If considering Vortec heads...are the "906" heads OK? I came across someone today that has a pair they are willing to sell for about $200...

If so, and assuming I have to replace the valve springs, can I use the ones right off my 882s? Also might upgrade the rockers to 1.6... Thsi is assuming I don't do a cam swap...

as for the 276HR--that would most likely be my cam of choice, if I went that direction...I have the 282HR in my camaro's 406 that I built , and it is a fantastic cam...considering the 350 is a tad smaller, I imagine it would be perfect!

 

I will also say that this is absolutely the proverbial slippery slope...If I wer going to open her up for a cam replacement, I may as well do a total rebuild...

I have on the shelf a set of TRW forged flat tops (4 valve relief that are .030 over)...If i were going to tear it apart that much, I might just go the full monty!!

Was really trying to go on a budget--the HR cams are a tad expensive (almost $1K for the full kit--inc springs, etc)...
I don't trust any flat tappets anymore...Hate to go through a rebuild just to wipe out a lobe on initial startup...

 

I'm with you on the flat tappet cam issues. I recommend an inexpensive vortec head swap and the 906's will be fine but get the .015 steel shim head gaskets for even more compression. Get new springs if you do a roller swap and leave the vortec springs on if you are not doing a cam swap at this time.

 

weren't vortec heads set up for roller cams? won't the stock vortec spring pressures be too stiff for the flat tappet cam?

 

The spring pressure isn't that great on factory vortecs. You are just limited on the lift to around .475 or so without machine work on the heads. I have a set of 062 vortecs on my factory L-48 and I didn't change anything on the head and used it as it came from the factory. They were removed from a 98 Z-71. Those heads and a set of Hooker headers really improved the L-48.

 

A couple things to keep in mind when you are planning your rebuild and upgrade. First, the 906 Vortec heads, which are a great upgrade over the stock heads, are limited to about a .450 lift without machining down the valve guides, even then about .510 lift is near absolute maximum. Second, flat top pistons with Vortec's 64cc combustion chambers on a 350 will give you 10:1 compression with a standard .041" gasket. That is pretty high for an iron headed engine on pump gas. You can do that compression with aluminum. I would stick with stock dished pistons if you want to run these heads.

The factory camshaft specs on the L-48 were .398/.410 lift with 198/208 duration @.050. I forget the lobe separation angle, but it was probably 113-114*. To figure lift with 1.6 ratio rockers on any small block Chevy camshaft, just divide the valve lift specs by 1.5 to get lobe lift, then multiply by 1.6. The duration will only go up about 1-2*.

Do not reuse your 40 year old valve springs with any cam upgrade. They are not that expensive. Our H8002K heads have the valve springs that will work with cams up to .575" lift and you can definitely run 10:1 compression with them on 91 octane gas.

Good luck.

Scott Liggett
BluePrint Engines
1(800)483-4263
info@blueprintengines.com
www.blueprintengines.com

 

Scott-
I see you have the HP8102 coming soon for seven bills, that's a great price. In what application would you recommended those heads?

 

If you're looking to "wake up" an L48, or most any old school engine for that matter, re-curving the distributor is the best 20 bucks you'll ever spend.

Scott

 

No weight was pulled out of the car with the exception of a ac compressor which was dead. When I got the car it did a 15.4. Now, I do have drag radials on the car so it stuck really good. That 12.71 was a best but I have a ton of 12.8s and mid to high 12.7s. I used to run the car alot during the corvette challenge drag racing series at Etown.

 

It actually did make it quicker then my c5 but that,was when the c5 was bone stock. With mods in my signature for the c5 I got down to 12.2 but it should have done better if the car would have stuck at the starting line. I had like 5 year old rock hard drag radials at the time . But without going into the engine on a c5 ls1 you can get into the 11s....My c5 was tuned by me so a professional tuner can get more out of her I am sure...

 

Stock LS1 with a cam and heaers will not make 450lbs tq to the tire
It takes quite a bit to get them to 430 at the tire it will be finicky just like a Gen 1 would. Use a little less cam timing yes

They are good platforms but sometimes a little overrated
To get big power youll spend big $ getting there.
The stock LS1 heads are not impressive...LS6 arent bad
I would still stick with a Gen 1 platform there are 300cfm heads nice intake out there you can still make great power. Just put a bigger arm in it thats where the "thats it!" factor comes from when you step on a new build.
A stock stroke rebuild wiht fresh ring/valve seal and a cam sure feels alittle better but most times leaves you hoping it would make more power than it did. Always build bigger when you can.

 

To go with vortec heads and a cam kit you need a different intake, valve covers, Different springs, likely beehives to fit the pockets, right pressure and get the lift of a decent cam, retainers to fit the beehives and, buy the heads. The stock L48 actually calculates out under 8 to 1 so 64 CC vortecs would be lucky to go over 9 to 1. The Trickflow 175 CC heads with 56 CC chamber with the installed springs setup for the cam you choose is a cheaper, better flowing option that will bump you up to about 9.75 to 1. and make more power across the board.

EDIT: The 461 heads have no accessory holes for your front mount alt, AC, ect.

 

Out of all the options and opinions here, this one rings truest with me. Keep the originality, keep the essence, keep the soul... Just make it the best it can be while keeping it.