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Chevy 409

9K views 33 replies 10 participants last post by  Harper790 
#1 ·
I have a 1965 chevy 409 bare block which has a 4.1435 bore on it. I guess I'm debating on trying to rebuild or sell it. What's your thoughts
 
#2 ·
One thing is that they aren't exactly cheap to build. Especially if you need to buy everything else for it which can add up really quick with a 409. Heads, rotating assembly, brackets, intake.

It depends what you want I guess and how much you are willing to spend.

I just did a research on building up a 348 which is similar. A rotating assembly for a BBC would be the same. The one I looked at was around $2500. Edelbrock sells heads. I think they are just over $1100 each. Then you still need quite a few others things to finish it.
 
#3 ·
Can't be a 409 block, stock bore for a 409 was 4.312". Stock bore for a 348 block was 4.125". Are you sure about your measuring? 4.1435" would be eighteen and a half thousandths over stock (+0.0185).
I would record all the numbers off the block and run it for sale in Hemmings Motor News as a 348 block. There is someone, somewhere who needs this block to finish his/her restoration. It would cost you far more to build out this motor and make less horsepower than you could with a, for instance, 454 with oval port heads.
 
#4 ·
If you are so inclined to build it'don't spend a dime on it until the block is thoroughly ckd out.A lot of the W blocks were bad about cracking & a lot of ppl have pd good money for cracked or welded up blocks.If you don't have the original main caps,I'd pass on it as well.
 
#5 ·
Missed the bore size. Anything over .060 on a 348 is a no no. Another thing you should check is to make sure it's not a pre 62 truck motor. They are worthless for hot rodding as you can't get the compression up high enough with the two cut outs in the cylinder and the available pistons.

348's can be easily stroked to well over 400 ci. But like I said if it needs to be bored to .060 it can cause overheating because of the thin cylinder walls. The 409 on the other hand can be bored in excess of .100 to .120. Either motor can be huge money pits but they are a lot of fun because of their huge torque capability. Imo their looks can only be topped by maybe a Nailhead, Hemi or Cammer. But for Chevys there is nothing cooler.
 
#7 ·
.
. Good catch, Tech... prolly a 0.020" overbore 348... if it's even a W block and not a SBC 400 block or BBC 402/427 block...

. Yes, the cool '409' looks of the W engine would be the main reason to keep/build it... unless needed for a correct engine restoration... since a SBC 400 can be dirt cheap built to make more power and torque...
 
#8 ·
Chevy Overbore 409

My error. I just went out and took out a dial bore caliper and re-measured all the cylinder walls. They measure exactly 4.4345. It is an over bore block. Probably was used for racing. I do have the heads (in great shape) the intake and dual carbs, the crank has been turned .020/.020 and I have the snorkel breather. I've spent a lot of time with SBC and this is my first time dealing with a 409. The block just came from shop where I had it cleaned and checked for crack and cast painted. Being an over bore and a W block, I'm not sure if I could have it sleeved? I think the project it over my head and I'm wondering if I should count my loss and sell it. That's why I was asking if there was a market for it. The casting is a 3857656.
 
#10 ·
I do have the heads (in great shape) the intake and dual carbs, the crank has been turned .020/.020 and I have the snorkel breather. I've spent a lot of time with SBC and this is my first time dealing with a 409. Being an over bore and a W block, I'm not sure if I could have it sleeved?
. WHY are you talking about sleeving? Is it cracked in a cylinder?

. You would just rebuild it with .020" oversize pistons... or if bore is worn, overbore to .030" or .040" and rebuild with those pistons... 99% of it is same things you would do to rebuild a SBC...
 
#11 · (Edited)
If you measured correct this time, that means your block is 0.122" overbore. How are you measuring bore with a dial caliper?? as top of bore is relieved bigger than the actual bore size due to the 74° deck surface. Make sure of what you are actually measuring.

I don't know what the max recommended overbore for a 409 is, but my guess is you are very near it or possible beyond it already if you did get the actual bore size correct..

A 348-409 specific forum or 61-65 Chevy Full-size forum might have a better answer for you.

Wait a while, maybe some of the old timers here could help.

You could also try the H.A.M.B. forum.
 
#12 · (Edited)
If you measured correct this time, that means your block is 0.122" overbore.
. Oops, Eric, I didn't notice that huge overbore... must have been why he was talking sleeving... prices vary wildly from shop to shop on having that done...

. 1950's 283's could often be bored .125 over to make a '301'... poster above claimed 409's can, also...

. Prolly need a sonic test and magnaflux of block to decide between: 1/8" over pistons... or sleeves... or put it back together with the last pistons that were in it depending on bore condition...
 
#17 ·
Do you have the 348/409 standard 340 or 360 HP heads, or the taller port 380-425 HP heads??

Looks like you are at maximum overbore from what I could find out, unless you sonic check it and find out it is a thicker walled block...no way to visually tell this.

If another .005-.010" honed out could clean up the bores, there is always the custom piston option, which is a given at any bore bigger than .060" over anyway....$750 area for custom from most piston companies like Ross, JE, Wiseco, BME, CP, Probe, Diamond.
 
#25 ·
this could be a Z-11 427" W-block with a .030" overbore...? 433" now... What does that make it worth?
I believe the Z-11 used a standard 409 block with a 3.65" stroke
And, it's a '65 block, so it's unlikely
A Z-11 crank, OTOH, just might be worth more than the car cost new

Didn't the W-blocks used in trucks and early cars have a cast iron timing cover... later ones sheet metal?
Not that I'm aware of
 
#29 ·
If you went the custom piston route, and used a BBC crank with the mains reduced to fit your 409 block, you'd get a 468 cubes using the 3.75" stroke 396/427 crank, a 494 using the 4.0" 454 crank, and a whopping 525 using the now common 4.25" "stroker " crank used to make a 496 out of a 454 block.

That's one monster 409 ;)
 
#30 ·
Hope I didn't miss something reading through this, but is there a problem with the present bore? Is it too worn, or hurt to not allow it to be honed and reuse the parts you presently have? I've never owned a W engine, but always thought I'd like to build a car around one if I found one cheap enough.
 
#34 ·
The cylinder walls look good. The motor was disassembled when I purchased it. I purchase the motor in SC for my brother in TX in Oct. He never paid me. I considered putting it in a 32 I'm working on but its way too much motor and I can't finish my project because too much is tied up in the 409. In located in Salisbury NC. You can email me at harper790@gmail.com and I can send pics of anything you want to see.
 
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