What is the standard bore for the 350?

I am looking for heads to fit a GM 400 block that has a 3.980 bore....
Also, which heads? What specs should I look for?
It has siamesed cylinder walls, cast nodular caps, four bolts on all five main caps; the outer bolts on the three center main caps are splayed 20 degrees. Grade 8 bolts secure the caps. It features priority main oiling and 9.025" deck height. The blocks come finished bored at 3.980" and the maximum recommended bore is 4.150". This block features a two-piece rear main seal; "400" main size (2.65"). It features lifter bore heights (.842").


Could someone translate this into english for me?
I'm trying to learn this stuff because I plan on swapping this into my car at some point within the next couple of years. I want to build it during that time as I gain the money...
Thanks for the help!

Later,
Daniel

 

the bore for the 350 is 4.00". It is the same as the 400. Any 350 heads will fit a 400. It sounds like a pretty good engine.

 

What about pistons, cam (roller), What do all those numbers in the description mean?

How do you decide which pistons, crank and heads to use?

Thanks!
Daniel

 

uh, 400s have something like a 4.150" bore

 

I think that's 4.125". With a 3.75" stroke...let's see what that computes too: 400.921 cid (looks like I'm correct). A 383 is a 4.03" bore with a 3.75" stroke. A 350 is a 4.00" bore with a 3.48" stroke. The 305 is a 3.7-" or so bore with a 3.48" stroke.
These are all small blocks and the heads and such are interchangeable. The 400 blocks had siamesed coolant passages, or something, that will require some head work when putting a non-400 head on the 400 block (steam passage modification). If you don't do it, overheating will be a problem (this is why the 400's became notorious for overheating). Hope this clears everything up...

-Mark W.
<A HREF="http://www.angelfire.com/al3/thegreycar">'88 SC Camaro w/ 305 TBI</A>

[This message has been edited by Mark305TBI (edited September 28, 2000).]

 

Kiz,

You're on the right track, and off to a good start. Do the research first, then start buying hardware. Put the case in a stand and work on it as time/budget allows. By the time you've finished, you should have one horse-whippin' rice-munchin' small block.

There are a few tricks to making the 400 case a solid engine. If you're really nice, Box O' Rocks may pipe up and share some of his insight. Some of the things I know are that the steam holes between the cylinders can to be drilled deeper and larger. The crank/rod/piston balance can get a little tricky, and you can actually internally balance a 400 rotating assembly with short rods if you are so inclined. This makes flywheel and balancer selection a lot easier. The crank journal size allows more treatment to reduce friction and increase durability, like rolling and undercutting the radiused ends of the throws, and gun-drilling the crank oil passages. Your piston and rod geometry can be changed to suit the kind of driving you intend to do. Shorter rod and low pin boss pistons can allow more power at higher RPM operation, whereas longer rods and higher pins can provide some real neck-snapping torque but sacrifice a little durability at higher RPM. As always, cam selection should be done with consideration for how the vehicle is going to be used, but a roller is probably the way to go regardless of the lobe profile. And you can pack some pretty hefty valve sizes into the larger bore chambers, so the cam doesn't have to provide for all the flow.

Overall, the 400 case can be a really good starting point for serious power. Now if you could just get your hands on a Super Ram and some big injectors...

------------------
Later,
Vader
------------------
"Make Me Bad"
Adobe Acrobat Reader 4.0

 

Ok,
Thanks so far!
Any help on interpreting the numbers and such would be appreciated!

What is a decent cam to get, as far as 000/000? It will be my daily driver. Highways and the city, so a mildly aggressive cam is what Im looking for.. Nothing too extreme... I want the idle to be nice and smooth until I decide to eat some rice ........

Thanks again!

Any more?

Daniel

 

That discription sounds a lot like a Bow-Tie. If your spending that kind of money, I'd be looking at the Rocket block as well. The possibilities are endless with Rocket block.

Here's a couple links for you to look over. One is 421 build up using a LT1 (gen II) block, a 434 build using a Bow-Tie block and one using a Rocket block. All are big money, but will give you some food for thought.
http://www.spoperformanceparts.com/
http://corvetteforum.com/ubb/Forum7/HTML/004514.html
http://corvetteforum.com/ubb/Forum7/HTML/003151.html
http://www.c-zone.net/montalvo/LT4_4...ifications.xls


You're going to get a multitude of differing opinions on your quest of information. I would listen to them all but don't take any as gospel. Get yourself a few books as well and listen to people that have had success with the 400+ cid small blocks. There's a few here that are sharp as hell. But there are also those that are pretty stuck with there ideas and aren't very open to new ideas.

A couple here that have given me some excellent advise are: Vader, JCB999, RB83L69.
BOR is also very knowledgable and will fill your head with an abundanse of information.

Good luck, Mike

 

Anyone else?

 

You can use any head that is avaiable for the 350 on a 400 block. There was nothing special about 400 heads except the steam holes. All you need is a 400 head gasket as a template and you can drill steam hols in any head.

For a cam choice go a little more agressive than what you think is a good 350 cam. A bigger engine will tolerate a larger cam. As an example, a radical cam in a 305 will be milder in a 350 and tame in a 400.

------------------
Stephen's racing page

87 IROC-Z Pro ET Bracket Race Car and knocking on the SuperPro ET class
383 stroker (carbed) with double hump cast iron heads and pump gas
LS6 Big Block buildup now in progress

Best results before the engine blew up
Best ET on a time slip: 11.857
Best corrected ET: 11.163
Best MPH on a time slip: 117.87
Best corrected MPH: 126.10
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!

Member of the Calgary Drag Racing Association

 

Thanks, Great info, I did not know that!

