havermear

I have a 305 motor in my '85 Iroc and want to swap it out for a bigger engine and a six speed trans. I am pretty set on a T56 transmission, but should I go with a 350 engine or a 400 engine? Ideas, comments, concerns?

Apeiron

Do you have a 400 available?

havermear

Both are available to me (400 from further away and costs a bit more).

Jim85IROC

iTrader: (2)

Or perhaps take the hybrid approach and build a 383? That way you don't have to deal with the drawbacks of the 400... namely the 2 piece rear main seal, flat tappet cam, and the need for steam holes in the heads. The 383 only gives up a few cubes compared to the 400, costs the same to build as a 350, and allows for using a more modern block. You also can get an internally balanced rotating assembly so that you can avoid buying a rather expensive weighted flywheel for that T56.

mmadden55

I wouldn't use a 400 short rods poor design etc. I would go with a late model 4 bolt main one piece rear seal 350 block and go either 350 or 383 with flat top pistons and aftermarket aluminum heads.

Confuzed1

iTrader: (4)

Cheapest route is the 383....lots of kits still around on the cheap to build one. As said, it will cost more to build a good 400ish...I wouldn't call them "drawbacks", but more expensive for sure....ask me how I know...

watajob

iTrader: (29)

Or, give these folks a ring and call it good:

http://www.tristarengines.com/catalo...shp-block.html

1gary

When a bare SHP block costs from $1,500 to $1,900,you can only envision what kind of parts your getting at $2,600. It is again a prime example of what I have been tell you guys about "packaged deals". You don't get something for nothing because of the competition for sales because the profit margin in this stuff isn't that great.

Same case for there are "Cheap Stroker Kits" out there.Yepper there are. And it exactly what they are.Cheap!!.

When the first stroker kits came to pass when we where cutting down 3.75 cast cranks down to fit into 350 bearing sizes we learned alot. And at the same time we where using spacer bearings to fit 350 cranks into 400's. Again we learned tons and you guys can elect to listen from those yrs or not.

One primary reason behind a 350 block based stroker aside from relatively new(1996 to 2000) L31 roller blocks and the use of roller cams,was-is the 350 bores are more stable for ring sealing. My racing operation under some of the best block preps you can find anywhere still have issues leaking down our OEM 400 based blocks.(torque plates with new CNC machining) That plus as stated the steam holes,out board bolts on the mains with cracks,non-roller blocks that require expensive conversion kits.

I worked on these 400's at the Chevy Engine Plant when they where new and I can tell you those where never intended for high performance use. Do we get around those things in Hot Rodding??. Of course we do,but with trade offs. And thus the reason behind the development of the aftermarket blocks for big inch SBC's. Those blocks do have stages that cost. So a key question is do you wear the big boy pants bringing you wallet not wasting it on a relatively small 406??. If you going to do it,then you going big or stay home as the saying goes.

As far as costs go,a well built for intended use 383=a LS which=a stroker 496 BBC.

Oh one more time guys.Take the words "Cheap and Budget" out of your vocabulary when talking about swaps and hot rodding. You pay your dues with money management saving what you can to do the job right the first time and NOT waste money on do overs. I am very sure many of you could break the"electronic addiction" you have and be very surprised how much you would have to build a car..........

abray1

I used a 400 but it is a solid roller motor with 6 inch H beam rods, Forged wiseco flat tops, and a 3.75 eagle forged crank with brodix track 1s. It is mainly a race motor though with solid roller lifters and higher compression (11.5). This car also has a ford 9 with detroit locker and low gears. 400s will run hot since the bores are siamezed. Meaning that the water cannot go between the cylinders like a 350 so you will have to have a good radiator and high cfm fan. If it is going to be a street motor then the 383 suggestion with a 1pc roller 350 block is probably the wise choice. But, there is no replacement for Displacement. My vert is going to have a 1pc 350 roller engine.

Confuzed1

iTrader: (4)

Wow Gary....pretty opinionated aren't we? About the only thing you didn't throw in is the legend of the overheating.....we know the cylinders are siamezed, but it doesn't need to overheat...

So...the cylinder walls are so thin on OEM 400 blocks that rings won't seal? Sure....maybe....if I'm interested in running 30 pounds of boost and revving it to 7K all the time.

