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I bought a '73 four-barrel intake manifold off of a guy on this forum and it has some slight rust. Before I put it on my '71 I would like to get it cleaned up and repainted. I plan to take it to a local machine shop and get it glass-bead blasted and then clean it thoroughly. After cleaning it, I will coat it with POR-15 Rust Prevention to prime it and then use POR-15 Olds Gold Engine Enamel as a top coat.
Am I missing anything? Any tips or tricks you all have? I do not know if I am going overboard or not as this is my first project car and I want to do things right.
Look for a reputable engine rebuild shop in your area and ask if they can clean your part. Many shops now bake parts clean, then spin them in beads to make them look like new. I paid around $20 to have this done recently. You'll also want to contact Bill Hirsch Paint to order the correct Olds gold paint for your intake... one can should cover your intake. I have a 455 and their paint has held up well so far. No primer is necessary for cast iron pieces, just mask off the gasket surfaces. Good luck with your project.
I just replaced my intake manifold gasket on OE intake manifold. Soaking of Easy Off oven cleaner, power washed it, wire brushed it off, carburetor cleaner for a final cleaning and painted it. You can get brand new Grade 8 bolts at Ace Hardware (exact fit). Use the old bolts to insert into the holes while you paint it.
I just replaced my intake manifold gasket on OE intake manifold. Soaking of Easy Off oven cleaner, power washed it, wire brushed it off, carburetor cleaner for a final cleaning and painted it. You can get brand new Grade 8 bolts at Ace Hardware (exact fit). Use the old bolts to insert into the holes while you paint it.
Note in both your and Vintage Chief's pictures the amount of pitting on the exhaust crossovers. That is due to the factory paint cooking off and leaving the cast iron exposed to the elements for decades.
Like Mike said, see if a local machine shop has a shot blaster. Ours makes cast iron pretty much look like new. No matter which method you use, glass bead or shot blast, make sure you spend however much time needed to make sure that every single bit of the media is out of the manifold.
Like Mike said, see if a local machine shop has a shot blaster. Ours makes cast iron pretty much look like new. No matter which method you use, glass bead or shot blast, make sure you spend however much time needed to make sure that every single bit of the media is out of the manifold.
This certainly works, but as noted you have to take care to remove all the media. I've taken a different approach. If your local machine shop has a real caustic hot tank (as opposed to the vapor degreasers that most shops have today), just have them tank the manifold. Mine came out clean and rust free.
Thank you all for the help and insight. Currently the manifold is soaking in Mineral Spirits for a few days and then after a thorough pressure washing I will soak it again before I clean it up and apply the rust prevention and paint. Will post pics when it is finished!
As Joe mentioned, and I will attest - a caustic washing/soaking will dissolve the carbon. Easy Off oven cleaner is caustic. Obviously oil & grease are carbon compounds. Red Devil Lye, Roebic Crystal Drain Opener are both NaOH (Sodium Hydroxide). If you find the mineral spirits hasn't removed what you had hoped it would remove, try any of the three I just mentioned. Obviously, the Easy Off you can simply spray on and watch the grease dissolve right before your eyes. With either the Red Devil Lye or Roebic Crystal Drain Opener, you can make your own solution yet, be mindful, always add the NaOH to the water, and not the reverse. Good luck.
Last edited by Vintage Chief; January 7th, 2019 at 01:46 PM.
I don't remember if it was here on CO or not, but I once saw an intake that had been cleaned and repainted to look like an aftermarket aluminum unit and it looked SHARP! Just a thought...
Ended up soaking the manifold in mineral spirits for a week and them power washing it. I then applied a POR-15 rust preventive coat and then a layer of their Olds Gold engine enamel. The pic below is was is looked like after I painted it, since then I've removed the masking tape, chased the threads and honed the mating edges for the gasket. Just waiting on a set of bolts now. Thank you all for your advice!
Looks good. Glad you posted a picture. I was curious what your 1973 intake manifold looked like compared to my 1971 intake manifold. Is your 1973 intake manifold going on top of a 1971 350 sbo?
EDIT: I just looked at your other posts & answered my own question. It's going onto a 1971 350 sbo.
Last edited by Vintage Chief; February 19th, 2019 at 05:32 AM.
Looks good. Glad you posted a picture. I was curious what your 1973 intake manifold looked like compared to my 1971 intake manifold. Is your 1973 intake manifold going on top of a 1971 350 sbo?
EDIT: I just looked at your other posts & answered my own question. It's going onto a 1971 350 sbo.
I'm more or less tracking your threads/progress since we have some similarities in vehicle/engine. So, to validate, you purchased a 1971 CS w/ a sbo 2bbl carb which you stated was 4 banger trans (but is really a 3 banger) which you planned to upgrade to a 4-barrel manifold and carb to fix a vacuum leak and increase airflow. You were searching for a 1971 4bbl intake manifold & carb. You purchased the 4bbl carb, the 4bbl intake manifold was not available. You then obtained a 1973 4bbl intake manifold and the 4bbl carburetor you're going to stick on your 1973 intake manifold is the period correct (1973 Quadrajet 7043250).
