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Thread: Not sure if this is the right forum or not...

  1. #1
    Registered User 87_355_Blazer's Avatar
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    Not sure if this is the right forum or not...



    First the good news, the new motor in the blazer seems to run pretty well. Now the bad, the brakes aren't doing so well. They were fine before the swap, not "great", but definitely got you stopped.

    My gut feeling here is that the booster was maybe marginal to start with, and now with the slightly lower vacuum from the XE 274, it's just not enough. Here are the symptoms: For the first half of the pedal travel, everything seems normal. After that point, the pedal gets hard as a rock, and you just keep going. I did throw another master cylinder on it today, and that wasn't it. I'm also not losing fluid anywhere, and the brake warning light isn't coming on.

    As a refresher, here is the system: 87 S-Blazer 2wd stock brake system except for 87 IROC rear disks

    I'm getting about 15 inches of vacuum at idle with the 274, anyone else having issues with this cam, and power brakes?

    -- Brad

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    sounds like ur booster is a little weak or ur calipers might be sticking at a certain point..somehow ur brake pedal might be out of adjustment and the hardness u are feeling is the end of pedal travel

  3. #3
    STREET SPEC KUSTOMS ridenlow's Avatar
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    How big is the cam, because my brother had to put a vacuum cannister on his camaro with a .501 lift
    Drive 'em low..Drag 'em hard
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  4. #4
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    I don't have problems with the XE274 in my 350. Check the booster and also check for vacuum leaks.

  5. #5
    Registered User oldcarguy85's Avatar
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    could just be the check valve maybe. on the booster
    1988 s-15 jimmy
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  6. #6
    Registered User 87_355_Blazer's Avatar
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    I am leaning toward a bad booster at this point. The brakes were working fine before the swap, but now they just aren't cutting it. That would tend to rule out any sort of pedal problem I think. Nothing was taken apart there anyway...

    I checked vacuum, and got 15 inches at idle, so I really don't think there are leaks. Seems to run pretty strong as well, so that would seem to rule it out.

    The comp 274 really isn't all that much cam. .490 lift.

    I appreciate the input though, keep it coming...

    -- Brad

  7. #7
    Registered User oldcarguy85's Avatar
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    did u do the back brake swap before or after the engine swap?
    1988 s-15 jimmy
    500hp 383
    700r4
    4.10s posi

  8. #8
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    Try some 1.6 ratio rockers. Livened my motor up quite a bit. Did you ever have teh engine backfire through teh carb??? Sometimes that can hurt the vacuum diaphram in the booster.

  9. #9
    Registered User 87_355_Blazer's Avatar
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    Originally posted by oldcarguy85
    did u do the back brake swap before or after the engine swap?
    The brake swap was done by the previous owner, and I've had the thing for like 3 years now.. cleaning up his mistakes. So, in short... the swap was definitely before the new motor...

    -- Brad

  10. #10
    Registered User 87_355_Blazer's Avatar
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    Originally posted by knudsonm
    Try some 1.6 ratio rockers. Livened my motor up quite a bit. Did you ever have teh engine backfire through teh carb??? Sometimes that can hurt the vacuum diaphram in the booster.
    I may actually try some 1.6 rockers at some point down the road. At this point though, I'd be real happy just to be able to drive the thing without mortal terror I won't be able to stop.

    There haven't been any sort of backfires though that I can remember. Actually, now that you mention it... I may have had a small one with the old motor right before we pulled it. Hmm... leaning more towards a bad booster all the time.

    -- Brad

  11. #11
    Your mom's box! slammins15's Avatar
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    I am not sure if you have this or not but with the disc brakes in the back from a camaro you also need the master cylinder from a disc brake setup.
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  12. #12
    Registered User 87_355_Blazer's Avatar
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    Weird, I just tried to add a reply, and nothing happened. Oh well...

    with the disc brakes in the back from a camaro you also need the master cylinder from a disc brake setup
    I have heard this too. I don't want to come off as argumentative, just ignorant and confused. I see people getting the advice to use the camaro MC, but I also see on other forums where guys are running S-10 masters on older GM stuff with 4 wheel disks. Makes no sense to me.

    That aside, those pass. side lines from the camaro cyl look like a giant pain to deal with. I've also heard that the line sizing is not the same. Can anyone point me to some detail on this swap that explains that? Or possibly, better yet.. explain why guys that put 4 wheel disks on a 68 camaro or 70 GTO would choose an S10 MC out of all the available GM stuff, and why you would want to swap the S10 cylinder for the F-body deal on an S10? :confused:

    -- Brad

  13. #13
    Your mom's box! slammins15's Avatar
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    I never said it had to be a MC off a camaro I said off a disc brake setup.I think my mechanic also said something about the lines also being different but can't remember clearly
    Last edited by slammins15; 10-13-2003 at 11:13 PM.
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  14. #14
    Registered User 87_355_Blazer's Avatar
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    Ok, I just wasn't aware of a 4 wheel disk S-10 master, at least not one with the standard fittings like my S-truck. Am I wrong on that one?

    This stuff is really confusing the hell outta me...

    I am getting some advice to just adapt all F-body stuff from the firewall out, other advice that the S10 booster/cyl should be fine, just put an adjustable prop valve in there, still more advice that I should use a S10 booster/F-body master, and the list goes on and on.

    Truthfully, at this point I wish it just still had the stock drums on the back. These things have been a pain since just about day one. I hate to rip the stuff off there and move backwards to a drum setup in back though... just seems well -- wrong.

    -- Brad

  15. #15
    Your mom's box! slammins15's Avatar
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    Do you have aim chat? I am slammins15 talk to me there if you want
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