Replacing starter-port intake?
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Northstar Engines and System Technical Discussion Discussion, Replacing starter-port intake? in Cadillac Engine Technical Discussion; Well, it looks like I need to do a starter this week. Has anyone had their intake off to replace ...
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    darien99's Avatar
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    Replacing starter-port intake?

    Well, it looks like I need to do a starter this week.
    Has anyone had their intake off to replace the starter? Was there any room at all for cleaning up/matching the ports? Any pics?

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    Submariner409's Avatar
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    Re: Replacing starter-port intake?

    It's a plastic composition manifold. Most of the passages are darn near impossible to get to because of the runner design. Don't mess with it. Search for "plenum" (you don't have one, but good pics in the threads), "fuel injector", "intake manifold", similar. Look at AJxtrcman's posts on intake work. LOTS of words on the subject.

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    Re: Replacing starter-port intake?

    Quote Originally Posted by submariner409 View Post
    It's a plastic composition manifold. Most of the passages are darn near impossible to get to because of the runner design. Don't mess with it. Search for "plenum" (you don't have one, but good pics in the threads), "fuel injector", "intake manifold", similar. Look at AJxtrcman's posts on intake work. LOTS of words on the subject.
    Thanks for the info, will do.

    I took the "manifold' off and I found alittle room for improvement. There's a large ridge between the manifold bore and spacer bore (bottom half of the bore is smaller on the manifold side). There's another small ridge between the spacer and TB. Ofcourse LOTS of carbon from the egr, the egr was almost completely blocked shut)

    Also noticed the gaskets themselves need to be taken out alittle for the head ports and manifold ports to match better.

    All I see so far. I'll be knife-edging the tb blade and giving the tb a bellmouth while I'm in here. This little mod was good from .1 on my Dakota and .2 on the neon.
    Too bad nobody wants to bore out these TB'S!

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    Re: Replacing starter-port intake?

    The PCM overcompensates for the bored TB and you wind up with a flat spot off-idle and a midrange acceleration stumble. The present intake system flows plenty of volume for a 280 c.i. engine. EGR's on the Northstar are problems for city-driven vehicles. One of the yearly tricks is to clean the TB and passages religiously, stuffing a rag past the TB, scrubbing like mad with TB cleaner and a toothbrush, blot it all up, and pull the rag with needlenose. Northstars dislike running on pools of TB cleaner, which is where it all goes unless you make a dam. I've had some luck with using a 20 oz. jug of TECHRON while filling up for a long highway trip. Instead of blowing $$$ on so-called CAI's, open up the bottom inlet to the airbox and run a tube down into the lower bumper area. (Hmmmmm......maybe post-'00 models.....) The WIX stock panel filter goes to less than 0.5" of vacuum at WOT redline with that airbox mod. Nothing wrong with cleaning up the intake bumps and warts.......jig up a 2 3/4 - 3" exhaust into 2 1/2" Y and mufflers. The stock cat is pretty open as is, be careful on mufflers or the drone will drive you out of the car.

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    Re: Replacing starter-port intake?

    Well when I bought this car the kid who owned it before removed the cat and then replaced it with a cherry bomb.

    It was crudely clamped on, and my mufflers were rotted. I ended up getting a hi flo converter (bullet style) and replaced both mufflers with borla pro's. the piping is still stock however (for now). Oh, I also removed that other resonator. Car has a very mellow rumble at idle. You can barely tell it has mufflers and missing a resonator. So for now the exhaust is ok. My car went from a 14.1 to a 13.7 in the 1/4 mile.

    For the intake, I ended up removing my entire air cleaner assembly last summer and built my own 3.5" cold air intake that leads down into the fender. The car went from a 14.3 to a 14.1 in the 1/4 mile, my best modification thus far.

    Next I'll be running this setup at the track, seeing what the plenum/tb work does for me. That sucks about the flat spot, did it really mess up drivablility, or just show up on the dyno? I heard ~10ft/lbs of torque on the dyno, was that true?

    Next mod will be a chip.

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    Thumbs up Re: Replacing starter-port intake?

    Oops, edit.

    My best modification thus far was the exhaust.

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    fubar569 is offline Cadillac Owners Fanatic
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    Re: Replacing starter-port intake?

    in order to properly modify this intake...you have 2 options...

    1. about 24"of rotary tool extensions/drill entensions and a VERY STEADY HAND...

    2. cut the intake in half (top/bottom) with a bandsaw/hacksaw and glue it back together

    option 1 requires removal of the valve on the backside of the intake, and it is a dick to remove it. once you have done this, you use the tool extensions to shorten each runner by about 1-3"...it takes FOREVER to do right and properly smooth them out after cutting.

    option 2 is by far the easiest. one member here went this route and has not had a leak yet. he DOES NOT SPRAY NOS...he sawed the intake in 2, shortened, ported, & polished whatever he could get to, and screwed and glued the intake together then used another adhesive around the outside of the cut to permanently seal it back up.

    you will be giving up additional low end torque because of the shorter runner length, however you should notice a pronounced gain in the higher RPM's by fully going through with this mod.

    As far as boring the throttle body...check out this company:

    http://www.rvmorsemachine.com/index.html

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    Re: Replacing starter-port intake?

    Quote Originally Posted by fubar569 View Post
    in order to properly modify this intake...you have 2 options...

    1. about 24"of rotary tool extensions/drill entensions and a VERY STEADY HAND...

