Vortec Cam Selection Assistance Needed [Archive] - Team Camaro Tech

: Vortec Cam Selection Assistance Needed


jsabowabo
Aug 18th, 06, 07:55 PM
Here's what I've got. 74 Chevy small block 350, freshly rebuilt, cam unknown (seller said it was a Crane Blue Racer RV grind, compression ration unknown. I just pulled the heads and found the pistons are slighly dished with valve reliefs. Here's a picture (I didn't check to make sure piston was at TDC):
http://img223.imageshack.us/img223/3764/pistonpics001mc5.jpg

I'm taking a wild stab here and saying the compression ratio was probably around 8:1 or 8.5:1 with the stock 882 heads (76cc chambers). With my Vortec heads and a .20 head gasket I should be at 9.5:1 or 10:1. My car is a 69 Camaro with a 700R4 (Stock converter) and 3.55 gears (Ford 9"). I'm looking for somthing to get me to about 400hp, nice lope and still work with my stock converter. This is not a daily driver, but a weekend cruising car. I'd like to go with the bigger cam, but I don't want somthing that is going cause me to change out my converter.

Here are my options (I'm on a very tight budget).

Summit K1103 214/224 @.50 .442/.465 112 LSA
Summit K1105 224/234 @.50 .465/.488 114 LSA

http://store.summitracing.com/partdetail.asp?part=SUM%2DK1103&N=700+115&autoview=sku
K1105
http://store.summitracing.com/partdetail.asp?part=SUM%2DK1105&N=700+115&autoview=sku

Thanks in advance.

travis
Aug 19th, 06, 01:56 AM
Lopey idle plus a stock convertor is a bad combination, for driveability and performance. Neither cam you listed has a very rough idle. The 2nd cam (the 224/234 summit grind) will make right about 400 "magazine" horsepower with a performer rpm type intake and a 650-750 cfm carb and headers. There was an article in a chevy rumble mag a year or 2 ago exactly as you have outlined. You'll be able to hear the cam, but I would consider it more of a "healthy" sound than "lopey". A 2500 rpm stall convertor, if it is a decent quality unit, will not hurt driveability one bit and will greatly help performance.

jsabowabo
Aug 19th, 06, 08:01 PM
travis, thank for the input.

Do any of you guys know if this is a stock type piston? Any ideas on how many cc's of volume this piston has with the dish and valve reliefs? I'm trying to deduce the compression ratio of my engine, but being it's an obscure 1974 short block I'm having issues, and I'm lazy and haven't gotten off my butt to measure the piston to deck height yet.

Larger Dave
Aug 19th, 06, 09:06 PM
Look like stone stock standard bore cast pistons to me. I would go with your smaller cam (Summit K1103 214/224 @.50 .442/.465 112 LSA) because the tighter LSA will give more cam sound at idle without killing driveability. If you can find a converter out of a Corvette they are good for 1800 RPM (or about 400 to 600 RPM more than a stock converter). They are still sold over the counter as a stock replacement part and will not have any of the goodies such as bearings instead of bushings, etc.; but it is a little bit looser than the grocery getter or Pick-up converter.

Joe Harrison
Aug 20th, 06, 08:53 AM
I say go with the GM cam ground for Vortecs. I put a link in your other posts. Look at this article from GM. I am thinking the crate engine has dished pistons also so your most you may end up with 9:1 as with the crate engine. http://www.sallee-chevrolet.com/frame.html?/Cylinder_Heads/Vortec.html

Cam specs:
24502476 Hydraulic Flat Tappet (300 HP 350 HO Camshaft)

This hydraulic flat tappet is used on the 350-300 and 330 HP special performance engine P/N 12355345, and 12486014. The duration at lash point in degrees (intake/exhaust) is 320/324; duration at .050” tappet lift (intake/exhaust) is 212/222 and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 435/460. Valve lash is zero/zero and lobe centerline is 112.5 degrees.

GM says it will do what your looking for and it's specificly ground by GM for the vortec heads. Call the parts department ask for a crate engine take out they sell them for around $40.00 (salle Cev is Now Gilbert Chev, I just saw this)

From GM about the engine and how it sounds:
Add to the strong foundation a pair of 64cc Vortec cast iron cylinder heads and a dual pattern camshaft with just a bit of a “lumpy” idle, and you've got the muscle car small block that you've been looking for.

The cylinder heads on this great little performer use 1.94” intake and 1.50” exhaust valves that are sprung with 1999 L31 valve springs. The 64cc chambers yield a healthy, but streetable 9.1 to 1 compression ratio.

The cam is a modern dual pattern interpretation of the old 1965 to 1967 Corvette 327 cam. But with more lift and duration on the exhaust side, it does a better job of clearing exhaust from the combustion chamber. We also decreased duration and lift ever so slightly on the intake side to build more cylinder pressure. The result is a cam that makes great torque and horsepower with the 350 HO’s 9.1 to 1 compression ratio.

I think the general has put it all togehter. It might not have the numbers your looking for at 400HP but I do think it has everything else you want and does have great torque. Any artical I have ever read in the magazines find it very hard to improve on this cam. It also has a torque curve that is very steady and I think will work very well with your overdrive trans and will be friendly at the pump also. I have this set up in my 327 but have not run it yet. I have seen the crate engine run at the drags and heard one though and it sounds just awsome. From what you desribe your looking for basicly the same thing I was. I hope I found it, from what I have seen and heard I think I did.

Joe

jsabowabo
Aug 21st, 06, 06:00 PM
I ended up going with the 224/234 cam. I'm afraid I'm going to wish I went with a bigger cam if I don't. Being it's just a weekend car, I think I'll be able to live just fine with the bigger cam, especially on a 114 LSA.

pdq67
Aug 22nd, 06, 05:18 PM
I think you are too big b/c a Goodwrench motor is like 8 to 1 even if they say 8.5 to 1!

I'd be hard-pressed to run a good old CC 268HE at this low a CR. Much better their CC 260HE........

As always, jmho..

pdq67

jsabowabo
Aug 23rd, 06, 11:04 AM
With my Vortec heads and .020 head gasket my compression ratio will be right at 9.3 to 9.4:1, which is fine for this cam. I agree 8:1 or 8.5:1 is no good. Hopefully my stock stall converter will be fine in the ol' 700R4.

pdq67
Aug 23rd, 06, 05:19 PM
Ooop's, forgot your 62 to 64 cc Vortec heads..

My bad.......

pdq67

Dave69Z
Aug 24th, 06, 06:37 PM
Just to add another option to your choice, Sallee chevrolet changes the cam in the 350/330 ho motor to the comp cams xe268 to get a 375 horse motor. I run a lunati voodoo 268 in my 350/330 ho motor. Te stock cam mentioneed in an earlier post made 291 rear wheel horse power. I change to the lunati cam and it actually widened the power band and the car has run a best of 13.06 with 4.10 gears and runs around town fine. Good luck with your cam choice.

VI009DZ
Nov 27th, 06, 06:49 AM
Sorry to dig up an old thread here, but I'm in the same situation; basically the exact same shortblock to start with and a pair of stocl 062 casting '98 Vortec heads.

My '69 is a 4-speed, and I'd like a VERY lumpy idle. I do not plan on adding the LS1 beehive springs to these heads, I just want to add a cam and lifter set. Will restricting the lift to ~.450" really hurt me? Has anyone else put this same formula together? What will I need for pushrods?

travis
Nov 27th, 06, 08:37 AM
The stock vortec springs are weak...they only have like 80#'s of seat pressure. They will work ok with the old style performance cams like the 350hp 327 grind or anything else that has very gentle ramps on it. The LT-4 spring and retainer upgrade is a drop in deal and would be very worthwhile if you would like for the valvetrain to stay together above 4K rpms.
Isky (and others) make some long duration, lift rule hydraulic cams with tight lsa's that would shake the fenders right off the car at idle. Streetability will suffer though.

VI009DZ
Nov 27th, 06, 08:44 AM
I've read of LS1 beehive springs, but nothing with the LT4. Is it the same list of part numbers?

-Valvespring
Comp Cams 26915 / 26918 (difference between the two??)

-Retainer
Comp Cams 774

-Keepers, 7-degree
Comp Cams 648-16

travis
Nov 27th, 06, 12:57 PM
No...its all GM factory parts. I don't have the part numbers handy here at work but it is a set of LT-4 springs and lightweight retainers...for a lot less $$$'s than the behive stuff, and it is a drop in deal. Check out scroggins-dickey or pace chevrolet...they will have them.

67 Plum
Nov 27th, 06, 02:32 PM
Put a crane 274HO6 cam in it .450 lift 218 at .050 on a 106LSA.Great sounding idle works well with stock springs and rockers.Jegs #270-100172 cam and lifters $119.99.

Dirt Reynolds
Nov 27th, 06, 06:46 PM
Just to add another option to your choice, Sallee chevrolet changes the cam in the 350/330 ho motor to the comp cams xe268 to get a 375 horse motor. I run a lunati voodoo 268 in my 350/330 ho motor. Te stock cam mentioneed in an earlier post made 291 rear wheel horse power. I change to the lunati cam and it actually widened the power band and the car has run a best of 13.06 with 4.10 gears and runs around town fine. Good luck with your cam choice.

