fastivab6tg25mr

Looking for a bit of advice. I've been building an FE3N DOHC 2.0Lfor about 2 years. Lots of set backs and parts availability problems. Bottom end is done, head is done. Set my valve clearances and doing my final checks before assembly. The motor is non-interference from the factory. I have .360" lift intake and .420" lift on the exhaust on the new cams which gives me 1mm(.040") clearance of the intake valve fully opened to the piston @tdc. The exhaust valves contact the piston. With the timing belt on the clearance is over .250"

With the cam profiles as they are the cams lightly spring towards each other on the compression stroke causing the timing belt to slacken between the gears. It looks like it will add up to repeated shock load of the belt which will lead to failure. I have so much time and money into this engine that I'd really like to err on the side of caution and keep the engine non-interference.

From what I see I have 2 options.
1. A .060"(1.5mm) thicker head gasket which would make a total of .120"( 3mm) thick which seems really thick to me. The plus side is no machining, down side is compression ratio loss and waiting another 3 months for a custom head gasket.

2. Pull the pistons and mill the exhaust valve pockets .060" deeper. Plus side is it's the cheapest and fastest option. Less loss of compression ratio. The down side is theres a risk of damaging the piston. Wiseco is closed till Jan 3rd so I'd still need to double check with them that the dome is thick enough that cutting the pockets deeper wouldn't compromise the strength.

Gee Emm

Isn't this the function of a cam tensioner? I assume that engine has one, and that would be my first port of call in addressing this issue. - I'd check the spring and/or hydraulic action, especially any bleed or relief valving, maybe see if the spring can be replaced with a heavier one?.

I assume this is you turning the engine over by hand, a running engine will have totally different dynamics. I don't know, but I suspect that the 'problem' you see now will disappear when the engine is running, but I would defer to someone with more expertise in valve train behaviour if one surfaces here.

curly

iTrader: (25)

It’s typically done with a torqued head, TDC, rotating the cam. So a scenario you’d only see with a broken belt.

if I’m honest, you picked a difficult engine with little aftermarket support, don’t get me started on the chassis it’s in. So the answer to any of your issues will probably be difficult in one way or another, this is sort of a pick your poison scenario. Choose time (HG) or labor (pistons).

or option 3: send it.

fastivab6tg25mr

Verified there's plenty of room for machining the pockets deeper from Wiseco. I ordered an angle plate for my Bridgeport mill that will be here Monday. Can't wait to actually finish this engine.