Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 21
  1. #11
    Join Date
    Sep 2007
    Location
    Hilperton,Wiltshire
    Posts
    2,613
    You mentioned that your valve seals have gone. What makes you suspect that?

    Andy

  2. #12
    Join Date
    Mar 2020
    Location
    Norfolk
    Posts
    26
    Quote Originally Posted by corn plaster View Post
    You mentioned that your valve seals have gone. What makes you suspect that?
    There's a bit of oil smelling smoke on start up, and an embarrassing amount at start up once the engine is hot and restarted after a few minutes of standing. It clears, but on a 200ml drive is using a bit of oil. The engine builder came round and strongly suspected it's valve seals.

    I'll have a word with him about the heads, was going too anyway, but wanted to get some other opinions beforehand.

  3. #13
    Join Date
    May 2004
    Location
    Cowbridge, United Kingdom
    Age
    62
    Posts
    10,102
    Hi 911, Do we gather that your car is already registered and on the road?
    Kev Davies
    South Wales Area Rep. UKCC Membership Secretary
    DAX Mk4, 383 Chevy Stroker, Tremec. SOLD
    Contemporary CCX 3-4028, 445ci Big Block FORD FE,TKO 600, Old School IVA'd and SOLD
    Dax De Dion LS2 and T56 IVA'd June '17 SOLD
    1965 Ford Mustang 289 Convertible SOLD
    In build- Hawk 289 Sebring Awaiting IVA

  4. #14
    Join Date
    Mar 2020
    Location
    Norfolk
    Posts
    26
    Yep been on the road since the late 90's . . . sorry should have made that clearer

  5. #15
    Join Date
    Jan 2006
    Location
    Chelmsford Essex
    Posts
    1,363
    A good indicator is the state of your spark plugs. If your valve guides are worn they will be blacking up and exhaust pipe black. Burning oil could be other reasons ( piston rings) but as you say on start up your seeing smoke. Quick compression test will also give you a good guide the state of pistons and valve seating if wear is occurring.
    Dax 351 Cleveland T5 2.88 PL

  6. #16
    Join Date
    Feb 2011
    Location
    Northampton
    Age
    42
    Posts
    4,300
    Quote Originally Posted by early_911 View Post
    I'll have a word with him about the heads, was going too anyway, but wanted to get some other opinions beforehand.
    I was just chatting to Clive about your heads - well, actually I was chatting to him about my engine but we got onto the topic of other Cobra related stuff he's doing - I'd grab a set of Eddy, Dart or Trick Flow heads; I think Clive is probably most familiar with Eddy heads but no doubt he'll have some advice there (for what it's worth he said "Yeah, I'd just grab a set of Eddy heads" to me). That and some Googling and you can find a lot of tests of head vs head (Trick Flow seem to come out with the best torque, Eddy as best bang-for-buck, Dart are generally expensive). Whatever you get, it's best to have someone go through them and make sure everything is just-so before you put them on, though.

    BTW, does it smoke on overrun? That's another classic symptom of stem seals (the OHs BMW MINI was simply embarrassing on the M25 until I did the stem seals!).
    My DeDion build diary..
    Hon Sec of the Digidash branch of the Unpopular Kit Car Design club

  7. #17
    Join Date
    Aug 2007
    Location
    Bournemouth
    Posts
    383
    Just mirroring a couple of points already stated.
    A 383 generally utilises a bespoke crank or some people have used a crank from a 400ci, but I believe there could be problems with this crank setup. Also a rebore to 0.030” and new pistons to match. The camshaft has nothing to do with engine displacement.
    Signs of obvious valve stem seals leaking is a belch of smoke on first start up. The longer the car has sat in the garage, the more of a belch. Spark plugs colour in this instance won’t necessarily show problems with the valve stem seals unless the car has been started then stopped very shortly afterwards.
    Once the car is warmed through and through normal driving you may not get any smoke out of the exhaust due to stem seals. However if you use the gearbox to slow down then accelerate away sharply, a puff of smoke will indicate dodgy stem seals.
    If your valve guides are worn then you may get irregular compressions on a cylinder during a compression test. The needle may jump around in an odd fashion as the valve will sometimes seat properly, and sometimes not. Constant smoke will also indicate worn guides.
    If you have overheated your engine lately then depending on the duration, rubber components within the engine will suffer, especially valve guide seals. They will harden up and can fall apart.

    Be careful with your choice of ally heads. There are a lot of reproduction items out there which are of very inferior quality. Buy them from a reputable supplier. You will pay more but eBay items in my opinion, unless you know exactly what you are looking at should be avoided.

    Just my 2d’s worth.

    David.
    Life is driving the Cobra. The rest of the time is just waiting.

    Wessex region caretaker rep.

  8. #18
    Join Date
    Mar 2020
    Location
    Norfolk
    Posts
    26
    I've taken the heads off (well one side so far).
    They are numbered 333882 which having done a bit of research appear to be pretty cr+p. Considering the hassle of taking them off I've decided, now is the time to upgrade to aluminium. Any comments on my cylinders?

    20201018_155230 by Philip Johnson, on Flickr

    20201018_155246 by Philip Johnson, on Flickr

  9. #19
    Join Date
    Jan 2006
    Location
    Chelmsford Essex
    Posts
    1,363
    Later 882 heads have hardened induction seat valves so not all.bad news. They have 76cc chamber low compression and flow ok.
    Thin casting so check for cracks between valves.
    Going to a larger intake 2.02 valve head would up the flow and hp. Just consider one up grade usually leads you to more.
    Stroking gets you big bang for bucks you cannot beat cubin inches.

  10. #20
    Join Date
    Aug 2007
    Location
    Bournemouth
    Posts
    383
    I had similar heads and swapped them out for my current ones. I cant remember the casting numbers but they are 64cc, 1.6" exhaust, 2.02" induction. I worked this out to be about 10.3:1 CR. My next step is also to go to aluminium heads but with larger ports to allow it to breath a little easier. Was considering a single plane induction manifold but this may be a little too racey for the application.
    A Holley 650 vacuum secondary would would well with my engine with ally heads.

    Cheers,

    David.
    Life is driving the Cobra. The rest of the time is just waiting.

    Wessex region caretaker rep.

Page 2 of 3 FirstFirst 123 LastLast

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •