Hi,

Getting ready to build the motor for my 91 rs. Been out of Sm Blk Chevys for a little while and need some advice. I have a set of 882 heads and possibly a set of vortec heads and intake. The 882's I believe have a 155 cc intake runner and the Vortecs have 175cc. Valves in both heads are 1.94/?. The 882's have 72 cc chambers and vortecs have a 64cc chamber. I understand that the vortecs flow great, but for my motor which will only see 5500 rpm, and have a cam in the 216 dur range, **will I notice a difference. ** I need to know this so I can order pistons with the correct compression ratio for my combo.
Is the power gain from vortecs across the entire rpm band?
Thanks!

 

The Vortec heads, far and away, are the better heads... they will give you more power, better gas mileage, and better driveability.

There are only two downfalls of the Vortec heads... in stock form, they can't handle much cam (only about .480" lift or so) but any machine shop should be able to fix that fairly easily if you need it. The other, is that they require a unique intake manifold that normal SBC heads won't need/use.

The 882 heads are terrible... they are low compression smog heads, they flow very poorly, often have small valves, and they are thin "light weight" casting heads... and that makes them VERY prone to cracking.

 

Well, sounds like a vote for the vortecs!
thanks

 

Make it 2 votes for the vortecs,especially since you already have access to the matching intake.

I personally would pick the vortecs over any stock type production SB head for a daily driven performance combination.

 

The vortecs are worth minimum 78HP and 64ft/lbs torque over the whole usable rpm band ( not just peak power) over 882's Direct swap real dyno test comparision. My 350 In my Fbird gained 1 sec ET and 4 MPH just by switching from 882's to vortec heads. Well worth it.
You will notice the difference. My cam was only 214-224 @.050. same as in the dyno test.

Car ran 13.0@104.5 not bad for a daily driver with good fuel mileage.
I have since changed to a 406 with ported vortecs. very nice...

 

here's a pic. Need I say more

 

COOL!

I'll stop worrying over it now for sure. Mine will be street driven and hopefully get decent mileage.

 

Well, the one advantage of the 882's is they are commonly available at your local marine supply. Look in the "anchor" section.

 

 

whats your setup?

 

Which one
The 350 or the 406?

 

the 350 please seein how mine compares

 

350+.060 with FM h345np pistons
stock cast crank
block was decked ( pistons .015 in the hole)
Crane blue racer 214-224-112-.442-.465 cam
Vortec heads 1.94 x1.50" valves with screwin studs, high perf springs guide bosses milled and mild polishing on the exhaust ports.
Edelbrock performer RPM (vortec)
Holley List#3255-1 735cfm vac sec carb (old 60's OEM Ford HiPerf 427cid carb) or Edelbrock performer 750
10.03:1 compression ratio
long tube 1-5/8" headers, custom 2.5" dual exhaust No cats
FM carter mechanical fuel pump
GM HEI vac adv distributor stock module with MSD coil, MSD wires 36deg timing.

Th350 with 3500stall 4.10 gearing
(ran 13.4 with a tired th700r4 and 2200stall)
Mickey Thompson Et streets

The compression ratio was actually higher with the 882's installed 10.3:1 as they were shaved to 69cc and used .015" shim gaskets
Sunoco 94 Ultra gasoline

ran consistant 13.00's @103-104.5mph jetting and timing changes didn't seeem to affect the performance any.
Starting line traction had more to do with ET's than jetting. ran just as good with a stock plain vac sec spring as the light yellow one. (no change) Any where from 32 to 36deg advance ran the same.

The old OEM Holley carb is a little more refined than the typical #3310 750 vac sec. (downleg boosters, special fuel distribution tabs in the venturi for dual plane manifolds, more refined metering block tune.) {I had a 3310 before}.
This is a more refined carb overall. {I've had it a long time and used it on many cars over the years}
On another car I compared it ( the 735vs ) to a 750DP holley 4779. It performed the same but feels smoother.
The Edelbrock 750 carb actually made the best MPH by a bit.
The ET's are pretty much a toss up between the two carbs.
The Edelbrock is good carb.
Even with the 4.10's the fuel mileage was very reasonable.

LCA relocation brackets are on the wish list for next spring.

 

Can somebody tell me what the best size cam would be to run with stock vortec heads?

 

A "stock" GM vortec head as assembled by GM has a physical valve lift limit of .450"-.480" The valve guide tops need to be machined shorter to allow more lift clearance or damage will result.

The next issue is the stock valve springs. good to about 5000rpm. If that is all the rpm you want they are fine to .500" lift.

New high(er) pressure springs require spring seat machining as the bottom of the guide boss/inner spring seat is a odd diameter resulting in spring binding interferience on most replacement springs.

Both these machining operation can be handled by a automotive machine shop for reasonable cost.

then you want to select a cam that has the right amount of valve open duration and overlap.
The cam I used works very well in near stock motors for daily driven performance. 375hp 400+ftlbs torque, 13.0ets on the street with good mileage is not too shabby.
this cam will run with the stock springs.just check the guide to retainer clearance at full valve lift. (.465"+.050" minimum.

If you just got to run it with the stock guides height limitiation then,, ISKY Cams has a whole series of .450" lift cams with various durations and rpm ranges to suite any street combination. Isky cams work very well.
Need more specific information on your car/ engine plans and parts to recommend a specific grind.

 

Check out the baddest unported Vortec head motor car in my area...

http://www.davemilcarek.com/112605/p...6-R1%20007.htm

11.60's N/A in a 3600lb car on drag radials... Built on all junky parts. 400, unported Vortecs, XS282, 3.42 gears, 110% street car driven 50 miles one way to the track

 

Very nice.. the XS282 was on my short list for the 400, but went with the hydraulic version.(XE284H) if its not up to the task then the XS282 is going in.