The L31 Vortec Heads are rated at .450" Lift. Would it be safe to use the LT4 cam wich has a lift of (.476/.480) with these heads? Or should i pay the $200 extra dollars and get the high performance vortec heads which have springs that are good up to .550" lift, have better valves, and are machined for screw-in studs and guide plates?

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Pat Hirsz
www.iit.edu/~hirspat/MyPage2.htm
88 305TBI
Mods:Hooker Aerochamber 3" exhaust, no cat,SLP 1 5/8" headers and y-pipe March pullies, no smog, 180 thermo,
14x4 K&N, 3.42 gears(open), Ultimate TBI Mods,AFPR,MSD(ignition,coil&wires),Edelbrock TBI Manifold, 190ltr/hr fuel pump,
Eibach springs with KYB's all around,
Harwood cowl hood, Z-28 wing, fresh paint(black)
120,000 miles, 5spd, T-tops
0-60mph-7.2s-Gteched

92 RS, 305TBI, auto, 3.08 gears, 180 thermo, glasspack (no muffler)

 

Crane makes .050 offset keys and .050 shims that will raise the coil assy. to give the clearance that you need. I have just put this combo into a 350. You will also have to grind the pushrod hole closer to the studs to clear since the 1.6 rockers that the LT4 series of cams are made for. Or just use 1.5 rockers and give up some lift.

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91 RS 350TBI..... Vortec heads..... Holley 670..... Edel. intake .... Lt4 cam 1.6 rollers ..... Edel. TES headers .. 3" exhaust ..... 5spd 3.08

 

I think i'll just get the high performance vortec heads for inurance. Will i have any problems using these heads with the LT4 cam and 1.6 rockers on the 305?? (They will be getting milled .035" to keep the compression) Thanks.
Also, can someone explain to me what the advanatage of screw-in studs and guide plates are? and how much they would cost me because they are not included in the heads.

 

Screw in studs and guidplates are more of a strength factor than anything. There is really no performance gain. Some will argue this ans say that the guideplates keep more consistent lift on the valve which is true, but on an engine with a mild cam (like LT1, LT4) you would really see no difference. Now on engine with high spring pressures and high RPM usuage, Screw in studs and guide plates are almost a must. One of the best things about them being on Vortec heads(or any late model centerbolt head) is the fact that if you have them, you won't have to use expensive self-aligning rockers. They are definetly a nice mod.

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82 Z28 383, Ported 215cc Dart Iron Eagle Heads 72 cc Comb. Chambers, Comp custom grind Hyd roller cam, Speed Pro .250" domes, Wheeler Motorsports 4340 I beam rods, Eagle 5140 steel crank, Weiand Team G intake, Holley 830 DP, hedman headers
Trans: Turbo 350 w/ 4000 stall -- Rearend 7.5 w/ Richmond 4.10's, Auburn Minispool
Best ET:11.60 @ 114.56, w/ a 7.34 1/8 @ 93.50, and a 1.622 60'


89 RS, L03 305, Hypertech Chip,cat delete, Dynomax exhaust,K&N open element Filter,160 stat, MSD coil --Trans:700R4 Corvette Servo -- Rearend: 7.5 GM 3.42 w/ posi-lock

Bassett Racing

 

Thanks, i guess its worth it would be worth it to go with the high performance heads then. I'm planning on buying these heads along with a holley 670TBI, vortec/edelbrock rpm manifold, LT4cam, and custom chip in the next couple of weeks. I won't have any valve to piston or cylinder clearance problems right?? Thanks a lot.

 

I have that combo with the 1.6 rockers and flat top pistons and it can make 300 to 330 hp in my opinion. Now if I can ever get this thing running right I will let you know.


Brian

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1989 Camaro RS

305 .030 over Hydro Pistons
Vortech heads milled to 58cc...Performer RPM intake....LT4 cam..Crane Gold rockers...FastChip custom chip...ALum. Driveshaft...3.73 gears with Posi...underdrive pullys...Rebuilt 700R4 with Vette Servo and B&M shift Kit...MSD ignition...A/C Delete No SMOG junk....1997 SS leather interior...B&M Shifter... Ultimate TBI mods...14X3 K&N open Element Non-Drop...Hooker headers....3" exhaust with Flowmaster Cross flow 16X8 Wheels from 97 RS Spohn LCA's Spohn Panhard Bar..LETS PLAY FORD!!

www.geocities.com/feltsb

 

I'm not sure what these guys are talking about but THE VALVE SPRINGS in the OEM VORTEC HEADS are good for .450" lift. Has nothing to do with the heads themselves. The heads are good for about .480" lift out of the box but good for much more with a little machining ang screw-in studs.

Call a reputable machine shop. They have been seeing these heads for years now...

 

Brian, I was planning on getting my custom chip from fastchip also. What kind of problems are you experiencing? I hope its not the chip.

 

Brian, a 300+hp 305cid with that cam???

Is that DYNOED 300+hp or SOTP???

[This message has been edited by FastBroker (edited July 09, 2001).]

 

What do you mean by that Fastbroker? You mean its too mellow to produce that kind of power? I think he is right with his estimate, after reading the old article that carcraft did when they got 325hp on a 305 using these vortec heads, but i don't know the specs of that cam. I'm assuming the cam must not have been more then .450" lift because they used the stock vortec heads.

 

How do you feel these estimates are not accurate. Car craft got 325hp with a flat tappet block and less cam and non roller rockers...... I have more lift ,full roller block and rockers better fuel curve.


I think i am close
Brian

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1989 Camaro RS

305 .030 over Hydro Pistons
Vortech heads milled to 58cc...Performer RPM intake....LT4 cam..Crane Gold rockers...FastChip custom chip...ALum. Driveshaft...3.73 gears with Posi...underdrive pullys...Rebuilt 700R4 with Vette Servo and B&M shift Kit...MSD ignition...A/C Delete No SMOG junk....1997 SS leather interior...B&M Shifter... Ultimate TBI mods...14X3 K&N open Element Non-Drop...Hooker headers....3" exhaust with Flowmaster Cross flow 16X8 Wheels from 97 RS Spohn LCA's Spohn Panhard Bar..LETS PLAY FORD!!

www.geocities.com/feltsb

 

Just wondered if you had it dynoed to verify... Chassis dyno is the best 35-50 bucks you'll spend and can shut people up quickly., myself included...

I thought the Car Craft engine had MUCH higher compresion and MUCH HIGHER .050" duration... I could be mistaken, that is for sure. And, that setup/LT4 cam in a 350cid with 9.0:1CR wouldn't make much more than 325-330hp, if that... Been there, done that. IMO the LT4 cam is rather mellow at 203/210deg at .050" even with the .476"/.480 lift...

I have to admit, though, that your combination makes for a great street driver/racer, for sure, and must run great...

[This message has been edited by FastBroker (edited July 10, 2001).]