Do I need spacer on my center bolts on my aftermarket intake manifold

[chevy_turbo454]

Hi:
Guys I have a concern. I bought an aftermarket intake manifold for my 350 Chevy engine. The intake came with some spacers for the 4 center bolts because this intake can be used neither for old engines (iron heads) or new engines (assuming like Vortec's). I build an old 350 engine (like 82-84 sbc) but when I start the engine and make some heat cycles it start to have oil and water leaks. So I take of the intake to change gaskets, but I found that these spacer for that 4 bolds didn't do the job to retain the intake... I really appreciate any HELP....

 

[Schurkey]

WHAT INTAKE BOLT PATTERN?

First guess: the spacers are tapered so the intake can be installed on the old-style, 6-bolts-in-line original bolt pattern from '55 to '85 model years, and certain Corvette aluminum heads newer than '85; or the intake can be installed on iron cylinder heads having the two center bolts on each head standing up at a goofy angle. That intake WILL NOT fit "Vortec" heads.

So which heads do you have--the six-in-line, or the two center bolts different from the others?

It's a bottom-feeder Chinese intake manifold that may have been improperly machined.

Were the block decks, or the cylinder heads planed? Excessive stock removal from the engine may result in the intake manifold not fitting properly, ESPECIALLY if you use the rubber seals instead of RTV Silicone on the ends of the block.

Are you using quality intake gaskets?

Did you put sealer or thread-locker on the intake bolts?

Did you torque the bolts properly?

 

[Erik the Awful]

That looks like a pre-87 intake manifold that's been adapted for post-87 heads. You said your engine is pre-87, but what heads are you using?

There are three intake bolt patterns for SBCs. The pre-87, the post-87, and the Vortec. The Vortec won't bolt up to anything other than Vortec, because even the end bolts are spaced differently. The pre- and post- '87 intakes are swappable, but need the angled spacers.

Left side head is post-87 TBI, right side is Vortec. It's the TBI manifold that came with the TBI head. You can see the bolt holes don't line up, and the TBI runner doesn't cover the taller Vortec port on the head.

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