sbc 400 in a 97 suburban

[Tempted]

Pretty much take the 400, or any gen 1 for that matter, and swap your heads, intake and fuel system over. 283-400, they'll all work.

 

[DGA1]

Just a light thread jack...since you can buy a GM crate vortec motor, 383 I belive, bolt it in with stock fuel management and get almost 350 HP, I imagine you could bore and stroke the existing block with any sort of SBC kit, like Eagle, and be alright? Maybe a better truck roller cam with a tune and be all peechey?

 

[Tempted]

Just a light thread jack...since you can buy a GM crate vortec motor, 383 I belive, bolt it in with stock fuel management and get almost 350 HP, I imagine you could bore and stroke the existing block with any sort of SBC kit, like Eagle, and be alright? Maybe a better truck roller cam with a tune and be all peechey?

Yeah as long as the cam isn't too radical you are fine. Big cam = no vacuum = way too much fuel being dumped at idle. TBI is easier to stroke, all it needs to dump fuel and throw spark is a tach signal, a VSS reading, a MAP reading, CTS signal and TPS signal.

 

[MOBS]

This was the same engine in my 98, unfortunately all the conversion had been done when i got the truck, so I can't tell you what all needed done as far as machine work.

It had an external crank trigger assembly(reluctor/sensor), and ran pretty well on a 118 degree cam, it also had the 4l80e trans but no cruise(didn't have it stock). It ofcourse used the 400 balancer and flexplate, I definitely don't recall it running excessively rich at idle, the tune prolly had wideband sensors.

I got around 14hwy(70mph) and 10city....once tested 55mph hwy run and got 16. A 400 isn't something you build up for mpg's though.

 

[DGA1]

Great thanks. Once my engine goes, I was going to bore it and rebuild it to emulate the GM 383 crate engine, with an Eagle rotating assembly, a slightly bigger bump stick, stock heads and fuel system, and a tuned 411 ECU via Black Bear. Nothing wild, just something around 350 hp and 400lbs of torque. I imagine this would be quite a bit cheaper than buying the near $4G crate engine.

 

[MOBS]

Yeah, you're looking at about 1800 probably, but all depends on how much work you do yourself. My Scat crank ran me $350, it's an internally balanced 400 crank made for 1-pc seal engines.....requires a shitton of machine work on the block though.

 

[silver97]

efi connection sells a billet timing cover for early sbc engines with a provision for the crank sensor. The plastic one is supposed to leak on early blocks. They suggest a timing chain with a thin crank gear such as a single roller to allow for the reluctor wheel. I read somewhere that the harmonic balancer on the vortec L31 is not as thick as a standard sbc to allow for the timing cover with the crank sensor provision. Does anybody know if this is correct?

 

[MOBS]

Not sure, but there's a difference between a harmonic dampener(used on all sbc except 400), and a harmonic balancer(externally balanced sbc like a 400)....the way mine looked to have been done, they just extended everything out then adjusted accessory brackets to extend all the pulleys forwards along with a longnose waterpump....there was like 1-2" between pulleys and radiator with pusher fans....you'll have to research a bit more on what needs to be used, using an internal crank trigger will definitely require a single row timing chain(i'd suggest 1-pc steel gears versus aluminum or pressed plate steel gears). I wish now that I still had easy access to the truck(new owner lives +3hrs away), that way i could go check some of the paperwork out and upload a scan of the parts list. I know the "non-stock" parts on the engine(what all was needed for conversion)totaled around $1100....if that helps any.

 

[silver97]

No electric fans for me. I am wanting to do this upgrade for better towing. I just recently installed the hd radiator, waterpump and fan clutch. My L31 has 248,000 miles is a little tired and is leaking oil. My friend has offered his sbc 400 to me and i would like to make it work if it doesn't need more than the vortec heads, cam change and a tune.

 

[Aloicious]

you'll need to use a 400 balancer and flexplate/flywheel as has already been stated. for using the vortec PCM control (for the fuel injection/etc), you'll need the crank sensor as you know, but you'll also need to use a vortec distributor to get the correct CMP signal, and with using the vortec distributor, it doesn't have any built in ignition module like some SBC's did, so you'll need to use a vortec ignition module too, but it sounds like you're just planning on swapping most things from your L31 to the 400, so all the external sensors and stuff will be the same.

really the only sensors that are specifically block related will be the CKP (crank) sensor, CMP (cam) sensor (which is part of the vortec distributor), and knock sensor. at least thats all I can think of off hand right now.

EDIT- oh I forgot, the oil pressure sender lives on the block too.