i just bought an '86 IROC 305TPI.it has the centerbolt valve covers.but does it have a factory roller cam? i don't know too much abuot this generation of small blocks.

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82Z 305 w/comp 270 magnum cam,holly.TH700R4 w/B&M holeshot 2000 converter,& megashifter. 9bolt 3.27 w/1LE rear brakes 70mph@2200rpm ASE Master Tech plus L2
also recently obtained a
'69 chevelle SS396 w/Turbo 400,3.31 posi,11.0 to 1, headers,etc

 

I don't think so. The best way to tell is to pull a pushrod out. It will be shorter than a flat tappet cam pushrod.

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1986 CAMARO Z28 -> 151,000 original miles, 43,000 on 89' vette 350 block, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys, T5 with 3.35 1st gear, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, Spohn LCA's, Spohn adjustable panhard rod, Subframes connectors, polyurethane swaybar bushings/endlinks, 2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp. ET 13.22@ 106.4MPH Next mods-> Homemade ram air, B&M shifter, Extreme Energy 230/236 cam, Holley Street Dom intake.

 

Hmm, Im no history expert but Im pretty sure the 86 didnt have centerbolt covers. Sounds to me like some work has been done to the car so it will be hard to tell without digging in.

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Mark Lock
- 86 IROC-Z - Torn down for 383/SuperRam T56 setup
- -= IROC Online =- - The site dedicated to the IROC-Z

 

Mark is right. Centerbolt heads made their initial appearance in 1987.

The roller hydraulic block also was introduced in 1987. The only sure way to tell whether you have a roller block is to check the stampings on a flat section of the block hidden by the alternator. Post your stampings here and someone should be able to decipher it.

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Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
12.57 @ 111 mph.
12.04 @ 114 mph (50-hp nitrous).
http://members.optushome.com/au/downunder1/rides/willie/willie.html

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.