Help with 340 build - chicagoland area

[340runner]

Crosspost from FABO, sorry if not allowed or if you've already read it

have a 71 340 that's in need of a rebuild, I'm just unsure and kind of worried about doing it myself. It has already been freshly rebuilt, but the guy who last did it mixed and matched parts, it has 30 over stock replacement pistons, but for the low comp 340s, the l2385f. It also has a torker single plane intake, speedmaster heads and a 243/257 "big mutha thumpr cam". Right now, it's been driven for about half a year and is now starting to leak badly from the timing cover and is slinging oil everywhere, and when I step on the gas it puffs out a little bit of smoke, I'm thinking the valve seals.

Id like to use the above issues as basically an excuse to pull the engine and do a rebuild on it, swapping out the pistons for l2316f pistons, but I'm kind of nervous about doing the rebuild myself. This will be the first time I'm doing this kind of thing, and it'll be on a engine that currently does run, so the whole "can't be worse than before" thing doesn't apply. Does anyone know anyone in the Chicagoland area that'd either be willing to help with a rebuild, or i would be able to pay to rebuild it?

Thanks very much,
Paul

Also, I will be at Mo Power Madness if you would want to either see the car/engine or just meet me before tackling anything

 

[MWbirdLOVER70]

Crosspost from FABO, sorry if not allowed or if you've already read it

have a 71 340 that's in need of a rebuild, I'm just unsure and kind of worried about doing it myself. It has already been freshly rebuilt, but the guy who last did it mixed and matched parts, it has 30 over stock replacement pistons, but for the low comp 340s, the l2385f. It also has a torker single plane intake, speedmaster heads and a 243/257 "big mutha thumpr cam". Right now, it's been driven for about half a year and is now starting to leak badly from the timing cover and is slinging oil everywhere, and when I step on the gas it puffs out a little bit of smoke, I'm thinking the valve seals.

Id like to use the above issues as basically an excuse to pull the engine and do a rebuild on it, swapping out the pistons for l2316f pistons, but I'm kind of nervous about doing the rebuild myself. This will be the first time I'm doing this kind of thing, and it'll be on a engine that currently does run, so the whole "can't be worse than before" thing doesn't apply. Does anyone know anyone in the Chicagoland area that'd either be willing to help with a rebuild, or i would be able to pay to rebuild it?

Thanks very much,
Paul

Also, I will be at Mo Power Madness if you would want to either see the car/engine or just meet me before tackling anything

Talk to Larry or Mike at Mopar City in Oregon IL about doing the rebuild

 

[DanielSlocum]

Changing pistons usually requires rebalancing. Something to keep in mind.

 

[340runner]

Changing pistons usually requires rebalancing. Something to keep in mind.

Its a 5 gram difference, with the l2316f being heavier than what I have now. I've done research here and on FABO, and watched videos on it. It would be less than a 1% bobweight change, so it should be okay is what I've gathered. They're my pistons but with a 1.840 compression height instead of 1.760 basically

 

[MWbirdLOVER70]

Its a 5 gram difference, with the l2316f being heavier than what I have now. I've done research here and on FABO, and watched videos on it. It would be less than a 1% bobweight change, so it should be okay is what I've gathered. They're my pistons but with a 1.840 compression height instead of 1.760 basically

I say have at and build it

 

[340runner]

I say have at and build it

I'm gonna be doing that, going to mo power madness in bleak hopes someone else has pistons used that would work for me, and also seeing if anyone could help me at the next chicago mopar connection chapter meet but either way im gonna FAFO and hopefully not break anything major along the way. Will probably ask a lot more questions here and in FABO, and will try to remember to take photos

 

[MWbirdLOVER70]

I'm gonna be doing that, going to mo power madness in bleak hopes someone else has pistons used that would work for me, and also seeing if anyone could help me at the next chicago mopar connection chapter meet but either way im gonna FAFO and hopefully not break anything major along the way. Will probably ask a lot more questions here and in FABO, and will try to remember to take photos

Lotta good people in that chapter and Rock Valley

 

[Cranky]

In the early/mid 70's I did my first engine. Lots of things I didn't know back then but the engine turned out really well. But with today's parts being questionable more often than not, I'd go with someone that has a good deal of experience. I started my machinist career in 1980 and learned to check everything and found that things you would think were good, weren't. Sent out a block to be aligned honed and it came back with all the bearing fits .003" out of round and this was from a shop that supposedly built Pro Stock engines!

 

[340runner]

In the early/mid 70's I did my first engine. Lots of things I didn't know back then but the engine turned out really well. But with today's parts being questionable more often than not, I'd go with someone that has a good deal of experience. I started my machinist career in 1980 and learned to check everything and found that things you would think were good, weren't. Sent out a block to be aligned honed and it came back with all the bearing fits .003" out of round and this was from a shop that supposedly built Pro Stock engines!

Well, im hoping limiting the amount of parts swapped will help me out with the whole questionable parts thing. Im pretty much just swapping pistons and bearings if they need replaced. Thought process is hopefully if they're already running alright now, they'll run alright when I disassemble and reassemble

 

[Curiousyellow71]

If it still has the 340 free floating wrist pins a piston swap is simple.
I don't have much faith in anything sold by speedmaster. They likely need to be gone through.

 

[1wild&crazyguy]

Crosspost from FABO, sorry if not allowed or if you've already read it

have a 71 340 that's in need of a rebuild, I'm just unsure and kind of worried about doing it myself. It has already been freshly rebuilt, but the guy who last did it mixed and matched parts, it has 30 over stock replacement pistons, but for the low comp 340s, the l2385f. It also has a torker single plane intake, speedmaster heads and a 243/257 "big mutha thumpr cam". Right now, it's been driven for about half a year and is now starting to leak badly from the timing cover and is slinging oil everywhere, and when I step on the gas it puffs out a little bit of smoke, I'm thinking the valve seals.

Id like to use the above issues as basically an excuse to pull the engine and do a rebuild on it, swapping out the pistons for l2316f pistons, but I'm kind of nervous about doing the rebuild myself. This will be the first time I'm doing this kind of thing, and it'll be on a engine that currently does run, so the whole "can't be worse than before" thing doesn't apply. Does anyone know anyone in the Chicagoland area that'd either be willing to help with a rebuild, or i would be able to pay to rebuild it?

Thanks very much,
Paul

Also, I will be at Mo Power Madness if you would want to either see the car/engine or just meet me before tackling anything

Im not in Chicago.. but one thing I would compare piston weight and base whether it needs a rebalance on that.
Have the heads checked, guides, redo the valve job if ootb because the in house vj is 2 angle and less than ideal.