400 budget build

[Paul_G]

I have a worn out 72 400. I need it to replace my 505 while it is out of the car getting refreshed. The 400 is stripped down to the bare block ready to go to the machine shop. I would like to just do a rings and bearings refresh if possible. The cylinder bores have some ridge, the cross hatch is gone. Surprisingly the bearings are not worn through which I expected based on the amount of crud inside the engine. The machinist will tell me if I can rering or if it will need an overbore.

So wanting to do it on the cheap, rering is first choice. Back to the 7:1 compression pistons and 195 HP. If that is not an option Summit has a .020" over KB piston kit that will bring the compression up to 9:1+. $700 for the kit. So for the magic question, What kind of HP gain over stock with these pistons?

The rest of this 400 build is using junk I already have for the B engine.

Holley carb, Edelbrock Performer 383 intake, 1 7/8" long tubes, refreshed 452 heads, Summit 6401 cam 298/303, Lift .466/.488.

What say you?

 

[super-bee_ski]

Well..we have experts on this forum. But pistons should not inhibit horsepower...unless you build a Race engine.
Going to Aluminum pistons can add to your cost.
Sealed power pistons are good.
You said: "So wanting to do it on the cheap, rering is first choice. Back to the 7:1 compression pistons and 195 HP. If that is not an option Summit has a .020" over KB piston kit that will bring the compression up to 9:1+. $700 for the kit. So for the magic question, What kind of HP gain over stock with these pistons?"
Your heads have a dramatic effect on HP as an engine is an Air Pump.
Compression, CFM flow, Performance Valve job, and of course expelling exhaust.
Im certain some of our Forum embers have built the 400 for more efficiency and power....

 

[BeatersRus]

lets preface this with im no expert,ive just had a lot of experience over the years.

i would deffo get the 9-1 pistons,and build the motor from there with your parts.
if you decide later that you dont need the 400,it will be a lot easier and higher value to sell as an upgraded motor than a stock 7-1 compression.
or
if you end up needing another motor for a diff project later on,the 400 will be ready.
the combo specs seem decent,altho you didnt say what holley carb it has,a minor spec.

 

[496 polara]

It will like all of those upgrades much better with 9.00-1 compression. But can be made to work with the 7.5-1 as well. Go for it I say. I think it would like 1 3/4 headers better but run what ya brung!

 

[RemCharger]

My new stock stroke 400 build

 

[rickseeman]

You said you wanted cheap. I don't think you have to have a machine shop. Ball hone it and put it back together with the cheapest rings you can find. People do it every day. The last 46 year old 400 I tore down the bearings looked perfect. If you change pistons this might get expensive.

 

[BSB67]

KB240? You better do the math to confirm the 9:1 CR. Unless you machine the deck and run a 0.020 shim gasket you might be closer to low 8s.

 

[Jeremiah]

If you end up using the original pistons ask your machinist if he can angle mill the heads to get more compression. You might end up doing that with aftermarket pistons also depending on where the deck height ends up.

 

[496 polara]

The slug 400 on the dyno.

 

[kramer]

This option is on the cheap and might work for you, just get a .030 overbore low compression Silvolite 440 piston which has a deck height of 1.912 which should get you close to deck height and the pistons only cost $206. You would have to most likely have to HONE out the bore about .010" over on a 400 std bore block to make these pistons work. Just an idea.

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[qkcuda]

This option is on the cheap and might work for you, just get a .030 overbore low compression Silvolite 440 piston which has a deck height of 1.912 which should get you close to deck height and the pistons only cost $206. You would have to most likely have to HONE out the bore about .010" over on a 400 std bore block to make these pistons work. Just an idea.

http://[URL]https://www.summitracin...2JxG5h8aAjnSS13tuxQNpSfXuWR4Ce1AEyOGOBcqdcRmE

[/URL]

I did this on a previous 400 build. The problem is that those are 440 pistons and quite a bit heavier than 400 pistons, and you will end up using the savings to pay for rebalancing. They also have no valve reliefs which limits cam choice. The KB 240's will net you around 8.5:1 compression with stock heads.

 

[Lefty71]

If you could find a nice set of big valve '915 heads on the cheap ( since everyone jump on the aluminum bandwagon), that would make a nice upgrade in the quench department....
But if you cant find them cheap, you may as well splurge for edelbrocks, etc. or stick with what you have. The right cam selection will make any head work for you.