620 Walt Posted February 19, 2020 Report Share Posted February 19, 2020 Building a 620 like we did in the 80s l20b peanut head ported/polished mild cam 40mm side draft Weber but engine fight starting and sounds like lawnmower when running then dies after few seconds of running any advice? Quote Link to comment
datzenmike Posted February 19, 2020 Report Share Posted February 19, 2020 Have no idea on the fuel delivery but other than that, check the firing order.... 1342 in a counter clockwise direction. Turn the distributor slightly counter clockwise, sounds too advanced. Quote Link to comment
620 Walt Posted February 19, 2020 Author Report Share Posted February 19, 2020 Thank you for your help did all that including new timing chain Quote Link to comment
banzai510(hainz) Posted February 19, 2020 Report Share Posted February 19, 2020 (edited) valve lash correct. if too tight wont start or maybe idle fire order, dist set correctly timed? 1 3 4 2 counter clock wise Fuel in carb, hear it squirting gas when you cycle the linkage. stock or aftermarket ignition???was changed? coil different? otherwise it should start if cam was timed and distributor oil pump is correct Edited February 19, 2020 by banzai510(hainz) Quote Link to comment
620 Walt Posted February 19, 2020 Author Report Share Posted February 19, 2020 Thanks for reply stock ignition and coil everything gone through rechecked think thing has grimlans lol Quote Link to comment
datzenmike Posted February 20, 2020 Report Share Posted February 20, 2020 OK before the timing chain was done did it run right??? Trying to eliminate the carbs as the cause. If it was running OK then has to be something done during the chain replacement. Quote Link to comment
620 Walt Posted February 20, 2020 Author Report Share Posted February 20, 2020 No not really when I got it engine was used for road race had to have head milled and put new timing chain both cam timing and ignition timing is dead on valve lash is supposed to be right but can't find what lash is supposed to be set at with cam size man that did head passed on cam size is 485 lift 235 duration Quote Link to comment
datzenmike Posted February 20, 2020 Report Share Posted February 20, 2020 Try 0.010" intake and 0.012" exhaust on a hot engine. These are the hot specs for the L series cam. A regrind only changes the lobe profile not the valve and rocker so they should require the same clearance. If this has never run for you it could be anything Quote Link to comment
banzai510(hainz) Posted February 20, 2020 Report Share Posted February 20, 2020 stock ignition mean stock coil sand ballast resisitor.??? sometimes they arch out if not ballast or bad condenser or a worn out bushing that causes point bounce, wiggle the dist shaft. if loose sideways then the bushing worn. If its timed maechanicall and eleltrically it should fire off. Im not a single sidedraft carb setup expert. I know my carbs are good but has this setup run before. Maybe run on a downdraft set up first to make sure its working. I do my cam 0006 and 008 cold.. but long as the rocker arm wiggles on back side of the cam then you know its closing fully to get compression Quote Link to comment
620 Walt Posted February 20, 2020 Author Report Share Posted February 20, 2020 I thank everyone for your help will try that Quote Link to comment
Stoffregen Motorsports Posted February 20, 2020 Report Share Posted February 20, 2020 More like .010"/.010" cold. Some cams like tighter lash, like .008"/.010" (intake/exhaust). Quote Link to comment
datzenmike Posted February 21, 2020 Report Share Posted February 21, 2020 I published the Nissan FSM clearances for hot setting. (0.010" intake and 0.012" exhaust ) Cold assumes that it will expand to the correct clearance while setting them hot is what it runs at. No where does it recommend a cold setting though you can if things have been replaced and you have to start somewhere..... followed by setting them hot later when running. Quote Link to comment
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