Hello my fellow Buick gurus! I'm about to swap the stock intake on the 400 in my 69 GS400 to the Edelbrock 2146 (Performer). This was brought on by a leaking intake gasket (vacuum), and getting a great deal on a used one. I figured that I will only have to lug that stock intake around 1 time this way... . I wanted the Performer so I can keep the stock ram air set-up. Since I'm pulling the intake I also plan to check the condition of the cam. So far I've purchased the intake manifold, a 1/2" NPT plug to go where the vacuum switch is, a new thermostat and gasket, Fel-Pro MS 9005 intake gasket, some Permatex high tack, a gallon of antifreeze (pre-mixed), Permatex ultra-black RTV, some hardened steel washers (3/8), a Fel-Pro VS 5004C valve cover gasket set, AC Delco PF24 oil filter, Valvoline VR1 oil, new transmission vacuum line (steel one), a new brake booster vacuum line (steel one), new PCV hose, brake booster check valve and grommet, all of the rubber vacuum lines, vacuum cap assortment (just in case), new pump to carb fuel line (metal), 1/4" thick carburetor gasket, and replacement choke pull-off. Originally I had just planned to fix the gaskets and replace the bent and kinked steel lines, the old rubber lines, and the choke pull-off, in hopes to repair the current vacuum leaks... until the intake manifold came along! I have never done this on a Buick big block before, but have on plenty of small and big block Chevy motors. Are there any issues that y'all can warn me about ahead of time? Or any Buick specific tips and tricks I should know? Thank you!
(Since you have done intakes, much of the below may be "Cap'n Oblivious" stuff, but other's who have never done intakes, might benefit.) Jack the ass end up as high as you can. Drain the coolant, then remove the lower hose and drain that. I use a shop vac and tape a small 3/8 ID hose to the end to suck all the coolant I can from the lower outlet on the pump. Then drop the car to pull the intake, be careful and keep it level to prevent any coolant from draining into the valley. (a friend is nice to have, but I use my engine hoist just because it is handy pulling and setting an intake, and I do most everything by myself) Mop and dry any coolant from the coolant passages in the heads. Pull the splash shield and pack in towels in the valley to catch debris, and be careful after your done cleaning and ready to put the intake on, and fold all the edges of the towel into the center and lift it carefully so you don't get crud in the oil return in the valley. Carefully clean gasket surfaces on the head and china walls (front/back of block) using good clean edge of a scraper, keep the scraper at a shallow angle and do not gouge or scratch the surface. Use a razor blade to fine clean. Do not use "scrubbies", many of them have grit that can get embedded in the iron and the dust/grit can shed and get into the engine, where it will get into the oil and can damage bearings. Check the mating surfaces on the heads to ensure they are flat and straight (since you had vacuum leak), and look for any evidence of cracks. (most likely you will find nothing in either case) Fit check the intake with gaskets and check for any bolt hole or other alignment issues, if none, then press on. Use carb cleaner, prep-all, or reducer to clean and de-grease prior to gasketing. Chase all the holes with the appropriate thread chaser or carefully with taps. (keep the shop vac hose near the holes as you work.) Use Permatex "Right stuff" on the front and rear "china walls". Gaskets for intake and head should go on dry, (hence the de-greasing above) I use short wood dowels to help hold gaskets in place as I set the intake, then put in a couple bolts on each side and pull the dowels, and this helps keep from disturbing the "Right Stuff". Torque center to front/back in the criss-cross (per manual). Others can add anyting I left out.
You don’t use/ need any silicone on the valley pan or aluminum cylinder heads or intake manifolds? Just on the front and back China wall where there’s a huge space? I had all kinds of vacuum leaks after using red silllycones on the cylinder head and cast iron manifold and on both sides of the valley pan. I’m getting ready to install a new aluminum intake here tomorrow.
I'll tell you how I do it. On the composite gaskets, or stock metal valley pan I use RTV around the coolant passages. I start with the heads bare. I put some on my finger and I outline the coolant passages, just a thin coat. I then use Gasgacinch around the intake ports. Then I lay the gaskets on, and repeat on top of the gasket, RTV around the coolant passages, and Gasgacinch around the intake ports. If you use the rubber seals, use some RTV at the ends where it tucks under the head. Lay the intake on. Torque the bolts to half torque. Wait for the RTV to set up and torque the rest of the way. You should use a sealant around the intake ports. I use Gasgacinch because it seals well, and you can frequently remove the gaskets and reuse them with it. You can also use spray tack or copper coat. I like Gasgacinch, http://gasgacinch.com/ https://www.summitracing.com/parts/edl-9300
The valley pan goes on the heads before the gaskets on my engine. So would I put sealer and gas garinch on the top side of the valley pan? Then put the gaskets on and then sealer on the top of the gasket? That would put sealer on all mating surfaces.
The valley pan is the gasket. Put a small amount of rtv around the water passages on the heads. Coat the intake passages on the with Gasgacinch, both sides of valley pan. Put the pan in place on the heads. Run a small bead of rtv around the water passages on the top side of the valley pan. Set the end seals on the china wall with a small dab of rtv where they touch the head (or just use rtv instead of the seals). Set the manifold on and torque.
When I did my aluminum intake to the stock heads, I used the metal pan gasket (FelPro). I sprayed 2 decent coats of the copper coat sealant (that Larry referenced) to both sides of the intake gasket and let it dry for a day. On the China walls, the Edelbrock instructions said not to use the rubber gaskets and to use a 1/4" tall bead of silicone sealer instead. So, that is what I did (used the Permatex Ultra Black). I let the silicone sealer set up for a couple hours before dropping the intake on. It was way easier than I anticipated. So far there is no leaks. I wish I would have put that thin layer of sealer around the water passages though, just for piece of mind.
