Cam change?

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hotrod68

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I'm currently running a comp solid flat tappet in my 512, its a 12.0 to 1 eddy rpm headed (ported, flow 320's at .600) victor intake 1050 carb. Current cam specs are 264 intake and 270 exhaust @.50 .624 .616 lift 106 icl and 108 lsa. Looking at going to comp solid flat tappet "Because I have it new on the shelf" 290 intake 290 exhaust @.50 .650 lift intake and exhaust 108 icl and 108 lsa. I'm looking at changing to try and tame down the hit and get more mid range and top end charge out of it because it feels like it quits pulling at the end of the track. Any thoughts?
 
I've not had the priveledge of running that one myself, but I can tell you Herb McCandless claimed that cam will make more power than any other flat tappet cam at the time it was introduced. I guess more information is needed here, though. What gears and converter, transmission, and vehicle. Also, 400 or 440 block and what rod legnth?
 
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Garrett Ellison said:
I've not had the priveledge of running that one myself, but I can tell you Herb McCandless claimed that cam will make more power than any other flat tappet cam at the time it was introduced. I guess more infirmation is needed here, though. What gears and converter, transmission, and vehicle. Also, 400 or 440 block and what rod legnth?
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69 dart, 2855 race wieght, 400 based 512, 727 with 5500 convertor dana 60 with 4.10 gear
 
hotrod68 said:
I'm currently running a comp solid flat tappet in my 512, its a 12.0 to 1 eddy rpm headed (ported, flow 320's at .600) victor intake 1050 carb. Current cam specs are 264 intake and 270 exhaust @.50 .624 .616 lift 106 icl and 108 lsa. Looking at going to comp solid flat tappet "Because I have it new on the shelf" 290 intake 290 exhaust @.50 .650 lift intake and exhaust 108 icl and 108 lsa. I'm looking at changing to try and tame down the hit and get more mid range and top end charge out of it because it feels like it quits pulling at the end of the track. Any thoughts?
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Before you take the old one out, record it's icl and cranking compression. New cam should be an improvement because you still have a small head on big cid. Measure the p2v on the intake at 104 and the exhaust with the icl at 108. I'd probably put it around 105 to start. I'd be curious to know what the duration is at .200" What does it run now?
 
“1050 carb”
4150 or 4500?

If the cam fits…..try it.
That much duration uses up a lot of V/P clearance.

Are you running 1.5 or 1.6 rockers?
 
Why not tame the gearing? if the hit is to hard. 4:10 vs say 3:91 or 3:73. Wouldn’t that in fact decrease your low end and increase the top end. I guess this is where you have to choose your poison. Is it easier to swap cams than rear gear set? I don’t like the idea of opening up good running motors unless absolutely necessary. Maybe the cam is the easiest choice. A 400 stroker is always going to be a stump puller in the torque department. Which then leads to the idea of a gear change and perhaps a looser torque converter. Sorry I’m no help. I’m confusion my self over here. Haha.
 
Guessing it's a small tire car. How much rpm are you missing on the big end. Maybe retard the current cam a bit to knock down the hit and give a few rev's up top. Then again if you're cyl head limited, while that new cam may raise the peak power, i'm not sure you will gain much for average power thru a pass. If it's a bracket car and you are just looking for consistency them maybe a lower number gear change might be the answer.

P.S. I should say that my only experience with that large of a cam was hi 280ish in a 13-1 big port 3.76 stroke 427 Chebby with a 4spd and the shift points were in the 7800/8k range. Just a thought regarding the rpm's that might be needed with a [email protected] camshaft.
 
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I'm with PRH on this one. If you have enough piston to valve clearance, run it.
 
PRH said:
That’s what I was thinking when I asked.

I think any “suitable” spring will end up with open pressures that might be iffy.
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Right? But even the HS that were commonly used back in the day on that cam were close to 1.54RR (which yielded closer to 1.5 in NET) and they worked decent with the Isky 8005. But we all see the actual ratios vary significantly on different rockers. But all these reasons show the OP how this really isn't a no-brainer drop-in and go swap. With the small heads and big cam it'll still peak HP low, I'd guess around 6000 depending on the intake. So being it can 'trap' around 6500 it should be pretty stable IMO.
 
“If it were me”, I probably wouldn’t go thru the effort of swapping in that particular cam if I was planning on using 1.6 rockers.

I could see the merit in trying it with 1.5’s(because he has it), but don’t have high confidence in the results with 1.6’s.

If I was buying a cam, I’d be more inclined to run about 10* less than that 290 cam, and a lobe design intended for higher rocker ratios, so the spring situation was easier to deal with.

Be interesting to know the lobes used on the current cam, along with what springs are being used, and at what installed height……….as well as the brand of rocker.

I measured a set of HS 1.6’s on some SR heads……..1.67 with checking springs………and still 1.63 with 700lbs open force.
It’s always a good idea to know what you’re working with.
 
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hotrod68 said:
I'm currently running a comp solid flat tappet in my 512, its a 12.0 to 1 eddy rpm headed (ported, flow 320's at .600) victor intake 1050 carb. Current cam specs are 264 intake and 270 exhaust @.50 .624 .616 lift 106 icl and 108 lsa. Looking at going to comp solid flat tappet "Because I have it new on the shelf" 290 intake 290 exhaust @.50 .650 lift intake and exhaust 108 icl and 108 lsa. I'm looking at changing to try and tame down the hit and get more mid range and top end charge out of it because it feels like it quits pulling at the end of the track. Any thoughts?
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You didn't mention whether it's a 1/4 or 1/8 mile car. I would change tire size and rear gear before I would get into the engine unless you have valve spring or tuning issues. Show us your time slips and see if the car is really topped out before the finish line. Does the rpm quit climbing at a particular rpm and what is that rpm? IF so that could be a dozen different things.
 
A thought, is there a beehive type spring that will compliment that cam? I am thinking it may work well, but may like a looser converter?
on comparison, i went from a 590 flat tappet to a 286 @ 50, .750lift roller on a 535 with ported 906 heads many years ago. I went from 10.50s to 10.20s and gained over 4 mph.
 
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