88_are_s

Yes, I did search before I posted. Searched here, and google.

My 82 Z28 has the LG4 engine and T10 transmission. The LG4 is weak and running like total crap. My buddy scored a running 400 sbc for $100 a year ago but found a 1970 LS6 454 for cheap and went with that route. He will sell the 400 to me.

Here's my question.

Can I just simply bolt the LG4's flywheel to the 400, mate the T10 to the engine and drop em into the car? Or am I gonna need a new flywheel?

Jorlain

iTrader: (4)

I believe you'll need a different flywheel. The flywheel from the LG4 is meant for internal balance use, while the 400 requires a flywheel setup for external balance.

88_are_s

So I go to Summit Racing and look for a flywheel for external balance and how many teeth? 10.5" diameter?

The 400 does have a harmonic balancer, does that mean anything wether or not it is internal or externally balanced?

sofakingdom

iTrader: (1)

The 400 crank damper has a notch taken out of it to unbalance it.

You need a flywheel EXACTLY like the one you have (probably 12.8" 153 teeth) except unbalanced to the stock 400 spec. In fact you could easily enough have that done to your existing one: just take it to a balancing shop and tell em to do that to it. Usually about 15 - 20 ½" dia holes about ½" deep around one "corner" of the flywheel.



That's a 400 crank. The holes need to be directly opposite the big "lump" part of the flange; which is. directly opposite the dowel pin hole in the flywheel. Correct unbalance inertia spec for the 400 is about 25 oz-in. Which is, a weight of 25 oz 1 in from the crank centerline, a 1 oz weight 25" from the CL, or any other numbers that make that product where oz x in = 25ish... it'll take about 4½ oz at 6" from the CL which is where they're gonna end up on a 12.8" wheel.

88_are_s

Thanks Sofa. Ill call around my local balancing shops. Next challenge is finding the exact bracketry the camel hump headed V8's used. And i will be using my water pump the car has now. Which is a long or short pump?

sofakingdom

iTrader: (1)

Your stock brackets work fine on the only kind of camel humps you should be using at all; 186, 492, or 041 castings.



Your 82 water pump is long. Also works fine on the 400 block.

88_are_s

I wish i had those castings, but no. My camel hump heads are the true ones with the giant double hump pad with absolutely 0 bolt holes at all. So im just gonna seek those castings you provided. Trade mine for them, throw some $ on them to make the trade i guess. You know a lot of stuff Sofa. Just wanna let you know that i appreciate you entering my thread

sofakingdom

iTrader: (1)

Oh, those old crappy things...

Too bad you don't have the good ones, like in the pic. Throw em away and get something that works and will run on modern fuel. Sorry, some old things just aren't suitable for the world as it stands today, no matter how great they were back in the day. (or at least, in legend)

Wouldn't want to trade. I have no use for those 461 castings either. Won't work in any car built since the early 70s.

Frankly, I wouldn't recommend looking for old heads like mine, either. I've had a bunch of sets of em over the years, going back to the 70s. Today, if I were building a motor and needed heads, I wouldn't go that route anymore. I'd go either with Vortec or aftermarket. Especially for a 400. But if you want some, there's the numbers; the 186, which is what those in the pic are, were stock on a lot of 69 - 70 350 4-bbl. I would usually get em out of Impalas, especially station wagons, when scouring junkyards back then.

Glad to help. Sorry to be the bearer of bad news this time though.

88_are_s

Bad news, good news dont matter. Knowledge is key to an engine swap. Id rather know enough, than to just jump into the swap with no knowledge haha. Well theres always someone that is doing matching number resto, theyll buy em off me and ill just seek the castings you provided me with. Ill just pull Vortecs off an L31 from a junkyard. Oh hear is another question. Whats with all the 2 Vortec casting numbers thing and that one is worst due to the restrictive exhaust seat/throat? That all speculation?

88_are_s

Either 041, 186, & 492 heads or vortecs. If i go Vortec will i need to do a full serpentine conversion? Also does my 4-speed have 10 or 26 spline?

five7kid

iTrader: (14)

Pretty much has been debunked. The exhaust ports are a bit restrictive compared to the intakes.

What isn't bunk is the valve springs are junk. You'll need new ones that fit over the large OD of the guides (or have the guides cut). The press-in rocker studs are nothing to write home about, either.

You haven't said what cam or power range you're looking for. I assume you're not looking for a barn burner.

Would you consider alternative suggestions?

