400 small block

by Sam_snead01 Tue Feb 22, 2011 5:31 pm

I have decided to rebuild the 400 small block that came in the el camino I purchased. Right now the heads, crank, and block are at the machine shop. I have done big blocks and Furd fe's but never a small block chevy. I was wondering what performance upgrades you guys suggest. Its the 059 high nickel content block. 1.94 intake and 1.5 exhaust valves. I'm keeping the cast heads and using the steam holes. The el camino will be used to as a cruiser and to tow my drag boat. I am looking to build for torque. The car has 3:73 right now (that need to be shimmed...i have another thread on that...lol)....the tranny is a th 350 with 2500 stall and shift kit. Like i said i'm building for torque and just want some people's advice that have built these motors. Cam? Bore? Cut Valves? Thanks.

by The Dude Tue Feb 22, 2011 5:44 pm

Best bet is to keep the cam small (210-220 duration) & compression in the 9-9.5 range. Go with a good dual plane intake designed for idle-1500 rpm range. Other than that, 400's make decent torque.

What head castings do you have? Might I recommend a set of TBI heads? (last 3 casting digits are 193) They came on 87-95 trucks & make great pulling power while getting better gas mileage than the older heads due to the swirl vane built into the intake valve. All you would need to do is have steam holes drilled & find an intake designed for 87-95 heads. These aren't typically a desired head by the performance crowd, so they can be had for next to nothing. For your application they would be perfect.

by Sam_snead01 Tue Feb 22, 2011 5:50 pm

Thats the first i've herd of that suggestion. I can't rember the casting number on the heads, but my machine shop said they would not drill the steam holes. They wanted to pulg them, but I have read enough on various forums that I feel I need to keep them for a street application. So since they won't drill the holes I'm stuck with these heads wich are 1977s. Do you have any suggestions for a cam?

by JB2wheeler Tue Feb 22, 2011 7:17 pm

I have a 41,000 mile 400 engine in my garage tha came in my 74 Elky. One of these days I plan on just buying a straight out complete system of heads/cam/etc. from Edelbrock to put on that now unused 400. . They offer several levels of improvemnent in HP. The stock heads that come on the 400s are not worth the effort to improve them, thats a losing battle. There are many cheap head combos out there for reasonable prices that are far better than reworked stock heads. . JB

by The Dude Tue Feb 22, 2011 9:14 pm

You definitely need steam holes on 400s & like JB said, most stock 400 heads aren't really worth messing with. I'm sure there are some out there that can be played with though. I find it strange that a machine shop won't drill steam holes for you. My cousin built up a 400 a few years bac & had steam holes drilled in a set of aluminum heads. It's fairly straightforward to do & some guys do it themselves. Here's a pretty well laid out procedure for it:

http://shadetreemechanic.activeboard.com/index.spark?aBID=120280&p=3&topicID=19041427

As far as the cam I'd like to know what compression, heads, & intake you are running, but there are several out there that would do the job. Look into Crane Energizer or Comp High Energy cams for a good single pattern cam. I'd say Comp's 260 or even 268 would suit you fine, but if you go with a different manufacturer, keep to something in those sizes. Stick with a 750 cfm carb & smaller sized headers for more torque down low. 450 ft/lbs. from a relatively mild 400 isn't out of the question.

by Sam_snead01 Tue Feb 22, 2011 10:06 pm

The car has headers, 750 holley, and a edelbrock performer intake....I am going to stick with all of those to save some money on the build. I'm probably going to end up boring .10 over and us a comp cam for made for low end torque torque. Probally stick to an 8:1 -9.5-1 comp ratio. I find a lot of times you can sink a bunch of money into performance you will never use or not use often.

by pila Tue Feb 22, 2011 11:24 pm

I have a 400 (408) in my Malibu. I used 350 rods, 5.7" in place of the shorter 5.565" 400 rods. On the last rebuild I used KB 9.2:1 pistons ( to match rod length) I have a Comp 280 Magnum cam in it, with Rhoads lifters, which get good vacuum for brakes etc, and It will idle down in the 700 range.