Look - I'll admit, 400's were never intended to be "performance" engines by definition...neither were 350's. But you see, people tend to build up otherwise stock engines to make more power...I can find top-of-the-line parts to build any engine...but as you said, it depends on what the intended use of the engine will be. In ANY case, it does need to be assembled properly. And truth is, it doesn't require the best of everything if your goal is to have more power on the street for daily driving.

Using your logic, Everyone should buy DART blocks, Callies cranks and other parts made from unobtainium..."Go big or go home"...right? Not everyone doing an engine swap is trying to build a NASCAR or John Force type engine.

The OP is just asking whether to go with a 350 or 400....he might keep it bone stock for all we know....which is fine.

1gary

If memory serves me correctly we over the yrs used like a haft dozen 400's of various sizes in 9.90 racing.

Confuzed1

iTrader: (4)

Honestly Gary, I'm not trying to bash you in any way...the OP is simply doing an engine swap. Heck, I'll say it myself...if I were interested in 9.90 racing, I wouldn't waste time with a OEM 400 block...I'd go straight for a DART block for the better cooling, along with other advantages it offers.

But on topic, there really are good 383 kits out there that utilize proven decent parts, such as Eagle SIR rods, steel cranks and the like. Plenty good enough for occasional blast between traffic lights...and down the 1/4 mile.

But - If I'm building a "serious" engine I want to really compete with, I'd want to "Go Big" as your saying... -Can we agree on that?

InfernalVortex

iTrader: (4)

Gary is, of course, always right, but Gary's advice usually seems better suited towards competitive racing more than street-driven cruiser cars.

1gary

Thank you for your comments. I do build street engines too. In fact outside of the racing partnership I am building independently a 9.3 SCR torque monster 383 for myself. Should have at the flywheel just short of 500lbs of torque at slightly over 3,000 RPM.

1gary

Honestly-we have dealt with so many of those kits and tried to straighten them out,it just isn't worth the hassle. In the end just like everything else in life-you get what you pay for.
I don't advise guys to spend what it takes to run a 9.90 class,but on the other hand I do think the foundation of hot rodding isn't what is just good enough.
It is that market of "Cheap Parts" that has undermine hot rodding.

1gary

Sir-here is my advise as a life long hot rodder,racer,engine enthusiast,engine builder whos thrust for knowledge is still on going. The best money you can spend is for a LS engine.If you don't have that kind of money right now,hold off until you do. I seriously regret not building one for myself and as soon as I can I will be putting one together.

Tinbender59

Gary: I agree with you to a point, havermear it is your car, just like my Vert is mine. I will build the way I want it. Like Gary, I am an old gear head and I have been around and owned a lot of hot rods, my nick name in high school was "Macer the Racer". my third car was a 1969 Chevelle with a junkyard 327 bought it with a burnt valve and a flat cam", pulled a set of heads and cam off of of a wrecked '69 Chevelle wagon 300hp 350, put it all together with a Qjet and raised all kinds of heck. I even burned up three sets of tires in one day; that was a fun day, LOL. back on topic, I personaly live, eat, sleep, and @$^&, Small Block Chevys. LS's are the new and up coming beast, but I just don't like the feel of them. I am not out here to prove who is or has the badest, just that I did; I did it my way!! Now with all of that said havermear do your resarch, then do it your way. In the end it is your happiness wit your rig that matters not my happiness with your car. so do it and enjoy the heck out of it

DeltaElite121

I wouldn't touch a 400 unless you really know what to look for. Most of the guys I know that outwardly go looking for them find 6-8 bad cores before they find a good one.. and 400 blocks aren't exactly cheap, either (in part to the dirt track guys using them up so frequently along with everyone else). I think they're an awesome starting point if you actually have a GOOD block, but you just don't see those often anymore.

I'd vote for a 1 piece 350 block and do as you please with it. Build a nice 383 or take it a bit further and go with a 396 stroker.

That's my opinion.

watajob

iTrader: (29)

This.

Tinbender59

the real question is what are your expectations for the car, brute power, high HP "aka RPM" or a cross of the two. Personaly I LOVE the LT1, mine has a bunch of torque and HP, while pulling, I have more torque than truck, and I have had it to 110mph "just this last week" that is enough for me plus 13 to 16 mpg normal driving. it is a good compromise in my book. now put the ol LT in a 3000lb camaro aprox 1/2 the weight of the truck, I think that I will have to learn how to drive again! the LT1-4 are the last stand for the SBC, pushed to the absolute max in the technology of the time.

1gary

Well either you didn't read the whole thread or you choose to quote out of context. It is kind of pointless then.