0013

Hi Guys,

Please help me spec a 383 build.

A little background: I’ve been lurking and searching here for a while in anticipation of my next project. The time has come… driving season is coming to a close, and budget is in the bank (although I’ll probably exceed what I have saved). I’m dubbing this “Operation in Over my Head” – if you continue reading you will soon realize why.

For the last 10 years I’ve been enjoying my 1978 Silver Anniversary Edition coupe, L48, 3 speed auto with 3.08 rear gears. Mods include VB&P performance plus suspension, headman street headers, 2 ½ in pipes with sweet-thunder exhaust, MSD ignition, stainless steel brakes corp. calipers with cross-drilled power stop brake rotors, and miscellaneous other stuff. I have enjoyed it, but the time has come for more – bringing me to “Operation in-over-my-head” which will include (among other items) a new aluminum radiator, a new 383 stroker, 5-speed manual conversion, and new rear gears. I’m thinking a setup like this should pep things up a bit over what I’ve got today.

So… all you experienced builders chime in… please explore, question, and scrutinize my engine build before I actually buy a bunch of parts that won’t fit the expectation. Also understand that other than relatively superficial stuff in the engine compartment, I am a novice here and still learning – eagerly learning. I definitely appreciate the thoughts and suggestions of those of you more experienced in these matters.

As for the 383 build, the goal is to target 450-500 hp that will run reliably down the street on pump gas – I’ve never really been a track guy and don’t see myself there in the future; but who knows. I do really want to wake up the beast for a fun, weekend, snap you back into the seat, driver. My new block originated in a 1970 truck, 4-bolt main; cleaning and testing at the machine shop came back good. We’ll go for a 4.030 bore and a 3.750 stroke.

For the short block I am looking at Scat Engine Rotating Assemblies 1-40855BI including, Forged Crank, Forged Pistons, I-Beam Rods, Forged aluminum dome style pistons (with two valve reliefs and a head volume of -7.00cc). A forged 4340 steel internally balanced crankshaft. 4340 forged I-bean connecting rods, and the requisite 2-piece rear main seal. (Probably overbuild for my requirements, but who knows where I’ll be in the next 10 years.)

I’m planning on AFR 195cc SBC Eliminator Street Heads – fully assembled, 75cc chambers, and 195cc intake.

I’m all over the place on the cam selection – most recently leaning toward Comp Cams 283THR7; hydraulic roller thumper cam, 227/241 duration with 0.513/0.498 lift, basic operating range from 1900 to 5600 RPM – I was originally thinking of the XR282HR and I’ve had a couple folks tell me that would be more than I’m looking for in a weekend driver; I’m not sure “scaling back” to the thumper is really scaling back at all. The cam selection if probably my biggest hang-up to date. I also plan to do the Comp Cam kit that comes with the hydraulic roller lifters and the double roller timing chain.

I’m planning to top the setup off with an Edelbrock Performer RPM Air-Gap Intake Manifold and a Holley 750 cfm Carburetor.

Exhaust will be Hooker Super Competition Sidemount Headers (1 7/8 primary tube diameter) and Hooker Super Competition Sidetubes (4 in inlet and outlet).

One of the many on line calculators is estimated a 9.9:1 compression if I zero deck the block. (not exactly sure I did this right or not – from what I understand, 10.1 compression is still within the range for pump gas.)

As I mentioned earlier, the combination will be married up to a Keisler RS500 5 speed transmission (3.37, 1.99, 1.34, 1.00, 0.67) and new rear gears (going from 308 to 373 most likely – anyone have another recommendation).

What other information would y’all need to help me determine if I’m on the right path here? Do any of you have any other recommendations? Any advice is greatly appreciated.

Thanks,
Jeff

George Ries

Dont waste your time with comp cams the thumper cams are crap go with a bullet custom grind cam they will grind a cam to fit your motor and your driving needs

George Ries

Comps been having lifter problems there products aren't what they used to be comp = junk

MrJlr

uxojerry

Take a look at the AFR Titan intake that Paul Dana is using on his SBC 427. AFR will spec out an entire top end if you talk to Tony Mamo.

Street Rat

Submit some cam recommedation forms online to your favorite cam grinders. Tell them what you are building and all of the specs. They will recommend a cam to fit within your rpm range and engine specs. Oh and one more thing...I'm jealous!

bluedawg

Google Straub technologies for a cms recommendation. I've got the xe288hr in my 400 sbc it's streetable. I would figure the 282 would have manners as well. Good luck.

0013

Thanks for the comments guys – I knew y’all would be good for more paths to research and more phone calls.

Has anyone else had ‘problems’ with Comp Cams? The mechanic at my local garage (where I go when I can’t fix the problem) does a lot of drag racing (semiprofessional) and swears by Comp – I haven’t really looked elsewhere because of his recommendation.

