[1970GTOECKLEY]

Hey everyone just finishing up a Pontiac 400 build .030 over forged pistons,stock rods arp bolts,#62 heads new valves,springs etc,mild port work,XE274h cam,Torker 1 intake,Holley 750DP carb,Tri-y headers,HEI dist. Im 18 years old this is my first engine build and its going into my 1970 GTO it will be dynoed at the trade school I go to and im just wondering how much power the engine should make crank/rear wheel. Share your build and dyno numbers also please if it is a similar build.

[Dragncar]

Cool deal kid. First car, 70 GTO. That is something these days.
My first car was a 69 GTO but that was 1982.
I would get up the 250$ for some offshore 5140 units and get rid of the cast rods. Seen too many on 13 and 12 second 400s fail.
The T1 should be replaced. NOOOO bottom end at all on a 400. You get a good pull past 5000RPM but you have to shift by 5800-6000 with cast rods.You are even better off with a 70 iron unit with the right setup. Get a T2 instead. They work very well on mild 400-428s.
You have the right heads for a pump gas 400 with TRW flat tops.

[1970GTOECKLEY]

Already have it pretty much built. hopefully the rods will be fine how much power you thinking it will make and I love a 69 GTO!

[ponyakr]

I realize that the engine is already built. But just for what its worth. From what I've read, the XE 274 cam is too much for a street 400. Most run that cam in a 455+ engine. And the steep ramp cam may help make the 400+.030 with #62 heads have detonation problems with pump gas.

But, I could be wrong. If so, some of the experts will correct me, I'm sure.

I just ran some numbers thru the CR calculator and came up with 9.92 CR. That's assuming 75cc chambers, .039 x 4.3 Fel-Pro head gaskets, and .010 deck. If it's been zero decked, that'll add some. And if the heads have been shaved for less than 75cc, that will add some. And, the XE cam will add some cylinder pressure for more dynamic comp.

http://www.wallaceracing.com/cr_test2.php

I've read that most Pontiac engine builders recommend no more than 9.5 CR for pump gas engines. I know this has been debated many times. But the OP has probably never read these debates. So, some other opinions may be helpful here.

Also, if you have an auto trans, you'll need a stall converter, cause the motor with a Torker intake and a double pumper, will have very little low end torque.

Hey, we're not trying to spoil your party. But we also don't want you to build a motor that you won't like. If it has no low end torque, and has detonation problems with pump gas, you will not be happy with it.

[dmac]

Sounds similar to a 400, .030 over I had years ago. I loved to drive it on the freeways/highways. I think I had a 2.73 rear ratio, and it pulled hard from 50-100 mph. Only downside was having to drive around town in low gear, up to about 30 mph. I once drove from the SF bay area to Reno in 2nd gear, just cruising at 70 mph. I had made homemade snorkels from aluminum dryer vent tubing forcing a lot of air into 12.5:1 compression chambers, 115 octane rating, ice cold air. Stock rods, pistons saw 6000 rpm only a few times. With the 2.73 gear ratio, you don't need a lot of rpm to build up speed, but it takes a little longer.

[4mula73]

I'm building a 400 that's pretty similar to yours. My cam is a tad smaller than the XE274, and I mean just a couple degrees of duration and about .030" of lift. I'm using 6X-4 heads with mild portwork, 9.44 compression, Performer intake, quadrajet, and Hooker 1.75" headers. I built mine wanting to be close to 400hp at the crank. All in all, very close to your build. I'm 18 too! Mines going in a 73 Formula 400. I'll be getting it dynoed sometime around May or June. We'll have to keep in touch and see what our builds made!

[screamingchief]

Originally Posted by 1970GTOECKLEY

im just wondering how much power the engine should make crank/rear wheel.

I'd say around 350-375 @ the crank,+/- say a 10 hp "fudge factor" either way.
And maybe 275-290 @ the wheels,that depends on drivetrain losses though.

JMWAG

No armchair quaterbacking from me,I'll leave that to the others.

