rad928music

Anybody running a 400 small block?
I saw a 400 small block chevy that was bored over .030 to get 406cid in a 1987 corvette that i almost bought before getting my 86 (i didnt get it because the bank would not help me with a loan on it).
The guy said it was a 400 small block that was in some trucks and vans in the early 70's.
He changed the cam and ported the heads and used the TPI intake system.
He said the car was faster than a ZR1.
I did some searching and there are 1970's 400 small block remanufactured engines for around $1,500, that makes it a good replacement for my old 350 with 123,000 miles on it now, if i keep it.
I was thinking about getting a new 370Z but i dont want to part with allot of money right now.

mcm95403

You'd better do some more digging. The 400's are siamese bore blocks since they are 4.125" bore instead of 4" like the 350's. They also have steam holes in the deck sruface that need to be matched with the heads (you need to drill matching holes in the heads). They also have a very poor rod ratio and very short rods, and as I recall also need small base-circle cams so that the rods don't hit the cam.

Remember that you get what you pay for. I wouldn't use a $1500 rebuild in a Vette, but that's just because I've seen too many of that low a quality engine fail. $1500 just can't buy you a well-built engine.

If you want much more power the route to go is a 383 (400 crank in a 350 block). Not too expensive to build and very reliable.

rad928music

Thanks for the input, the 400 remanufactured engines are not turn key and the price is with a core deposit of $900, the heads come with it and cam also, so the price is $2400 plus shipping.

Pete K

I am running one in my 87 coupe.
The common way to build one is to use 5.7 inch (350) rods and a special piston. Special is a bad word, because the aftermarket makes boatloads of them.
The advantage of a 406 over a 350 is larger bore and stroke.
A 383 build uses the 406 crankshaft ( or similar) and that extra stroke bumps up the torque.
The big advantage of the 406 is that the larger bore unshrouds the valves, and helps boost the power, assuming a decent compression ratio and open chamber head.

rad928music

Thanks for the input, ive seen some 406 small blocks at the drag strip up here in some novas and other chevys and they roll!

Pete K

Link to my build below, in case you want to see what is involved. Tuning is happening now, so 1/4 mile times are pending.
http://forums.corvetteforum.com/c4-t...-build-up.html

pkazsr

The first rebuild I ever did was a 400 from a Caprice to put in my 72 Vette. 2 bolt mains, stock rods, 10/1 forged pistons, 327ci/350hp cam (GM part no ended with 191, Holly 650 spreadbore with vacuum secondarys, Hooker Headers (open for the Dragstrip), bias ply G60/14 Goodyears, and a 3000 stall converter. Great street car but after about 10, 14 sec 102mph runs a rod decided it didn't want to be connected to the piston anymore.
I used the parts I could and built another 400 and sold it to a used car dealer for his personal use. I never saw the Vette again.

cv67

I love 400s the bigger bore really lets it breathe. Maybe get the shortblock and a slightly better head that will take advantage of that and work with your intake.
Bummer they use a flat tappet cam unless you go retro roller but still dont need much cam anyway to make them sing . THey make torque out the wazoo all damn day.

McGirk94LT1

May get some flack for this since its not the MORE TORQUE EVERYWHHHHEREEEE motto but could be somewhat original and just use it to make a 377. Then again, I dunno if TPI would really like as high as rpm's as that engine would wanna turn.

Klondike

I've built a lot of Ford engines but I'm not up on all the Chevy varibles. How come the 400 would need a small base circle cam but a 383 with what I presume would be the same crank would not. Please educate me. Is there a difference in deck heights between the blocks?
I had a friend with a slightly modified 400 in a truck and it was a racecar trailer pullin' son of a gun!

Pete K

TPI would not play well with it, but a miniram would make it sing. Lots of old timers in my area still use a 377 combo, and love it.

Pete K

Unlike the 302 vs 351 Ford stuff, the 400 is the same externally. Deck height, bore centers, cam height etc is the same as a 350 (or other Gen 1 small block).
A 400 block has larger mains, and an extra 1/4 inch stroke on the crank, compared to a 350.
To correct this difference on the assembly line, GM used a 5.56" length connecting rod to get more clearance between the rod and cam (shorter rod bolt also).
When building a 400 today, most use a 5.7 inch rod or longer, and cam clearance can be a concern depending on the connecting rod/cam combo.
I use small base circle cams on nearly eveything I build because it is an easy way to get clearance that you may or may not need.

JackDidley

I think Caboboy is running a 421 that started life as a 400 SBC. maybe he will chime in.

johnnymo63

LD85 has a mean sounding 406 in his, too.

Coupe89

I ran 418.
400 block and stroked. .020 over
Retro lifters / cam 230/236 / Super Ram / AFR 195 heads / Long Tube Headers.

I loved the power.

Not sure if was faster then my ZR1

If I were to do it all over again. I would buy the LT5 from the get go. Less money in the long run... And less hassel with SMOG

Not only you need to deal with the motor. But the transmission and rear end too. If built up right

rad928music

He ment C4 ZR1, you may laugh but ive seen mild built 400's up here at BIR running 11's in nova's, i wish i had pictures.
The guy was a mechanic and it looked built.
I wish i would have got the car, he scraped the deep oil pan while getting the car shiped after the paint job so i didnt drive it.
I wonder if anyone on here has the car.