Demon355

iTrader: (1)

So my 357ci motor went bye bye with 10psi of oil pressure. When I tore it all apart I found scored cylinder walls, chewed bearings and crank journals so I took this opportunity to build a 383. I've been talking to a few guys on here on which direction I should go with for my camshaft. I was debating getting a custom grind but with the season almost over and my eagerness to get this motor back into my car, I opted for a 280XFI-HR13. Thanks to Orr89RocZ for all the help. My block is out of a '98 Tahoe. It's a 2 bolt main, machined to the **** 350 bored .030 over. New frost plugs, seals, bearings etc. The crank is a Scat 9000, brand new. Connecting rods are Eagle "SIR" forged lightweight. Pistons are Speed Pro 12cc Dish. When I bought this shortblock off my buddy he was building it for a supercharger so thats why it has dished pistons. Clevite 77 Bearings. The heads I'm using are my freshly ported World/Dart Sportsman II's. 200cc runners, 64ishcc chambers, ARP rocker studs, Comp cam guide plates. Intake will be my Sportsman II dual plane for now but I would think swapping that out for an RPM Air Gap would be ideal, no? Carb would be my trusty Holley 650DP. People will tell me it's too small for a 383 but I know tons of guys running this same carb on 500hp motors. By the way, this motor will see street duty more then track duty so certain areas will reflect that. Back to the cam. Using the 280XFI-HR13 cam is almost perfect for what I want to do. The duration is moderate @ .050 with HUGE lift capabilities. Being that it's spun on a 113LSA is even more ideal. My old cam in the 357 was the XE284. I know most of you are familiar with that cam and know it's a 110LSA with 240/246 duration. That is NO good for power brakes. Seeing in how this car will see mostly street duty, I opted for a cam that will give me my brakes back. The specs on the 280XFI are 236/241 @.050 .576/.570 113LSA. I've seen on a few other sites the duration being 230/236 so maybe someone can shed some light on which duration is the proper one. That sums up pretty much what I've been doing and will be doing over the next few weeks.

Connected to the 383 will be my built 700R4 with a TCI 3200 stall, LS1 driveshaft and my "built" BW 9 bolt with 3.70's. I was told I should net around 370-375whp. That's good for a high 11 in the 1/4 correct? I plan on swapping out for a T56 when the money permits. My exhaust is Hedman LT's, custom 3" Ypipe and a SLP "Bullet-mouth". What are everyones thoughts? Give me anything, good or bad I want to hear it all. Input helps us all learn and discover more stuff about these awesome machines. Here are some pics of my block and parts. Enjoy!

1989GTATransAm

iTrader: (3)

Looks good. I have always seen the XFI280 camshaft listed as 230/236 @ .050". I think it is a fine choice for your application.

Word of caution with that block. If you use a double roller chain for the camshaft you will have to grind the top oil boss some for the chain to clear. The boss is located above the camshaft bore.

Viprklr

iTrader: (5)

Just the thought of building another 383 makes me all tingly inside.

Wouldn't a 2800 stall work out better for your application?

Demon355

iTrader: (1)

Yes I would use a 2800 stall if I could get one for the price I bought this 3200. Thats the only reason I couldn't pass it up. I might be sticking with an auto for a little while longer then I thought. My knees are terrible and my left one is getting worse. Doesn't look good.

Anyway, ordered a new water pump for the motor today too. Edelbrock Victor aluminum pump ftw! Along with the pump, I have a new flexplate already in the mail. I forgot to mention that I will be using Scorpion 1.6 roller rockers. Now with my block being a 98, the timing cover has a hole at the bottom for what looks to be some sort of sensor. Is there any aftermarket covers that fit my block that don't have that hole or do I have to buy the sensor just to use it as a plug? Anyone else use this type of block for their build?

fast82z

iTrader: (1)

Looks like the flat tap cam is the bigger duration that you've been finding. Yours being a roller is the 230/236 cam .576/.570 lift. I'd say the 375rwhp sounds about right. I'm betting that'll put you right around 11.9 for the 1/4. That setup sounds somewhat close to what I had 2 years ago, main diff. being 246/254 .558/.558 cam on trick flow 195cc heads. That motor dynoed 405rwhp, but was probably making more around 415 on the day that did its best of an 11.44.