Good luck with it,and enjoy the experience,just dont let any $h!t get to you,we've all BTDT,it's just part & parcel to the automotive hobby.

Bret P.

[steve25]

If your 70 is a auto and does not have at lest 3.73 rear gears than the T1 manifold will not have the low speed power your likely thinking your gonna have to peel rubber!
Your really going to want to search out a at least a use Edelbrock PB duel plane square bore carb manifold , or a performer rpm that will accept that Holley carb.
Does the Dyno at your school have sensors to track ping and knock as you may have some of that to deal with andthe way to go if you can make enough pulls would be to run 32 degrees of timing on up to 40 to see what the motor wants!
In stock form with those heads thise motors where between 325 and 350 hp and if you can spend enough tuning time on the dyno you should have 375 to 380 hp on tap.
Oh, I would advance that cam 4 degrees also as 2 degrees of it will make up for normal timing chain stretch at revs above 4500 and or once the motor gets 15K miles on it!

[meanone]

I'm with switching the intake to a '67-'70 cast iron stocker and put some 3.90-4.10 gears in there. I think that you'll be real happy with it. Call PTC and get a good stall converter, probably around 2,500-3,000rpm. Should be pretty quick. I would guess 380-390hp also, maybe 400.

[74Grandville]

what rear gears? As others have stated, I think 3.73s are needed to match your setup. here is what DD2000 is showing for me.

[grivera]

Thanks for carrying the torch for the new generation! My prior build was a 400 (+.040) with un-ported #62 heads at 75cc and the smaller XE-268, but I had the pistons dished and ended up with about 9.4 comp. With a TH-400, a Hughes GM20 converter and 3.08 rear, it went 13.78's first time at the track with no tuning. I've heard the XE-274 is a better choice for a 400 so hopefully you'll be pleasantly surprised. Here's a video of mine with the old engine:
https://www.youtube.com/watch?v=EobSWI7Ngi4

[rtanner]

Originally Posted by Dragncar

Cool deal kid. First car, 70 GTO. That is something these days.
My first car was a 69 GTO but that was 1982.
I would get up the 250$ for some offshore 5140 units and get rid of the cast rods. Seen too many on 13 and 12 second 400s fail.
The T1 should be replaced. NOOOO bottom end at all on a 400. You get a good pull past 5000RPM but you have to shift by 5800-6000 with cast rods.You are even better off with a 70 iron unit with the right setup. Get a T2 instead. They work very well on mild 400-428s.
You have the right heads for a pump gas 400 with TRW flat tops.

have never seen a stock pontiac rod fail, heard people repeat over and over they will, but 100s of passes tens of thousands of miles, tons of friends w pontiac, nope never seen one, and i started in 1977 w my first 400 fb, so sleep well kid your rods will be fine!!! that chevy cam will suck, but your rods w be fine

[Cliff R]

I've only seen one dyno sheet from a near identical build and it made 385hp/440tq at the crank, so you should make at least that much power.

Hopefully the block was decked/squared and quench is pretty tight in it so I even has a chance at managing pump fuel at near 10 to 1 compression.

As for the other stuff, I'd just run it, evaluate the performance at every level, and then put some upgrades on your wish list when funds allow for it.

I had a 400 in my Ventura when I first bought it, pretty much a "hodge-podge" of parts, Street Dominator intake, "low" compression 6X-8 heads, and Crower 210/221/112 camshaft. It ran fine for quite a few years and many thousands of miles. I did swap out the intake and go to a 1977 Pontiac carb early on, and still use that same carb today on my 455.

The little low compression 400 with a stock converter, 2.73 gears and BFG street radial ran 13.87 @ 101mph on it's best ever pass. Must have had some tail wind and good air that day, because most runs were 14.0-14.2 at 98-100mph.

