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Removing Air Tubes From Manifold ?

This is a discussion on Removing Air Tubes From Manifold ? within the Exhaust (S30) forums, part of the 1st Generation Z (S30) category; Now that the engine is out and on the engine stand, I'm planning to remove the air tubes from the ...


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    Registered User Oiluj's Avatar
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    Default Removing Air Tubes From Manifold ?

    Now that the engine is out and on the engine stand, I'm planning to remove the air tubes from the exhaust manifold. As they have been in the manifold for 36 years, I expect they will be hard to remove.

    Any suggestions before I begin? Any wisdom from those who have done this?

    I plan to spray them with PB Blaster and possibly heat them with a small propane torch.

    I understand that the threads are BPT. I'm considering driling them out and making them std metric. Any thoughts on this?

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    I think i cut them off and welded them closed. i had the manifold off so i could cut them off from the inside. good luck unthreading those rusty pieces!
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
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    When I picked up the manifold I have now the car was sitting in the junkyard for the past 25 years. The fittings were pretty frozen. I heated the manifold around them up cherry red and then gabbed them with a vice-grip to cool them fast and turn to break them loose. The cooling tends to get the fittings to shrink faster than the manifold can cool which seems to help.
    72 240Z, undergoing full restoration HLS30-73866

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    Thanks! The heating / rapid cooling sounds like the right approach.

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    Personally, I was never able to get the fittings out - with any type of Penetrating oil - until I started using Kroil... With Kroil (Aero Kroil) they simply break free and turn out.
    http://kanolabs.com

    FWIW,
    Carl B.

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    I've heard very good things about Kroil. Other than Eastwood & online, do you know who might distribute/sell it? I looked on the NAPA & Parts America sites and did not see it.

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    240Z Elec. Upgrade guy Zs-ondabrain's Avatar
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    Or..... Just remove the manifold and get yourself a good flowing 6 into 1 header. Better air flow, looks better, allows for a new, bigger diameter exhaust pipe and all around better performance.

    They start at about $150.

    Dave.
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    Quote Originally Posted by Zs-ondabrain View Post
    Or..... Just remove the manifold and get yourself a good flowing 6 into 1 header. Better air flow, looks better, allows for a new, bigger diameter exhaust pipe and all around better performance.

    They start at about $150.

    Dave.
    Even though I'm not going this route with my Z, I have to agree with Dave. And not to mention it just sounds MEAN!!!

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    Quote Originally Posted by Oiluj View Post
    I've heard very good things about Kroil. Other than Eastwood & online, do you know who might distribute/sell it? I looked on the NAPA & Parts America sites and did not see it.
    As far as I know - it has to be ordered on-line from Kano Labs. But it's worth the wait, nothing else compares here in the U.S.

    I've done side by side comparisons with several other types - nothing comes close.


    FWIW,
    Carl B.

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    Quote Originally Posted by Zs-ondabrain View Post
    Or..... Just remove the manifold and get yourself a good flowing 6 into 1 header. Better air flow, looks better, allows for a new, bigger diameter exhaust pipe and all around better performance.

    They start at about $150.

    Dave.
    I have to disagree with Dave on this one as it relates to the headers.

    I haven't seen any independent dyno tests that show headers producing more power on a stock or street mod'ed engine, than the OEM exhaust manifold, when you hold everything else the same.

    In addition to better looks with the headers - you get more under hood heat, noise and usually bad fitting flanges on the cheaper headers. That usually leads to exhaust leaks, which also corrode and then blow out your studs. (cheaper being under $325.00)

    Cutting the stock exhaust pipe open at the "Y" and going to a larger diameter exhaust system, with a free flowing muffler will pick up between 12 and 15 HP. Leaving the top off the stock Air Cleaner will pick up about 5 HP.

    If your building a full race engine, and need to tune the exhaust header to specific RPM ranges... sure, go for it. Like the look of "headers" when the car is parked and the hood is up - sure, go for it.

    Want less long term hassle, less nose in the cabin while cruising, less heat under the intake manifold/carbs, less heat under the hood and against the firewell - keep the OEM exhaust manifold.

    FWIW,
    Carl B.

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    As far as I know - it has to be ordered on-line from Kano Labs. But it's worth the wait, nothing else compares here in the U.S.

    I've done side by side comparisons with several other types - nothing comes close.
    Try CRC "Knocker Loose" it is a copy of Kroil and is available anywhere that sells CRC products. It DOES work as good as Kroil.

