Re: Help please - V8 backfire at 3000RPM only

"Chris Twibell" <chris@[EMAIL PROTECTED]
> wrote in message 
news:Xns99575DA4056A2chrisnospamtwibscouk@[EMAIL PROTECTED]
>I hope someone out there can help me with this one, it's got me baffled!
>
> I have recently taken the engine out of my boat (Volvo 5.7 GS) to
> replace the damaged ring gear, the engine went back in with no problems
> however, it has developed a backfire that occurs only between 2700 and
> 3200RPM.  At all other revs there is no problem and it runs better than
> ever at WOT.  The engine does not have electronic ignition and has a
> twin choke holley carb which I have stripped and found to be spotlessly
> clean.
>
> Can anyone shed any light on the possible problem please?
>
> Chris


Further faults.

backfires are usually cause by either faulty timing or a weak mixture.

Does the inlet manifold bridge the two banks and if so did you lift the 
engine by passing a rope under said manifold. If so you may have cracked
it 
or broken a gasket joint so it now sucks in air. However if it did I would

expect idle problems at the least.

Does the carb have any diaphragms on it, if so they are worth checking for

pinholes or splits.

Tony Brooks