One of the magazines awhile back did a dyno test on the 330HP 350. What they found was going from an 1850 (600cfm vac secondary) Holley to a 3310 (750 cfm vac secondary) Holley picked the engine up all the way to 370HP. They then installed the XE268 and picked up 7 HP to 377 HP. The stock GM cam seems to work very well in this engine.

Dave69Z
Nov 28th, 06, 07:55 AM
I used the crane 10309-01? springs for the iron lt-1 caprice engines. They are expensive but worked perfectly withthe new locks in the kit. Some people have just ground down the retainers to get some extra clearance. I also switched to the lunati voodoo 268 cam and it is a good combo.

VI009DZ
Dec 4th, 06, 06:48 AM
Put a crane 274HO6 cam in it .450 lift 218 at .050 on a 106LSA.Great sounding idle works well with stock springs and rockers.Jegs #270-100172 cam and lifters $119.99.

Plum....lemme just get this 100% straight. You're running a cam with .450" valve lift on completely stock heads and valvetrain with no issues? I did buy the Crane 100172 cam and lifter set (see below link) with the same .450/.450 lift. Just making sure this is going to be fine; I've seen advertised .420 lift with .030 retainer clearance on stock Vortecs, so .450" is pushing it, I know.

http://www.cranecams.com/index.php?show=browseParts&action=partSpec&partNumber=100172&lvl=2&prt=5

Dave69Z
Dec 4th, 06, 11:00 AM
The real problem is retainer to seal clearance. make sure the seals are driven on all the way some of mine wern't but I changed to the crane 10309-1 springs that allow for .550 lift. my 350/330 ho motor came stock with .435/.460 lift. You can always grind a little off the bottom of the retainers, if need be.

Joe Harrison
Dec 4th, 06, 08:10 PM
Plum....lemme just get this 100% straight. You're running a cam with .450" valve lift on completely stock heads and valvetrain with no issues? I did buy the Crane 100172 cam and lifter set (see below link) with the same .450/.450 lift. Just making sure this is going to be fine; I've seen advertised .420 lift with .030 retainer clearance on stock Vortecs, so .450" is pushing it, I know.

http://www.cranecams.com/index.php?show=browseParts&action=partSpec&partNumber=100172&lvl=2&prt=5

Stock cam specs GM uses with the 330HP engine:
This hydraulic flat tappet is used on the 350-300 and 330 HP special performance engine P/N 12355345, and 12486014. The duration at lash point in degrees (intake/exhaust) is 320/324; duration at .050” tappet lift (intake/exhaust) is 212/222 and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 435/460. Valve lash is zero/zero and lobe centerline is 112.5 degrees.

So .450 should not be a problem.

Joe

VI009DZ
Dec 5th, 06, 05:03 AM
Great...thanks for the information Joe.

VI009DZ
Dec 15th, 06, 05:22 AM
http://img223.imageshack.us/img223/3764/pistonpics001mc5.jpg

For calculating compression ratio....does anyone know what the dished volume of these pistons are?

pdq67
Dec 15th, 06, 04:17 PM
Isn't it a -15 cc's?? Or a -12??

pdq67

FRANK ESKRA
Dec 16th, 06, 11:20 PM
I dont know why anyone would use a camshaft out of a catalog. You can call a cam grinder and have one ground for your application at no extra cost. Granted a catalog cam may be close for your application and close is not good enough for optimum.... Air in and Air out makes a big difference on a 8-cyl. air pump!

wiskeesour
Dec 16th, 06, 11:33 PM
For calculating compression ratio....does anyone know what the dished volume of these pistons are?

looking at those pistons, I will guess they are -18cc 4valve relief standard chevy pistons...

Joe Harrison
Dec 17th, 06, 02:37 PM
I dont know why anyone would use a camshaft out of a catalog. You can call a cam grinder and have one ground for your application at no extra cost. Granted a catalog cam may be close for your application and close is not good enough for optimum.... Air in and Air out makes a big difference on a 8-cyl. air pump!

Because most people would not know what to pick or how to spec it out. I myself like the GM Cams, some engineers spent alot of time and company money making something work. It might not be optimum, but I am not looking for the last 10th of sec or .5 MPH, just decent performance and some fun.

Joe

67 Plum
Dec 17th, 06, 02:49 PM
Need to check it but MOST stock Vortec heads can accept .480 lift at the valve.