CAM PROBLEM

  • Tiny
  • loriphillip7
  • 1971 Holden HQ
  • 6 CYL
  • 2WD
  • manual

1971 Holden HQ 71 cam problem
sir; I have have a 71 hq holden that we have put a vk holden carby engine that has been going well, now my trouble is, after an engine freshen up and cam change [crow cam part no.35626, mechanical/solid type profile] the thing won't start. It turns over ok, tapet adjustments ok, fuel ok, carbys ok cam and crank timeing marks set right [dot to dot] but I feel its somthing to do with the ignition timeing. I've been setting no/1 cylinder on t.D.S and dropping in the dissy also set at no/1 spark plug yet it's a no go; I believe it is to do with the way im maybe setting the crank timeing marks wrong nothing else has changed, and nothing is hitting or binding.[More cam detiles; inlet opens.32 b.T.D.C closes.66 dur.278. Exhaust opens.72 b.B.D.C b.B.D.S closes.30 dur.282. Inlet lobe lift at t.D.C on overlap.085; what am I doing wrong please. Hal

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Wednesday, May 18th, 2011 AT 9:24 AM

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  • Tiny
  • KHLow2008
  • Expert
  • 41,997 posts

Have you checked the compression pressure?

Did you check the static ignition timing and ensure it is correct?

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Wednesday, May 18th, 2011 AT 1:13 PM
  • Tiny
  • loriphillip7
  • Member

Hi, Static Timing ok, compression all over the place, timing marks on cam and crank were correctly set (dot - dot) with #1 cylinder on TDC.
#6 exhaust valve is not not open, it is exactly 180 deg out, when I get my exhaust valve to open #1 cylinder is now on BDC
Looks like I have to disregard cam timing mark and work as follows: set #1 piston on TDC and install cam in such a way as #1 valves are shut and #6 valve is fully open. Never struck this before!
What do you think?

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Tuesday, May 24th, 2011 AT 4:18 AM
  • Tiny
  • KHLow2008
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  • 41,997 posts

Yes, you should revert back to the basics.

Use the valve overlapping technique. With # 1 piston at TDC, get # 6 cylinder exhaust vale to almost fully closed with intake valve just starting to open.

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Tuesday, May 24th, 2011 AT 11:37 AM
  • Tiny
  • loriphillip7
  • Member

Update: I found that the timing mark on the cam gear was 180 deg out, once that was done I set the timing visually, getting NO.6 Cylindor on the rock, engine is fine, never struck that before. Thank you all for your help, you do a great job there.
Cheers

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Wednesday, August 17th, 2011 AT 4:43 AM
  • Tiny
  • KHLow2008
  • Expert
  • 41,997 posts

Glad to know you have fixed the problem.

Have a nice day.

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Wednesday, August 17th, 2011 AT 12:51 PM

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