George Ries

I have done 4 big blocks chevys and 2 sbc and had problems with their lifters falling apart some were roller and some flat tappet all in a matter of 3 months there quality control is just not there anymore

Scott Marzahl

You would have better flame travel with flat top pistons and smaller combustion chambers. For the money you are spending look at some Mahle flat top pistons.

v2racing

It looks like you have a pretty good selection of parts for the most part and it should be fairly easy to hit the 450-500 HP range. With a good cooling system, a cam that is matched to the build, and proper tuning, 10.5 to 1 will run fine on the street. If you can get a set of pistons with about a -10cc volume, you could go with the 64cc chambers and have close to 10.5 to 1. This is how I would do it. Set the squish (quench) tight, between .035" and .040" and this will help prevent any detonation and make a crisper running engine.

As others have said, you may want to check with StraubTech for a cam. He is a member and supporting vendor here.

With the tranny you have chosen, first gear will be very low with 3.73 gears. I think you would be happier with 3.55 or 3.36. Even the 3.08 gears you have will yield good acceleration in first as you will have 10.35 overall gearing in first which is the generally accepted first gear ratio to shoot for. I'm going to be dealing with a little too low first gear myself, but I had new 4.11 Richmond gears and a 4 series posi.

Do this a right and you will have a street friendly car that will have some serious go power.

bluedawg

It seems that most companies have different levels of quality. The higher the quality the more durable the more they cost. The roller lifters that cost $700 would probably hold up better than a $350 set at say 7500 rpm. But at 5500 or 6000 rpm is there a difference? I'm a firm believer in you get what you pay for.

63mako

I like your plan for the most part. I would make a couple changes. Go with the TKO RR600 trans, bump compression either with flat tops or 64cc heads or mill the heads to what you need to get near 10.5 to 1. Cam it up a little to take advantage of the heads, NO THUMPER. Those heads flow well on the exhaust side and you will give up a lot of power. Either of these look good. http://www.crower.com/index.php/cams...se-circle.html
http://www.compcams.com/Company/CC/c...?csid=152&sb=2 The crower is a small base circle. If you have clearance go with the standard base circle here.
http://www.crower.com/index.php/cams...-cam-5051.html Either will thump a little without the power loss.

Scott Marzahl

Be careful with the dome volumes, the -7 cc that Scat advertises is really a + 7cc by other piston manufacturers. If you used a dished piston like a Probe p3833f030 -12cc and a 64cc head with block decked at zero height you will be right at 10.5 with a .038" head gasket. I wouldn't go much longer than 230 duration @.050" either.

63mako

When looking at cams remember the operating range will drop about 500 RPM with a 383. Most are rated for a 350. Also your gearing will get you into the powerband fast and the additional torque of the 383 allows better pull at the bottom. If your going to stay under 10 to 1 you will have to downsize the cam but will also not see the full potential of the heads. Those heads want .550 or more lift.

0013

Thanks George – we’re stepping away from the comp cams

?!?!? Oh yeah – I’m much more comfortable about these calculations now
Hi Scott – I was originally looking at flat top pistons since I have no intention of adding extra juice. The online compression calculators pulled me away because I kept getting really high compression estimates. I’ve also heard good stuff about Mahle. I’ll have to go back to the calculators – maybe I’m doing something wrong.

v2racing – thanks for the recommendation for Straub – I’ll definitely check them out. I’ll call Keisler back as the 3.73 was partially based on their recommendation, but that was based on early (incomplete) data for this build. Their spec sheet show final gear at 2200 rpm at 83 mph – seems pretty high.

63mako – those are really high lift cams. Thanks for the clarifications in the second post; I was unaware about the rpm range dropping with a 383. Is it true one can have higher list with a hydraulic roller cam? And why the RS600 trans? I though their numbering basically corresponded to HP ratings.

larrywalk

If you're serious about running in overdrive and really low rpm for cruising mileage, too much valve overlap will kill mileage and may be nearly undriveable at less than 2000 rpm. From trying to read between the lines of your post, I'd think that a 112 deg or 114 deg lobe separation angle with an intake duration of 228 to 233 degrees would work best.

63mako

The gearing is the difference in the trans. The TKO 600 RR is a close ratio trans with a 2.87 first and a .82 overdrive 5th. With a 3.73 rear gear this gets you a 10.7 to 1 ratio in 1st to tame a bigger cam and higher compression. It will cruise like a 3.05 rear end in 5th. This will keep you in your powerband at cruise and not rev like crazy at highway speeds. Best of both worlds. The huge advantage the higher lift cam has is noticeably more power throughout the entire RPM range by taking full advantage of those awesome heads. They flow more up to .600 lift. You will not regret using the full capabilities of those heads. Your gearing will tame down the bigger cam significantly. Why leave 40-50 HP on the table if you can have it and still have a very street friendly combination for $0 extra cost? A roller cam compared to a flat tappet with the same duration @ .050 and LSA will give you more area under the curve, more lift, more power, more vacuum and be more responsive.