[Young Pontiac Guy]

Anyone running KRE Dports or Eddies with 72cc chambers on a 400/406?
What type of anticipated horsepower with the 290cfm or 310cfm ballpark?

[paul s.]

There are many variables, but depending on quality of the shortblock, the cam, valvetrain, and especially intake and carb set up; it can be anywhere from 450 for a bolt on deal with about 224-230 @ .050" cam to over 550hp with a ported intake and at least 10.5:1 compression and a 236 or more degree cam. Whatever you decide to do, get a cam with some lift to it... around .550" or so.

[Mr. P-Body]

In the middle of one right now. A "long rod" 408 CID, Edelbrock D-ports, Comp solid roller. Anticipating around 550 HP, as stated above. This one is for a road racer, though, so the cam specs are a little different, narrowing the band some and reducing low-end so he can "come off the corner".

The real advantage of a 400 over the larger engines is the ability to rev (IMO). We like to use the 6.8" Eagle rod (BBC specs), a light piston and spin 'er on up. One iron-headed version in NJ makes power to about 6,700 (pump gas, 6Xs), but with "more" head and 6 more degrees duration, he'd go to 7,200, no sweat.

And let's not forget what Vinnie has managed with 406 CID and KRE High Ports (6.35 @ 214). I've always said a 400 is "no punk". It can be built into a seathing monster and hold it's own against larger engines.

So go ahead. Gear it "down" and spin it UP!

Jim

[max 93]

I have a 400 with SD perf. 290 Kre Heads and there Stump puller cam. I plan on using a modified factory intake and q jet. SD estimated power around 500 hp and tq. Unfortunately the engine is not installed yet.

[68blackbird]

Where do you expect power to peak with the Stump Puller and KREs?

Rich

[max 93]

Around 6000 rpm

[gtofreek]

I built a 407 about 5 years ago with the KRE D-ports. I ported them to flow about 300/220. It runs a solid roller cam 237° @ .050", I & E. It has RA manifolds and complete 2 1/2" exhaust system with mufflers. Made 506 HP[about 540-550 HP on other dyno's] at 6400 rpm without friction added, and with entire exhaust system bolted up. With 4.11 gears, and TH400, this thing is a beast.

Here is a link to some video's: If you do a search on YouTube under my gtofreek name, you will find a video from when we originally dynoed it.

http://forums.maxperformanceinc.com/...d.php?t=738541

[tom s]

As this is the street section,what are your goals with the engine?The more HP wanted out of a 400 the less street able they can become.Large cams require lower rear gears,single plane intakes etc.Tom

[gtofreek]

The 407 in the 67 GTO I mentioned above is very streetable for the power it makes. Idles nice in gear, starts right up, has a Continental converter that drives like a stock converter until you get on it, and it has a Gear Vendors OD unit in it. It's very responsive at any RPM and is very fun to drive.

[Young Pontiac Guy]

Great responses, thanks to all.

My goals: fun street car that runs low 13/high 12s. Car is 4 speed Bird. Fine with reving to 6000rpm. Dont really want to drop the extra couple grand on doing a stroker, plainly. Plan on using my stock intake which is Felpro gasket matched and cleaned up, Qjet, etc. Car has a 2.56 rear gear currently but looking to remedy that over the winter as well with a 3.08/3.23 (dont have yet).

Would likely go with KRE 310 DPorts. They are close to me here in Ohio.

How would the car be from 2000rpm on up with a set up like this?

[Skip Fix]

Jim I have some 6.8 rods for a 4" stroke combo(will be topped by RAIV heads). I know the pistons will be lighter but is that offset by a heavier rod?

FWIW a 400 with better flowing heads (comparable to RAIV flow) like the new aluminums can make 400 hp on a conservative dyno through mufflers with something like a UD 288.296 HFT cam in it.

[Mr. P-Body]

Skip,

Not sure what you mean. What rods are they?

In olden times, when 455s were "cost prohibitive" to us ragedy misfits, we used 400s for EVERYTHING. You could go to Orange County on any Friday night and see at least a FEW 12 and 11 second GTOs, even in '73 or '74. With better bottom-end parts, a Ram Air IV can be a MONSTER. We put solid lifters on the 041 cam and WOO-HOO! 6,800 RPM, mid 11 second times, "streetable" (a looser definition in those days).

