Anybody run a 400 big block with a stock bottom end?

-
T67POWER

T67POWER

Well-Known Member
Joined
Sep 30, 2009
Messages
669
Reaction score
10
Do you run a 400 with a stock piston???
If you do,let me know what cam you run and what your set up is.
What are your et's for your car??

I am getting a freshly rebuild 400 (stock) big block and i might replace the cam and cut the heads for some compression.


Thanks for any information.8)
 
Just make sure you don't buzz it past 6 grand, and don't use nitrous with a stock bottom end and pistons.
Comp cams would be the best bet to set you up with a cam, call them. They are easy to work with, they will set you up on what you want.
JMHO.
Tom.
 
To make an appreciable difference in compression, you'd need to mill the heads ALOT. In other words, too much. The 400 has well under 8.1 compression stock. It blueprints in the 7.6 range. To get it to 8.1 you'd need to mill about .060" off the heads. See where I'm goin here? IF you're just gonna stick with the bottom end, either find a good matched camshaft and leave the heads alone or run a small shot of spray on it. It'll take it as long as the system does not run lean. Those stock pistons are a little better than people give them credit for. Don't believe it? Call NOS. They'll tell you. I've seen some of these rustang guys sprayin stock 302 bottom ends season after season with no damage. but they got their ducks in a row. you could always think about a turbo.....
 
Did it...in 1983-ish...IIRC. Well, not completely stock bottom end. I replaced the 400 crank with a 383 forged crank and rods, but ran the OEM cast piston and replacement rings. I had 67 915 heads and the block decked (again, IIRC...it was around -.010 deck height. What was CR? Who knows...

Yes, I had to mill the intake (a TM-6) to get it to fit.

With a 750 Holley, a MP (DC at the time) .509/292 cam, a B&M 10" (Super Holeshot...whoooo!) converter and 4.30's it ran 13.30's @ like...103.

Adding a glass 6-bbl hood and sealing the carb got me 13.0's @ 105-ish after playing with the jetting. It went 12.80-something after tying the frames, flipping the spring hangers, drilling some junkyard shocks for the front, etc.

Adding Centerlines (skinnies and 15x8 rears with a L60-15 McCreary dirt track tire) it went high 12.50's.

THEN we put a home made hidden bottle and plate on it. Yes, I said HOME MADE...man, was it crude...but way cheaper than buying a system. What HP? Don't have a clue, but we THINK it was around 75-80 HP, maybe...

12-teens @ 111 was the best it'd go.

I LOVED that car...beat on it, and then beat on it some more. All the while...it was my daily driver!! Young, broke and stupid...those were the days!
 
I currently have a '78 - 400 in my Magnum. The ratio mic'd out to a lowly 7.8-1 with the OE thin head gasket. I added Headman headers into a dual 2-1/2 "H" piped exhaust and a Holley Street Dominator intake. A T-Q sits up top.

If you plan on keeping it at 400 inchs, just build it like a 383 would be done. Piston replacement is a must for any decent thought of a good ratio. Once you have a decent ratio, your a go from there.
 
My dad runs a 400 in his Challenger, built back in the 80s. Stock cast pistons and stock rods with a forged 383 crank. The heads and block have been milled _a_lot_...no idea how much, I'll have to ask. Home ported iron heads with 2.08/1.74 valves (I think). Last I knew, he was running the 292/.509 Purple Shaft with cranking compression at 180-185.

Pushes the Challenger to low-12s. With near-perfect conditions, it should run high-11s.

Regularly spun to 6500 and has been run to 7000 more than a few times.

ROCK SOLID. He's been running it like this for as long as I can remember, 20+ years. It's been apart twice to check out clearances.
 
StrokerScamp said:
To make an appreciable difference in compression, you'd need to mill the heads ALOT. In other words, too much. The 400 has well under 8.1 compression stock. It blueprints in the 7.6 range. To get it to 8.1 you'd need to mill about .060" off the heads. See where I'm goin here? IF you're just gonna stick with the bottom end, either find a good matched camshaft and leave the heads alone or run a small shot of spray on it. It'll take it as long as the system does not run lean. Those stock pistons are a little better than people give them credit for. Don't believe it? Call NOS. They'll tell you. I've seen some of these rustang guys sprayin stock 302 bottom ends season after season with no damage. but they got their ducks in a row. you could always think about a turbo.....
Click to expand...

Totally agree, people who say stock pistons won't handle must is just true, its in the "tune".
 
The 400 i am buying is completely rebuilt with 30 over pistons.
It has never been fired and sits on a new engine stand.
It was built in 1992 and has been in dry storage.
There is no rust in the engine and the oil pump was cranked over with a drill to oil everything up.
I am thinking of taking it apart and checking everything out and installing a set of 30 over keith blacks.
The crank was done,block, all bearings,heads,new everything.
They spent $1800.00 on the rebuild but it was all stock with a economy cam.
It is real easy to build a 451 BUT, if everything checks out, it only needs a good piston and cam with a little bowl work to make it a great engine.
I most likely will get arp rod bolts and shot peen the rods.
It has the same stroke as a 383, so i would think it would scream.
It reminds me of a 340 as far as the stroke being less but the bore being even bigger then a 440.
If i go to a stroker crank,i think it will cost almost the same as turning a 440 crank and hardening it after the cut.
If i go that road then it will be a 512 cube engine instead.
If someone built a 451,how much coin did it cost in the end????????
 
T67POWER said:
The 400 i am buying is completely rebuilt with 30 over pistons.
It has never been fired and sits on a new engine stand.
It was built in 1992 and has been in dry storage.
There is no rust in the engine and the oil pump was cranked over with a drill to oil everything up.
I am thinking of taking it apart and checking everything out and installing a set of 30 over keith blacks.
The crank was done,block, all bearings,heads,new everything.
They spent $1800.00 on the rebuild but it was all stock with a economy cam.
It is real easy to build a 451 BUT, if everything checks out, it only needs a good piston and cam with a little bowl work to make it a great engine.
I most likely will get arp rod bolts and shot peen the rods.
It has the same stroke as a 383, so i would think it would scream.
It reminds me of a 340 as far as the stroke being less but the bore being even bigger then a 440.
If i go to a stroker crank,i think it will cost almost the same as turning a 440 crank and hardening it after the cut.
If i go that road then it will be a 512 cube engine instead.
If someone built a 451,how much coin did it cost in the end????????
Click to expand...

You're going to have to have the rods resized if adding new bolts. For a total cost you just simply add the cost of a turned down crank to what you already said above. The Hyper pistons should be very close in cost...eveything else is the same $$. Talk to a reputiable local crank grinder.
 
You must log in or register to reply here.
-

Back
Top