JimInMiami

Hi, I've been lurkin here since I bot my 1986 IROC-z in Oct 2017, tryin to get educated on restoration/modifications. Car is a true survivor with only 10,600 documented miles. It was a Texas car for most of its life and among other documentation PO provided annual inspection receipts attesting to mileage. Tho car body was sound, clear coat was flaking off all over, so I had the car repainted by a restoration shop in FT. Lauderdale. Here's a a short video of car after respray:
So far, I have made the following changes:
Brake calipers rebuilt, new rotors installed.
New Stereo head unit (Retrosound) and speakers.
Momo steering wheel.

It drives fine, but it needs more power. I want to keep the car as stock as possible and so will keep the 305 TPI that's in there, but give it some help breathing:
Vortec Heads
Headman Headers
Scoggin Dickey Intake
Low Restriction Catalyst
Flowmaster exhaust

QUESTION: what cam should I get for this combo?? The car has the stock auto tranny and is for cruising on the weekends, so drivability is a priority.

I appreciate pointing me in the right direction. Oh, please don't recommend a swap for a 350, for now I'm keeping the 305. I come from the world of vintage motorcycles and have to believe 5 liters can get the job done

Doomsayer88

I'm trying to do the same, any luck with choosing a cam?

skinny z

Get the compression ratio to where it's needed and a cam like Comps XR258HR or XR264HR will work well with the Vortecs. There are probably a hundred variations of the 305/Vortec combo but that should give you and idea. Keep in mind that the Vortecs in stock form have lift limitations.

JimInMiami

Thanks Skinny.
Doom, I reached out to Summit and they r steering me in a different direction:
1) COMP Cams Xtreme Fuel Injection Cam and Lifter Kits CL12-364-4
https://www.summitracing.com/parts/cca-cl12-364-4

2) BluePrint Engines Muscle Series Cylinder Heads H8002K
https://www.summitracing.com/parts/mll-h8002k

Though those heads r more expensive, they work with the stock intake manifold, making the overall price lower. And the BluePrint heads are better to boot. With the Vortecs you need to buy a new manifold and they sell em very dear...

nbressette

Wouldn't that larger combustion chamber (64cc) on the BP heads screw up your compression compared to say the 56cc heads from Trick flow? such as https://www.trickflow.com/parts/tfs-30310002

Orr89RocZ

iTrader: (20)

ShiftyCapone

iTrader: (7)

Agreed. Even if it didn't crash it would severely shroud airflow on one side of the valve.

JimInMiami

Orr, thanks for heads-up (pun intended), I checked the applications tab and the 305 motor is NOT listed. You would think the Summit tech would know better....

JimInMiami

@nbressette, thanks for the link, I'll check'em out.

Doomsayer88

I've researched it quite a bit and heard heard yes and no. Personally I think it would so I'm machining them down do 58cc. We'll see how it goes

skinny z

Machining heads from 64 cc chambers to 58 cc? Better check into that. At about .006" per cc, that's a lot of material. That's over 35 thousandths and will invite a few fitment issues. Intake manifold for one. A 26 thou pass on my 68cc heads was about the edge of what could be done without complimentary machine on the intake.
FWIW. A 305 with a 9:1 CR and a 58 cc combustion chamber will have a CR of about 8.4:1 with 64 cc's. That's not enough to be noticeable really (in a mild street build) but leaving the CR low (with an appropriately spec'd cam) leaves power on the table and can also reduces fuel economy with all else being equal and up to par. That is, a suitable ignition curve with all the timing the engine wants at WOT and cruise as well as good induction and exhaust.

JimInMiami

Digging around their site I came up with this one: Xtreme Energy™ XE249H; Hyd. Flat Tappet; '58-'98 Chevy Small Block

http://www.compperformancegroupstore...Category_Code=
Seems the lift numbers would work with the vortecs, is compatible with TPI and won't require aftermarket chips or programing.

Any comments on this choice would be greatly appreciated.

dmccain

iTrader: (2)

That cam isn't really much of an uprade. MAF cars can handle a lil more cam.

skinny z

Do you know exactly which engine is in the car now (engine code)? With a little effort the current CR can be worked out. Then you can math your way through to what the CR might be with the Vortecs. Cam selection follows.