10k in pocket. New block or EFI ?

[fkemmerer]

Originally Posted by FUNFER2

What were the specs. on the three cams ?

482 ci FE with TWM injection:

Intake Exhaust
Gross Valve Lift 0.645 in 0.635 in
Advertised Duration 304 315
Duration @ 0.050 in Lift 242 248
Lobe Separation 112


383 ci Blown and Injected SBC:

288/294 adv. duration and .520/.540 lift, LSA 110 degrees
duration at 0.50" - 236/242

I don't have the specs handy on the first motor (it was a 355 ci blown SBC) but I'd say it was similar to the previous motor with a little less lift.

The first 2 motors both make over 600 HP and 600 ft-lbs on pump gas. Both are very streetable. You can check out the dyno runs (torque and HP curves) on our website at:

http://www.anitafred.net/HotRod.htm

Note the wider LSA on the TWM injected motor. This is I am sure, in part, to limit overlap at low RPM to keep intake reversion under control. This would likely be a big problem on the large FE with its big valves, short intake runners, and big TWM stacks.

Again, its subtle stuff like this which makes it difficult for the average guy to "pick their own CAM" and really get the best possible performance. If you want to get some idea of what is involved in really doing CAM selection correctly, check out the following book (its excellent):

How to Build and Modify Chevrolet Small-Block V-8 Camshafts and Valves
by David Vizard

I hope that this helps you.

- Fred

[FUNFER2]

Hey Fred, those look like good numbers for the hyd. cams.

I know quite a bit about motors and cams so, it's just deciding on the type. I like rollers and Keith said the one's he uses, with oil holes drilled in the bottoms, have lasted around 20,000 miles, which is a lot for our cobras.
We lash the valves on the sprint car every week but, having to lash the cobra all the time,....I don't know. I guess I'll ask you guys and Keith apx,...how often, if driven weekly.

I check my solid flat tappet twice per season.

[fkemmerer]

Originally Posted by FUNFER2

Hey Fred, those look like good numbers for the hyd. cams.

I know quite a bit about motors and cams so, it's just deciding on the type. I like rollers and Keith said the one's he uses, with oil holes drilled in the bottoms, have lasted around 20,000 miles, which is a lot for our cobras.
We lash the valves on the sprint car every week but, having to lash the cobra all the time,....I don't know. I guess I'll ask you guys and Keith apx,...how often, if driven weekly.

I check my solid flat tappet twice per season.

Hi Kevin,

It was nice talking with you today! For the benefit of others on the forum, let me share some of what we talked about on the issue of a hydraulic roller vs a solid roller cam. The big difference between a hydraulic roller vs a solid roller CAM setup has to do with valve train strength, weight, and therefore how agressive you can get with the lobe profile (ie how fast the CAM can open an close the valves). The lighter valve train weight of a solid roller (the lifters are lighter) also allows the engine using one to rev to higher RPMs. There are lots of good reasons to run a solid roller CAM in a race applications (sprint cars, drags, etc) where high RPM HP is very important. On the street where lower end torque is usually more important the advatages are less. Consider this. To get the lifter to stay on a very radical lobe that most solid roller CAMs use to gain their performance advantage, you need to use VERY stiff springs and make all of the other valvetrain components as light as possible. Its not uncommon to see springs that increase seat pressure substainly and the use of exotic components like titanium valves and retainers in such engines for example. All of this works great in a race motor but you would have a hard time making such a setup last on the street. What did the CAM manufactures do to address the street guys who want to say they've running a "solid roller" cam? They created a less radical set of lobe profiles that don't require all of the exotic valvetrain components. These CAMs do produce some more lift and may rev a little higher than the hydraulic roller alternatives but the gains are much less pronounced than a race solid roller setup. In a street appplication that is operated below 3000 RPM and maybe buzzed to 5500 RPM once in awhile, I'm not sure that the performance gains would be great enough to justify the added expense and maintenance. I would build the motor with an aluminum flywheel instead and spend the difference somewhere else. This will get you a good bit of the fast reving performance that you are looking for and should be OK in a lightweight car like a cobra. Hope this helps.

- Fred