Essentially, you have a 1973 sbo intake manifold and 1973 Quadrajet 7043250 going onto a 1971 sbo. The Quadrajet 7043250 you are going to convert to electric choke. Am I tracking correctly?
I'm more or less tracking your threads/progress since we have some similarities in vehicle/engine. So, to validate, you purchased a 1971 CS w/ a sbo 2bbl carb which you stated was 4 banger trans (but is really a 3 banger) which you planned to upgrade to a 4-barrel manifold and carb to fix a vacuum leak and increase airflow. You were searching for a 1971 4bbl intake manifold & carb. You purchased the 4bbl carb, the 4bbl intake manifold was not available. You then obtained a 1973 4bbl intake manifold and the 4bbl carburetor you're going to stick on your 1973 intake manifold is the period correct (1973 Quadrajet 7043250).
Essentially, you have a 1973 sbo intake manifold and 1973 Quadrajet 7043250 going onto a 1971 sbo. The Quadrajet 7043250 you are going to convert to electric choke. Am I tracking correctly?
Your dead on, do you see an issue that I overlooked? I was told from the person I bought the manifold and carb from that it was a ‘72. The manifold is but the carb is a ‘73 it turns out. Irked me a bit.
No issues. So the intake manifold is 1972. OK.
I have some questions and thoughts we can discuss when I get a little more time. Thanks.
Yea, I was told it was a ‘72 and the carb came off the manifold so he assumed it was a ‘72 also. I found out that it was ‘73 when I was lookong for carb rebuild kits. But yea man, ask away, ill be asking also I’m sure!
OK, when looking at the pics I didn't see an EGR port, which confused me. Now that you say it's a '72 intake it makes sense.
I wouldn't worry much about the '72 vs '73 carb issue. My 1970 Supreme had a 1971 carb on it when my Dad bought the car from the original owner in 1977 and it ran just fine for the many years that the family drove it before I got behind the wheel and started rebuilding/modifying everything I could put my hands on.
I just have some basic observations/questions/ideas, etc.
(1) Do you own a Chassis Service Manual (CSM) for your 1971 Cutlass?
(2) Do you own a CSM for a 1972 Cutlass? Your 1972 intake manifold & your 1973 Quadrajet 7043250 are going on top of a 1971 sbo and there are some subtle differences, I am noticing (to be reviewed in a follow-up post).
(3) You obviously noticed the cutout next to cylinder #3 stamping on the 1972 intake manifold (highlighted in the pictures below) you just painted. In my original posting 350 Stock Small Oil Leak (Dec 1st, 2018 - Post #21) I suggested that cutout probably was a modification/repair to a cracked intake manifold (between cylinders #3 & #5); as it appeared someone probably sought to contain a crack & arrest possible elongation of the crack? No one responded to my suggestion and I don't know why that intake manifold bolt location has a cutout in the intake manifold.
I am curious if anyone reading this thread knows why that cutout exists? It's obviously on my OE 1971 intake manifold, and it's obviously on the 1972 intake manifold you just painted - why does it exist, what is its purpose?
I just have some basic observations/questions/ideas, etc.
(1) Do you own a Chassis Service Manual (CSM) for your 1971 Cutlass?
(2) Do you own a CSM for a 1972 Cutlass? Your 1972 intake manifold & your 1973 Quadrajet 7043250 are going on top of a 1971 sbo and there are some subtle differences, I am noticing (to be reviewed in a follow-up post).
(3) You obviously noticed the cutout next to cylinder #3 stamping on the 1972 intake manifold (highlighted in the pictures below) you just painted. In my original posting 350 Stock Small Oil Leak (Dec 1st, 2018 - Post #21) I suggested that cutout probably was a modification/repair to a cracked intake manifold (between cylinders #3 & #5); as it appeared someone probably sought to contain a crack & arrest possible elongation of the crack? No one responded to my suggestion and I don't know why that intake manifold bolt location has a cutout in the intake manifold.
I am curious if anyone reading this thread knows why that cutout exists? It's obviously on my OE 1971 intake manifold, and it's obviously on the 1972 intake manifold you just painted - why does it exist, what is its purpose?
Vintage Chief,
(1) Yes, I do.
(2) No I do not, but the carb rebuild kit came with measurements for multiple engines for multiple years that the carb can adjust to. I plan on going with '71 specs first to test and then tune and tweak as I go.
(3) I have noticed the cutout but I have no clue what its purpose is. I assumed it had a corresponding tab on top of the engine so nobody could not install the manifold backwards but now that I know that it does not have that, I have no idea.
There are a couple subtle differences you'll need to accommodate - nothing overburdening or difficult. My observations are only that - observations. My suggestions/ideas are only that - suggestions/ideas to assist you in thinking outside the box as you move forward. They're not to be taken as expert knowledge, but consider them more as things to be mindful of.
