GXP

I recently purchased a 350 block and heads to build up for my 87 firebird. Based off of the numbers from research, it all appears to be a '70 engine from a 1970 Caprice. The block is all original and in good shape, but I was wanting to build a 357 out of it, so I would bore it .040. A couple pushrods are missing, so I will get new ones, and more than likely new heads (Vortecs?) as well.

My main question is, would I still be able to use the original rocker arms regardless of heads/ pushrods? Are they even worth salvaging?

P.S. - The pistons aren't salvageable either, but since I wanted to bore I'm assuming that won't matter.

Night rider327

iTrader: (13)

Rocker arms needs to match your head's guiding system.

1955-86 heads have round holes in head that pushrods pass through and non self aligning rocker arms. The holes in heads acts as the pushrod guide.

1987-up uses self aligning rocker arms. The rockers have a ridge or lip on each side of the valve stem end and acts as the pushrod guide.

Some factory heads, modded by user heads and almost all aftermarket heads have screw in rocker arm studs and guide plates. If stock type heads, the pushrod hole is drilled large to keep from binding. The guide places are the pushrod guides.. You would use 1955-86 style non self aligning rockers for these.

You can't double guide the pushrods.. Most only use 1 type of guide.

sofakingdom

iTrader: (1)

Why bore it .040"? Correct way to maintain an engine is, bore it as little as possible, so that the next time it wears out, there's still as much left as possible. Which means, don't bore it at all, unless it needs it. Which it almost certainly does; but it doesn't need to go .040" unless it's already at .030"... which is highly possible, especially if the bores don't look very worn. For all you know, it could already have been "rebuilt" by a typical "rebuilder", and therefore might already be .060" over, because alotta those guys couldn't care less about re-using em; they just want to make em all the same, as quick as possible, and so they punch every one to the absolute max to make sure they clean up all the wear on all of em. Any 70 motor is highly likely to have already been down that road. Don't get too wrapped up in a bunch of .040" until you measure it. Then if it's still std bore, punch it out as little as possible to clean up the wear, subject to being able to buy pistons for that size.

Stock rockers are made from stamped sheet rubber. Why in the world would you want to actually build a motor and re-use that garbage? Throw that in the trash where it belongs.

Same for the stock push rods. Absolutely not worth salvaging.

Worry about rockers after you get heads. Put in whatever whichever heads you get require. It's too early to be thinking about that right now.

GXP

We measured the bore and checked the pistons. They are currently a 4.00" bore. The cylinders aren't bad but will definitely need boring out. I guess boring it as little as possible makes sense. And I was just wondering if the OEM rocker arms would be compatible with what heads I was looking at.

Thanks a lot!

five7kid

iTrader: (14)

Not to nitpick, but the self-aligning started in 1988 model year. And, self-aligning have round pushrod holes. '87-earlier non-self-aligning holes were more oval shaped (straight sides with rounded ends).

All Vortec SBC heads have round pushrod holes, and use self-aligning rockers.

Night rider327

iTrader: (13)

Sorry five7kid, you are incorrect. The self-aligning rockers started at the same time as the center bolt valve covers and 1 pc rear seal.

That was 1987..

Here's some sources
http://www.superchevy.com/how-to/vem...e-rocker-arms/
"Only a few insignificant design changes occurred during the life of the stamped rocker. Most notably, a self-aligning version replaced pushrod-guideplate-type rockers across the board in '87"

http://www.summitracing.com/parts/cc...et?prefilter=1
Make:CHEVROLET
Beginning Year:1987
Ending Year:2000
Engine Type:V8
Liter:5.7
CID:350
Engine Size:5.7L/350
Engine Family:Chevy small block Gen I

http://www.compperformancegroupstore...Category_Code=
" 1987+ SBC engines came equipped w/ self-aligning rockers. Guide plates are required when using non-self aligning rocker arms on engines originally equipped w/ self-aligning rockers."

You are correct on the pushrod hole shapes, but also the round holes in the vortec heads are much larger than the elongated holes in the 55-86 heads.

IIRC the 55-86 heads had a 3/8" or less wide opening and the vortec heads pushrod holes are closer to 7/16"

sofakingdom

iTrader: (1)

"Sources" aren't always very accurate. I prefer to simply LOOK AT THE PARTS, like everything else.

I'm quite sure for example that when we had to work on my brother's 87 Monte Carlo SS L69, the rockers were NOT self-aligning.

I've pretty much come to accept that the changeover was a bit more gradual than magazine articles seem to indicate; kinda like the 28-spline axle deal. They used whatever they had on hand until it ran out. And that happened at different times in different applications.

55 - 86ish heads had slots that were 5/16" wide, same as the push rods, except with a few .001"s of tolerance.

Bob88GTA

iTrader: (2)

"Stock rockers are made from stamped sheet rubber. Why in the world would you want to actually build a motor and re-use that garbage? Throw that in the trash where it belongs."

I just love your "straight to the point advise" Sofa!
We need more of that.

John in RI

iTrader: (167)

Can't believe everything that you read...... Here's a picture of stock 87 TPI heads with factory installed NSA rockers:

sofakingdom

iTrader: (1)

Thanks!!

I'm not very "politically correct" about most things, either.

Night rider327

iTrader: (13)

Yeah I guess that's the case here. I have a set of heads sitting under a bench in my shop that came off a stock 170K miles wrecked 1987 IROC TPI 305.. That would be the LB9 engine IIRC. They have the self aligning rockers.

John in RI

iTrader: (167)

I had always believed that the 87+ was the cut-off too,... till I learned otherwise. Since then I've had 3 sets of KNOWN 87 heads (all 081's), all used NSA, and all had the same type pushrod hole/slot shown above.


I haven't seen SA rockers on an 87' 081,..... Yet !