1776 down on power

[gagvanman]

As stated my 1776 has been down on power for some time, even to the point I was wondering if it really is a 1776.

Took the engine out and carried out a "leak down" test, all 4 cylinders are showing about 20% leakage, but as I was testing I noticed that if I put my rubber gloved hand on the barrel the glove would start to fill with air. So checked the heads and some of the bolts on both sides were not torqued down.

Off with the heads and checked the stroke and bore (69 x 90.5) so at least I know I have a 1776. Can't see any cracks but they need a full clean yet.

I also have low oil pressure at low revs when the engine is hot, so my dilemma now is do I strip it down fully to check bearing etc?

The heads are standard valve sizes, so also contemplating going for 40 x 35.5 heads.

 

[gvee]

I wouldn't be tearing it all down yet.
Torque the heads back on (follow the bolt order in the manual) and run a compression test to at least narrow down if one of the cylinders is problematic first.

Also; I wonder with your head bolts being loose might be a sign of the studs being lose in the block? Might be worth checking that you cannot move them at all with a pair of pliers.

 

[K@rlos]

If the heads were loose that’s not going to do it any favours. While they’re off, Check the valves aren’t leaking, re lap the barrels to the heads and fit, torquing the heads accordingly then do a compression test.

What’s the spec of the engine? A mild 1776 should be making at least 90 horsepower with stock sized valves. Personally I’d be looking into the oil pressure issues, check plungers, is it idling at the right speed? get a mechanical gauge and put it in the pressure switch port to see it where it’s at.

 

[gagvanman]

Thanks for the advice, I will clean everything up, check the head bolts, lap the barrels and valves. Check the full flow oil plungers. If nothing untoward found put it all back together and check the oil pressure.