These would probably cost you less than JY Vortecs by the time you got them up to snuff:
http://www.summitracing.com/parts/rh...make/chevrolet

Bigger name, lower price, more valve lift capability:
http://www.summitracing.com/parts/dr...make/chevrolet

Amazing what the aftermarket offers these days.

88_are_s

Im just looking to replace the worn out LG4 i have sputtering/dieing around in my engine bay. Power dont matter too much as i already know this 400 should put out no less than a lightly modded L98 with the cam lope and intake manifold the 400 already has on it. Just need to pay no more than $500 for 2 heads that have 64cc chambers. Because....im just looking for a replacement engine. My problem is, is that the heads on it now have no bolt holes. Thats it. BUT, those links you gave me WILL come in handy some day haha. Just need a dd for now. Can you tell me how many splines my 4-speed manual has? Doin the clutch would be smart since engine is already out of car when it comes time to swap

sofakingdom

iTrader: (1)

Should be 1-1/8" 26 spline.

88_are_s

Thank you guys sooo much

jmd

iTrader: (4)

Just FYI, if you keep your stock flywheel and run a weight (between crank and flywheel) it will work, but the starter pinion teeth and flywheel ring gear tend to wear unevenly. So avoid that.

Make sure your 400 block is drilled correctly for all 3 starter bolt holes.

88_are_s

Oh ok. Thanks

sofakingdom

iTrader: (1)

Good point, jmd:



Do you get the feeling that maybe I've put a 400 into one of these cars... Can't tell from the pics, but it was in there for around 15 yrs and drove a good 150k miles.

Oh BTW... Vortecs use the same bolt hole pattern on the ends as older heads AFAIK; the old brackets should bolt right up.

88_are_s

Hell yea! Im buyin me some Vortecs. Gonna need centerbolt valve covers. And steam holes drilled in

sofakingdom

iTrader: (1)

You can drill the steam holes yourself.

Lay a 400 head gasket on the head; put acoupla drill bits in the dowel pin holes to locate it accurately; mark the steam holes with a center punch. Drill the ones on the exh side straight in (90° to the deck surface); drill the ones on the int side at about a 30 - 45° angle toward the exh side, because it's right next to the bolt hole, and if you drill it straight up, it'll never hit the water jacket.




You can see in this pic of a 400 head gasket, how close the int side steam hole is to the head bolt. Yellow is head bolts, cyan is steam holes, red is dowel pins.

Here's something like what it should look like after you're done. These aren't stock heads, but the principle is the same.



Ya think I might have ever worked on a 400? Ya think? Really??

Incidentally, in the gasket pic, you'll notice the triangular group of holes underneath the 2 exh ports in the center of the head (the ABSOLUTE HOTTEST place in the whole motor), marked with magenta. Be ABSOLUTELY 100% POITIVELY CERTAIN that both the block and the head castings under those holes, clears the holes COMPLETELY. Use a die grinder, rat-tail file, or whatever else it takes, to open up the castings. That ONE THING right there is one of the mainmost causes of mystery "overheating" in the SBC but especially the 400.

88_are_s

Damn. Youve done it all lol. What size drill bit?

sofakingdom

iTrader: (1)

3/16" or so... exact size is not critical.

88_are_s

I cant find a shop that balances flywheels near me. Can i just use a counterweight on the flywheel?

sofakingdom

iTrader: (1)

You "can", but it's not risk-free. There's a chance that your clutch won't work right or other odd things can go wrong. OTOH, it might work fine.

I don't know where in So Cal you are , but there's GOTTA be about a billion places around you that do stuff like that. When I lived out there (Carlsbad) I didn't have any trouble finding such things.

ANY racing machine shop can either do it, or point you toward someone who can.

88_are_s

Hemet. Which is in Riverside county, Inland Empire

sofakingdom

iTrader: (1)

Yup I know Hemet...

Go to yer local speed shop. Can't tell you who/where that is, sorry, it's too far inland for anywhere I would have had to go to do business. Ask em for a few names of RACING machine shops. (not corner parts stores, although sometimes...) Give em a call.

Alternatively, go to yer local dirt oval track. Buy a pit pass. Hang around the guys THAT WIN. Ask em who does their machine work. Ask THEM whether they can balance it, or if they know who can.

Avoid drag strips for this endeavor. While there's some real knowledgeable people there and all that, they're too hard to get to. The environment is too polluted with n00bz that are too hard to weed out and ignore. Too hard to cut through the BS and get to some reality.

88_are_s

Perris Auto Speedway or Lucus oil in Lake Elsinore are the local dirt ovals near me. Thats a great idea to get some knowledge.