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Big Twin starting/running issue: seal intake manifold? (was Big Twin flywheel compatibility)

D

dh_user

New member
Hi all - I've had a prior thread on a 1961 40hp Lark... ruled out the flywheel, so I'm re-testing a few things.
[FONT=&quot]Hi all, a couple of updates here. I spent the morning reading some other threads on timing and carbs (and re-reading the service manuals). Really appreciate all your help and advice.[/FONT]
[FONT=&quot]1. Spark: confirmed spark with plug in boot and alligator leads from side electrode to ground.[/FONT]
[FONT=&quot]2. Points: I did see that the #2 point alignment was really sloppy (the rocker side was nice and even, but the common side was too high and also just angled wrong... I could see air space between the "closed" points and the armature plate). I took some 320 sandpaper to the common side but never got happy with it, and when adjusting the height I broke the plastic insulating layer. These are omc parts. I went back and compared that common side point to some old omc (and unused sierra) parts, and it's just no good. Swapped out, replaced, re-gapped, re-timed, and slid in a card dipped in acetone.[/FONT]
[FONT=&quot]3. Timing: I got the timing tool from Richard at classicomctools, to confirm my points were opening at the right time. All was good there, and I used that reference to mark my flywheel (I'm obviously just not seeing /feeling the factory markings, but it doesn't matter anymore because I have nice new sharpie lines now).[/FONT]
 
[FONT=&quot]Still to do :[/FONT]
[FONT=&quot]1. Sync and link: I had some slop in the carb roller cam, and I wasn't familiar with adjusting the eccentric plastic bushing, so I think the butterfly was opening late. Will pull flywheel and look at this again. I also don't yet have the stop collar on the throttle /carb link bar positioned quite right yet, so will do that while flywheel is off.[/FONT]
[FONT=&quot]2. Fuel: I'm going to take the carburetor apart, confirm float and needle seat operation, confirm open jets and passages, test idle and high speed circuits again, and make sure everything is there. It's all a brand new omc kit.[/FONT]
 
Also, would like to get the group's advice on whether the 2 intake gaskets (manifold to reed plate, reed plate to block) should be sealed or not. If yes, would you use BMP Sealer / Permatex 3, or something else?

[FONT=&quot]Potential vaccum issue: this is the first time I've opened a crank case, so I re-read some service manuals and went back to look at my photos from the process (mostly checking hardening vs non-hardening sealers, thread sealers, etc). Everything in the crank case looks right, seals are oriented correctly. Torque values are all correct. All that said, I didn't use any sealer on the intake gaskets (intake manifold to reed plate, or reed plate to block). That (and the head gasket) is the only place I didn't use gasket sealer. Every gasket on the engine is new. At the time, I read some threads, and the consistent advice was not to seal new gaskets on the intake side, but the condensed service manuals seem to indicate everything should be sealed: "the crank case and intake manifold must be completely sealed against both vacuum and pressure." What do you guys think on this one?[/FONT]
 
Yes the TWO crankcases must be sealed from atmosphere and from each other.-----Only use GEL SEAL or LOCTITE 518 on the crankcase halves to get a good seal there.
 
Thanks racerone. I sealed the crankcase halves with 518. It's the 2 intake gaskets - manifold to reed plate, reed plate to block - that I was wondering about. I put them in dry.
 
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