ScottyRS

iTrader: (2)

Okay, so I gave up on building a 383 (just can't afford it) and am dead set on a 355 now. I'm looking to make at least 450hp at the flywheel and have a few questions for some of the more experienced chaps out there...

I already have SRP forged aluminum flat top pistons, what compression ratio will these give me with 62cc combustion chambers?

If possible (affordable) I'd like to get as many GM Performance Parts on this thing as I can. I'm looking at the Aluminum Fast Burn cylinder heads. They have the 62cc combustions chambers ,78cc exhuast ports and runners, and 210cc intake runners. I plan on getting the Vortec ones too.

These heads require LT1 style flanges for the headers. What the hell am I supposed to do about that?

I also need a camshaft to complement the heads and make that 450hp. Anyone know any good cam specs?


This engine will require pump gas and I'm sure more questions will come up later, but thank you to anyone who can answer these.

Sonix

iTrader: (1)

450HP? cubes would be your friend, hence the 383... The cost of a $250 crank is what would break you on this?

What's the deck height with the pistons installed? is that flat top with 4 reliefs? 5cc perhaps? Got a part #?

Need LT1 style headers? Get headers meant for an LT1 car Think 4th gen I would guess. I also would guess that would be HUGELY expensive, compared to "normal" SBC headers. I didn't think the exhaust flanges were different though? I've seen people put LT1 heads on their SBC, and didn't mention weirdo headers needed...?

Those heads are pretty good from what i've heard. Roller or flat tappet block? You'll need a lot of lift and duration for that kind of power. I think like the cc306 I think it is, that'd do it for roller. Flat tappet, I think in the >230 intake duration, mid .500" lift. Those heads have weenie springs, i'd look into upgrading those.

Kinda vague eh?

ScottyRS

iTrader: (2)

Don't even get me started on how much machine work costs nowadays.

The 4th gen headers crossed my mind, but would they fit in the 3rd gen engine bay? Anyone out there that's done an LT1 swap, know how to work this out?

And I have no idea what the part number on the pistons is, but when I get them from the machine shop (engine was supposed to be done 2 weeks ago ) I'll let you know. The guy I ordered them from said that with 64cc chambers, they should give about 11:1 compression. But that was off the top of his head. And I'll be using 62cc...

Also, it will probably be a hydraulic flat tappet block. But I'm thinking 450hp out of a 355 with a Vortec intake should be doable. One more thing: I'm perfectly okay with a lopey idle. This won't be a daily driver anymore.

Rogue86

Just go with some cheap dart iron eagles, decent hydraulic flat tappet cam (call up the cam manufacturer and ask THE PROFESSIONALS not people on the internet), some speed-pro flat tops . Edelbrock performer RPM intake. Headman long tubes. Older non-computer HEI ignition, NEW 750 double pumper carb. Your compression will be 10:1 with the flat tops and 62-4cc heads. Keep it simple.

LT1 heads use the standard sbc flange on the headers. Honestly, if the machine shop thinks a 350 with flat tops and 62cc heads makes 11:1, you need to find another shop.

ScottyRS

iTrader: (2)

I already bought the pistons (the machinist needed them to bore the block). There is a guy around here that custom grinds cams, so I'll probably ask him about making one to match the heads (if it isn't too much). And it was the parts company I ordered the pistons from that came up with the 11:1 ratio.

Also, I hear a lot of mixed reviews about the aftermarket companies and that's why I'd like to go GM as much as possible.

Sonix

iTrader: (1)

What machine work for a 383? Assuming you get a 383 crank, you need 383 pistons, and grind a bit of the block, nothing a machine shop needs to do for ya...
well, if you're already set, then i'm barking up the wrong tree...

When you start assembling your shortblock, measure the deck height, then after that, you can pick your heads and head gaskets to suit.

ok, fair enough, not daily driver. Make sure you've got the gears, torque convertor and other jazz to match up with a high RPM motor. Mid 230* intake duration is still pretty streetable, and with the right heads, I don't think mid 400HP is unreasonable.

ok, you either have a roller block or you don't, your machinist knows, what is it? Or, should I say, are you willing to cough up the extra $500 or so to go to a retrofit roller setup?
Solid cam in your set of choices?
what induction setup?

F-BIRD'88

Use the Edelbrock ETEC 170 head instead of the fast burns.
It has a conventional exhaust port. uses standard 1-5/8" headers. use the GM performance parts hi rise vortec intake so it looks like GMPP's on your car if you want. use Crane cam #Part Number: 114681 Grind Number: F-280-2 This is a mechanical flat tappet cam.

your cr will not be 11:1 more like 9.87 with no block decking or 10.48:1 on a "0 decked block" (.030" over bore)
use a 750cfm carb 3500rpm stall converter ATI is good choice. 4.10:1 gearing.

ScottyRS

iTrader: (2)

What tools would be necessary to grind the block? And about how much clearance would I need? Because the cost of the extra machine work is the only thing keeping me from that 383.

The block is out of a '74 truck so it definitely isn't a roller block. And I really don't have any initiative to convert it (that's what I meant before).

A carbed Vortec setup is what I'm aiming at right now. But that's subject to change.

And the drivetrain will be rebuilt in due time. But I'll cross that bridge when I get to it.

Sonix

iTrader: (1)

well, for example, check out a new crankshaft, with 3.48" throw, or 3.75" throw. Virtually (sometimes is), the same price.
Rods - same for either
pistons - different compression distance, are usually the same price.