Your much higher compression 400 and bigger cam should certainly do better than that one did....IMHO.....Cliff

[Overkillphil]

Haven't broken one here either but have spun my share of rod bearings. Been using good bolts (like the OP has)for the past 25 years and no issues. But these days forged rods are abundant which wasn't the case when I started in this hobby. Like the 557 blocks, it just doesn't make good sense to use them when there are so many better choices these days. That's why I bought and installed a set of H-beams from Butler in my latest Pontiac. All future ones will be getting forged rods too.

I've seen a broken stock rod come through the block on someone else's car (69 T/A clone) with a 400 of unknown build quality and it was wound way too high during a street race. I can't really blame the rod for that one but a forged rod may have prevented the carnage.

[Cliff R]

Stock rods are fine if you observe the rpm limitations of the design.

Back when I was in High School we laughed at the Pontiac owners as many spent their weekends searching the local salvage yards for engines. This cam after they tossed a rod after doing burnouts in the High School parking lot after the Friday night ball game with the accelerator buried on the floorboard for a couple of minutes. Aside from the Super Duty 455's, most Pontiac engines had "soft" rods in them. The nodular iron rods are tougher than most folks think, but they can and will fail pretty quickly if you don't drive like you've got some sense......Cliff

[77 TRASHCAN]

Cliff,
Will a 1" spacer help this combo? Since it's going on a dyno, and the potential power difference can be measured...Might be worth the effort???

[prostreet64]

As others have said there is plenty of room for 'tweeking' this combo, but you have a solid starting point. We ran a similar build in my son's 69 400 many years ago. Factory rods, the dreaded 8 vr pistons, XE274 cam, #64 heads, RPM intake and 750 Demon carb. Granted the rods were resized and fitted with ARP bolts,but we never had a problem after running the combo pretty hard over a 4 year period. Many shifts at 5800 rpm. CR was at 9.4:1 and pump gas was fine. Other parts that worked well with this combo were the 3.73 gears and 2800 converter. We managed to coax a best of 12.06 @ 110 out of this package but it took several seasons of tuning to get it just right. Best of luck with your car and take time to have fun with it.

[i82much]

Originally Posted by Dragncar

Cool deal kid. First car, 70 GTO. That is something these days.
My first car was a 69 GTO but that was 1982.

I agree, this is as cool as it gets. My first was my 65, that was in 1991. You are talking about a 45 year old car, that is really awesome.

Let me ask you this - how far do you expect to drive every day? You are posting on a forum with a bunch of old guys that care about stuff like not running high rpms all the time, overall driveability, hell we even care about cold starts and all get annoyed with the slightest exhaust leak. We spend hours on forums researching our next oil filter purchase or trying to decide between running 27 or 28 PSI in our tires for our next road trip.

But you are freaking 18 years old! I say to hell with all this, slap some 3.90's or 4.11's in the back and go burn some goddamned rubber, cruise around at 3000 RPM, smack it in the ass every time you go around a corner. Break every last damned drivetrain part on the car and learn how to put it back together in your sleep. That's what we all did at your age.

20 years from now, you can log in and we can have a nice 37 page thread about PCV valve calibration or hydraulic lifter bleed-down rates. Right now, kid, you've got rubber to burn and hearts to break. So get to work

[PunchT37]

Originally Posted by i82much

But you are freaking 18 years old! I say to hell with all this, slap some 3.90's or 4.11's in the back and go burn some goddamned rubber, cruise around at 3000 RPM, smack it in the ass every time you go around a corner. Break every last damned drivetrain part on the car and learn how to put it back together in your sleep. That's what we all did at your age.

20 years from now, you can log in and we can have a nice 37 page thread about PCV valve calibration or hydraulic lifter bleed-down rates. Right now, kid, you've got rubber to burn and hearts to break. So get to work

LOL.

[PunchT37]

We ran a T1 on a 350 back in the day. We didn`t know better, or gave a sh!t. We turned it 7 grand with 3.90 gears. Lasted a good while before a couple of the cast pistons broke. Go figure. Pistons, not the rods.

Back to yours, run it as is or get a RPM manifold or at least a T2. Keep the Holley. That T1 does suck, especially on the "smaller" engines.

Just because we were dumb doesn`t mean...