Guys,

I finally reached the shop that did my dyno testing for me. The guy there said that he had several 400 blocks, cranks too. He said he had both 2 bolt (stronger) and the 4 bolts.

They are gonna get me prices on machined blocks and also just outright ones.

What do you guys think the prices should be around?

I am gonna ask them if they have any 509 casting numbers. From what I hear they are the best ones.

Later... :cheers:

 

I have a 400 motor sitting in my boat that I never take out and was contemplating a swap too. The engine is fresh with only about 50 hours on it with JE pistons, World Prod. heads, roller cam and rockers, but after researching the idea I think I'll stay with the newer style 350 Small block. I haven't found anyone who recommends the swap although initially I thought it would be a good idea. What are your thoughts and what have you heard?

 

Well,

Corkyvette and I have been trying to diagnose my stock engines problem. Upon performing a leakdown test, it revealed that nearly every cylinder is leaking down more than the allowable 10%. So I need to replace the shortblock.

If you have not seen the results Corky has gotten with his 406 then you need to observe his new 11.124sec 1/4mile pass.

We intend to bolt the heads, SR, etc I have on a freshly done 406.

I am in the stages of tracking down some blocks for the buildup.

 

Everybody going bigger....lol


Jay

 

might as well only do it once. I already made a mistake not checking the condition of the original block.

This time I'm going with the beef! :lol:

 

I would go with a Stroker 400 !

Vic

 

Im with Vic89 why not get a 3.875 (396) crank and go to 420ci does not cost much more and dont nead much to clear to make it fit or you could get a 4.00 crank but then you have more special parts and more to clear.

Jay

 

Jesse, congrats on the upgrade. (too bad on the way it came about. many of us follow your threads)
I have often heard the water jacket design ain't that great on 400 blocks. What have you heard. Any reassurances from 400 owners?

 

You talking GM 400's?
You will need to do some trickery if you plan on using the knock sensor. I have never seen a 400 block w/ a knock sensor boss.

 

i have heard the same thing, keeping these things cool in warmer climates is no easy task....but then again, i have never tried it myself!!!!

 

Ski, I've done a little research on 400 blocks the past several months and found there to be quite a bit of conflicting info on them. I think most of the stuff you hear is second and third hand, mostly pessimistic in regards to cooling issues. There's also a lot of confusion on block prep for a dedicated racing motor versus a motor used on the street. Do an archive search on "sbc 400 block" on the forum and you'll see what I mean. I've talked to a few people who actually run them as street motors and was satisfied enough that I bought one myself last month to use primarily on the street.

I just took mine in to have it checked and machined.( it's gonna be a 420 CI). I've found pricing ranges between 200 to 400 dollars for a bare block that hasn't been bored, and that's the key, a stock bore. Pricing in those parameters just depends on who's hungriest, buyer or seller. Shipping is always extra and so too is any machine work (including mag or sonic checking).

As far as high nickle or tin content, there seems to be a ton of conflicting info also. I wasn't too concerned since my motor is just gonna be a driver, so I didn't look into it too much. http://forums.corvetteforum.com/zerothread?id=328919 This thread has some interesting info on 400 blocks, and it just scratches the surface. There are soooo many knowledgeable people on this forum it's amazing!

If your guy has a 2 bolt 400 he wants to sell and will mag and sonic check it for me, I'd definately be interested buying the block, paying for the work to have that done, and shipping on top of it. Going thru a forum member is a whole lot better than buying sight unseen from some E-Bay vendor somewhere. :yesnod:

If there's something I can help you with, please feel free to shoot me an IM or EM. I don't know everything about these blocks (far from it), but like I said, I have done a lot of research lately and think I've got a pretty good handle on fact and fiction. Good luck! :cheers:

 

509's are the better blocks and the knock sensor screws into the block drain plug. LOTSA GRUNT !!!!

 

Glad to hear you found some 400's. In my opinion, go for the 2 bolt main only! The factory 400's were very weak in the main webs, that is the main reason gm only produced them for 18 months! :smash: If you want a very reliable/almost bulletproof 400, have the 2 bolt block drilled to accept "splayed" 4 bolt main caps. I've run several 400 based small blocks on the street, drag strip, and circle track racing and love them. The overheat problem will not be an issue as long as you make sure that you use the CORRECT HEAD GASKETS, and DRILL THE "STEAM HOLES" IN YOUR CYL. HEADS!,and have a quality radiator. Use the correct 400 head gasket(equipped with the steam holes) as a template. Some people even say to use steel frost plugs to plug some of the other coolant passages, in the block, and redrill them smaller. Supposably this will make them run cool :bs I've done this procedure twice once a 406/iron heads and the other was a 400/aluminum heads, and changed less than 5 degrees on both, not worth the effort! What I found with both of those was the 406/iron head, had too small of a radiator, and the 400/aluminum head had a bad water pump. The radiator was a recored vega unit, the motor was in a 73 vega, that was not done correctly. I took the radiator to another radiator shop that custom makes their own cores! This thing would run 220+ even on the highway, quality radiator and ran 186 on the highway, 192 sitting in traffic! The waterpump issue was me being cheap and using one off my shelf :D , it was a short style, and was not capable of flowing enough :mad ! As for the knock sensor, I built a 377 for my 81 Z-28 as well as a 406 for buddies 85 IROC, and used the coolant drain hole located on the side of the block just above the oil pan rail. We had no problems with either one of these. I sure hope this will help you, and if you have any questions, I'd be glad to try to answer them for you. :cheers: good luck, hope you can get it done before the season ends!!!! :cool:

 

These are some of the differances I've read about in my research, the cylinders are siamesed on the 400's, so the coolant doesn't run between the cylinders, but as mentioned before isn't a problem as long as those steam vent holes are in the heads and gaskets. The siamesed cylinders are believed to be a plus because the interconnecting of all the cylinders in each bank stabilize the bores and provide less distortion in the bore for a better ring seal. The bores are so close together that a flat deck is critical to prevent head gasket leakage in this area. I don't know how if any of this is fact or fiction, but sounds reasonable.

 

What is the typical "mild" hp results from people with these motors? By mild I mean people with a mild setup not crazy money for top HP/Tq.

 

I've seen 500-550HP really easily with a "mild" setup.