Right now I'm running the HSR, Protopline 200cc Al. heads, and a cc 306 bumpstick. 230/244 @ .05 and .544/.576 w/ my 1.6 rockers on a 112 LSA.

Anyway, I've noticed some of my LT1 friends as well as some other people using high lift cams in their applications. I was curious to find out if there was any down side to having a cam w/ lift in the upper .600 and lower .700" range. Beside the obvious clearance issues w/ long dur. and high lift exhaust side. The reason I'm asking is the heads that I'm running flow pretty darn good at .600 and .700" lift as do a lot of other heads. But I'm not seeing any of those numbers due to my cam.

I understand that all clearances will need to be checked, not just piston to valve. Retainer to guid, rock to retainer, crank to cam, etc. I was just thinking about a custom grind and wanted some feed back. Right now the car is jetted for a 300 shot. If I can get it to make a good (safe) pass on it, then I'll bump it up to 400 or more depending on traction. So a cam suited more for n2o would be better in my case. Any suggestions or comments are appreciated. Thanks.

 

If your heads flow good at over 0.600" lift, by all means try to exploit it.

The one bad thing about having a really high lift is the lower float point of the valves (due to greater acceleration/deceleration), so you need to go with springs wiith more pressure. But going with more spring pressure can collapse hydraulic lifters - its a catch-22.

Is that a roller can you are running? You have to use a roller to get those big lift #'s.

 

Yes the current cam is a roller. I have seriously thought about switching to a solid roller. When the project began the car was going to see a lot more street time. Now it's pretty much just drive it to the track and back home again.

I asked comp about a hydr. roller and they gave me this grind 08-468-8 it has 292/300 advertised duration with 242/248 at .050. The lift of the cam is
547/542 and it has a 113 lobe separation. I figured a large n2p shot would req. more time to get out of the cylinder.

 

I would look into a solid roller setup. When you start getting into big numbers and big rpm, you are going to be looking at valve float with a hydraulic roller camshaft. Lots of lift also kills valvesprings.

A solid roller setup would be the way to go if you are looking for more than .600 lift. Here is a very short list of what you would need:

Solid Roller Camshaft
Solid Roller lifters, .300 tall for a late model hyd. roller block assuming that is what you have (Crane makes a nice set)
Billet Timing set
Reinforced Timing Chain Cover
Thrust bearing to prevent cam walk
Bronze Distributor Gear
Solid Roller Valvesprings
Lash caps and 10* locks/retainers
Good rocker arms if you dont already have them
A good pushrod (like the Comp Hi-tech)
1 piece valves (like the Manley Racemaster Series) to handle the spring pressure

That is the condensed version .

 

Why would I need another timing set? And a stronger cover?

I have a retainer plate now that cam w/ the block, why would the cam walk to begin w/?

And why the bronze distributor gear?

What defines valve springs as "solid roller"? I thought they just had open and close pressures, and you chose the correct one.

Why do I need 10* locks and retainers?

I'm running promagnums now, will they do?

 

You need a timing set with a billet gear more for insurance than anything else. A good friend of mine used one of the $40.00 Comp double roller timing sets when he put his solid roller motor together. Not sure if it is the spring pressure, rpm, harmonics or what, but it broke several teeth off the cast cam gear. I definitely wouldn't risk it.

The cam walks because with a roller setup because there is nothing to hold it in place like a flat tappet setup. I am not sure on your retainer plate, might be something to look into. The camshaft end play will be setup using your timing cover, so if the timing cover flexes (you can see where I am going with that).

You need to use a bronze distributor gear when you run a steel roller camshaft. Premature wear occurs if you dont.

You are right, there is no such thing as a "solid roller spring". But the springs that have the spring pressure required for even a mild .650 lift solid roller would damage a hydraulic roller or solid flat tappet lifter/camshaft.

10* locks and retainers are a good idea when you are running that much spring pressure to keep from dropping valves.

Also, lash caps would be a good idea too to prevent wear on the tops of the valves.

I would talk to comp about the pushrods, however I think you will be looking at upgrading. Comp has done a lot of research about pushrod harmonics, that information is available on their website.

I just did a solid roller conversion on my motor, this will give you an idea of what I spent:

Used Billet Roller Camshaft: $100 (ebay)
New Crane .300 tall Solid Roller Lifters: $322.00 (summit)
New Lunati Valve springs (215/550 open) $100.00 (summit)
Used Titanium 10* locks: $40 (ebay)
New Comp Hitech 10* locks and lash caps: $75.00
New Manley Racemaster 1 piece forged valves: $190.00
Comp Billet Timing Set: $100.00
Summit Cast Aluminum Cover: $50.00
Comp Hitech Pushrods: $125
Total: $1102.00

 

so it's possible to convert a non-roller block to use a roller cam?

 

Yes.