    CRC also has a product out called "Freeze Out" (I think) that is good for "shocking" stubborn parts free.

    They also have a new version of Knocker Loose that incorporates freeze out with knocker loose!

    BTW, these products all cost at least 1/2 of what Kano charges for Kroil!

    Regards,

    Astrohog

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    My only thought is what are you guys going to do when the great powers that be. Decide you have to put all that smog gear back. With the stock manifold it is a matter of bolting the pieces back on. Yes, I do own all of them. After owning this car over thirty I can not honestly say it runs better or faster with out the smog gear. I only removed it because it took some time to find a smog pump.
    Jim
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    Still own it. Thirty plus years later.


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    Quote Originally Posted by astrohog View Post
    Try CRC "Knocker Loose" it is a copy of Kroil and is available anywhere that sells CRC products. It DOES work as good as Kroil.
    Thanks - I'll find some and try it.

    Carl B.

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    Default Got the air tubes out. Actually, it was pretty easy...

    I heated the manifold area around the tubes with a propane torch, Then, while still warm, gave them a good soaking w/ WD 40. Waited 1 hour and repeated the process. Got 2 loose, but the rest were still frozen.

    Took a cold chisel and cut the tubes off flush at the nut. I'm sure the impact of cold cutting the tubes probably helped to loosen the nuts.

    Then just put a socket on the nuts and they all turned-out relatively easily. They were stiff, but theyall came out with minimal effort. Victory!

    Now I have to get some BPS plugs. I'll try looking first in McMaster-Carr.


    Quote Originally Posted by a7dz View Post
    My only thought is what are you guys going to do when the great powers that be. Decide you have to put all that smog gear back. With the stock manifold it is a matter of bolting the pieces back on. Yes, I do own all of them. After owning this car over thirty I can not honestly say it runs better or faster with out the smog gear. I only removed it because it took some time to find a smog pump.
    It is highly unlikely that this will ever occur, there are just too few old cars to make them worth the governments effort. However, I'll still hang onto the old parts, becuase if down the road when I sell the car, someone may want to make it perfect "stock". I also have an extra smog manifold that came with the car.

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    Default Headers v. Stock Mainfold

    Quote Originally Posted by Zs-ondabrain View Post
    Or..... Just remove the manifold and get yourself a good flowing 6 into 1 header. Better air flow, looks better, allows for a new, bigger diameter exhaust pipe and all around better performance.
    Dave.
    When I spoke with the guys at Rebello, they told me that the stock exhaust manifold flows very well and would be quieter than headers. I can attest that this was the case when I put hearders on my MG, it did get louder. Also, you often lose a bit of low-end torque with headers. My bigger concern is as was pointed out, is heat under the hood.

    Later on I can always remove the stock exhaust and try MSA's 6 to 1 headers if I want more mid-range performance. I figure it would also require a better air intake system for the headers to do much good.

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    Default Exhaust Air Tube Fittings

    I did a bit of investigation and verified that the air tube fitting threads are BSPP, not BSPT, That is, they are a straight thread, not a tapered thread. They are J.I.S., but J.I.S. is a direct copy of British standard threads).

    I checked in McMaster-Carr and they have various plug forms in BSPT and BSPP in brass, 304 stainless, iron & steel. They cost about $2 each.

    So here's what I plan to do. I plan to use a BSPP hex key plug, threaded all the way to the bottom of the exhaust port. I'll apply a bit of high-temp thread sealant to assure a seal. While this would be adequate, (my being a belt & suspenders kind of guy), I'm also going to use a BSPP hex head plug to cover the hole.

    I also came-up with an alternate approach:

    I tried this on one old fitting just-for grins...

    Looking at the tube fitting, I found that the tube hole on the manifold side of the fitting is 0.203" dia. This is the perfect size for a 1/2-20 tap. I tapped the inside hole of the fitting from the manifold side with 1/4-20 threads. I coated a 1/4-20 x 1/2" threaded socket head set screw with high-temp epoxy to help "seal" the threads and inserted the set-screw into the fitting. I then used a moto-too to grind the tube sticking from the hex-head side of the fitting flush and dabbed a bit of epoxy on to look more "finished".

    I'm not going this route because the fittings are quite rusted and the hex heads are rounded, but it is a viable alternative.

