12/90 BG Engine failure head and long cranking answer

[LGAFF]

A few weeks ago I bought a head from Kinsler along with an intake. The parts were at Kinsler solely for test fitting intakes; the parts were received in 1991 and sat there til last week. The head had no cam cover and they offered it to me for $350.....I passed and we ended up at $125; with the thought I could match a cam cover and have it machined. Nice surprise was the head had valves, springs, caps/keepers. Date stamp on the valves Oct 1990. The head is a 1991

In December of 1990, production at Mercruiser stopped due to an engine failure at Bowling Green. The failure was a front camshaft bearing/journal. GM and Lotus dispatched Graham Behan to investigate. They soon discovered an impatient GM employee starting the cars at Wide Open Throttle in the dead of winter. They also discovered that CPC had shortened the crank to start time(This answer your long crank questions) ...the big kicker was that Bay City did also not bother to check the journal sizes before shipping. All of which contributed to the failure.

So back to my purchase, upon examining the head, I find front cam lobe damage on a 1991 head....with parts produced after 10/90. I wonder if this might be that head...maybe Graham will chime in....

[grahambehan]

There were a total of seven failed engines from BG, five before we got to the plant and two after we found what was happening. Lotus was responsible for the calibration on the LT5 so CPC did not "shorten the crank time". This head could be from one of the failed engines. Bay City did not keep records of the individual cam sizes or when a tooling change was made, but we never found a cam that measured oversize. Mercruiser on the other hand, had QC records on all their parts.

Graham.

[LGAFF]

Thanks Graham......all of my info came from the HOB book, some innaccurate info then....is the long crank time on the LT5 intended for building oil pressure or just related to the timing?

[grahambehan]

Originally Posted by LGAFF

Thanks Graham......all of my info came from the HOB book, some innaccurate info then....is the long crank time on the LT5 intended for building oil pressure or just related to the timing?

Yes Tony did a great job on the book, but talking to all the people he did on a couple of continents, led to a few "journalistic license issues". The long crank time is more a consequence of sync than a design intent.

Graham.