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View Full Version : 400 long block motor?.. or 350?



Mr.VENGEANCE
01-19-2007, 07:24 PM
Have to put in a motor in the chevelle and i have a lead on a couple of motors til i put together a 454 for the velle.

one choice is the 400 long block that was originally from a 67 chevelle.
its dirty but running. i dont know much about engines but he told me that the long block engine isnt the choice 400 engine.. is that a fact?

hes asking 475.

then.. my pops has an old 350 motor that has been sitting in the backyard garage that hasnt run for a long time.. and hes pretty much forgot his old days of messing with these motors so he doesnt know if its a good motor or not..

but.. its free.

now which should i do?.. rebuild the 350?.. or throw the 400?
:candle:

LowBuckX
01-19-2007, 10:21 PM
The 400 was introduced in 1970 and not original to a 67.

What heads are with the 400

i dont know much about engines but he told me that the long block engine isnt the choice 400 engine.. is that a fact?

hes asking 475.


:candle:
What do you mean by this. What are you refering to as a long block. Are you meaning to say small block?
Ask for casting numbers off the 400 and its heads.

LowBuckX
01-19-2007, 10:23 PM
double post

MonzaRacer
01-19-2007, 10:44 PM
IF its a 67 400 then I t Might just be a 396 inder all that grime,,, great as you can mock up a lot and its wont be such a chore to install the 454 later on.
I agree get casting number from back of block and maybe even the letter code from the id pad on the front of block.
If its a BBC then you struck pay dirt.
BUT if its a 400 SBC(look for a cast in balance section on the harmonic balancer and weight on flywheel) its 70 thru 80.
If its 400 then I would ripapart the 350 and see whats wrong, cause for less than $200 bucks Northern has a 350 rebuild kit, then option in moly rings and a mild cam , giver her a good ball hone and relap the valves and start her up.
Had to do a few of these to keep friend on the road. With ball hone I start with a little oil then switch to carb cleaner for hone lube and it give a very good break in finish that usually wont burn any oil.
Good Luck
Lee Abel

Mr.VENGEANCE
01-20-2007, 05:47 PM
well he kept saying that the 400 he has is diffrent than the ones that are used to make race engines.. now.. i dunno what that means.. so i figured id ask..

LowBuckX
01-20-2007, 08:49 PM
well he kept saying that the 400 he has is diffrent than the ones that are used to make race engines.. now.. i dunno what that means.. so i figured id ask..

confused :pat:

Mr.VENGEANCE
01-20-2007, 10:49 PM
i know.. me too... i thought.. hey.. a 400 is a 400 right?

LowBuckX
01-20-2007, 11:40 PM
Maybe he ment it isnt a 509 block or its a 2 bolt. either issue wouldnt bother me. 509 is the last 3 didgits on the casting number on upper drivers side bell housing area. Also 509 will be cast on the side of the block. I think the 509 block has 2 freeze plugs on the side of the block. Most 400s have 3 freeze plugs on the side of the engine

***EDIT****
I just went and looked at my 406 509 block and mine only has 2 freeze plugs. Some people used to cheat and run the 2 freeze plug 400 blocks and claim it was a smaller engine. The where called cheater blocks also

Mr.VENGEANCE
02-26-2007, 07:05 AM
back from the dead..

heres the block numbers

"39 51511 GM"

can someone tell me if this is a 400?

jknight16
02-26-2007, 07:50 AM
That's a 400 ci small block, built from 1970-1973, that has 4 bolt mains. Just for grins, that motor was originally rated at 255 hp and 265 lb/ft.

I used a similar block and make about 475-500 hp and around 520 lb/ft, and its been very reliable. Just remember to drill the steam holes in the heads or you'll be running hot...

Kenova
02-26-2007, 08:53 AM
I had one of these sb 400s in the mid '70s. I swapped on a set of heads with smaller chambers (300hp 327 heads) and stabbed a 350 hp 327 cam into it and topped it off with a Wiend Accelerator (single plain) manifold. Made for a nice little stump puller.
Ken

Mr.VENGEANCE
02-26-2007, 01:38 PM
are these the ones that folks usually turn into 406s?

jknight16
02-26-2007, 02:33 PM
That's right, when bored 0.30 over, you end up with a 406, or in the case of my engine a 0.40 over will give you a 408.

I also went to the effort of having a machine shop clearance the block to install 6" rods in my 400, which is another popular thing to do.

If I remember correctly, the 4 bolt main 400's have become quite rare these days, so if you have a good block than you have a fairly desirable engine on your hands. I may be biased since this is what I built and I've had good luck with it, but I'd recommend building a 400.

I think the guy you were talking to may be referring to the 406 small blocks used in sprint car racing. All of your world of outlaws cars and various sprint cars are alcohol injected high compression 406's, but I doubt they use GM blocks. That may be what he meant when he said it's a different 400 from the race engines. I dunno....

Mr.VENGEANCE
02-26-2007, 04:36 PM
yea i figured as much.. i just wanted to make sure that it was what it was.. either way Venomous has a 406 in it!.. and i love that engine.. just dont know much about it.

ha!

thanks alot guys!!!

and Jknight16 how do you like that 700R4 transmission with your engine setup?.. im concidering a new transmission for V and cant decide witch would be more painless and easier install.. 700r4 or 4L06E

slowcamaro
02-26-2007, 05:14 PM
Most consider the 2-bolt 400 a better block. With the bore of the 400 being so big the 2 outter bolts are actually rumored to make the main webbing weaker. (high) Performance guys usually buy the 2-bolt blocks and go to splayed caps.

Im too cheap for that so i am just going to stud my mains. At this point though it seems as any 400 block at a reasonable price is getting difficult to find.

Whatever you decide on the 700/4L60e swap call Dana at http://www.700r4l60e.com/ He is THE man when it comes to the 700s.

LowBuckX
02-26-2007, 06:16 PM
That's right, when bored 0.30 over, you end up with a 406, or in the case of my engine a 0.40 over will give you a 408.

....

I think you mean .030 and .040 a small block bore spacing is only 4.4" center to center

TUBED
02-26-2007, 08:51 PM
Don't take for granted that the 511 casting is a 4 bolt main block, they made the 511 casting with 2 bolt mains also so yank the pan to be sure either way you'll be please with the torque that 406 will make.
Gerald

jknight16
02-27-2007, 07:10 AM
Haha, Lowbuck, guess I left a decimal place out of there. "I always screw up some mundane detail" Good catch :twothumbs

I was just going off of some engine decoder online so you may well find that it has 2-bolt mains, I don't know for sure. FYI, my block is a 2 bolt with the splayed caps.

As for the 700-R4, I had that trans built about 6 years ago when not many people were doing 4L60E's and the like, so I didn't really know of it as an option. If I had it to do over again, I would definitely do a 4L60/65/80, whatever. Even though you have to utilize a computer to run the trans, I don't know how much more complicated and expensive it is than just running a PROPERLY adjusted a TV cable on a 700R4, which are kind of a pain to get right (from what I've heard, mine works fine).

I had a guy named Gary Gonzales (Abq, NM) build my 700R4 and he builds very strong and reliable race transmissions (he has built transmissions for 9 second cars that will go 300-400, maybe more, passes without a refresh) so I haven't had any of the reliability problems that some people associate with the 700R4.