i have 86 l89 that ive pulled down for rebuild.
im not looking for a race build,but slighty improved perfomance on a budget.
what is the stock compression for this motor?
what cam specs or cam would be a slight improvement over stock.
thanks steve

 

Keep in mind if you change the cam, you will need a tune for it to run and perform properly.

 

Lunati, comp etc make some 256-262 series cams that work well with stock motors driveablility wont suffer and youll get a nice torque increase

 

can some one direct me to stock cam specs for 1986 c4 350
thanks

 

are you running steel or alloy heads ?

 

steel heads

 

the stock cam for the early steel head engine was 202/206 duration, 403/415 lift, 114 lobe separation angle.
The stock compression ration is 8.5 : 1 (you will probably have the TRW forged flat top pistons if its a steel head engine)
The steel heads have big chambers in them (pretty sure its about 76 cc)

you can utilize the flat tops, (if the budget is tight) with a light hone and new rings ?
can you get some alloy heads from the late 86 engine onwards, they have 64cc heads and you will get 10:1 compression with the right thickness gasket.
as far as cam selection, cuisinartvette is right, the lunati voodoo cam is a good choice, dont go too crazy with too much duration.
A few moderate changes like this and the MAF engine will still run well without changing the computer chip.

 

The specs on my 85 stock was 9:1 c.r. with the 76cc "624" heads. Supposedly with forged pistons in 85. I'm assuming the iron headed 86's were the same, but not 100% sure.

I did a search in Google and found this:

1986 CORVETTE GENERAL INFO



Wheelbase: 96.2" Track: 59.6" Front / 60.4" Rear

Height: 46.7" Coupe

Length: 176.5" Width: 71"

Curb Weight: 3,239 lbs. Coupe

Tire Size: P255/70VR16

Base Engine:

(RPO L98) V-8, 90-degree Overhead valve
Block: Cast iron
Displacement: 350 cid (5.7 liters)
Bore & Stroke: 4.00" x 3.48"
Compression ratio: 9.0:1
Brake horsepower: 230 @ 4000
Torque: 330 lb-ft @ 3200
Main bearings: five
Valve lifters: hydraulic
Fuel supply: Tuned-port induction (TPI) system


Transmissions:

Automatic Transmission
* Four-speed Turbo Hydra-Matic (TMH 700-R4)
* floor-mounted gear shifter
* gear ratios:
* 1st = 3.06:1
* 2nd = 1.63:1
* 3rd = 1.00:1
* 4th = 0.70:1
* Rev = 2.29:1
* Diff ratio: 2.59:1 (RPO MXO) or 3.07:1 (RPO G92 or Z51)

Manual Transmission
* Four-speed manual with overdrive
* floor-mounted gear shifter
* gear ratios
* 1st = 2.88:1
* 2nd = 1.91:1
* 3rd = 1.33:1
* 4th = 1.00:1
* overdrive = 0.68:1
* Rev = 2.78:1
* Diff ratio: 3.07:1 (RPO MM4 or MM4/Z51)

Plant: Bowling Green

Introduced: October 3, 1985

Model-year production: 35,109. .

A 1986 Corvette convertible was the Official Pace Car for the 70th Indianapolis 500 race. The actual Indianapolis 500 Pace Car was Yellow, differing from showroom models only in its special track lights.

The 1986 Corvette convertible was the first factory convertible option since 1975 and all were designed as Pace Car Replicas. Special decals were packed in the car, but not installed. Instead of a conversion by an outside company, as had become the practice for most 1980s ragtops, Corvette's roadster was built by Chevrolet right alongside the coupe.

Chevrolet entered into a business relationship with Callaway Engineering to produce a 345hp twin-turbo Corvette at a cost of $51,000.

The ABS braking system became standard equipment with 1986 Corvettes based on a Bosch ABS II design.

50 Malcom Konner Commemorative Edition 1986 Corvettes were built in a special arrangement honoring the New Jersey Chevrolet dealership's founder Malcom Konner .

There were only 4 Copper Metallic colored Corvettes built and all were coupes.

Corvette's engine was the same 350-cid (5.7-liter) 230-hp tuned-port-injected V-8 as 1985, but with centrally-positioned copper-core spark plugs.

New aluminum cylinder heads had sintered metal valve seats and increased intake port flow, plus a higher (9.5:1) compression ratio. Aluminum cylinder heads were delayed half way through the model year due to cracking around the head attachment bosses which caused a redesign. As a result, all 1986 convertibles and late production coupes received the aluminum cylinder heads. The last 8,594 are believed to have received these heads. The aluminum cylinder heads resulted in an increase in horsepower to 235 hp; up 5hp from the previous model year.

The engine had an aluminum intake manifold with tuned runners, magnesium rocker covers and an outside-air inducútion system.

The new Vehicle Anti Theft System (VATS) debuted A small electrically-coded pellet was embedded in the ignition key, while a decoder was hidden in the car. When the key was placed in the ignition, its resistance code was "read." Unless that code was compatible, the starter relay wouldn't close and the Electronic Control Module wouldn't activate the fuel injectors.

A Center High Mounted Stop Lamp (CHMSL) above the rear hatch glass was added to comply with federal requirements.

Cast alloy wheel design changed slightly from the 1984-1985 model years. The wheel center section retained a natural finish vs. the black finish in 1984 and 1985.

Both four-plus-three manual and four-speed overdrive automatic transmissions were available, now with an upshift indicator light on the instrument cluster.

Three monolith catalytic converters in a new dual-exhaust system kept emissions down during warm up.

The instrument cluster was tilted to cut glare.

The sport seat from 1985 was made standard, with leather optional.

Electronic air conditioning, announced earlier, arrived as a late option. Otherwise, standard equipment was similar to 1985.

Corvette exterior colors (and code) were: Silver Metallic (13), Medium Gray Metallic (18), Medium Blue Metallic (20), Yellow (35), White (40), Black (41), Gold Metallic (53), Silver Beige Metallic (59), Copper Metallic (66), Medium Brown Metallic (69), Dark Red Metallic (74), Bright Red (81).

Two-tone combinations were: Silver and Gray (12/18), Gray and Black (18/41), White and Silver (40/13). Silver Beige and Medium Brown (59/69), Silver Beige and Black (Special Malcom Konner).

Upholstery colors: (cloth/leather & leather codes): Blue (21C, 212), Bronz (65C,652), Graphite (-,122), Green (12C,-), Medium Gray (15C, 152), Red (-,732), Saddle (62C,622) and White.