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    I'd just put the manifolod in my drill press and drill them out and tap them to whatever thread that would be easy to find plugs for and not worry about BSPT or BSPP. But that's just me.
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    Quote Originally Posted by sblake01 View Post
    I'd just put the manifolod in my drill press and drill them out and tap them to whatever thread that would be easy to find plugs for and not worry about BSPT or BSPP. But that's just me.
    I considered that as my best back-up solution, one I would have used in preferrence to tapping the original fittings with the 1/4-20 plug option. Getting the correct fittings from McMaster is less work. Call me lazy... *grin*

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    Oh, I don't know, maybe I'm the lazy one. If I drill them out on the press, I don't have to deal with removing them. Removing them would save the threads but it's harder to do than drilling them on a press. Besides we don't have a McMaster around here, we have Fastenal and they don't have a clue about BSPT.
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    I phone ordered from McMaster. They typically ship the same day and are a great source for anything mechanical.

    Here's the link: http://www.mcmaster.com/

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    Default Pics of Exhaust Air Tube Plugs

    Here's a pic of the exhaust air tube plugs I got from McMaster-Carr. They are 1/4" BSPT hex head and I think they look pretty nice.

    With that big hex head, I'll be able to remove them if required...
    Attached Thumbnails Attached Thumbnails Removing Air Tubes From Manifold ?-air_plugs.jpg  

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    My mind goes weak with age... I just did this with my son on his L20B manifold in the 510 Wagon... I had pipe plugs and a tap that went RIGHT into the factory straight threaded holes. Now, I preface this by saying I MAY have had a 'flushseal' tap and plugs laying around because these babies threaded right in and went in flush, and looked slick. I know I used liberal amounts of nikel-based anti-seize so if they need to come out later....

    Now, I also found some Toyota Bolts that threaded in as well, so there has to be a metric threaded plug (or metric setscrew) that will screw in similarly and then can be locked in using a 'staking' technique.

    As for headers-vs-manifolds...like Carl said, unless you are tuning for a peak at a specific rpm (we altered primary lengths considerably on our L20A Bonneville Racer to get our peak right where we needed it, cut almost 5" out of the primaries!) the stock manifold, ported and cleaned of casting irregularities will function VERY well even on relatively hot motor builds. The 79 L20B manifold my son and I just put on his car had a 2.5" headpipe hole, with only about 75% of it open due to a HUGE cast-in restriction bump. Took it out altogether, and really lightened up the manifold in the process. A little port matching and bump removal at the exhaust ports as well made it look really 'flowey'... If this performs like a similarly cleaned up N42 Manifold on my 75 Fairlady Z 2/2, I think he will be very happy with the results. And the best thing: "IT ALL LOOKS STOCK"!

    When the CHP pulls you over for a roadside emissions compliance check LOOKING STOCK becomes a VERY good thing!

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    Quote Originally Posted by sblake01 View Post
    Besides we don't have a McMaster around here, we have Fastenal and they don't have a clue about BSPT.
    Hey! McMaster is over in Norwalk... And if you order first thing in the AM, it will make their 9AM UPS Ground shipment...the parts will be at your door by 6PM that SAME DAY!

    At least they come to me in Perris/Moreno Valley that way... And that's only if I'm not driving down the 605 any time during the week.

    Fastenal is no substitute for the cornucopia this is McMaster-Carr.

    And if you want the stuff in Stainless, Mc-Fadden-Dale Hardware has an outlet in Ontario, and Corona. They got EVERYTHING hardware related! Flushseal/Dryseal plugs (and the taps), button-headed stainless steel metric machine screws (think M6X1.0 and you go "Ooooh! Tasty!") Right off the 91 at Maple St, or off the 60 or the 10 at Grove, just south of Mission...

    Oh, and McFadden-Dale stocks Kroil in spraycans, as well as gallon cans. They also have (believe it or not) COSMOLINE! Want to store some parts????

    SanBerdoo ain't Trona! Don't be that way!
    Last edited by Tony D; 03-03-2008 at 11:30 PM.

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    Anyone that owns a Z should have some kroil. I have been using the same spray can for years and it is the best I have ever used. PB Blaster comes in secound but it smells like he##. KANO Laboratories kanolabs.com Headers vs. OEM exhaust elimination of back pressure, or not is a topic for a different thread.
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    Quote Originally Posted by Tony D
    SanBerdoo ain't Trona! Don't be that way!
    I actually know where Trona is! I had the pleasure (!) of spending some tine at Fort Irwin back in the early 70s.
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    Quote Originally Posted by Tony D View Post
    When the CHP pulls you over for a roadside emissions compliance check LOOKING STOCK becomes a VERY good thing!
    Kinda off topic, but, what is the year limit on emissions in California? In Washington, if your Basic Vehicle (passenger cars, truck, vans, SUV - under 8501 LBS) is 25 years old or older, you're Exempt from the emissions check.

