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Discussion Starter #1
Valvetrain aside, what do I need to do to safely spin to 7k RPM on a stock bottom end? Double roller timing chain or LS2 timing chain? What else? Thanks. :coo:
 

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Discussion Starter #3
jub jub said:
Reliably? I would say a balanced and blueprinted forged rotating assy.
Ok, how about "somewhat reliably"? :lol:

Seriously, I don't want to dump a ton of cash into this motor - I'd rather save it towards a C5R 427. The heads/cam setup I'm looking at is designed to spin up to 7500 so hoping I can go 7k without problems.
 

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dmtnt said:
Ok, how about "somewhat reliably"? :lol:

Seriously, I don't want to dump a ton of cash into this motor - I'd rather save it towards a C5R 427. The heads/cam setup I'm looking at is designed to spin up to 7500 so hoping I can go 7k without problems.
I'm not an expert but, from everything I've read you're biggest concern at 7000 rpm will be your valve train, valve float, P to V clearance, etc.. Keep it tight and you shouldn't have any problems. I wouldn't spin it faster than that.
 

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jub jub said:
I'm not an expert but, from everything I've read you're biggest concern at 7000 rpm will be your valve train, valve float, P to V clearance, etc.. Keep it tight and you shouldn't have any problems. I wouldn't spin it faster than that.

Along with that remember Subdriver's post about his timing chain problems. That to me would be my biggest concern. :cheers:


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You need to look no further than the specs for the new LS7. As a minimum on an LS6 I would replace the OEM main caps with KaTech Billet Main Caps and the rod bolts with KaTech or ARP rod bolts. And since the engine is apart I would Blueprint and Balance the engine.

I would also consider:
- A gun drilled and aero leading edge forged crank
- Katech, Oliver or Carillo Rods
- Forged Pistons from Ross, Weisco, JE etc.
- Porting, Polishing and reshimming the Oil Pump

However the major impediment to spinning 7,000 RPM is in the valve train.

There is a good article in the March 2005 Corvette Fever, pp. 54-61, "Valvetrain Variations" as a reference.

My recommendations at the very least would be:
- Double Roller Timing Chain OR
- Chevy HD Timing Chain, Part # 88958608 and Timing Chain Damper Part # 88958607 (This is a single roller but has thicker sideplates) OR
- You could also consider a Jesel Belt Drive

You should stregthen and lighten the valvetrain with stronger:
- Roller Tip Rocker Arms (Comp Cams Pro Magnum)
- Push Rods
- Rocker Studs
- Push Rod Guide Plates
- Dual Valve Springs, possibly larger dia.
- Titanium Retainers
- Hydraulic Roller Tappets

You should also consider installing shaft mount rocker arms either from Jesel (J2K), T&D or Comp Cams

Another area frequently overlooked is the OEM plastic Lifter Retainer Box. You should seriously consider a Billet REV Kit from ARE. You can also drill 1/2" holes in the lower face of the Lifter Retainers to provide better oil control.
 

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For 300 more rpms than stock just get a good set of springs, pushtubes and roller chain. You aren't building a 8000 rpm stock car engine.
The bottom end is ok as long as you aren't spraying or blown.
 

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LS1Tech and some post here talk about 7k. Valvetrain will be obvious. Springs with Ti retainers are probably a requirement.

How much spring depends on the rest of your valvetrain. An aggressive aftermarket cam, more substantial rockers, solid core stainless valves, larger valves, etc will all add to the spring requirement.

If pushrods bend then pushrod. Most people who have reported 7k have changed the pushrods with their cam swap.

Some people swear by the stock rockers. Some change them. Just note that the stock pieces are very light reducing valve spring load.

And the double roller chain.

Most people say the stock bottom end is good for 7k. No personal experience here. DJWorm's shopping list would be good above 7k. Many builders sell a prepared bottom end with stock crank, stock or low-end aftermarket rods, and aftermarket pistons. Stock main caps. Around $2500-3000 is I remember correctly.

Again, if you are going to run a 24 hour endurance race or extensive DEs your requirements are different than a street engine which sees 7000 once in a while for a brief moment.

David
 

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DJWorm,

Jesel has a belt drive for the LS1? Is it priced like their lifters or reasonably like their rockers?

