What's the deal with 1987 and the small block chevy v8?

[Ragtop_Renegade]

Been trying to figure this out - I have a solid low mileage 1987 305 I'd like to use as a cheap temp powerplant in projects that are waiting for my budget to allow a more expensive custom built engine. For fit testing under the hood I'd want it to be the same size as a built up small block, and that means fitting it with the same dimension headers, intake, etc.

So, when it comes to aftermarket intakes, everything seems to indicate it fits either everything through 86, or a vortec engine. the 87-up small blocks aren't included.

As far as I can tell, the only difference with the 87 engine are:

Roller cam
Centerbolt valve covers
Center intake manifold bolts are at 75 degrees vs 90 on the old style.

So if that's the case, why can't I just elongate the center bolt holes
and pitch the upper surface the bolt head rests on by 15 degrees on a milling machine? It seems silly to need a set of old school heads just to swap an intake because of a 15 degree bolt angle....

Am I missing out on something here?

[curtis73]

Its a little backwards from your thinking...

The old intakes are 90 degree bolts. The deck surface is only about 1/4" thick. If you were to mill the holes for a 72 degree face, you wouldn't have any thickness left. Instead, the common alteration is to use a tapered washer over a hogged-out hole.

But, you may or may not need it. Starting in 87, TBI engines got the funky center bolts on the intake. TPI kept the standard small block layout. Starting in 96 was the Vortec pattern which was eight 45 degree bolts instead of the twelve 90 degree bolts. That one you can't really alter since the ports are taller as well.

Edelbrock makes plenty of TBI intakes with the 72 degree center bolts, as do a few other companies. For the sake of mocking up an engine, all of the intakes (of the same variety) are basically the same except vortecs. Vortec intakes are taller. So, if you want to mock up the engine, you can assume that pre-87 intakes are the same exact critter as 87-96 intakes, they're just cast with different center holes. For instance, a Performer RPM for a pre-87 engine would be the same height as a Performer RPM for an 87-96 engine.

Edelbrock has a section of their website devoted to intake measurements. You can compare the intakes first for yourself.

[Ragtop_Renegade]

Starting in 87, TBI engines got the funky center bolts on the intake. TPI kept the standard small block layout

What about the four barrel engines? Mine's the standard LG4 with the infamous electro-franken-quad computerized carb abomination. It's buried in storage right now so I can't really look at it directly.

[curtis73]

For the most part, carbed SBCs after 87 were rare. trucks, buses, and vans in commercial applications got them as late as 89 and in foreign markets until 88. Its also possible that your 87 was a late 86 during a crossover time when they started the 1-piece rear, but before they went with TBI.

But that's beside the point... a carbed intake should be all 90 degree bolts.

Carbed through 89 should be all 90 degree (traditional)
TPI 87-91 should also be 90 degree
TBI 87-95 should have the 72 degree centers
Vortec 96-later will all have the straight up and down bolts with only 8.

Its also possible that someone bought a carbed intake for a TBI engine, so its possible that you have a 72 degree bolt angle with a Qjet... but I doubt it.

[Ragtop_Renegade]

car was an 87 Camaro sport coupe, factory optioned with A/T A/C, T-tops, LG4 305 V-8 and rear spoiler (and therefore no CHMSL bubble on the hatch) but retained crank windows, manual locks and mirrors. It's a weird one.
Build date was May 87 - she's a late 87 model, that's for sure. Block serial numbers match the VIN, so it's the original engine. RPO matches anyway. I'll see if I can get a pic of the RPO sticker.
Not that we need to determine anything more about the intake bolts, got that figured out. Just thought we might as well have fun discussing how ODD this car was.