pete86iroc

this is from the tech section on this site..

The original 215hp 305 TPI motor came out in 1985 available both in the Z28 and IROC-Z. The motor was detuned for 1986 losing 25hp due to a cam change.

so, if i got a new cam , i could gain back that 25 hp lost? from the cam change, i don't know much about cams, what kind would i need?

Jim85IROC

iTrader: (2)

You could, or you could get a better aftermarket cam and make even more horsepower. Either would require a PROM reprogramming to take full advantage of the new bumpstick, however.

tpi_roc

To much cam could put you worse off than you were when you started, keep that in mind.

Jim85IROC

iTrader: (2)

Very true, and it's always safe to err on the side of not enough cam, but there's still a good bit of room to improve on the factory cam. Summit sells a cam that claims a 40hp gain on a stock 86, although I don't have any actual experience with it, so I hate to actually recommend it.

tpi_roc

60hp gain on a stock engine with just a cam kinda makes me want to go out and wash your sasquach

Morley

The specs on that cam are the same as the '85 factory TPI cam, so 40 is stretching it a tad.

~M~

pete86iroc

so if i looked into this cam i'd be safe to say i could gain that 20-25 hp?, which cam was this if someone could post the link

thanks

Morley

Summit sells the cam kit...but it is back ordered for who knows how long.

Jim85IROC

iTrader: (2)

I didn't know that. I had no idea it was the same as a stock 85/L98 cam. I still think that you can easily get away with a little bigger cam than the 85 piece, especially if you've got headers and do a PROM reprogramming. A decent cam could probably get you 15 hp over an 85 cam, so that would be a 40hp bump over a peanut cam.

Morley

Here is the cam from Summit.



Click to view image

$159.99


Overview
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Material Cast Iron

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Up to 40 more horsepower for your TPI engine


Chevy: 1985-87 Camaro 305, 350, 1985-87 Corvette 350; Pontiac: 1985-87 Firebird 305, 350, 268/278 degrees duration TPI camshaft kit


Advertised duration: 268 intake/278 exhaust
Duration at .050 in. cam lift: 204 intake/214 exhaust
Gross valve lift: .420 in. intake/.442 exhaust
Lobe separation: 112 degrees

Stuffed in an '86 IROC Camaro with a 305 TPI motor and an ADS Super Chip installed, our TPI cam kit made 40 extra horsepower and knocked almost a full second off the IROC's 0-60 times--and the computer worked perfectly. This kit includes the cam, lifters, springs, retainers, and lube. If your car has more than 30,000 miles, we suggest you add a new timing chain.



Sold as a kit.

SMOKEN

that summit cam is bigger than all the cams gm put stock inthere 305 350 tpi cars.

Morley

This is supposedly the cam that was in the '85 TPI, very close to the Summit cam. I have also seen elsewhere that the 85's cam had the same grind as the summit one.

1985 305 TPI




Lift: intake .404
exhaust .415

Duration: intake 320
(crank) exhaust 320

Jim85IROC

iTrader: (2)

The 85 cam had the following specifications:

1985 (L69 & LB9)
Duration @ 50: 202/206
Lift (1.5): 403/415
LSA: 114.5
GM Part #14088843

87 cam:
1987 (LB9 5-Speed, L98)
Duration @ 50: 202/207
Lift (1.5): 404/415
LSA: 114.5
GM Part #10088155

88 & 89 cam:
1988 (LB9 5 speed, L98)
Duration @ 50: 207/213
Lift (1.5): 415/430
LSA: 117.0
GM Part #10066049

90 cam:
1990 (305 5-speed w/G92 & 350)
Duration @ 50: 202/207
Lift (1.5): 413/428
LSA: 114.5
GM Part #10111773

highhat

Hey Jim you wouldn't happen to have the specs for an 89 350 TPI 700R4 factory cam? :hail:

Jim85IROC

iTrader: (2)

From above:
88 & 89 cam:
1988 (LB9 5 speed, L98)
Duration @ 50: 207/213
Lift (1.5): 415/430
LSA: 117.0
GM Part #10066049

highhat

Sorry missed that