On the first rebuild, I used the 350 rods, and stock 400 (406) pistons, but milled the tops off the .135 " for the deck, and cut valve recesses in the tops. Second time around I was too lazy to fool with the pistons, and bought the KB type. I had the bigger valve seats cut in the stock heads , like 2.05/ 1.65 and did quite a bit of port work on them.

The steam holes are no big deal to drill in the heads. Just a 400 head gasket to locate the holes, and drill them.

The 400 has plenty of torque, so a TH350 needs some beef in it to hold up. I ate a couple 350s that shops overhauled, then did my own, using a Transgo kit, with no problems.

by Pdawgie Wed Feb 23, 2011 2:07 pm

I second the 5.7" rods. I'm running a 406 with the 5.7's in one of my camaros, and it has been very strong and dependable. The problem with the shorter rods are that the motor will scatter easy if wound up very much, very well known problem with the SB 400, the longer rods keep this from happening so easy, so if by chance it does wind a bit more like when towing up a hill, you don't have to worry about over reving the shorter rods and causing damage to your motor. I just ordered pistons that would work with the longer rods.

by Jim_Rockford Thu Feb 24, 2011 10:52 pm

best thing you can do is a small cam , and a set of vortec heads drilled with the steam holes,edelbrock vortec bolt pattern intake and a good Rochester q jet, with the right gear you will get close to 20mpg on the highway. with you towing stuff you are gonna want the steam holes in the heads, They are easy to do.

by pila Thu Feb 24, 2011 11:11 pm

I wasn't aware that folks were running 400s without the steam holes. I figured that the siamese cylinder design needed those holes because of the trapped area there (?)

by Sam_snead01 Fri Feb 25, 2011 12:51 am

is it really that big of a deal to run stock rods for a primarily stock engine with a decent rv type cam?

by pila Fri Feb 25, 2011 7:29 am

I've always used stock rods, if that includes the "pink" GM rods. A mildly hopped up engine doesn't need expensive after market rods. It won't likely see 6000 RPM anyway, and stock rods will work that high. New rod bolts are mandatory in my opinion though. Many people use expensive parts that are mostly over-kill, on mildly built engines. Distributors are a good example. It's tough to beat a stock GM HEI with a good module & coil. Cam selection will depend on which pistons you choose. Flat-top pistons like KB hypereutectics with valve reliefs in a 400 with 76 CC heads will be around 9.2:1 CR, so an example cam for towing etc would be a Comp HE260 with that combo. I'm not familiar with RV cams in regard to duration etc.

by The Dude Fri Feb 25, 2011 10:57 am

Pila, the majority of us believe it's necessary to run steam holes. Only crazy people try not to run them on a 400. drunken

Sam, there's nothing wrong with running stock rods. If so, then why are so many stock 400's still running today? If RV cam means small cam in the 252-266 Adv. duration range, then you are spot on. Like I said, something with no more than 268 Adv. or around 220 @ 0.050 is what you are probably gonna want, but static compression is gonna be the deciding factor on cam choice. You want to keep your dynamic compression in the 7-7.5 range for a good trade off of ability to run pump gas while still making good power.

by Sam_snead01 Mon Feb 28, 2011 9:05 pm

This is where I'm at on the 400 idea. Please add anything you think I should change as I always listen to people who have been there an done that.

1. Have the crank measured...grind to 1 under if needed

2. Hot tank heads, New valves with valve job, guides, locks, seals, (all the nickel and dime stuff), valve springs to match cam

*Still trying to decide wheather to cut valves from 1.94 in and 1.5 ex to 2.025 in and 1.055 exhaust. Any pros or cons on this matter would be great.

