348/409 Motor

[John Brown]

[ QUOTE ]
Be wary of truck blocks unless you're planning on building a blower motor. They have 2 fly-cut wedges removed from the combustion chamber to lower compression to about 7.5. You can't make that up with different pistons.
Verne

[/ QUOTE ]

Won't most of those fly cuts go away when the block is bored?? A picture would be nice. It would help i.d. a truck block if I were to see one apart. Are those eyebrows in the last picture what you are talking about?

[Verne_Frantz]

John,
Sorry, but I don't have any pics of the truck block notches. (or externally) Maybe you might find one on the 348-409 site? The notches are very deep, maybe 1/4", so overboring won't do much to reclaim compression. You'd have to bore it almost .090" just to begin to cut into the combustion area where the notches are. That area is rough machined and a larger diameter than the finished machined cylinder wall.
The pic I posted is of a '62 409hp block (.057" over). IT was only to illustrate the swept part of the cylinder vs the wedge chamber above it.

Verne

[PeteLeathersac]

Is this the truck block notch Verne?.

http://www.superchevy.com/features/p.../photo_04.html

And they're on all truck blocks whether 348 or 409's?.

What's the whole story on the two notches in earlier blocks and one notch on the later blocks thing...two is worse?.

Do 409's always have the counterbalanced crank and the 348's the round one where the flywheel bolts on?.

And are the distributors and waterpumps W-motor only or do SB or BB ones fit?.

Thanks!.

~ Pete

[Verne_Frantz]

Pete,
Not to cast any disparaging remarks toward Super Chevy, but that picture is NOT of a machined wedge in a truck block. That’s a severely damaged block from a failure. It’s a mess. Note that the cylinder next to it doesn’t have any such “notch”.

As to the other questions, I’ll respond later as accurately as I can after I recheck some references on the “notch” issue.


Verne

[Verne_Frantz]

"And they're on all truck blocks whether 348 or 409's?."

All truck blocks, whether 348 or 409 have 2 notches. Both engines were rated at 7.75:1 CR.

"What's the whole story on the two notches in earlier blocks and one notch on the later blocks thing...two is worse?."

I don't believe that's accurate. Because of the 348's smaller bore, one notch was milled to provide exhaust valve clearance. With the standard piston (low perf), that produced 9.5:1 CR. For the hi-perf 348s with compression higher than 10:1 the piston dome was modified (raised) in the wedge area which made the combustion chamber smaller. Two notches are obviously worse, because you're starting with a base 7.75 CR. Even with hi-perf pistons, I doubt you could get to 9.0:1 CR.

"Do 409's always have the counterbalanced crank and the 348's the round one where the flywheel bolts on?."

As far as I know, all 348s have a round flywheel flange on the crank and all 409s have one that's asymmetrical.

"And are the distributors and waterpumps W-motor only or do SB or BB ones fit?."

Yep, they're W-motor only, along with the oil pump drive shaft due to the shorter distributor. The water pump bearing & shaft are the same as SB though, so there's no problem having them rebuilt.

Verne

[PeteLeathersac]

Thanks Verne!.

I appreciate the info and clarification.


~ Pete

[JChlupsa]

Just got this from a friend:

[ QUOTE ]
<font color="red"> Hey I just bought a motor I've known of for 20 years It's a 64 409 QB 425hp Dual quad manual trans motor Its all together and comes with 4 intakes (or I would sell motor alone) Single factory 4 barrel Inline factory dual quad M/T dual quad xram Weiand 2X6

For everything its $7500.00

Let me know, be perfect for someone with a old school impala
</font>

[/ QUOTE ]

not sure if this is a good price or ?? Verne might be better to reply to what he thinks of the engine and intakes. I did ask for numbers off the engine/intakes/carbs itc

[Salvatore]

I beleive that is a good price for that stuff. I was just discussing the 409 prices today with the master 409 man himself in Pottstown, Pa. Call him if you want. Pete (610-326-8322. There are 3 in his shop right now.

[RPOLS3]

Here is a site that has what appears to be a comparable 64 425 HP QB setup (scroll down a little) for $7,200.

http://www.409chevyperformance.com/E...rformance.html

Anyone know about this guy? We have been talking to him about a date correct 62 QB block for us.

Jake

[JChlupsa]

My mistake on the 409, no carbs. This is more info on it.

[ QUOTE ]
<font color="red"> It a QB 1964 425 horse dual quad in line manual trans motor 11-1 comp., all stock, no carbs, the intakes are one 4barrel stock gm, dual quad in line stock gm, x ram M/T with linkage, 6x2 Weiand., the motor has sat for years however its complete, looking at 7500.00 for everything, been offered $5500 for the motor w/inline dual quads (I'm strongly considering it), </font>

[/ QUOTE ]