Any interpretations on what the numbers mean when describing cams and such, lift, duration......... degrees.....

Thanks!

 

kiztope,

Your doing your homework up front. That's smart. Good for you.

Have you purchased the block yet? If not, check out the Dart and Rocket block that I mentioned earlier. The Bow Tie is a great block but if you punch it out to 4.125", the number of times it can be rebuilt (bored over) is reduced. With the other two, you can go with a smaller bore and longer crank throw to acheive the same c.i.d. (or more). They both have raised cam locations and spread pan rails. This will allow you to use up to a 4.125" stroke crank without major clearencing work,(Something to keep in mind).

I'll try and answer a few of your earlier questions.

Siamesed cylinder walls- In short, this means that the web (metal between the cylinders) is solid. Therefor the cylinders are joined together (siamesed) instead of an open chamber between them. The reason for this is the larger bore of the 400's reduces the area between the cylinders. If they weren't siamesed, the cylinder walls would be dangerously thin.

Splayed caps- these are an aftermarket four bolt main cap. The outer bolts are at an angle (splayed). What this does is get the bolts to an area of the block that has more metal (structurally stronger). This is necessary for the 400's larger main journal (2.65"). Otherwise, the outer bolts will be tapped into an area of the main journal girth beam that is laking in structural integrety (for lack of better verbiage).

9.025" deck height- this is the stock SBC deck height. It is a measurement representing the distance between the crank centerline to the top of the cylinder deck. The Rocket block is available in standard or 9.150".

Priorety main oiling- I'm not sure what this term actually means. All SBC's have a form of priorety main oiling. This just means that the oil has to go through the main journals prior to the rod journals. The Bow Tie's may have redirected the oil path to flow through the main galley first then to the lifter galleys. I dont know, haven't had the privilage to work on one.

The 4.150" max is the maximum that you can bore the block before compromising the thickness of the cylinder walls. When building a max performance engine, I will not accept a block with less than .200" of wall thickness (after the finish hone).

Two peice rear main seal is all you will find in the aftermarket performance block world. It was changed to a one peice in '86 OEM sbc's.

The lifter bore height is what it say's. The height of the lifter bore. It gives you a reference when selecting lifters. If you go roller, a retro-fit roller cam and lifters are required. The retro-fit lifters have a link bar between the intake and exhaust lifters stabalizing them because they are taller than flat tappet lifters. The lifter bore height is given so you can verify that the link bar will not interfear with the lifter boss.

Heads- these need to be sized to the cid, desired compression, cam lift, flow and other conciderations. Too much to talk about here.

Pistons- I like forged but many people use hyper's with success. If you go with a forged piston that has a high silica alloy, the clearances are comperable to cast or hypers. The standard forged pistons are made with a very dense alloy that will expand much more than the others. They require more piston clearance. A noticable piston clatter is heard untill the engine gets to operational temp and the piston expands (some people don't like to hear this).

Crank- cast is good for 500 hp but others will disagree. You can get a good forged crank (highly recommended) for about $700. There are many advantages in going forged (too much to talk about). The next step is a billit crank. $1000 and up. They are used in all-out race enginges.

Cam- roller cams will give you much more lift at the same duration that a flat tappet cam will. I would HIGHLY recommend you budjet for a roller.

Duration- this the amount of time the lifter is off the cam's base circle in relation to cam rotation. (how long the valve will be open). The advertised duration is a measurement that is taken is degrees of cam rotation at the beginning and ending of the lobe as it nears the cam's base circle. The manufactures will not take this measurement at the same point (much to many engine builders frustration). It can varry from as little as .002" lobe lift to .008". The other, and only standard measurement is @ .050" lobe lift. When comparing cam profiles, always use the @ .050" measurement.

Lift- this is the height of the cam lobe. It directly affects how far the valve will open.

Lobe center/seperation angle- if you were to look at the cam from the end and find the center of the cam lobes (intake and exhaust), draw lines from the lobe centers to the center of the cam, the angle that the two intersecting lines make is the lobe seperation angle.

Lobe center- this is often confused with the lobe center/seperation angle. It is a measurement that represents the intake lobe's center position in relation to the piston at top dead center. The measurement is in crank degrees. Meaning, when the piston is ATDC, the intake lobe center will be ### degrees of crankshaft rotation. It is usually around 106-112* BTDC. The LSA is usually 106-116*. The two numbers look the same, so they are confused. They are entirely different in meaning though.

Overlap- the intake and exhaust will always have a point durring the cam's rotation when both are open at the same time. This is lobe overlap.

As far as selecting a cam, you will have to detirmine what C.I.D., heads, compression, rod length, intake, desired hp/ trq, operating rpm, vehicle weight, gears, converter / tranny, tire size, ect., ect. you will use. The cam is the heart of the engine and should not be a WAG but carefull planning and componant matching. It's easy to over-cam an engine (or under cam for that matte). If you get the above figured out, the cam selection can take place.

A couple excellent books you would benefit from:

Small block Chevy Performance (the 2000 edition) by Dave Emanuel (all of Emanuel's books are good)

John Lingenfelter's modifying small block chevy enginges (Great book for anybody)

How to build Max Chevy Performance small blocks on a budjet by David Vizard (any of his books are great reading)

Engine Blueprinting by Rick Voegelin (excellent Blue Printing book)

Big inch chevy small block (don't remember the publisher)

Power Secrets by Smokey Yunick (old but still excellent, it was way ahead of its time when written)

I've been researching 400's and stroked 400's (415, 420, 434, ect.) for over a year now. If you decide to go that route, I'll be glad to help. They are quite a different animal than the typical sbc but well worth the effort.

Mike