My '66 fastback has a Roush 342R crate engine. The engine has travelled 5000 miles from when I purchased it as a new crate. From brand new it has had a rear main oil seal leak, and very noisy tappets. I have just taken it apart to fix both problems. The rear main seal was an easy fix - Roush hadn't installed it within the block correctly so it wasn't seated, allowing oil to pour out.
I am still having trouble with very excessive tappet noise. Every time I adjusted the rockers, they would bleed back, allowing the rocker arms to go slack, and causing excessive tappet noise.
The first thig I checked was the valve springs - suspecting they were causing bleed down of the hydraulic lifters. The cam Roush installed is a Comp Cams XE247 HR hydraulic roller.
The valve springs for that cam are said to be 135lbs. Roush had 185 lb srings installed so I changed the springs to the correct 135lbs; and adjusted the rockers to 1 - 1/2 turns down. However much I adjusted the rockers I still had lots of tappet noise; and still had bleed down of the lifters within about a minute of stopping the engine. At that stage the rockers would be slack, and I could easily turn the pushrod, and fit a feeler gauge between the rocker and the valve.
Next I replaced the 5000 mile lifters with brand new specified hydraulic lifters. I adjusted the tappets with the engine running but still cannot stop the tappet noise no matter how much I wind down on the adjusters. There is still bleed down of the lifters, although it is less than it was with the original roush lifters. I can still turn the pushrods after I stop the engine.
Push rods have been inspected and seem ok. The cam lobes have been inspected and seem ok. There is ample oil at all the roller rockers. Oil is now 20w50. I have tried various oil grades and they don't make any appreciable difference to the tappet noise.
I live outside the USA and the Roush warranty does not apply outside the U.S, so I'm not expecting any great assistance from there.
Any ideas please ?
I am still having trouble with very excessive tappet noise. Every time I adjusted the rockers, they would bleed back, allowing the rocker arms to go slack, and causing excessive tappet noise.
The first thig I checked was the valve springs - suspecting they were causing bleed down of the hydraulic lifters. The cam Roush installed is a Comp Cams XE247 HR hydraulic roller.
The valve springs for that cam are said to be 135lbs. Roush had 185 lb srings installed so I changed the springs to the correct 135lbs; and adjusted the rockers to 1 - 1/2 turns down. However much I adjusted the rockers I still had lots of tappet noise; and still had bleed down of the lifters within about a minute of stopping the engine. At that stage the rockers would be slack, and I could easily turn the pushrod, and fit a feeler gauge between the rocker and the valve.
Next I replaced the 5000 mile lifters with brand new specified hydraulic lifters. I adjusted the tappets with the engine running but still cannot stop the tappet noise no matter how much I wind down on the adjusters. There is still bleed down of the lifters, although it is less than it was with the original roush lifters. I can still turn the pushrods after I stop the engine.
Push rods have been inspected and seem ok. The cam lobes have been inspected and seem ok. There is ample oil at all the roller rockers. Oil is now 20w50. I have tried various oil grades and they don't make any appreciable difference to the tappet noise.
I live outside the USA and the Roush warranty does not apply outside the U.S, so I'm not expecting any great assistance from there.
Any ideas please ?