What Camshaft

[djfxall]

71 chevelle 3400 lbs guessing
355
9.5:1 compression
AFR 195cc street heads 2.05/1.60
Performer RPM air gap
650 or 750 cfm carb have both
700r4 2600 stall
2.73 but 3.73 or 3.90 going in the spring
26" tire

Can not afford a roller so solid flat tappet it will be
Lunati recommended
30120741 Voodoo series
2600-6800
276/282
241/249
.520/.540
110/106

Comp has 4/7 swap
12-664-47
2400-6800
282 / 290
244 / 252
.520/.540
110 / 106

I ran the comp non 4/7 swap same spec in desktop dyno 2003 did not do as well as Lunati's grinds

Open to suggestions will be ran on the street or I would have ran Lunati's oval tight lash 2
30121102 which kicked the most in dyno simulation but for the street not so much
2500-6500
272/280
243/251
.530/.543051
106/102

Open to opinions and suggestions

[Schwartz Performance]

What are you doing with the car? That duration is fairly high for a street car- I have a single pattern 244 @.050 in my 400 SBC with an 850 edelbrock and rpm air gap manifold, vortec heads. 110 LSA on it, idles great but isn't over the top. There are a lot of engine builds in magazines like Car Craft, you could do some searches on there for similar setups.

-Dale

[TheJDMan]

I'm running an Edelbrock 22015 retrofit roller in my 355 and I'm totally sold on it. Yes the roller is a bit more money but in the long run it is a much better alternative to a flat tappet given the fact that ZDDP has been removed from today's oils.

http://www.summitracing.com/parts/edl-22015/overview/

[Ron Sutton]

I'm running an Edelbrock 22015 retrofit roller in my 355 and I'm totally sold on it. Yes the roller is a bit more money but in the long run it is a much better alternative to a flat tappet given the fact that ZDDP has been removed from today's oils.

http://www.summitracing.com/parts/edl-22015/overview/

Agreed X2.



Hey John,

As an experienced engine developer, I suggest you do not base your decision of cam brand from simulation software. I use simulation software all the time & love it. It will show you factual trends, but can not account for lobe profiles in the real world.

I developed a 410" race engine a few years back where we did 5 days of dyno tested with:
5 cams (from 5 cam companies) in 3 different phasings each
12 rocker arm combinations
3 Intakes
2 carburetors
3 Headers

All 5 cams, from different manufacturers, had very similar specs but the power ranged 20Hp & 23 foot pounds of torque from worst to best. This is because of the different cam lobe shapes, which can be mapped on a cam doctor, but is not in the common specs we look at in catalogs.

I find Comp Cams lobes tends to get the valve & air moving quicker, with more lift & airflow under the lift curve than other cams. In all my years of racing & developing engines, Comp Cams has performed best 9 out of 10 times. When I don't have time or budget to "develop" an engine like we did this one, I simply go with a Comp Cam. When I do develop an engine like this, it gives me the opportunity to see if any cam companies have caught up to Comp ... and frankly to keep Comp honest ... and me unbiased.

That doesn't mean you won't be happy with another brand. Plus, I have not "developed" street engines in many years. My info is based purely off of building power. So fuel mileage, idle & drivability are not things I evaluate, but may be very important to you. I just didn't want you to take the software as gospel.

[cornfedbill]

It looks like you have a lot of converter stall for the basic engine combination. I have always been happiest with a bit milder cam to get the best throttle response and low end torque. I don't think that engine will like tight lobe centers. With the modest compression, I would lean towards something with 112 or 114 lobe centers.

Small block Chevys always seem to like split duration cams with a bit more on the exhaust than the intake.

With a '71 Chevelle, I would look a bit milder on the cam and a bit tighter on the converter so it pulls harder at the bottom end and you don't lose everything through the torque converter.

If you want to run more cam, you may want more compression. My guess it you will be happy with the heads, intake and carbs you have chosen. You will want to try both carbs to see which one gives the best performance. The 650 will probably breath well enough for this combination.

[djfxall]

I would go retro roller if my budget allowed right (2 year old son and family own my budget) now but as it stands the current cam in the block is a mystery hydraulic flat tappet. I am trying to squeze more power than have a enjoyable cruise around the town so to say. It's also why I run a full manual valve body on the street also. Why I chose the solid flat tappet ponies per dollar the way to go for me right now. I did graph up my desktop dyno results and I agree Ron that simulation is just that and understand also that running some these cams are far from ideal for a street cruiser that seconds I building to head to the track for track days. Watkins Glen and Lime Rock are pretty close. I know I could throw an effiect cam and gobs of power to 4500 then watch it fall on it's face after that no good to me. I will look at more of the comp grinds also they were my first choice ron the simulation data is what pushed me towards Lunati they seemed to do the best in the mid 2000- mid 6000 range.
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P.S. Ron look forward to your book

[djfxall]

How do guys feel the comp x-treme energy 12-677-4 wo understand be on the street 2000-6400 274 / 280 236/242 .501/.510 110/106 also a solid flat tappet