So due to time and budget constraints I'm building the L03 305 up a little bit. My buddy has a new cam that i can have for free so it will help me alot if it will work. The cam is a comp 280h magnum single pattern 230 duration, .480 lift and 110 lobe seperation. I know i already have a roller setup but free is free and i have the flat tappet lifters and pushrods already. My question is will this be too much cam for a 305? It will be the stock bottom end, mildly ported 187 heads, edelbrock 650 cfm carb, edelbrock performer rpm intake, msd ready to run pro billet distributor, headers and true dual exhaust. My main concern would be that they say the compression ratio is an optimistic 9.3-1, i have the 308 gears right now which are being swapped for 342s shortly. Please help i miss my car and need to get it back together!

 

WAAAAAAAAAAAY too much cam.

Like so much cam you'll go SLOWER than a stock L03.

An otherwise stock 305 will choke that cam and run like crap.

I have a 231/239 in my GTA, you can listen to the clips from the sig links.

 

Thanks for the input. What would you recommend. I want to go as big as possible without losing performance

 

Its so hard to recommend a cam to people unless its way out there. Not only is there the parts involved, but what is acceptable to you the owner.

But for what you describing having, I don't think you should really go beyond the durations found in stock LT1 and L98 cams. Stay under 210° intake duration at .050 with a small LSA. You will need a split duration cam. Probably 10° or so more exhaust duration than intake because your heads have poor exhaust flow.

But more than that. In a another thread you may find people who disagree and say that 210° is too small. It really all depends on what you want, and what you are willing to sacrifice.

 

204/214 @.050" with a 112 lsa. Something like one of the elgin cam kits for $80

 

Summit K1102, 1103 at the most.

 

Thanks guys. Id be willing to sacrifice some at the bottom end to get more mid and top end if that helps. Also the cars a 5 speed. What kind of performance gains could i expect going with something like the lt1 or l98 cam?

 

That depends on how good of job on the head porting because stock these heads really hurt the cars performance. I wouldn't expect more than 200-220 HP. Stock LB9 range maybe. But again a lot of it depends on the heads.

 

This would be one of those perfect examples to run through my software. If you have port flows for the heads and the rest of the normal engine parameters. I'll run your numbers and post the results. message me or post them.

 

Rick I can get those numbers for you.

I really like the Elgin 210/215 @ .050 roller can in a stock internal L03. It is 210/215 @ .050, .462/.470" lift, 110° LSA on a 106° ICL.

 

^^^^LMAO.....I love the false information kicked out on these heads practically everywhere. Stock swirl port 305 heads EASILY support 250-275 hp at the crank when cammed correctly. It is the stock cam and exhaust that is the major strangle hold.

 

Post the bore, stroke, rod length, compression, valve diameters, port flows at .400" and .500" lift, bench pressure (in/h2o), rocker ratios, hydr or mech cam, lash if mech, and the RPM you want maximum horsepower to occur (Max-HP RPM).

 

3.735 bore
3.48 stroke
5.7" rod
9.3:1 c/r
1.84" intake
1.5" exhaust

28 in/h20
Intake @ .400" 158 cfm
Intake @ .500" 165 cfm

Exhaust @ .400" 133 cfm
Exhaust @ .500" 140 cfm

1.5:1 rocker ratio

Hydraulic Roller cam (Zero lash)

Stock drivetrain and short block would want the peak power between 4,500 and 5,000 rpm with shift points about 10% over

Edit- I have always felt people use the wrong cam with these heads and then wonder why they don't run well with a huge intake/exhaust duration, massive duration and lift split on a wider LSA. I feel these heads run best with a mild duration/lift bump, nearly square pattern grind, tighter LSAs and advanced valve timing. In a carbureted 10.4:1 350 application I actually ran a 282/282 @ .004, 224/224 @ .050, .480/.480" lift, 106* LSA, 102* ICL cam and it was a torque making monster.

 

That is enough information to determine the cam. Good thing you didn't want to turn it with those ports.

 

I took a little liberty with the RPM

 

Can you run a few more???

With the 305 use a pair of TPI heads.

Intake @ .400 182
Intake @ .500 195
Exhaust @ .400 107
Exhaust @ .500 110

Also same setup as above except a 350 with a 4.00" bore, 1.94" intake valve, with a hydraulic flat tappet cam (truck) and roller cam (car)

193 TBI head
Intake @ .400 172
Intake @ .500 178

Exhaust @ .400 140
Exhaust @ .500 146

Not that I think it will make much difference, but these engines have a 9.025" deck height, .028" compressed head gasket, and 12cc dished pistons. 305 uses a 56-58cc head and the 350 head comes in at 65cc.

 

These engines are more GRUNT engines than anything and for good reason. With the ~26" tall tires and 2.73 rear axle gears of the automatic cars they are moving ~45 mph in 1st shifting at ~5,200 and 90 mph shifting out of 2nd. The factory torque converter stalls in the 1,400-1,600 rpm range as well.

 

Only one.

 

Lets do the 350 with a hydraulic roller cam. It is the common engine to run after swapping out the L03.