Chevy engine but the transmission will not fit.

[C-10volvo]

the 350 is the way to go. it would be a lot quicker to install! thats it, so drop it in!!!!!

[Tom]

Forgot to add, if this is a full build up, then go for the chevy 400. Cubes rule. Why not a big block even?

[1FaastC10]

ok guys, stop encouraging me. i've been through GM catalogs back to '66, trying to find stuff that would interchange. i came up with nothing that way, which has worked for me before. i've got a Vortec 350 and a pair of Pontiac 400s that i could use. i'd like to use the Vortec in my 91 as a torque monster 383, so how would the Pontiac 400 be for a daily driver? maybe backed by a 2004R?

[Hardrock2]

If Pontiac built trucks, I wouldn't be driving a Chevy! Ha,Ha!

Seriously, a well built Pontiac would be a sweet motor.
The P 400 is a near perfect design, as far as stroke/rod length, bore, etc. goes.
The fact that Pontiac created the same displacement (400) as Chevy, WITHOUT resorting to a "siamese bore" (and it's over-heating problems) is a good place to start.
Add to that a far more "stable" block casting, along with more precise factory machining, factory "Armasteel"cranks, etc.
Did you know that Pontiacs need line boring less frequently than SBC's?
That all the combustion chambers in the heads are factory MACHINED? (Near equal CC's across the head) no need to CC the heads, like on the SBC!
Stock intake design is better than the best HI-PO manifold that Chevy offers. (factory)
Some of the best flowing heads, right from the factory, along with a beefy valvetrain too!
Factory windage trays, forged rods! (hi-po motors)
OEM cam profiles so radical, GM wouldn't even offer A/C in the cars so equipped!! (R/A IV's, SD's)
Oil consumption, on average, is less in a high mile Pontiac engine, than a Chevy. (As well as better fuel mileage.)
I always felt they were the missing link between the high winding (short lived) small block Chevy, and the Stump pulling Big Block Chevy!
They will drop in ALMOST anywhere a SBC will go and anywhere a BB will fit...................usually with OEM parts!

The down side is ....Higher cost to rebuild, modify, and scarcity of core motors to start with. Fewer aftermarket parts available.
Some bottom end weakness that is easily remedied. (oiling)

Any one can build a high $$$ mega HP Chevy, but why not be different?
I'd love to see someone fit a full-tilt "one off" TPI setup on a 406 Poncho!! LOL!

Mike

IN A CHEVY PICKUP, OF COURSE!!!!

[Longhorn Man]

Do it up with the Poncho power.
How many times can you look at a small block under the hood and still get excited?
That's one of the reasons I installed a Caddy big block in my '70 one ton. (that and the gobs of torque)

[messed up c-10]

The First two pics are of a 400 in a 77 Grand Prix SJ. I can get the longblock and trans. from it for $300. The third pic is of the other 400. I didn't want to try to flip it over by my self but we have turned it over before. I'm not sure what kind of heads it has on it but theres no intake and only the waterpump is attached. Its $150, but the motor mounts on it are trashed. Both blocks are guerented not to be cracked. Should I get the one out of the car and just beef up my th-350 or should I try to get the TH-400 too? I might try to just get the 400 in the car and leave the trans. for right now because I still have to buy books for school and exhaust for my truck. I will probably end up leaving most of the stuff on the front end. I'll get a new alternator maybe power steering pump and water pump and try to get a chevy BB radiator instead of using the pontiac radiator.

[jimfulco]

'77 400 should have 6X heads, one of the best flowing factory D-port heads. The chamber is a bit large, around 100cc or so, & with the factory smog pistons with heavily beveled edges, it has well under 8:1 compression ratio. Flat-tops will get it to about 8:1. Pontiac also used 6X heads on 350's, and those have a smaller chamber. Used on a flat-top 400, they'll go around 9:1 or so. There's a vertical projection behind & above the #1 exhaust port that has a number stamped into the upper outer face. The number 8 designates a large (400) chamber. Number 4 is a 350 head. The late model intake manifold is VERY restrictive.

http://www.boyleworks.com/ta400/psp/6XheadID.html

[messed up c-10]

So what kind of comp. ratio should I shoot for to keep it runing on 87 or maybe 89 octane?

[jimfulco]

I had a '72 Wagon with a 455, Qjet, flat-tops, 8.4:1 CR, & a stock 2-bbl cam that was fit for a dump truck. I don't remember the octane rating (this was around 1984 or '85), but I used the cheapest gas available with no detonation problems ever. The Pontiac heads are not a "fast-burn" head by any means, so they won't tolerate as much as a more modern design (Vortec, etc.), but I don't think you could get into too much trouble with that low of a CR. Probably more likely to over-cam it than anything.

[messed up c-10]

I'm going to try to get the heads ported and maybe milled. I'll probably go with a comp Cams 268XE or a 274XE. An edelbrock Performer RPM and a 750 edelbrock carb. I'd like to try to get headers but I don't know if I can get any that fit yet. I think hedman makes some shorty headers that I could use.

[jimfulco]

Sites for Pontiac stuff:
www.gbronline.com/jwpalmer/default.html (shop in Tulsa)
www.jbp-pontiac.com
www.dapa.org
www.pontiacwarriors.com
www.nunzi-pontiac-expert.com
www.pontiacpower.com

[Hardrock2]

performanceyears.com

has a thread on a 400/455 PONCHO in a Chevy pickup.

Alot of good info on "Tin Indians" over there!


Mike





Just watch the bottom ends in those 400's real close!!!