will they just interchange. whats the chances of needing ot enlarge the pushrod holes? should i change the pushrods aswell, can they be changed w/o pulling the manifold?

thanks

-Stell

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1988 IROC 305TPI MINT!!
Mods= Accell SuperCoil, MSD 6A, Ported Plenum, No MAF Screans , K & N, 160 Thermostat+ Temp Switch, Relocated MAT, Cold Air

They will interchange. You presently have self-aligning rockers (1988 was the first year). The pushrods do not stabilize the valvetrain, the rockers do. Therefore, no other modifications are necessary. Just make you you get new 1.6 self-aligning rockers.

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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.

The previous answer is incorrect. The 1988 cast iron heads still have the push rod guide slots in them. They also have the self aligning rocker arms. I believe GM made all the rocker arms from 1988 on up self aligning so they did not have to manufacture two types of rocker arms. With this in mind, the push rod guide slots are still in the head and they will bind with the push rods if you put 1.6 rockers on without elongating the push rod guide slots. As a note to this, you do not need self aligning rockers on any engine with push rod guide slots in the head. My car, which is a 1988 305 TPI had both self aligning rockers and push rod guide slots in the head. I removed the self aligning stock rockers and added 1.52 Comp Cams roller tipped non guided rockers. This combination has been on my car for 60,000 miles with no problems. The cylinder head push rod guide slots are keeping the rocker arms guided. The L98 Corvette engine with the Alum heads needed the self guided rockers the cast iron headed cars do not need the self aligning rockers.

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1988 Formula 5L/5sp 3.45 gears, SLP cold air kit, MAS gutted, TPIS air foil, TPIS AFPR, MAC headers, Mac under drive pulleys, MAC cat back, Relocated MAT.
Best ET street tires 13.85
Best 60 FT street tires 1.930
Best MPH street tires 99.29

[This message has been edited by bjankuski (edited November 18, 2000).]

[This message has been edited by bjankuski (edited November 18, 2000).]

My information comes from various reference books AND various manufacturers of rockers, such as Crane -- 1988 was the first year for self-aligning rockers. I never re-iterate information that I "hear" through the grapevine. Everything I state is from the written word, not what someone tells me as "truth" (that's how mis-information always starts).

If it's true that GM used self-aligning rockers AND pushrod guide slots in 1988, I must ask WHY? Why would GM spend time and money redesigning rockers if they weren't necessary? Was this a "transition" year and GM was using an old stock of heads?

I'd like to hear from other owners of 1988 V8's who know whether these heads have guide slots or holes with no pushrod "guidance". Until this can be verified by the masses, I stand by my original statement.

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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.

[This message has been edited by Willie (edited November 18, 2000).]

GM redesigned the rocker because the Corvette had Alum heads did not have push rod guide slots in them. Since they did not have push rod guide slots a new rocker arm was developed to solve the problem. GM could have used guide plates and hardned push rods to guide the rocker arms but they choose to design a new rocker arm. I am not sure why they went this route. Maybe it saved them money and reduced the complexity of the cylinder head?

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1988 Formula 5L/5sp 3.45 gears, SLP cold air kit, MAS gutted, TPIS air foil, TPIS AFPR, MAC headers, Mac under drive pulleys, MAC cat back, Relocated MAT.
Best ET street tires 13.85
Best 60 FT street tires 1.930
Best MPH street tires 99.29

I have 88 heads that have large round holes in them, and self aligning rockers. I'm gonna say you are both wrong, GM was playing games for a while and wasnt consistent in their use of self aligning and non self aligning from what I have seen.

The Corvette aluminum head was introduced in 1986, available on convertibles only that year. I have some from that year, and they came with guideplates with a GM number stamped right on them. I have also seen some without guideplates, and with self aligning rockers. Another example of GM's perfect consistency.

As for the original question... well... Can I suggest pulling a valve cover off and checking it, because you never know.

i am gonna do that when it gets a little warmer now if they are the self alighning heads, will the rockers fit right up?
and if they do have guideplates, what hasto be done to fit them up

-Stell

BTT anyone else ever install these? on 88+ heads?

on your motor, with the mods you list, I think 1.6's would net you <5 hp(less if you have the peanut cam). Is this money well spent? Or would it be better to invest in a good quality catback(10 -15 hp) first?

seems to me, i recall there's a performance shop in your area(Tom's River) that specializes in hi-perf for f-bodies. can't remember the name of the place, but the owner's name is groundbeef, or frankfurter, or something like that.


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He who hesitates,... is lost!

[This message has been edited by 88IROCs (edited November 22, 2000).]

SLP, http://www.slponline.com/ Dave Hamburger.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

I have a 1988 GTA 5.7L since it was new from the factory. The slots in the heads DO NOT guide the pushrod, the self aligning rocker does. I have also had experience dealing w/ 1987 blocks 5.0 and 5.7 and all 1987 head slots align the pushrod and all the rocker arms of that year are non self aligning. 1988 and on 5.0's and 5.7's have self aligning rockers from the factory. No engine was to have both the head and the rocker arm alignment. It is either one or the other. I have installed 1.52 Roller Rockers from Comp Cams and they work fine. I'm not that sure though about the 1.6's they may hit the head. An easy way to check to see what kind of guides you have for the rocker arms are to just remove the oil cap and look at the slot in the head for the pushrod. If it is round and doesn't come in contact with the pushrod, than you have self aligning rockers. If it is snug to the pushrod and comes in contact to the side of the pushrod, than you have non self aligning rocker arms. This is a sure way to see if the heads were not replace by a previous owner.

Maybe GM was playing around with the combination of parts in 1988? I have a 1988 305 TPI, it came with self guided rocker arms and slots in the cylinder head to guide the rocker arms. I removed the self guided rocker arms and added a set of Comp Cams 1.52 non guided roller tipped rockers. The cylinder head slots are guiding the rocker arms not the self aligning rocker arms. Maybe my car was built in early 1988 and they were getting rid of the older left over parts? I really do not know the answer, but I do know what was on my car, and how it is currently operating.

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1988 Formula 5L/5sp 3.45 gears, SLP cold air kit, MAS gutted, TPIS air foil, TPIS AFPR, MAC headers, Mac under drive pulleys, MAC cat back, Relocated MAT.
Best ET street tires 13.85
Best 60 FT street tires 1.930
Best MPH street tires 99.29

[This message has been edited by bjankuski (edited November 22, 2000).]

Being that I have Torqer 305 heads, I don't know if this would apply to me or not, but I installed a set of 1.6 roller rockers on these heads and they work fine. They were made by Proform and there're fairly cheap, only $150, same price as the 1.5's. I'm pretty sure the S/R Torqer 305 heads and the Gm stock heads are the same as far as dimensions go, and I'm pretty sure they come with self-aligning slots with them, so yes the 1.6 pushrods will work.

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88'TA 305TPI 330HP, NATURALLY ASPIRATED, PASSES N.J. EMMISIONS. "I AM JUST THAT GOOD"

Ok, why did everyone under the sun tell me that i have non-self aligning rockers in my 305 tpi? Even the summit tech guys did. I now have non-self aligning 1.5 roller golds in my 355 tpi w/trick flow heads. Do i have a messed up combo?

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"Ever notice how imports sound like weedwackers"