Choosing a small block for my truck

[KnockingDiesel]

I have 1973 K10 I bought in December and put quite a bit of work into. when I bought the truck it was rigged so that only the engine ran. So after rebuilding the entire harness (under dash and engine harness were fried thanks to 30 amp fuses used in 3-15 amp slots) I installed a new cooling system (water pump, thermostat, hoses, radiator, etc.).

The engine has Edelbrock Aluminum Heads (performer rpm) and Edelbrock Aluminum Intake (rpm air gap). There is a demon carb on top of that (not sure of the cfm). It was originally thought to be a 350 but turned out to be a 400 (330817). I don't know the cam but the engine needs to get past 3000 rpm to get in the power band and pulls hard to 5000 rpm ( I am sure it would go past that but I am not comfortable shifting beyond that).

So the questions I have for you all are,

I want to daily drive the truck, are aluminum heads a good idea?

I have never owned an aluminum headed engine before, will they hold up for stop and go traffic?

I have a 350 that is all stock (230 hp/310tq) with less than 5k mi. on it, would that be better suited to daily drive the truck?

Or should put a different cam in the 400?

Also is there anything I should be aware of that is different between the 400 and other small blocks? I think thee 400s were externally balanced but not sure.

All I want out of the truck is a reliable daily driver, it has an sm465 that I am going to keep. It won't see much highway use other than in town (65 mph) and even 15 min tops. I am a contractor by trade so it may pull a trailer now and then (4500lb max in town only).

At this point I am going to pull the engine to clean up the engine bay and must decide whats going back. I would love to hear your comments, questions or concerns.

There is nothing wrong with the engine in it other than the higher RPM power band but I am not opposed to pulling and storing it, dropping the 350 in its place. Or replacing the cam/lifters in the 400 to achieve low end power, so long as its reliable.

Thanks!

 

[KnockingDiesel]

Should I build a iron head 383 and an aluminum head 377? I mean I have most of the parts right?

 

[CSFJ]

If the rest of the 400 assembly is sound, no reason not to put in a new cam and lifter set that will put the powerband back into a useable range.

 

[Green79Scottsdale]

Put a different cam in the 400 and go! Call up your favorite cam manufacturer and get their recommendation. Aluminum heads will be fine. If you have a 400 there is no reason to even think about a 377, imo, at least for a truck.

 

[1987 GMC Jimmy]

^^^Agreed 100%.

 

[hirschdalechevy]

400's are a great truck motor , pull the cam , then you will know what cam you have and go from there. The bad part is you dont really know what compression you have to choose the right cam. Eddie rpm heads come in 64cc and 70cc and who knows what pistons you have or where they are at in the deck or head gasket thickness. That being said once you know what cam is in there any smaller cam will build more cylinder pressure which will give you more bottom end.

 

[Handy Andy]

I just built a 400. I installed the motor and have yet to drive it. During the motor install I found that the bellhousing on my transmission was cracked pretty bad so it is currently off being rebuilt and swapped to a new case. CamQuest tells me I will be making about 425 hp and 525 ftlbs of torque. My build is set to make all of its power and torque between 1200 and 2800 rpms. I built it this way so that it will pull my boat and whatever else I choose to pull with it. It's just a half ton so I won't be getting too crazy with it.
Aluminum heads on a 400 are perfectly fine... In fact I'd say they are great because they will help to dissipate heat pretty well.
I would definately put a different cam in if your just wanting to daily drive this truck with a little bit of towing. I went with the Comp Cams 12-234-2. This is a great low end power cam. My truck runs great at Idle. Not very choppy like it wants to die out.

I wouldn't waste my time building a 377 unless you plan to turn some massive RPM's. Drag racing and Circuit racing are going to be better applications for a 377 because a vehicle in these applications is usually trying to make a lot of power in the upper ends of the RPM range. 377's will do that.

There's nothing wrong with a good solid 383 stroker though. They are great motors and will do pretty much everything you are wanting to do. But, seeings as you already have a built 400, I'd probably just stick with a new cam and let er rip. You won't be disappointed.

 

[KnockingDiesel]

Thank you all! 400 it is, I will pull the engine when I have time in the next few weeks.... should I do the rear main seal while I have it out on a stand? I'm gonna do a pan change and gasket, maybe oil pump....

Once I get it cleaned I'll put up some pics

 

[KnockingDiesel]

Would I be able to tell by looking at the piston what type it is? I guess that would only help if it's flat topped, if it were domed or dished we'd be guessing how much? I have a camera that would fit down through the spark plug hole. Also thinking of doing timing set with gears, or should I stick with a chain?

 

[CSFJ]

A chain timing set is fine, unless you really want the gear whine to sound like a blower. And by all means definitely replace the rear main while it's on a stand. Don't forget to look over the block casting (freeze) plugs while it's out too.

 

[KnockingDiesel]

A chain timing set is fine, unless you really want the gear whine to sound like a blower. And by all means definitely replace the rear main while it's on a stand. Don't forget to look over the block casting (freeze) plugs while it's out too.

Absolutely, I think I'll just keep the chain set up.

 

[Handy Andy]

are you able to run 87 octane fuel in it? how much timing is in it? If the timing isn't turned way down and you don't have to run premium octane fuel in it, i would bet the motor probably has dished pistons in it. I had to run 12.5cc dished pistons and 72cc combustion chambers in my build to get a CR that is proper for burning 87 octane fuel.

I think that most 400s came with smogger pistons that were dished, and if the person that put the new heads on it didn't have the block bored out then they could have just re-rung those and kept them in.

Chances are pretty slim that your going to have domed, or even flat top pistons because that would put your compression ratio up into a range where you'd be required to either take a bunch of timing out or run very high octane fuel.

 

[KnockingDiesel]

are you able to run 87 octane fuel in it? how much timing is in it? If the timing isn't turned way down and you don't have to run premium octane fuel in it, i would bet the motor probably has dished pistons in it. I had to run 12.5cc dished pistons and 72cc combustion chambers in my build to get a CR that is proper for burning 87 octane fuel.

I think that most 400s came with smogger pistons that were dished, and if the person that put the new heads on it didn't have the block bored out then they could have just re-rung those and kept them in.

Chances are pretty slim that your going to have domed, or even flat top pistons because that would put your compression ratio up into a range where you'd be required to either take a bunch of timing out or run very high octane fuel.

I have not checked timing as of yet and I am running premium (91) in right now. I have driven it but not very much, I don't like reving the engine so high. Maybe I'll drive it around this weekend and fill up on 87 and see how it runs.

 

[Handy Andy]

I have not checked timing as of yet and I am running premium (91) in right now. I have driven it but not very much, I don't like reving the engine so high. Maybe I'll drive it around this weekend and fill up on 87 and see how it runs.

I would fill it with 89 first and run it with that. Keep a spare bottle of octane boost in your truck when you do. If you fill it with 89 and it starts to ping add the octane boost and that should stop the pinging until you use up the 89 octane you put in.

 

[KnockingDiesel]

I would fill it with 89 first and run it with that. Keep a spare bottle of octane boost in your truck when you do. If you fill it with 89 and it starts to ping add the octane boost and that should stop the pinging until you use up the 89 octane you put in.

Sounds like a plan