    2. cut the intake in half (top/bottom) with a bandsaw/hacksaw and glue it back together

    option 1 requires removal of the valve on the backside of the intake, and it is a dick to remove it. once you have done this, you use the tool extensions to shorten each runner by about 1-3"...it takes FOREVER to do right and properly smooth them out after cutting.

    option 2 is by far the easiest. one member here went this route and has not had a leak yet. he DOES NOT SPRAY NOS...he sawed the intake in 2, shortened, ported, & polished whatever he could get to, and screwed and glued the intake together then used another adhesive around the outside of the cut to permanently seal it back up.

    you will be giving up additional low end torque because of the shorter runner length, however you should notice a pronounced gain in the higher RPM's by fully going through with this mod.

    As far as boring the throttle body...check out this company:

    http://www.rvmorsemachine.com/index.html
    Thanks for the info, I've done similiar modification to my plastic dodge neon intake plenum, it gave the car .4 in the 1/4 mile...a very nice gain. Maybe if I find another plenum I'll mess around with it. Are all the plenums the same throughout the years and sls/sts?

    Thanks for the link on the tb!

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    Re: Replacing starter-port intake?

    I might have a modified shortened runner intake for sale soon. I went with "option 1", where I took rotary rasps to the intake runners. There is probably 20+ hours worth of work in it. Port matched, runners shortened by ~2-3", smoothed out, etc. I haven't taken it to the dyno, but it would be a easy option to bolt it on and see what difference it makes. If you're interested, let me know. I would probably be willing to make a trade for dyno time, because I'm really curious what it does, but don't have the time to dyno it myself. I need to finish my next intake though (independent throttle bodies), so it might be a few months.

    edit: I would have a 80mm bored throttle body and spacer to go with it.

    err... hmm.. you have a 95, so you could only use the intake.

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    fubar569 is offline Cadillac Owners Fanatic
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    Re: Replacing starter-port intake?

    Quote Originally Posted by eldorado1 View Post
    I might have a modified shortened runner intake for sale soon. I went with "option 1", where I took rotary rasps to the intake runners. There is probably 20+ hours worth of work in it. Port matched, runners shortened by ~2-3", smoothed out, etc. I haven't taken it to the dyno, but it would be a easy option to bolt it on and see what difference it makes. If you're interested, let me know. I would probably be willing to make a trade for dyno time, because I'm really curious what it does, but don't have the time to dyno it myself. I need to finish my next intake though (independent throttle bodies), so it might be a few months.

    edit: I would have a 80mm bored throttle body and spacer to go with it.

    err... hmm.. you have a 95, so you could only use the intake.
    oh eldo...what year is your setup from? i have a 97...we could make a deal depending on fit...i've wanted the 80mm TB and spacer since forever...i have a core TB to be sent in plus although i went with option 1 to start with i want to finish my intake with option 2...however since yours is done and complete...hey if it fits my 97...lets work out the details for the complete rig!

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    Re: Replacing starter-port intake?

    Quote Originally Posted by eldorado1 View Post
    I might have a modified shortened runner intake for sale soon. I went with "option 1", where I took rotary rasps to the intake runners. There is probably 20+ hours worth of work in it. Port matched, runners shortened by ~2-3", smoothed out, etc. I haven't taken it to the dyno, but it would be a easy option to bolt it on and see what difference it makes. If you're interested, let me know. I would probably be willing to make a trade for dyno time, because I'm really curious what it does, but don't have the time to dyno it myself. I need to finish my next intake though (independent throttle bodies), so it might be a few months.

    edit: I would have a 80mm bored throttle body and spacer to go with it.

    err... hmm.. you have a 95, so you could only use the intake.
    I'm interested. I take it the manifold isn't off a '95?

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    Re: Replacing starter-port intake?

    Quote Originally Posted by darien99 View Post
    I'm interested. I take it the manifold isn't off a '95?
    Nope, at least I don't think it is. But the 95-99 intakes are all the same, except for some vacuum ports that jumped around. I'd include the FPR vacuum line so you should be good.

    Quote Originally Posted by fubar569 View Post
    oh eldo...what year is your setup from? i have a 97...we could make a deal depending on fit...i've wanted the 80mm TB and spacer since forever...i have a core TB to be sent in plus although i went with option 1 to start with i want to finish my intake with option 2...however since yours is done and complete...hey if it fits my 97...lets work out the details for the complete rig!
    I don't remember. Darien99 has dibs on the intake, but since he can't use the TB/spacer, we can work something out. Like I said, it wouldn't be for a few months yet...

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    Re: Replacing starter-port intake?

    Cool. Get some pics up or emailed to me. Price too. I'll be able to run it at a 1/4 mile track within' a few weeks, but a dyno will take a lot longer since the closest is around 250 miles from here.

    I'll even swap the intake right at the track so there's no weather differences for comparison.

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    Thumbs up Re: Replacing starter-port intake?

    Well it's all back together. Cranks a lot faster with the new starter.

    Ended up bellmouthing the throttle body, tapering the blade, portmatching tb->adapter->plenum. Smoothed out tb and adapter with 400 grit, much better! Also sanded off plastic flashings in the intake gaskets.

    Power difference? Feels like it, but I haven't driven the car for quite awhile, so I'm not as attuned to it as usual. It appears to be pulling A LOT further into redline than it did before. Seems to pull passed 100 mph a lot faster than it used to.

    We'll see what the track says! Then its chip time!

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    Re: Replacing starter-port intake?

    Quote Originally Posted by darien99 View Post
    The car went from a 14.3 to a 14.1 in the 1/4 mile, my best modification thus far
    lol
    lets see a time slip.....

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