283 vortec heads

Tech, I was not calling you a liar, and i hope no offense was taken as none was intended. I guess you can make power out of anything so long as you spin it to the moon. I definitely would not even consider that combo for the street, unless you like replacing clutches and don't mind running a 5.13:1 gear.


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Nothing hurt. I agree with you that it isn't a motor you would want to drive on the street every day, it's just a weekend playtoy. But here's a different Dynosim, taming it down.....

OK, here's a nice little 375hp 283 street motor with hydraulic cam that would operate well with a stock converter.

Assuming that is would be possible to cut the L31 decks for 60 cc's (about 0.028") without making a cracking problem, you could make 9.15:1 static compression ratio with flat-top 6cc pistons and a 0.035" squish. I remember reading years ago when these heads came out that it was not recommended to use a domed piston with them to raise static c.r. I wouldn't do it anyway because in my opinion, the dome gets in the way of flame propogation across the chamber.

283 bored 0.060" with flat-top, KB165 6cc pistons. Cut block decks to 9.015" for 0.010" piston deck height. Victor Reinz 5746 head gaskets, 4.100" bore, 0.025" compressed thickness for squish of 0.035". L31 heads with stock 1.94"/1.50" valves. Cut head decks 0.028"-0.030" for 60cc chambers, 9.15:1 static compression ratio. (598 cylinder, 60 head, 5.4 gasket, 2 deck, 6 piston).

1 3/4" long-tube, equal-length headers, RPM Vortec intake, 600 carb.

Compcams part number 12-230-2, grind number XE250H, 250/260, 206/212, 0.432"/0.444", installed 2 degrees retarded at 108/112/110.

RPM HP TQ
1500 85 300
2000 123 323
2500 158 332
3000 202 353
3500 249 374
4000 292 384
4500 329 384
5000 362 380
5500 374 358
6000 375 328
6500 354 286

This motor makes 91.8% VE @ 4500

that's a much more streetable engine. I'd still try beefind up the TQ some, but it is a good example of waht you can do with stock style parts.

Tech- Is DynoSIm the comp cams software? Not sure, I have it but on my laptop that's currently down and out. Anywho, if so, I've think I've stated this before but I've 'rebuilt' the engines dynoed in CHP and HotRod given their specs for the engine, cam, flow rates for heads, carb cfm, cam timing events @ .050 and I've seen HP be pretty much realistic within +/- 7% but torque was WAY off the mark +/- 15% and usually was 2-300 RPM over or under what the magazines were showing...

I would think those numbers for that 283 build would be especially optimistic on both the HP and TQ side- on both builds. I would think on a good day and this is totally shooting from the hip but that hydrallic cammed 283 would be good for maybe 325hp. If compression was a bit higher then maybe 335-340.

Along with RPM, especially on the first build you had, I just don't see where 248 degrees of adv. duration would feed that engine to 8,000 even under 300ci, maybe I'm the only one.

However, that being said totally like the both builds, would just like more compression. I think KB sells a +4cc hyper piston with a 1/16th ring pack, a very light .1 dome so I dont think flame travel would really be an issue, so this piston could be a alternative fix to shaving heads or decking.

Anywho...

Yeah, none of it amounts to a hill of beans anyway. It's just a way for me to keep busy and have some fun in my retirement. Yes, the Dynosim is the Comp software.

I doubt if I'll ever get into building motors any more. I did it for 50 years as a hobby aside from work and really enjoyed it, but money and physical restraints have relegated it to the past for me.

I am still holding onto my part time gig as chief technical inspector at Firebird and will more than likely do that until the grave diggers shovel dirt in my face. The Friday Nite Drags and Team Firebird events are fun, but I really get excited when the fuel cars come to town and I can get my hands on some real race machinery. You couldn't yank the grin off my face with a slide hammer.

Retirement good for you! I've got about 40 more years until that happens unfortunately... anyway, I do agree that the dynosim stuff is a good rough estimate of what a combo will do and it's nice that you providing a 'free service' to others without it... sounds like a cool gig you got going on the weekends but how do you stay away from building engines? Let me know the secret because I'm tired of lining the pockets of aftermarket performance companies! Well not lining them exactly but dropping a good bit of my residual income atleast.

i am a couple days from starting up this combo, what do you think for a play toy on the weekends. its in a s 10

283 Bored 40 over
Harlen Sharp 1.5 ratio
Hydraulic lifters with a Summit Cam 254/264 .533/.555
Summit Bracket Racer SFI Harmonic Balancer
Eagle I-Beam Rods with the small journal (5.7 in length)
Original crank, brand new condition, never been cut ( Forged)
Weiand high rise intake
Speed pro forged pistons
Double roller timing chain
375 double hump heads. reworked with the big valves
Rotating assembly balanced and blue printed
650 Edlebrock
headman headers
True duals with no cats.
4.11 posi unit
B and R shifter
350 turbo tranny with shift kit, red line clutches, harden sprag ect....
Summit ignition steet and strip
Rev limiter
hei blue printed distr.
Taylor plugs
3200 stall
3in exhuast

I am hopping she will run on the strong side

What's the deck height & cc of valve reliefs in piston, head gasket thickness?
That cam may be a ton too large.

I second ss64's concerns... that's alot of duration, better be packing a mean punch in compression for that small displacement.

2.02's in in the 40 over 283 isn't going to work.

Dump the humps and get a vortec, etec 170, or twick flow 1.94 aluminum....you are just leaving power on the table without them. (Unless you have had some solid port work done by a proven artist).

not a fan off the edelbrock carb for the race-rpms you are going to be turning... bigger cfm and holley or holley type carb is needed in my opinion

4.11, even in an S-10 might not be deep enough... I would settle for a 4.56

3200 stall... I would lean to a smaller converter than this.

3" exhaust might be a bit much also but I guess that can't be changed at this point.

Using what you've got, I would notch the bores around the intake valve ("ala" Big Block), install the cam at least 6 degrees advanced (around 106-107 degree intake lobe centerline). 3500 would be my minimum on stall, if this is more of a playtoy/racer then 4000 would be my lowest pick. I have to agree, get rid of the edelbrock carb, a 650 or 700 DP Holley style or a modified 750 Vacuum Holley would be toasty. Run a short 26-inch tall tire. It's a small motor, got to get it revved up a little to get anything out of it, but it will make you grin in something light like an S-10

750 double pumper, minimum 4.56 gears. That may be a tad too much cam. All the cam I could use on the DynoSim on page 1 of this thread was 248 and still have the motor run at all on the low end.

Sorry, but you've got another 40 years of boltin' iron together ahead of you.

Too much cam suration, and if you haven't bought the rockers yet 1.6's would be a better choice. It looks like a great mild track combo, but you're going to need so much compression it won't run on pump gas. With that cam I'd say 12:1-ish. I'd go with a milder cam and a dual plane if you plan on putting any street time on it.

no its cool i read a smokey yunick book on making a 301