1989GTATransAm

iTrader: (3)

I'm using a 1999 version of that block. Use the timing cover off of your L98 motor.

Demon355

iTrader: (1)

I didn't have an L98 block before this one. I used a 70's Camaro block. So any L98 timing cover will fit, even the years out of our cars?

Seeing high 11's would be pretty sweet. Obviously if I were to use a different cam and intake I could get myself over 400whp but I've mentioned before that I want a bit more streetability so I'm happy with that.

Figured I'd get more responses than this

Hello, Michael

Wow. Looks great! I'm gonna be starting my very own 383 build shortly

Demon355

iTrader: (1)

Motor is finally done. Looks like **** but I'm painting the heads silver to give it a "wannabee" aluminum head look. Should be in the car by the weekend. Balancing took forever and I might need a new balancer.

jpeden31

pretty! can't wait to start my build. hope it doesnt let you down

Orr89RocZ

iTrader: (20)

nice. the cam is liek stated, 230/236 but thats good duration for a 383. Make sure those heads have the valve springs to support the aggressiveness of that cam. They will want some stiff springs

cam will support 400whp, just need compression and good heads to get there.
depending on how well ported those heads are, you may get close to there. 375 would be my guess well setup. Still good numbers. Definately high 11's if you can launch low 1.6 high 1.5 60 foots.

Demon355

iTrader: (1)

Yeah the heads have been smoothed out pretty good. The springs are good enough for .600 lift so I'm sure I'm good. I'll be happy if I get 375whp or into the 11's. I have horrible tires right now so until I get me some DR's I doubt I'll be getting 1.5-1.6's without them. Like I said, it's going into the car this weekend and all the bugs will be sorted out if any. I still have to weld in a new panel to cover my AC holes.

Orr89RocZ

iTrader: (20)

.600 lift is good but what are the pressures at seat and open at max cam lift? Do you happen to know what springs are in it?

urbanhunter44

iTrader: (3)

looks good demon, i picked up my motor and all the parts from the machine shop this morning. Mines similar just 355 cid and more cam/rpm. Have fun!

Demon355

iTrader: (1)

Not too sure about the seat pressures but my buddy who builds motors for fun said the springs should be fine. If I do run into bind issues (testing stuff before hand) then I'll swap them out for some high rate Beehives or something similar. Anything you can point me towards that won't break my bank account?

High rpm V8's are awesome! I should be able to take mine to 6500 but that extra 500 rpm would be badass! Hope all goes well with your build, should post some pics of it in the process of being built. I don't think I've seen your new Nova yet?

Orr89RocZ

iTrader: (20)

depends on the seat pocket size for your head. Patriot extreme gold springs are decent for the price.

150 for a set. they are small dual springs designed for LSx cams that are aggressive like the XFI stuff. They are similar to my springs which are AFR 8019 springs. My cam isnt as aggressive lobe wise as the XFI but pulls just as high rpm so i wanted to make sure i got no valve float.

patriot's base Gold spring is 128 a set from Patriot and they should be enough spring, i'd shim them to a 1.75 installed height and that should be a good deal of pressure for that cam. Still good to .600 lift with 1.75" install height

you could try calling AFR to see about a price. Probly gonna be abit more than the Patriots. They cost me 100 bucks for the upgrade over the base 8017 spring so i imagine they were atleast 50 bucks for a set probly closer to 75-100.
All you need then is proper spring seat cups and retainers/locks.

Comp/crane both make larger dual springs that could work but i like a smaller spring for less weight.