    Just wondering, in case we ever move to SoCal or something.

    Dave.

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    Quote Originally Posted by Zs-ondabrain View Post
    Kinda off topic, but, what is the year limit on emissions in California? .
    In California, (from the DMV web page), model year 1975 and older for vehicles less than 14K pounds.

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    Quote Originally Posted by Zs-ondabrain View Post
    Just wondering, in case we ever move to SoCal or something.
    No smog tests in Oregon if you are outside the Portland metro area, and not in Jackson County (Medford/Ashland). The rest of the state is free of such things.
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    Quote Originally Posted by Oiluj View Post
    In California, (from the DMV web page), model year 1975 and older for vehicles less than 14K pounds.
    Oh, don't get me started on that policy. I have been waiting 7 years for 1976 model years to be exempt. (they discontinued the 30+ year rolling exemption 3 months before my 76 would have been exempt - barstards!!!)
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    The exemption is for TESTING only.NO emissions equiptment may be removed from ANY vehicle.

    And people ask why i left that Gestapo run state.
    Faster than anyone in Oceanside

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    Oiluj, Do you happen to have the McMaster part number. I've been digging around on their web site and all I find is BSPT taps and dies, no bolts.

    Thanks!
    The boys have theirs, I got one too. 71 & 73 240Z, 1985 300ZXT

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    You can get Aero Kroil direct from Kano Labs 1-800-311-3374

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    you can get Aero Kroil direct from Kano Labs 1-800-311-3374

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    Default Air Plug Part Numbers

    Quote Originally Posted by Ttiger View Post
    Oiluj, Do you happen to have the McMaster part number. I've been digging around on their web site and all I find is BSPT taps and dies, no bolts.
    McMaster-Carr p/n 4810T192 1/4" BSPT Hex Head Plug, 304 S. Steel - $2.10 ea

    or if you prefer

    McMaster-Carr p/n 4810T182 1/4" BSPT Square Head Plug, 304 S. Steel - $2.22 ea

    If you go to the McMaster-Carr website, type in the p/n in the upper box for the catalog page with pictures.

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    So, is the consensus stock manifold?

    The PO of my 76 L28 had cut the tubes off at the nut and filled with epoxy. I've got an extra manifold that I'm grinding off the nuts and will braze the hole from the port side. and will replace the current manifold.

    Is this a reasonable approach?

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    definately use PB blaster(Walmart) religiously. Kroil is my secret weapon, but it's expensive. I picked up a can at an industrial equipment supplier for like $10. It has never let me down so its worth it.
    240Z

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    Default More on header v stock manifold

    I am currently cleaning up a 73. I have to do the exhaust - it's about to turn to dust and looking down the road I am thinking about a street (midrange) cam, so working backward I figured I should start with a header and a 2.5 exhaust in order to acount for the future intentions.
    Anyway I just ordered a coated header 3-2 and 2.5 turbo exhaust at MSA. Now I am scratching my head (top my shoulders - NPI), after reading this thread and Carl's comments.
    Hope I did the right thing - shipping was over $100. Sucks to have to order everything cross country.

    *A local circut racer cut the tubes close to the studs and crimped the tubes closed. The car was not used extensively after that so I can't say how well it worked out.
    Cali 4/77
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    FA 90 300TT
    C220 Mercedes 96 (DD)

  38. #38
    Registered User vercingetorix's Avatar
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    "Cutting the stock exhaust pipe open at the "Y" and going to a larger diameter exhaust system, with a free flowing muffler will pick up between 12 and 15 HP. "

    Mr Beck,
    What exactly did you mean by this? Are you referring to the divder in the neck of the exaust manifold itself or something further down the tube?
    I've never seen a stock setup so forgive my ignorance,
    Best,
    H Houghton
    9/70 HLS30-10734

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    ZCCIV Webmaster motorman7's Avatar
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    Quote Originally Posted by Oiluj View Post
    Here's a pic of the exhaust air tube plugs I got from McMaster-Carr. They are 1/4" BSPT hex head and I think they look pretty nice.