I think your upgrade from the original 2 bbl carb/intake manifold>4 bbl carb/intake manifold was a good choice.
I'm going to put together a couple of images and highlight those differences so we have some common discussion points moving forward.
You originally had a 1971 2bbl carb on a 1971 2bbl intake manifold (I assume); therefore, when you view your original 2bbl carb & 2bbl intake manifold (if you still have them), you might notice some subtle differences in ports & vacuums compared to a 4bbl Quadrajet & a 4bbl intake manifold. Additionally, your Quadrajet 7043250 (correct for a 1973 sbo 350 intake manifold) may or may not be similar to a model correct 1971 Quadrajet 7041250 - the correct Quadrajet for a 1971 sbo 350. Again, these are only talking points.
My Quadrajet is a model 7041251 - correct for a 1971 bbo 455; yet, I have it installed on my 1971 sbo 350. I don't know if there was any significant changes to these Quadrajets other than the jetting. Yet, you should be aware there may be differences other than internal jetting on your 7043250.
Therefore, consider the intake manifold you have is for a 1973 sbo 350. I don't know what the differences, if any, were between 1971 and 1973 regarding the availability of intake manifold vacuum ports and any internal changes in casting; yet, I see a couple things on your 1973 intake manifold which will simply need to be accommodated - I'll point these out in the images to follow.
Last edited by Vintage Chief; February 20th, 2019 at 10:24 AM.
At the end of the day, these are nothing more than intake manifold vacuum inlets w/ accompanying nipples. The availability of these inlets on your 1973 intake manifold compared to my 1971 intake manifold appears different in only one regard - you have one less intake manifold vacuum inlet (identified in red). Although, there may exist a slight difference in the sizing of your vacuum inlets. Whether this has any significance is going to depend on the required vacuum ports on your carburetor, whether you use the TVS/DVCS system, single vs. dual air cleaner PCV valve configuration, location of your Power Vacuum Cylinder, location of your Transmission Modulator vacuum line & whether you are venting your Fuel (Charcoal) canister vent.
Again, only discussion points but considerations once you reinstall the intake manifold.
(3) I have noticed the cutout but I have no clue what its purpose is. I assumed it had a corresponding tab on top of the engine so nobody could not install the manifold backwards but now that I know that it does not have that, I have no idea.
No other CO user (reading this thread) has suggested what the cutout is for. So, I'm going to take a SWAG - obviously, a SWAG.
In the early 1970s, there weren't many assembly line robots, as there are today. Most (automotive) assembly lines would have employed electric overhead pulleys for many of the assembly lines for many of the various items required to assemble a vehicle. Alignment key ways of any type would have allowed for rapid positioning & assembly. I might imagine at a particular assembly line station (after the cylinder heads were bolted on), after the turkey tray intake manifold gasket was put in place, or just prior to placement of the intake manifold, someone quickly inserts/drops in a steel dowel-rod into that cylinder head bolt hole (maybe a rod ~4"-5" in length/tall). As the worker maneuvers the intake manifold into position from the overhead pulley, the worker easily & quickly finds the correct position of the intake manifold since the cutout provides a reference point (alignment key way) for positioning. Just a SWAG.
I am curious if anyone reading this thread knows why that cutout exists? It's obviously on my OE 1971 intake manifold, and it's obviously on the 1972 intake manifold you just painted - why does it exist, what is its purpose?
1971 Intake Manifold Cutout - Zoom
Norm, the factory purposely sized this slot very close to the bolt diameter. During installation, you put the first bolt in that position and it axially aligns the manifold ports to the head ports.
Norm, the factory purposely sized this slot very close to the bolt diameter. During installation, you put the first bolt in that position and it axially aligns the manifold ports to the head ports.
I suspected that was most likely the case as I stated above (Post #35):
No other CO user (reading this thread) has suggested what the cutout is for. So, I'm going to take a SWAG - obviously, a SWAG.
In the early 1970s, there weren't many assembly line robots, as there are today. Most (automotive) assembly lines would have employed electric overhead pulleys for many of the assembly lines for many of the various items required to assemble a vehicle. Alignment key ways of any type would have allowed for rapid positioning & assembly. I might imagine at a particular assembly line station (after the cylinder heads were bolted on), after the turkey tray intake manifold gasket was put in place, or just prior to placement of the intake manifold, someone quickly inserts/drops in a steel dowel-rod into that cylinder head bolt hole (maybe a rod ~4"-5" in length/tall). As the worker maneuvers the intake manifold into position from the overhead pulley, the worker easily & quickly finds the correct position of the intake manifold since the cutout provides a reference point (alignment key way) for positioning. Just a SWAG.
Thanks Gary
On EDIT: Interestingly enough, when I slapped that 50lb intake manifold on top of the cylinder heads, I actually made a 4" tall steel dowel rod and inserted into that exact hole as I dropped the intake manifold into place.
Last edited by Vintage Chief; February 28th, 2019 at 01:40 PM.
January 4th, 2019, 12:26 PM