Thanks,

David
 

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Discussion Starter #10
DavidNJ said:
Again, if you are going to run a 24 hour endurance race or extensive DEs your requirements are different than a street engine which sees 7000 once in a while for a brief moment.
Extensive DE's is my intent. I'm likely going to go with the GM Grand Am cam which is low lift, long duration, and the GMPP Lingenfelter CNC LS6 heads. That combo likes to spin up past 7k, but I don't want to sink a bunch of $$'s into this motor - would rather save for a 427.

It'd be nice not to have to shift into 5th before going into turn 17 at Sebring. :D
 

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AHH....Jesel does have an LS1/LS6 application but on further review I found that it is for dry sump systems and also drives the external oil pump. It's used on the C5R. I knew I had seen it some where.

The cover does not allow for a crankshaft snout mounted Gearotor pump as on the wet sump block. Sorry

BTW Cloyes or Rollmaster would be my choice of double roller chain/sprocket sets.
 

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DJWorm said:
AHH....Jesel does have an LS1/LS6 application but on further review I found that it is for dry sump systems and also drives the external oil pump. It's used on the C5R. I knew I had seen it some where.

The cover does not allow for a crankshaft snout mounted Gearotor pump as on the wet sump block. Sorry

BTW Cloyes or Rollmaster would be my choice of double roller chain/sprocket sets.
Although I haven't used them with a cam-in-block, I like the sport import style ones that allow you to adjust the cam timing with five bolts. I believe Crane sells one.

Ideally it would be coupled with a 9 slot lower gear to get into the ballpark, and both would be billet.

IMHO.

David
 

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To not spend much money, I would keep the revs lower. Revs make power, add to maintenance, and break things.

Just pick a cam that gives you a nice, fat 4000-6500 range, or 4500-6500 range. Wow, that sounds like a carb limited oval track engine!

For a carb-limit 350 SBC we would be looking at a 248/254 106/+4 solid flat tappet. Like a Comp Cams MH grind. Typlcially with 1.6 rockers.

I use a 248/256 107/+4 MA grind with 1.8/1.7 i/e rockers.

Either may be too long a duration for the street. And definitely too long for emissions.
 

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dmtnt said:
Extensive DE's is my intent. I'm likely going to go with the GM Grand Am cam which is low lift, long duration, and the GMPP Lingenfelter CNC LS6 heads. That combo likes to spin up past 7k, but I don't want to sink a bunch of $$'s into this motor - would rather save for a 427.

It'd be nice not to have to shift into 5th before going into turn 17 at Sebring. :D
That Grand Am cam is a bad mutha! Along with the LS6 CNC heads and LS6 springs you won't have a problem. That is exactly what that cam was intended for, high RPM and reliable operation using the stock valve train. The key is in the low lift, long duration.

Sounds like your planning on having some fun! :thumb:
 

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speedpup said:
What does LPE say?
They say get a smaller sig pic. 344k is way to big :yeadog:

(not to mention the 450x60 nazi's will get you too)
 

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Here's a comparison of the available Chevy Cams:

CAM Type / Part # /Dur. In-Ex deg. / " Lift In-Ex / Lobe Centerline deg.

'01 LS6 / 12560950 / 204 - 211 / .525 - .525 / 116
+'02 LS6 / 12565308 / 204 - 218 / .555 - .551 / 117.5

"HOT" / 12480033 / 219 - 228 / .525 - .525 / 112
"ASA" / 12480110 / 226 -236 / .525 - .525 / 110

LS2
LS7
 

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And the GM Grand Am cam

239/251, 0.570/0.570, @ 106

Designed to be used with the GM CNC LS6 heads and stock valve springs and retainers. Good for for about 450 rwhp and 400 torque.
 

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Discussion Starter #19
jub jub said:
Sounds like your planning on having some fun! :thumb:
:yeadog: That's the plan for this summer. Also adding LSX 90mm, Nick Williams 90mm TB, and an ASP pulley. :D

Oh, and a LOT of tuning.
 

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dmtnt said:
:yeadog: That's the plan for this summer. Also adding LSX 90mm, Nick Williams 90mm TB, and an ASP pulley. :D

Oh, and a LOT of tuning.
Because of the powerband of that cam I wonder if a MAFless tune would be the way to go?
 
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