trumpet base and piston qustions.

Bobbybedtime · Post by **Bobbybedtime** » Wed Jul 27, 2011 6:16 pm

Hi all,
Got a couple of questions I hope you can help with.

Slowly getting thing together with my rebuild and have noticed that the trumpet base has probably been played with. Reason I say this is all the trumpets are numbered, scratched on the side of the trumpets and one of the trumpets is not fully home in the base. Guessing either it was cut to short or someone couldn't press it home.
Does anyone have a drawing or dimensions I could use to see what I need to do to put right.

Other question is pistons. The manuals say the pistons are marked 'front' and need to go in a certain way. Mine aren't marked but do have writing. I was going to assume the writing identifies which way is front, ie the front of the piston is above the writing ... any thoughts?

Thanks,
BBT.

DEVONMAN · Post by **DEVONMAN** » Wed Jul 27, 2011 6:35 pm

On the subject of pistons,
If you have a 4.2 or a 4.0 or a 4.6 engine the pistons will have an arrow on top to indicate front.
If you have a 3.5 or a 3.9 engine the pistons are not marked and can go either way round.

Cheers Denis

Bobbybedtime · Post by **Bobbybedtime** » Wed Jul 27, 2011 6:48 pm

Thanks Devonman, its a 3.9.
Regards,
BBT.

mgbv8 · Post by **mgbv8** » Wed Jul 27, 2011 8:07 pm

Dont forget that the engine may have been played with at sometime in the past. So make sure that when you put it together to make sure the dimples on the con rods face each other on each crank journal.
I've had many secondhand V8's to play with and piston markings have been all over the place.

Bobbybedtime · Post by **Bobbybedtime** » Sat Jul 30, 2011 8:15 am

Yep, will make sure dimples are correct.
Thanks,
BBT.

spend · Post by **spend** » Sat Jul 30, 2011 9:17 am

Bobbybedtime wrote:..noticed that the trumpet base has probably been played with. Reason I say this is all the trumpets are numbered, scratched on the side of the trumpets and one of the trumpets is not fully home in the base. Guessing either it was cut to short or someone couldn't press it home.
Does anyone have a drawing or dimensions I could use to see what I need to do to put right..

Original trumpets quite often 'break out' anyway.

They will be around 3-4" long if original, some modify by cutting down @25mm or so, some replace with larger flared trumpets (but they are typically ally or CF). Various adhesives have been successfully used to fix the trumpets in place, epoxies and hi-temp silicones I believe. Personally I'm in the ditch em & grind flares into the base (getting out of the must have circles syndrome ~ oval is bigger & better as you go down the manifold:lol:), but I guess that is outside of the scope of your question...

Bobbybedtime · Post by **Bobbybedtime** » Tue Aug 02, 2011 8:36 pm

Thanks Spend, a little out of scope ... tried to keep it simple but the more I look the more I find.
Rgds,
BBT.

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trumpet base and piston qustions.

trumpet base and piston qustions.

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