monkez

So I've been chasing an intake leak on my '85 for the better part of 12 months (it's not all i've done, but it feels like it). With the help of a DIY smoker and a cheap boroscope, i was able to confirm that my leak is coming from where the intake tubes marry up to the heads.

I'm not quite sure what my options are. My initial instinct is to reinstall the intakes with a gasket sealer and hope that takes care of the leaks. But i'm open to cautionary tales and other suggestions.

thanks!

-adam

Mrmerlin

remove the intake legs and surface them on a piece of sand paper thats taped down onto a flat surface.

76FJ55

Tape some 120 grit sand paper to a piece of flat glass and use that to lap the surfaces of each runner just enough to see sanding marks on the full surface. I typically use a figure 8 pattern, and you'll want to hold and apply pressure just at the base of the runner so there's no moment force tipping the runner to either side.

monkez

Gentlemen, thank you for the 120 grit on a a smooth surface recommendation. I taped 120 grit sandpaper to a plane of glass and in about 40 minutes of sanding and changing sandpaper, the surfaces looked amazing. Bottom line, my car idled at 790 rpm after buttoning everything up. It's not perfect, but its the first time in my 2 years of ownership that I was able to get the idle under 950.

time to tackle the AC!

thanks again!

-adam

SwayBar

Nice job to all!

davek9

Good to hear you found the issue and fixed it
Can you please share what was the High Idle RPM at before you re did the intake?
Also was there any popping when you hit the throttle?

Thanks!

Dave K

monkez

Well, it wouldn't pass smog, partly because it would not idle under 1,000 RPM. After the refresh, the engine would idle anywhere from 950 - 1050. Sometimes hitting the throttle would only make the engine idle higher. Never noticed a popping sound when hitting the throttle.

-adam

davek9

Thank you, I'd expect popping as it would have been an un-metered air leak, perhaps just not big enough for the mix to be that far off.

Dave K.

monkez

What i do recall is that the exhaust fumes smelled very rich. Also, how loud would the popping sound? I'm pretty much a hack and do not always know what i am hearing or what I should be listening for.

davek9

Loud is a relative term as you know, what is loud to some is normal to others
The popping would be noticeable with a stutter as the mix would have been lean.

Thanks,

Dave K

monkez

Ah, a stutter we noticed, but it always felt more sub-sonic. I kept think that it felt like it was missing every now and then. Again, I'm clueless on what to call stuff.

However, it's gone now.