| Re: [GMCnet] losing power [message #220226 is a reply to message #220223] |
Wed, 28 August 2013 14:00   |
James Hupy
Messages: 6806
Registered: May 2010
Karma:
|
Senior Member |
|
|
Karen, what timing chain set did you use, and where did you time it.?
Jim Hupy
Salem, Or
78 Gmc Royale 403
On Aug 28, 2013 11:21 AM, "KB" <kab7@sonic.net> wrote:
> thanks guys. (sorry to hijack the thread)
>
> Vac is about 15- at idle, used to be 18+ish on the old engine.
> I've checked for vac leaks and can't find any (yes, I remembered
> to goop the right rear bolt hole on the TBI gasket :-). I changed the dist
> module and cleaned up the contacts and saw no change. I've double-checked
> timing at 8 BTDC, but not sure how I'd tell if the timing mark is
> wrong. It's the same balancer as was on the old engine and looked ok
> (all this stuff was supposedly replaced only 12k miles ago). Intake is
> stock
> in good condition with Dick P's block-off gaskets. No obvious problems
> on the fit.
>
> It runs ok with the computer in control, though the idle isn't
> as smooth as I'd like. That could be because the fuel and spark tables
> haven't been tuned yet. I went back to an earlier tune closer
> to what the amazing Randy uses. On the old engine, I'd been backing
> off more and more on the spark trying to reduce knock counts.
> Turns out the "knocks" were probably the wrist pin or whatever
> is ailing piston number 8, which we couldn't hear until it got really bad.
>
> Current theory is the combination of new engine and RV cam is giving
> us a lower vac reading. I noticed the IAC step counts were also
> significantly higher than before (ie, has to open more to let in air),
> which could also be due to the higher friction of a new engine.
>
> So, I'll just check everything carefully, get the new fan clutch
> and shroud installed, and we'll try a very gentle short trip to see what
> happens. Fingers crossed... we really want to make Coos Bay.
>
> thanks
> Karen
> 1973 23'
> 1975 26'
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