I recently posted an opinion on PZ that has given many "food for thought", when one of my new friends (and customer) thanked me ENDLESSLY for NOT trying to sell him a stroker. Not everyone wants a big motor. Not everyone even wants a HOT motor. As a business owner and engine builder (by trade, not "in name"), it's my job to provide my customer with what THEY want. Period. I AM expected, however, to keep one from shooting themselves in the foot...(:-

Do research before you buy heads. Not all "numbers" are created equal. Compare flow numbers across the "range". Average them from .200" lift to .600" lift. The head with the highest average will make the most power, not necessarily the one with the highest "peak" number. For a street engine, look more at .300 and .400 lift than over .500... The very best Pontiac heads don't come from "traditional" Pontiac vendors. They come from professional porters. Cerelli's, BES, H&M are good examples.

FWIW

Jim

[Skip Fix]

Jim generally most brands I've seen a 6.8 rod is heavier than a 6.625(mine are Crower Sportsman). So we get a few grams lighter piston from a shorter CH but a slightly heavier rod and was wondering if the bob weight changes that much?

I raced a 400 for a number of years and they can be fun-and even run with some of the 455 boys! Don't hit the tires quite as hard and can rev!

[Dave Bisschop]

Originally Posted by Young Pontiac Guy

Great responses, thanks to all.

My goals: fun street car that runs low 13/high 12s. Car is 4 speed Bird. Fine with reving to 6000rpm. Dont really want to drop the extra couple grand on doing a stroker, plainly. Plan on using my stock intake which is Felpro gasket matched and cleaned up, Qjet, etc. Car has a 2.56 rear gear currently but looking to remedy that over the winter as well with a 3.08/3.23 (dont have yet).

Would likely go with KRE 310 DPorts. They are close to me here in Ohio.

How would the car be from 2000rpm on up with a set up like this?

We've built many 400 combo's over the years, we use to run a 413ci cast iron headed (265cfm) engine in our 3600lb 65 GTO which ran 10.20's @ 130mph. I love the 400 combo's but they are a bit more sensative to having the gearing (conv. if auto) matched correctly with the engine combo, not saying it isn't important with the 455 or stroker combo's but the bigger torque of the longer stroke can overcome a lack of conv. stall or rearend gear and still perform very well.

If your plan is to run 3.08-3.23 rearend gears along with a stock intake then I'd suggest a 290-295cfm max as the higher flowing head with it's larger port entrance won't match the OE intake vary well and the larger cross section will push the power curve higher in the rpm range which will be better complimented by a longer duration cam which won't work very well with the modest rear gear you plan to run.

Years ago we set up a customer with a 73 Formula, factory 4 speed and 3.42 gears, with a set of mildly ported 4X heads (225-230cfm) and a Summit 2801 cam. He bolted these on to a basic 406 shortblock which yielded 8.5 to 1 compression for 87 octane daily driver usage and for exhaust he had RA exh manifolds with 2.5" pipes. He used a stock intake with a Q-jet that he tuned and the car on regular street radial tires (read traction impaired) laid down 13.40's @ 105-106mph and he reported fuel ecomony in the mid teens as this car was used as a daily driver.

Here's a link to another one of our customers we built a 400 combo for http://www.sdperformance.com/custome...01.php?carID=9 obviously he has a bunch more rear gear and a 5 speed trans but it gives you an idea what can be done with 290ish cfm cylinder head on a 400 combo.

You won't have a problem reaching your goals, just keep in mind bigger isn't always better when it comes to cams and heads. The stock intake with a bit of work is an excellent choice. Get in touch with Cliff Ruggles for some tuning parts for your Q-jet.

We got my 17 year old son Zac out to the track this year in a borrowed 67 Lemans (ran out of time to get our 65 Tempest together), we took a runner 400 shortblock with 40,000 original miles on it (never been apart since Pontiac put it together), Old Crower 224/228 112 lobe sep cam, bolted on a set of 250cfm cast iron heads (9 to 1 compression), prepped iron intake and a 750 Q-jet with a Cliff's tune up in it and the car ran 12.68 @ 106mph with a 3.73 rear gear and a 3500ish stall, leaving the car in drive (column shift) and no tach so it was short shifting big time.

What type of camshaft were you planning to run? (flat tappet or roller)

What is your plans for exhaust system?

Dave

[Young Pontiac Guy]

I really appreciate the comments. Especially not trying to veer me toward a stroker kit.

I would like to run a flat tappet cam. I currently run a 2802 cam in my 670, ported head 400. It was a very budget minded build- just a rering, stock rods/pistons etc. This time looking to do forged piston setup. I am aware that I will likely want more lift than the 2802 offers. Any suggestions are appreciated as to cam, rockers, etc. Like the Crower stuff but open to other suggestions.

[69fireburger]

These are great comments and I appreciate them as well. I also did a cheap rebuild on a 400 and am gearing up to do it over in the next year or so with some ported KRE's from SD. By the time it's all said and done it doesn't cost much more at all to build the stroker motor. That being the case I can honestly say, I don't want one! I have a manual trans and a 3.55 rear. This car has one purpose - FUN!

I've had a lot of fun cars over the years but the best engine that I ever had was a 300 horse 327 chevy that I could rev forever. I've talked to many of the chevy faithful who just cannot understand why anyone would choose a "small" 327 over the standard 350 (or even a 383). In my opinion, there certainly is a "replacement for displacement". A well built short-stroke motor in a properly geared car is more fun on the street -- at least for me it is.

--Bob

[Dave Bisschop]

Originally Posted by Young Pontiac Guy

I really appreciate the comments. Especially not trying to veer me toward a stroker kit.

I would like to run a flat tappet cam. I currently run a 2802 cam in my 670, ported head 400. It was a very budget minded build- just a rering, stock rods/pistons etc. This time looking to do forged piston setup. I am aware that I will likely want more lift than the 2802 offers. Any suggestions are appreciated as to cam, rockers, etc. Like the Crower stuff but open to other suggestions.

It comes down to personal preference, it's hard to argue with more displacement especially for a heavy street car, but a properly designed 400 combo will put many 455 and strokers to shame.

Do you have any flow data on your current 670's?

You won't want to go much bigger on duration than the 2802 cam with the rear gearing you have planned, the Crower 60243 would be something to consider along with 1.65 rockers. You'll want to keep the overlap in check especially with a manual trans. otherwise you won't have much fun trying to cruise around at lower speeds as it will want to buck.

Personally if you have a decent set of heads already, if it was me I think I'd look at investing the money into a 5 speed overdrive transmission and up the rearend gear to probably 3.90's. The performance gains you'd make with that and the increased fun factor would no doubt exceed the real world performance any head or cam upgrade you could make with a stock 4 speed and 3.08 to 3.23 gears.

Use as light of a piston as you can and for a forged rod the Eagle H-beams are hard to beat for reduced weight and strength.

I learned early on to make these 400's last turning some rpm with the stock cast cranks reducing the weight of the rotating assembly was huge. My first race 400 had 540 gram JE pistons and fairly heavy Crower rods. It hung together pretty well until we started turning over 7000rpm. After that we went to 412 gram JE pistons and aluminum rods, which held up very well even tagging the limiter in the burnout box at 8200rpm probably a few too many times!! We sure surprised the local crowd with their "Pontiac's can't rev" attitude!!LOL

It's your choice of course but I think you might want to consider the 5 speed idea, I've never had a customer regret that investment from a pure driving enjoyment standpoint.

Dave

[Young Pontiac Guy]

No port numbers, just a visual "big hog job" done a long time ago!

Exhaust is already headers, H-crossover, flowmasters. 2 1/2in exhaust.

Not a bad idea on 5 speed and some gearing. Just doesnt solve my rev problem! I take it to 5200rpm currently (pertronix with built in rev limiter). I hit it doing burnouts regularly. As well, typically dont wind it over 4800-5000 when shifting hard.

[ho428]

I run a 407 with 290 KRE's road racing with a 3.55 rear gear and 25.5" OD rear tires.
Very, very few cars can out pull me off a corner, but consider that a rolling start. Off a line standing start something with more tq would probably beat you off the line, but no matter what you build someone will always have something bigger or better. You just want fun, not king of the street.
Get a set of Probe/Icon pistons and forged rods, factory crank is fine. I run a solid flat tappet with less than .600 lift with 1.65 rockers. Regularly shift at 6200 but it'll pull hard from 3500, my Northwind intake is too big for a street 400 based engine, your dual plane would be better and give you more Tq, but you'll probably have to do some serious grinding to get it to match the 290 port.

[Dave Bisschop]

Originally Posted by Young Pontiac Guy

No port numbers, just a visual "big hog job" done a long time ago!

Exhaust is already headers, H-crossover, flowmasters. 2 1/2in exhaust.

Not a bad idea on 5 speed and some gearing. Just doesnt solve my rev problem! I take it to 5200rpm currently (pertronix with built in rev limiter). I hit it doing burnouts regularly. As well, typically dont wind it over 4800-5000 when shifting hard.

I'm not suggesting you don't build a better shortblock, I'm just suggesting instead of buying aluminum heads put the money into a 5 speed. My 670's on our race 400 flowed 265-270cfm and the engine made peak power at 6800rpm (carried the power to 7800rpm on the dyno), granted we ran a large solid roller and a heavily modified Warrior intake with a 1050 Dom. carb., but if your heads flow 240-250cfm with a bit more cam you will have a combo that will pull hard to 6500rpm and make peak hp around 6000rpm.

Dave