Intake Removal

[bozkm]

I am going to remove my weber today or tomorrow to put back on the heat shield. After reading RallyBob's article on porting the intake to match the weber throats, I was thinking about attempting the job also. A few quick questions (I hope).

Is the Intake easy to remove without removing the exhaust manifold?? I notice that it has 3 bolt on each side, but one is on the bottom. Haven't really had a chance to really look at it yet.

Can the gasket be reused, or do I need to buy a new one first?

I'm assuming that after doing the manifold, I would have to enlarge the holes on the heat shield....same method and tools, or would a grinding stone bit work. I'm kinda a little worried that thin piece of metal will get bent, as to not seal tight/flat.

Thanks.

[bosco]

It seems you could probably do all the grinding on the intake without taking it off.....IF you were diligent enough about blocking off the runners and the rest of the engine bay to keep the shavings out of the engine. The heat shield is VERY easy to open up....it's thin but doesnt bend, at least not if you use a dremel or dye grinder. A file would probably make a mess of it tho.

[bozkm]

yeh, I was thinking of that also. When porting the heat shield, do you just open up the holes, or remove the center piece also, and make it one big hole..which is the shape of the gaskets anyway.

[GTJIM]

The intake is bolted to the exhaust manifold with four screws around the carb flange that are usually a bear to remove. It is worth a try to get them undone before removing the manifold to head bolts - try using plenty of penetrating oil before trying to undo them. They have a 12 point head the same size as the cam bolts and need a special toolbit to undo them ( 8mm 12point - I think from memory). Sometimes one or more of these screws need to have the heads drilled off to get the manifolds apart. an impact screw driver may be of use here to get these bolts started.

If you can get these four bolts out then the intake cam be removed leaving the exhaust held in place by the two end bolts. If you are going to reuse the heat stove type exhaust then access to these bolts will need to be retained and the porting of the intake manifold be done in a little more restrained manner.

The gasket between the intake and ehaust should be replaced as it is usually damaged or blown and may have been there from new. With extreme care the manifold to head gasket my be reused with a smear of RTV on the sealing surfaces around the intake runners.

[jerseyopel]

I have yet to see if anyone can reply about whether or not you would remove the center piece in the heat shield.I did see in Bob LeGere's instructions about when you would install a carb spacer that it should have a center in it and not be open. Wouldn't this also apply to the heat shield.

[jerseyopel]

BUMP! Bob, Dave, anyone??

[bozkm]

I have cutout the opening in my heat shield, to match the opening to the intake, and it seems to work good.

[kwilford]

I suspect that the rational for leaving the centre of the spacer intact is to reduce (as much as a possible) the intake plenum volume, for better throttle response. I think it might be better to leave the heat shield centre intact as well (opened up to match the carb throats) to back up the spacer. Bob?

[tekenaar]

Originally Posted by kwilford I suspect that the rational for leaving the centre of the spacer intact is to reduce (as much as a possible) the intake plenum volume, for better throttle response. I think it might be better to leave the heat shield centre intact as well (opened up to match the carb throats) to back up the spacer. Bob?

I agree that it's much more rational to leave the spacer's center separator intact for the very rationale (raison d'être) Keith has stated!

[jerseyopel]

I had also taken a 1 inch piece of aluminum square stock, milled a flat off to make a triangle, and tacked it inside like the epoxy ramp in Bobs post. Will try it soon and we will see if it works.

[bozkm]

Please don't take this post wrong...I'm am saying (typing it) with a smile..but it would've been nice to have an answer for this 2 months ago before I cut out the heat shield , but as stated above it still runs good with it cut out.....

[RallyBob]

Doesn't really matter either way, as the heat shield is rather thin. The intent of using a multi-hole spacer (considerably thicker than the heat shield) is to keep the plenum volume reasonably sized and to aid in maintaining a high velocity through the carburetor's venturis, as the multi-hole spacer effectively lengthens the carburetor's air tract. A spacer with a single hole tends to increase plenum volume, further reducing the carburetor's 'signal' strength, and often reducing torque. JMTC.

[Sven]

You mention one or more of those funky 12point bolts heads might need to be drilled off. Well i managed to undo 3/4 of those, one broke. And now i can get the mainfolds apart.. i'm not sure if its because of this leftover bolt inside.. or something else hodling it. undid 4 intake to head bolts and 4 intake to exhaust manifold bolts... but intake won't budge. Thanks.

[madhatterpdc]

I picked up a spare manifold set (intake and exhaust still joined at the stove) from ebay a while back. The exhaust manifold was still attached to the head pipe and was cut off right after the flange, presumably by the seller during removal.

I tried to seperate the manifolds correctly by removing the intake to exhaust manifold bolts one at a time using the correct tool. Three came out very easily, but the last defied all attempts of removal, even after destroying a couple of the star dirvers, several days of diligent PB Blaster application, and even heating to a glowing red. I was trying to be so careful becuase I hate to destroy anything that might be useful someday to someone. Finally I resorted to drilling the head off the last bolt. But it still it wouldn't seperate, so I had to vice the intake, heat the area around the offending stud and hammer the holy crap out of the exhaust manifold. After ten to fifteen minutes of steady pounding and my father heating, it finally clanged to the floor.

It turns out that the offending bolt had rusted so thoroughly that it had swelled up and locked itself tight as a drum. Inspection ruled that both manifolds are still good after all that pounding. Of course this was at the beginning of summer and I have yet to start porting the intake manifold which was the whole point of this excercise. If you wind up destroying your exhaust manifold during this, you should locate a sprint exhaust manifold.

[Sven]

I doubt that the broken bolt is still keeping them stuck together.. because it turned before it broke.. so its not seized, just a bit rusty on the thread. The intake can be nudged a bit but i can't take it off.. its like something is still keeping it on. i'll try a hammer tomorow.. the intake manifold is not important anyway, since the only reason i'm taking it off is to put a bigger one on.

btw... i'd love to get a sprint header, but those are not available here... best i can do is try to find a better stock opel manifold, since this one doesen't look very efficient being stuck to the intake (why is that anyway?) doesen't seem right.

[greensmurf20]

the manifolds bolt together so the exhaust manifold heats up the intake to make the car run better when its cold. Jstock is selling a sprint manifold on the forums right now, for what seems to be a fair price for those, and headers pop up on ebay alot. both help to keep the intake cooler which will make it run better onces its up to temp.

[Chuck Luther]

here's my recent port job:

...but I haven't started the engine yet.. I added a sprint manifold and side pipes so I haven't gotten a custom head pipe molded yet... too afraid to start it with out a muffler. LOUD!

but the porting seems to look okay. I did cut my heat sheild in the middle..

I bought the sprint and a new intake manifold before I removed my old one - it was in terrible shape.