Budget 406

[z ya]

After figuring out all that is needed to be done to the z , I decided that I need to budget a little. I still need paint,cage,seats,tranny work

so I need to get the best bang for the buck on my

short block. I am thinking about going for a 400

sbc with the factory 5.56 rods. I would just put in some good rod bolts and some forged or kb pistons and a 292/501 comp cam. With this set up

I would save a bunch from custom pistons, crank,

and machine work. I wanted to go crazy with a really trick bottom end but after coming to grips

with all that is left to do to the Z , I felt I needed to chill a bit.

[Mike C]

IMO, it's WAY cheaper to build another 355 rather than go for the 400. Advantage 400 for torque, but since the 355 is more comfortable up higher, hp is pretty much a wash with same cylinder heads and cam. Not only do you have the cost of a 400 rebuilder which is usually priced at a premium to the 355, parts are higher. Pistons are about the same as the entire 350 rebuild kit in some cases! Added expenses come with having to use the 400 flexplate and damper which you will have to pony up for if you don't already have them. The 355 is also more comfortable cruising at a higher rpm than the 400 which may be important depending on your trans/gearing. 355 with its 5.7 rod has a better rod/stroke ratio as well. Anecdotal, I had an 84 'vetter for awhile. It went around corners like a train and made tons of low speed torque. It just flat quit at 4200 rpm. Not good in a sportscar IMO. I like the 6000 rpm power spread much better that my Z has and think you will be happier with the slightly more rev happy motor ~500rpm or so.

[jt1]

I agree with MikeC, if you're on a budget go with a 350, esp if you already have a block. I have built several 406's over the years, and 400 blocks are getting hard to find and pricey. If you stick with a stock crank, it's cast, you could find a steel 350 crank pretty easily. The worst part is the stock 400 rods. They have a large notch into the big end where the bolt head sits which weakens them considerably. IMO any 406 should have 350 rods, which means going with the higher priced pistons. The 400 cast crank is in thin air above 6K rpm (don't ask how I know this, it wasn't pretty). Also you have to deal with the external balance issue's of the 400, weighted flexplate and big damper. Without upgrading your topend, more cubes just lowers your torque and hp peak, not necessarily gives you more power. So, I think you would be better off to spend what you can on your 350 and leave the 400 till you can do it with a forged crank and good rods and pistons.

 

John

[z ya]

Thanks guys, Back to the drawing board!

[Guest Anonymous]

I built a 406 on a tight budget ($1800) and went with stock rods with ARP bolts, stock 400 crank, Chevy 461 casting "camel hump" heads with 1.94 valves, 10:1 forged pistons, Edelbrock Performer RPM intake, modified Q-Jet, stock HEI, and a Comp Cams 280H Magnum cam. I did spring for an extra hi-zoot balancing job, as I'd heard a lot of horror stories about 400s flying apart. The result: 13.67 @102 in a huge-ass 4-door '65 Impala with 3.31 gears and a TH350. I never went above 5500 RPM, which didn't really matter as the thing grunted out yard-tons of torque at all speeds (even with the lumpy cam). The engine is still working fine today, 3 years and 2 cars later.

 

Anyway, my point is that the added torque of the 406 compensates somewhat for the restricted redline with the stock rods, though Mike C is correct that 400s are getting kind of scarce these days- I was lucky to score mine at Pick Your Part. Just don't forget to get those extra steam holes drilled in your heads!