3. Bore block to 1 - 2 over to clean up cylinder walls as needed. Torque hone I here is the way to go.

4. Probably just use the stock rods as this is not a high rpm or horse power build.

5. Buy a decent rebuild kit with clevite, victor renznor, sealed power, federal mogul, well known names. Looking at this now:

http://cgi.ebay.com/ebaymotors/GM-Chevy-400-6-6-Master-Engine-Rebuild-Kit-1970-1980-_W0QQcmdZViewItemQQhashZitem3cb0d46a93QQitemZ260664748691QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

and this:

http://cgi.ebay.com/ebaymotors/Chevy-400-MASTER-Engine-Kit-Torque-1975-76-77-78-79-_W0QQcmdZViewItemQQhashZitem2c5898044eQQitemZ190464918606QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

As far as the cam kit both of these kits have "RV" cam and performance grind cam upgrade options for 60-90 more. (duration 268/268 lift .477/.477 for the "rv" cam)

Also interested in these cams as well:

http://www.summitracing.com/parts/TFS-31401000/

and

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=87&sb=1

After that pushrods that fit the valve train...more than likely hardened stock and 1.5 stock rockers.

Headers

4 barrel holley 750 cfm

stock ignition

3:73 gears

Edelbrock perfomer intake

I'm building for towing low end torque and decent street machine...nothing radical

by JB2wheeler Mon Feb 28, 2011 9:42 pm

I have been ignoring this for a week or so, but can't any longer. Steam holes in the heads are essential for any 400 engine to evenly distrubute heat evenly thruout the engine. 400s have a bad rep for overheating, this is because a lot of people do not use all means of preventing overheating. The steam holes must be drilled at a certian angle to ensure that you do not break thru into the wrong cavity. Yes, it is easy to drill the holes IF you know the right angle. It is not much of an angle, but safe is better than sorry. That is the reason I recommend a good machine shop do the drilling. JB

by Sam_snead01 Mon Feb 28, 2011 9:52 pm

I'm using the stock heads and steam holes are in there. If you really searched the net you will find a variety of opinions on the matter. I for one agree that steam holes should be used. If thats the way it was from the factory then there is a good reason for them. I've read a lot about it and about using the 400 head gasket as a template. The machine shop I'm using tends to more racing style engines. It is pretty common in a racing situation not to use the steam holes from what I understand.

I am using the steam holes.

by The Dude Tue Mar 01, 2011 11:21 am

Sam, those two cams that you posted aren't even close to each other. The comp cam is way too big for what you want, but the TFS one would work.

Normally on a 400, you would really want 2.02/1.6 valves, but for what you are doing, it would likely hinder low end performance. Stick with the stock valve sizing & the rest of your combo looks doable. Don't forget to buy a roller timing chain while you got it opened up. Later on, you won't regret spending the extra dough for that extra insurance against chain stretch.

Here's a few cams I could recommend:

Crane Cams
http://www.summitracing.com/parts/CRN-100042
http://www.summitracing.com/parts/CRN-100172?part=CRN-100172&autoview=sku *

Comp Cams
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=72&sb=2
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=95&sb=2

Lunati
http://www.lunatipower.com/Product.aspx?id=2323&gid=297
http://www.lunatipower.com/Product.aspx?id=2324&gid=297 *

* The largest cams I would suggest for what you are looking for. In case you want some lope to your idle without killing off too much bottom end.

by Sam_snead01 Tue Mar 01, 2011 11:25 pm

ok...i knew this would happen...I'm switchings up a bit here...goint with these for heads as it was going to cost me 530 to rework the heads i have.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=330514277551&ssPageName=STRK:MEWNX:IT

****the steam holes WILL be drilled******

my main question is if I go with a stock rebuild what will my compression ratio be with a 64cc head?

by The Dude Wed Mar 02, 2011 10:42 am

Holy crap those are cheap! Wonder what heads they are a knock off of?

The compression ratio will depend mainly on piston dish & gasket thickness. There's a calculator somewhere online to help you figure it out. I'll search for it later.

by JB2wheeler Wed Mar 02, 2011 12:43 pm

Rago wrote:Holy crap those are cheap! Wonder what heads they are a knock off of?

That would be embossed on the side of the head, in Chinese. LOL. I'm not knocking the heads, just saying... JB

by Sam_snead01 Wed Mar 02, 2011 8:01 pm

yea they are cheap....but less than half the price of of one head from edelbrock and probably a smarter move than putting 550 buck into a pair of cast heads....I like the fact that they are machined for both early and late model stuff............plus I'm sure edelbrock doesn't have anywhere close to 1200 bux in a set of their heads

I was looking at the calculators last night...really need to find the deck volume or at lest what is was stock

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