400 SBC Daily Driver Buildup

According to Comp Cams, with the XE268H, over 9:1 compression will begin to work against the cam. That grind is more for stock compression ratios in the 7.5-9:1 range. It is meant compensate for the lower cylinder pressures.


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Hi,
It seems there are differing opinions as to how an engine like this can be built. As we all know, there is a lot of compromises when it comes to building a street engine. I don't think any particular way to build it is either right or wrong. Just a different approach to the same problem. I have been learning a lot from this conversation in regards to compression ratios, cam selection etc. I have also been doing some reading on these subjects myself. They sure are complex subjects, especially how they relate to each other.
lluciano77 and TurboS10, could each of you give your idea of the best build for this engine? Lets just start with the .030 over block and the Sportsman 64cc heads and go from there. What intake and carb would you use? What pistons? Camshaft selection? Anything else that would effect the engine? Keep in mind that this is a daily driver and I would like to use pump gas. 87 octane would be better but 93 octane is OK too. It will have to run in stop and go traffic, operate power brakes, operate the a/c etc. It probably won't ever get over 5500 rpm and even that will be on a rare occasion. Thanks again. I look forward to hearing each of your thoughts on the ideal buidup.

Mike

I am assuming you are going to stick with the 5.7 rods as well and keep the 700R4 and 3.73 gears. I am not sure of the weight of the 64 Chevelle, but I know that it is no light weight. Since you are driving it every day, I will assume that you also want to stick with a stock type convertor which I would suggest. I have done the whole high compression, big cam, big convertor daily driver thing and IMO it is a major PIA. As a matter of fact, my 57 is going to get EFI, smaller cam, and smaller convertor to make it pleasant to cruise around in. You have to realize that off idle power and cruise speed are very important in something you drive every day. So many people try to over cam and push a street engine to the edge. If you do this, I guarantee you will regret it......I did.

If I were you, I would go with a D dish piston that will yield as close to 9:1 CR as you can get. Little higher or lower will not make much difference, but I would not exceed 9.5:1 if you want to run 87 octane fuel with those iron heads and that is pushing it. The 18cc dish with 64cc chambers should get you to about that point depending on deck height and gasket thickness. 22-26 cc would be a little better IMO. I would also try to get piston that uses standard thick rings and not the thin race style. You will get better wear out of the thicker rings.

For an intake, I would stick with a dual plane like the Edelbrock Performer RPM or the Air Gap. I like the Air Gap best, but I have no experience with it. Carb would definately be a Vacuum Secondary 750cfm Holley. They just work great, when well tuned, on the street. IMO, the only thing that might be better is a Barry Grant 750 Vacuum Secondary.

For a cam, I would suggest the XE262H after looking at the specs a little closer. When you start approaching 230 dur. with 110 lsa, you are going to suffer in the mileage and off idle performance. Like I said before, most people tend to really over cam engines.

Now for the heads that really dont match this combination. They will make good power on the street, but those are really high performance heads. Heads are a really hard call on a street engine. With off idle performance being a must, IMO, 200cc intake runners is a bit large. You will not have good port velocity in the lower RPM range. The good news is that the larger cube engine will move more air and will help to compensate for this. In the end I think they will work okay, but are not optimal for a daily driver.

Chris

you know if your going to completly change your whole set-up. sell it...and buy a crate motor... 200cc to big for a 400cid? maybe for a 283....lol...



Dont change what you have, and if you completly want to change it sell it and buy a crate motor, you will be disapointed with the 400 otherwise.. check out Scoogin dicky, Vortec head packages for like 700 including intake, short block's etc, why? put all that money in the 400 and kill it? thats all Im saying...2wld4u

Hi Chris,
Sounds like you gave it some thought. Your suggestion is pretty close to what I had worked up on my own after doing some homework on it. I also questioned the size of the heads. I had a guy offer to trade a set of Dart 180cc heads with 72cc chambers for my Sportsmans. The smaller heads may be the way to go. I might consider a crate engine but really haven't made up my mind yet. Thats why I started this thread, to get ideas and suggestions and then go from there. I already have most of the parts to build it as you suggested except the different cam and pistons. So with that in mind my cost might be alot less than a crate engine. I don't mind spending some bucks, but I'd still like to keep it as reasonable as possable. BTW I am keeping the 700r4, but now I am thinking of going back to the stock 3:08 gear. I still have it and shouldn't be too difficult to change back. Thanks for the reply.

Mike

I would run a Performer RPM Air Gap. I have one on my engine, and it works great.

I also use a Holley model #4609 that not too many people know about. It is 730 CFMs and has bell shaped truck boosters in the front, and the high performance down leg boosters in the rear. The bell shaped boosters meter the fuel extremely well, and when the secondaries kick in, it has the higher RPM metering covered by the down legs. It is like having a squarebore that acts like a spreadbore. The jets up front are 66s and in the rear are 79s.

Here is a picture of one that is very similar. This is a 4279. They are more expensive than the 4609 that I am talking about.

http://cgi.ebay.com/ebaymotors/ws/e...ssPageName=WDVW

You could go with something like these for the pistons.
http://cgi.ebay.com/ebaymotors/ws/e...2478730355&rd=1

I think that the 180 heads might be the way to go. It would also get you right were you need to be on CR with the 18cc dish pistons.

Chris

What torque converter are you using?