I have a chance to buy a 400 small block chevy out of a 69 station wagon that was rebuilt as a stock short block (but with stock bore) and a completely rebuilt set of z28 double hump heads with a rhodes valvetrain.
What I was wondering was if this was a common block/head combination, and if I use this for street use is it a big deal to run unleaded 92 octane in it? It's got flat top pistons and the heads were milled slightly.
Any idea on wether or not this is a common combination and if it will be a good street engine?

It's gonna cost me about $450 after some trades of mountain bike parts, sounds like a good deal to me...
My other option would be to buy a GM targetmaster or AC delco remanufactured 350 long block for $1200... Money is a slight issue. the engine is a stock bore, but low miles, block and heads were magnafluxed, and the unleaded thing is an issue. is it a lot of $ to get hardened valve seats installed, or is it not necessary?


all info is MUCH appreciated... THANKS!

I will bite,
The double hump heads (64/66cc) will put you over the street CR range because I have them on my 406 and had to put large dished pistons in it.

The nonhardened valve seats are another concern, but if you don't drive your car a lot under a load or hard they will last a supprisingly long time , BUT THEY WILL GO AWAY eventually.

It sounds like for the money the stuff will cost you that you will be able to use the 400 block as a foundation for a very good engine because only money beats cubic inches!!!

Buy the stuff, save your money for a set of Darts or whatever you like and build the 400 up into the 450hp/450t range that will run on 92 gas in the street rpm range... pdq67

Guy's, what are good stock 400 blocks going for nowadays????

How much do stock 400 small blocks go for these days?????

Also, are there any places that I can check the #'s on the block and heads to verify that it is a 400 and see what years they are? I was told that if it's a 72/73 (?) or newer it would have hardened valve seats already, but what was the last year the double hump heads were made???

I'm going to be using this as a semi daily driver, so I want it to be durable. my posi is a 2.51, so I get good mileage with about anything, that's not a big deal.


Also, what are the specs on the large dished pistons that I should look for? What brands are recommended???

Should I bother spending a few extra hundred bucks to bore it .030 to a 406 to have fresh cylinder walls? I understand it wasn't a high mileage engine, but is it a good idea? It was also in a station wagon, so I would assume no hard use here.


THANKS!

last but not least, this long block was rebuilt about 4 years ago and never used, I was going to swap it for my 305 a year ago and the guy asked $1,000 for it. I held off, not knowing the potential and rareness of a good 400. He tracked me down this time offering it for $500 becuase he's moving and wants to unload it... for the blockwith a stock bore and the good rebuilt double hump heads it seems like a good deal. With some trades it will be about $450.


LAST QUESTION -
Are the double hump heads going to have too small of valves for 400 cubes??????

chuck post the casting number`s one of us here can help you thats for sure,
i think heads made after 71? were all of the 76cc`s, i think dont quote me on this, till later on in the the early 90? some of the heads are back tot he 58-54cc`
one thing I would CHECK AND MAKE SURE OF IS STEAM HOLES have been DRILLED! for the 400,
if they are true z/28 heads they will have 2.02 valves not aprob for the 400, 1.94 wouldnt be all that bad ethier,
oh and one otehrt hing, just cause it was in wagon dose not mean it has not been beat, wagons are cool for street raceing (grins)
the 400 blocks are getting up there in price, i`ve sen them from 300-700 for long blocks in the local paper, I`d say get it, if noting else for the bottom end,
and as for comp. being to high i run 10.5:1 on the street, and have evn run 11:1, just got to tune it right.
any way
cerbz

I found a site helpful with some casting #'s, but I was wondering if anyone could tell me what the engine suffix code (three letters) for all early small block chevy 400's were...

What do you mean to check and make sure that steam holes have been drilled?????
Is this a modification to make them not overheat?????


If I use this as a daily driver, and I have a higher compression due to the small volume of the double hump heads with flat top pistons, and I going to effect the longjevity of the engine in the least bit????? is it possibly going to ping a lot on pump gas??? What is the downside to it?

Does anyone know how I can check to see the compression ratio? I think my dad has a compression tester (the kind you put in place of the plug). What readings should I look for?

To the guy who runs a 400 with double hump heads - how high was the compression originally with your setup, and what are the specs on the pistons that you changed to?


THANKS!

I live in the Denver area and I have seen a number of 400sb engines in the $200 - $300 range. These are typically builders and most are already overbored a bit. I bought a stock bore 400 last Christmas from a local junkyard for $125 ( they kept the crank). It needed to be bored but that was fine with me.

Smaller heads like the camel humps can be fine - they'll generate great low end torque. If you want a street racer then you'll want to step up to performance heads.

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Scott
'69 400SB, Richmond 5-speed; '99 HD Road King Classic
www.geocities.com/sdenning1 (http://www.geocities.com/sdenning1)

Steam holes.... 400 SB's have siamesed cylinders which means they touch each other in the water jacket area (due to the larger bore diameter) instead of having water all around them. This makes it harder to cool them and it can also lead to the creation of steam in the upper part of the water jacket in the block. Chevy drilled small (3/16" I think) holes in the block and heads on 400's to allow this steam presure to escape into the heads and keep the cooling water circulating correctly. If you forget to drill these when adding other heads you'll definitely have overheating problems.

I would buy the motor. It sounds like a good deal IMO.

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Scott
'69 400SB, Richmond 5-speed; '99 HD Road King Classic
www.geocities.com/sdenning1 (http://www.geocities.com/sdenning1)

My pistons were the big dish TRW's for the stock length connecting rod. My heads are 461's 2.02"/1.60" with measured 66cc's. I asked PAW 18+ years ago to supply 9.5 to 1 pistons and that is what they sent with my master rebuild kit. Sorry I don't remember the stock # of my pistons. pdq67

Back again, my pistons are TRW PN 2410.

Now that I think of all this, better design pistons are on the market now. Like the "reverse dish" type that are dished just as much to hold the same CR, but that are designed to match the combustion chambers outline so that quinch or squish is much better then the older style round dish/ chamfered piston circummference ones. pdq67