Mechanics

CAM PROBLEM

1971 Holden HQ • 6 cylinder 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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Loriphillip7
May 18, 2011.




Have you checked the compression pressure?

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

KHLow2008
May 18, 2011.
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?

Tiny
Loriphillip7
May 24, 2011.
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.

KHLow2008
May 24, 2011.
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
AD

Tiny
Loriphillip7
Aug 17, 2011.
Glad to know you have fixed the problem.

Have a nice day.

KHLow2008
Aug 17, 2011.

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