Hey guys i have an all original 1969 442 with all original 400 with the high performance factory heads and Z exhaust manifolds. The car i have is extremely nice and a unbelievable 1 owner car (Barn find) We are believing that this car only has an incredible 45,000 miles on her the car is a virgin that no one has cobbled or messed with.. to get back to my question i was wondering what kind of HP you could get out of a 1969 400.. i have been told that your better off going with the 455 and i already have a 1969 455 block. If i were to build the 455 and swap it i would DEFINITELY KEEP THE 400 in a crate and throw it back in later... so i was just wondering if i could get some nice street reliable HP (500+) out of a 400 if not i will just build my 455 i have and keep the 400 in storage thanks for your input... (Sorry for rambling but just wanted you all to know the story, and yes i will get pics when i get a new digital camera)

 

If you left the 400 in it you would be doing something different than other people have done. Back in the day when the 400 died people would throw a 455 in them. I not saying not to put the 455 in it. You can make a lot of power out of a 455. My first question would be what are plans for the car. How much are going to be driving it. What kind of driving. Racing, mild street, or just want more power.

 

Those 68-69 400's have a bad rep. If you spin them too high (over 6250 I've read) the rod bearings can spin. The problems seem to be the bore is small so the valves are shrouded and because the stroke is so long and the pistons are small the loads on the rod bearings are great. In an engine with a larger piston to control the rock (like the 455) the rod bearings have a little more relief. I know a lot of 400's got changed out in the old days especially in 4 speed cars so there's definitely some issues there.

If you're not going to pound the hell out of you could do the usual cam, head work, headers, etc you'd do with any other engine but I don't think you're going to hit 500 HP with a 400 long stroke.
The 400 in my 442 runs excellent but just turned 100K so I was putting together a 455 for the day my 400 goes on a shelf. I'd like to do a little drag racing here and there too so why put the original engine in jeopardy?

 

X2

You don't want to wreck the original engine. So if you're going for the high HP like you say you are, use something expendable and easier to get where you want to go: a 455.

 

First, have you checked the VIN derivative to see if this is the original engine? If so, I'd set it aside and build a 455 (which, in fact, is exactly what I'm doing for my 69 442). The long-stroke G-block 400 from 1968-69 has one of the worst bore/stroke ratios of any US-built engine. The small bores, combined with the big valves, lead to shrouding and less-than-optimal performance.

 

If I was going "spin" it to 6250, I would build a 425 with a big oil pan.

 

I'm glad you found that term amusing.

 

Back to intended use: the 455 has a different casting number (396021F) next to the oil filler tube than the G 400 block, so origiinality is compromised a little. However, the swap was common even back in 68-9. Neither of the long stroke engines, 400 or 455, likes high rpm, especially without careful mods to keep them alive. Al Steinmetz has been racing in NHRA stock for decades and he shifts his 455 at 5500 rpm. I suspect the 400 had more problems largely because people were used to the earlier 400 with shorter stroke (3.975" vs. 4.25") and tried to run the "new" 400 the same way. If I had to run a late 400 (I have a bare block if someone wants it) I'd either (1) bore it the max same amount with sonic checking of bore thickness all the way around and up and down, and then accept the limitation of bore size that I ended up with; or (2) have a competent race shop bore out all cylinders and sleeve them, furnace brazing if necessary as was done back in the 70s with some Ford blocks. Of course, #2 is expensive.

 

can you get 500 hp from a iron head dual plain 400 or 455 ?? will the w-30 intake make that much power with any set up other that a blower or no2?

 

When building a street engine the focus needs to on tq not so much on hp.
No the stock intake wouldn't be the best choice for a engine making that much power. The intake is only part of the build. Heads, compression, stroke, cam, and machine work are going to be where your going to make changes to make that kind of power. You don't need a blower or no2 unless your going to race it on the track. Most people just want more power for the street. Want spend a lot of money on a engine not thinking about trans, stall conv., rear end, gear, tires, and car weight. A 500 hp engine you have to build up the whole car to handle that much power. 350-400hp with the right gears all you need on the street.

 

If you decide to stay 400, I have a '67 Olds 400 "E" shortblock for sale, which is more diserable BBO 400...

 

To four four Tony, Sorry about the "spin" comment. Getting back to the first post. I agree with Run to Rund. I would "crate" the 400 and build a "mild" torque engine 455 with RPM's around 5000. I like around 3:36 gear ratio for the street. If u get too carried it won't be much fun to drive on the street. Good Luck

 

No problem Kennybill. I hope it made you chuckle a little.

 

SO DO I- and it is free to whomever wants to drive over and get it outta here.

Jim