Put your crank in the block and rotate it around my hand, have a .060" chunk of whatever, to use as a "feeler gauge". Make sure there is .060" clearance, if not, grind. Use a die grinder, or a file if you've got too much time on your hands

Other then that, you were planning on getting the motor balanced either way? New flywheel and dampner either way? Those things would be different then on a 350, but not really more $$... Well, double check on some of those, but yea, not a huge price diff, and I don't think there's any machining needed to be done (at least by a shop).

nelapse

iTrader: (17)

You will need a die grinder to take a smidge off the bolt shoulders and the bolt ends of the connecting rods... you will also need to make clearances for the bottom of the cylinder walls for the rods to clear... It isn't difficult.just put on rod in at a time and then work it. A 383 would be just the same as the 355 in the long run... a 383 crankshaft brand new is $189 made by eagle and sold by summit.

ScottyRS

iTrader: (2)

All I bought was the block and the 30-year-old pistons inside it. So I have to get a new everything anyway.

I do believe I have a die grinder sitting around here somewhere. Now I just need to figure out how to measure 0.060". Could I use something like this...
Dial Indicator
or this...
Summit Magnetic Base and Dial Indicator Kits: SUM-900016-1 - summitracing.com
...for that, and to measure the deck height of the pistons?

Thank you so much for the help guys.

*Edit*
One more thing, 6" or 5.7" rods?

wezeles

another thing depending on your cam... if its over 500 lift you might have to clearance the rods a bit more then the bolt shoulders if your sticking to stock rods or even after market rods not cam clearanced already, its not to bad i did mine last year on an old truck block 4 bolt

machine work cost me 500 bucks this was because it needed to be alinged honed because i wanted beefier caps...

before that it would have been like 275 bucks

the crank clearance you can do yourself just fine spin the crank and wereever it is less than 60 like he said grind it...

the crank you can get for 175.00 for a plain 383 eagle steel crank little more if you want forged..

the rods you can use the stockers or if you want a nice set of stockers that are cam clearanced and balanced i can get you a set through the company i went through on my last 383 they are like 120 bucks balanced and shot peened

and a 4 valve relif pistons cost little to nothing more than a regular 350 would...

thats about it... if you were to build a 355 to a 383 using fairly stock style parts i would say most cases your only talking a couple hundered dollar difference... if you wanted to go all out forged and everything then it might make a bit more difference but not much

wezeles

and the rods really the 5.7 to 6.0 isnt a matter of performance its preference the 6.0 rods will help the motor last longer than the 5.7 just because of less pressure on the sidewall.... i went with 5.85 rods they were really popular before the 6.0 and larger hit the market full blast so i got a set really cheep and it still makes me feel good cause the wrist pin isnt in the oil rings... sure i know thats not a big deal and it works fine but it still freaks me out ...

nelapse

iTrader: (17)

6.0 actually is a huge difference in the fact that you almost have to do virtually no clearance issues. If you can afford them.... then use them. They are recommended by alot of engine builders... racers use them or bigger.

Sonix

iTrader: (1)

.060", use a 1/16" drill bit or something, just make sure you can fit it between the crank/rods and the block, at any and all places. If it doesn't fit, touch it with your sharpie/grease pencil, mark it all up, then move all your nice clean machined parts OUT OF THE ROOM, and grind the block. reclean it all up, and try again.

check deck height : use a feeler gauge ($6) and a steel ruler ($10). There you go, you just blueprinted your motor.

Dial indicator can be used for that, but it's harder to do.

5.7" rods are usually cheaper, plus the pistons to go with 5.7" rods and 3.75" stroke is more common/cheaper than 6" rod ones, **usually**. Look around.

Grinding rods - if you use capscrew rods (bit more $), then that's usually eliminated... Or remember if you're getting the rotating assembly balanced, do the grinding first. Try to grind the block rather then the rods, if you have the choice.

Bingo! Usually even less than a few hundred, plus, $ for $, it's the cheapest way to boost power. You can bet on that.

ScottyRS

iTrader: (2)

Would a small circle base cam allow enough clearance for the rods? I'm thinking it will, but I suppose the only way to know for sure is to put it all together. And maybe I will convert it to a roller cam. But again, I'll cross that bridge when I get to it.

And I have no idea what rod size my pistons are for. In hindsight, I will probably be ordering on Summit from now on so I know exactly what I'm getting. And a cast steel crank should be strong enough, right?

nelapse

iTrader: (17)

The whole cast vs forged thing is a little hairy... forged cranks are stronger than cast, but forged seems to crack more... clear as mud?
it may be because people who use forged cranks abuse their motors but statistically forged cranks have the most talleys for cracked cranks...
But yes cast would be strong enough.

ScottyRS

iTrader: (2)

That's all I needed.

nelapse

iTrader: (17)

Well, you arent going to boost or nitrous this motor right? If not it will be adequate.

Sonix

iTrader: (1)

Look up the part number of the pistons you have. If you already have them, then a 383 is out of the question I think. Unless you go to 5.65" rods I think (the stock 400CID rods).

Most likely for 5.7" rods, they're the most common.

nelapse

iTrader: (17)

5.65' rods are a waste... no 383 I have ever seen uses those rods and for good reason. lol

ScottyRS

iTrader: (2)

They should be 383 pistons (damn well better be!). And again, they're at the machine shop now, so no part numbers...