Greetings all - I'm in a bit of a bind as I recently installed a replacement 5.7 however it was built using flat tappets despite the block being an '86+ (has the bosses in the lifter valley for the 'spider', etc).
The issue is that I encountered ignition issues/timing when trying to fire it to do the break in - been hearing you cannot overcrank without running the risk of wiping the cam lube off (used Isky Rev Lube) thus causing cam lobe damage once the engine fires. (REALLY wishing I went with a roller cam - tons of nightmare stories online about wiped lobes).
Anyhew, I surmise I'm at a point where I haven't wiped any lobes off that now's a good time to install a roller cam ... or what are y'all's thoughts on the overcrank thing? Will the Rev Lube still have any protection or does it get promptly wiped off?
I found a GM truck roller cam (Melling) with the following specs that will work with the OEM GM roller lifters/guides, etc:
Advertised Exhaust Duration 263
Advertised Intake Duration 261
Exhaust Duration at .050 inch Lift 194
Exhaust Valve Lift 0.428"
Intake Duration .050 Inch Lift 191
Intake Valve Lift 0.414"
Lifter Type Roller
Lobe Separation 106
(I realize I must use the matching pushrods). Higher duration cams from what I understand can cause reversion - an obvious no-no in a wet exhaust application).
Sorry for the long post but the wiped cam lobe thing's got me wigged out - engine was totally rebuilt using marine spec stuff so I want to save this engine even if I have to swap the cam out). Never did get it started - getting fuel, getting spark but kept popping thru the carb like a timing issue - verified firing order several times, re-checked static timing - no clue as to what's causing this.
Many thanks!
-Larry
The issue is that I encountered ignition issues/timing when trying to fire it to do the break in - been hearing you cannot overcrank without running the risk of wiping the cam lube off (used Isky Rev Lube) thus causing cam lobe damage once the engine fires. (REALLY wishing I went with a roller cam - tons of nightmare stories online about wiped lobes).
Anyhew, I surmise I'm at a point where I haven't wiped any lobes off that now's a good time to install a roller cam ... or what are y'all's thoughts on the overcrank thing? Will the Rev Lube still have any protection or does it get promptly wiped off?
I found a GM truck roller cam (Melling) with the following specs that will work with the OEM GM roller lifters/guides, etc:
Advertised Exhaust Duration 263
Advertised Intake Duration 261
Exhaust Duration at .050 inch Lift 194
Exhaust Valve Lift 0.428"
Intake Duration .050 Inch Lift 191
Intake Valve Lift 0.414"
Lifter Type Roller
Lobe Separation 106
(I realize I must use the matching pushrods). Higher duration cams from what I understand can cause reversion - an obvious no-no in a wet exhaust application).
Sorry for the long post but the wiped cam lobe thing's got me wigged out - engine was totally rebuilt using marine spec stuff so I want to save this engine even if I have to swap the cam out). Never did get it started - getting fuel, getting spark but kept popping thru the carb like a timing issue - verified firing order several times, re-checked static timing - no clue as to what's causing this.
Many thanks!
-Larry
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