    With that big hex head, I'll be able to remove them if required...
    Just for reference, anyone planning on tapping the holes out to install the original air galley should use the -19 BSPP tap. The BSPT will not go deep enough to allow you to start the threaded fittings of the air galley. Unfortunately, I ordered the BSPT tap and the fittings will not start into the holes. Got out my calipers and found that about half way up the tap, the thread max OD is 0.537. The air galley fittings are 0.542 OD and will not thread into the smaller diamter. The upper portion of the tap is 0.545, so that part will work. I will take a die grinder to the tap this afternoon and cut-off the lower, smaller diameter portion of the tap. This should make it possible to tap the hole to the right diameter, instead of popping another $20 for the BSPP tap. The tap can be purchased from McMaster-Carr as discussed earlier here.

    HLS30-02614 in the Cocoon
    HLS30-40147 Very Yellow Daily Driver
    HLS30-40498 Next resto
    SPL311-27444 It lives
    http://www.rcdeng.com

  40. #40
    ZCCIV Webmaster motorman7's Avatar
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    Cut the bottom 1/3 of the BSPT Tap and it worked perfect. Was able to run tap all the way into the hole. Attached the air galley into the manifold using some anti-seize copmpound for lube. Will install assembly in Silver Z today or tomorrow.
    Attached Thumbnails Attached Thumbnails Removing Air Tubes From Manifold ?-bspt-tap-air-galley.jpg  

    HLS30-02614 in the Cocoon
    HLS30-40147 Very Yellow Daily Driver
    HLS30-40498 Next resto
    SPL311-27444 It lives
    http://www.rcdeng.com

  41. #41
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    Quote Originally Posted by motorman7 View Post
    Just for reference, anyone planning on tapping the holes out to install the original air galley should use the ”-19 BSPP tap. The BSPT will not go deep enough to allow you to start the threaded fittings of the air galley. Unfortunately, I ordered the BSPT tap and the fittings will not start into the holes. Got out my calipers and found that about half way up the tap, the thread max OD is 0.537”. The air galley fittings are 0.542” OD and will not thread into the smaller diamter. The upper portion of the tap is 0.545”, so that part will work. I will take a die grinder to the tap this afternoon and cut-off the lower, smaller diameter portion of the tap. This should make it possible to tap the hole to the right diameter, instead of popping another $20 for the BSPP tap. The tap can be purchased from McMaster-Carr as discussed earlier here.
    Was there a reason you had to tap the holes at all? Wouldn't the new air galley bolt right in?
    I just sent out my exhaust mainfold to be ceramic coated and I was figuring I may need to tap the holes once I got it back so your experience with the tap will be very helpful.

  42. #42
    Registered User Kurbycar32's Avatar
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    I just cut the air tubes out and welded the holes shut. After grinding down the welds and repainting with exhaust paint the thing looks like a new stock part
    Early 1974 260z
    https://sites.google.com/a/thecomputerrehab.com/260z/

  43. #43
    Furthur GreenZZZ's Avatar
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    When I did mine, I found bolts, not plugs. I locktight'd them in, cut them with a cutting disk on a dremmel and ground them down with a grinder. After which I painted with POR-20. Pretty happy with it...

    Lee - 2/72 240Z

    Thinking ahead is NO EXCUSE for thinking!

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    My brother-in-law (84 Corvette, 56 Ford Pickup) works for Zep, and he gave me this product called Groovy and it works great. I took my 10/70's brake lines apart with it with no kinking! Just sprayed a little on it the night before, went back the next day shot a little more and whola, like a hot knife through butter.

  45. #45
    Formerly known as Koalia Reverend's Avatar
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    Quote Originally Posted by GreenZZZ View Post
    When I did mine, I found bolts, not plugs. I locktight'd them in, cut them with a cutting disk on a dremmel and ground them down with a grinder. After which I painted with POR-20. Pretty happy with it...

    Is that the "original" colour of the manifold? I've been planning to paint it with something, just dont know with what. Its rusty-poo'ish looking now.
    -72 240Z "Goldie"

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    Furthur GreenZZZ's Avatar
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    Quote Originally Posted by Koalia View Post
    Is that the "original" colour of the manifold? I've been planning to paint it with something, just dont know with what. Its rusty-poo'ish looking now.
    The POR-20 looks almost identical to the color of the steal when it comes out of the sand blaster, so I guess its a bare steal look. You have to cure the paint so I popped it in the oven when the wife was out running errands, then ran a self clean cycle... "Hey honey, I cleaned the oven!"


    Lee - 2/72 240Z

    Thinking ahead is NO EXCUSE for thinking!

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