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Discussion Starter · #1 ·
ok so a guy i work with has a 305 from a 88 full size p/u with 90k on it with a trans i cant remember but he only changed the t-case and a b&m drag only t-case he is willing to let go for 250$
i want to try my fist rebuild and was wondering if this would go good in my 98 tj? i know not a god danm thing about these things so please school me.
he would let the motor go for 50$
thanks aron





-aron (just for ff)
 

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well before you buy it let me tell you a few things.
the 305/350 blocks of this vintage are prone to "porosity" as GM called it. the blocks were cast thin and they would pick up sand while being cast and it would get trapped in certain areas of the mold. the 305/350 seem to show signs of this in the lifter vallys . the first signs of it are what lloks like pancake batter in the oil cap & valve covers. I have seen the stuff inchs thick inside the engines. if you suspect you have one of these you can see it as huge globs of slugdy looking goo on the vally walls and the majority have a pattern to them. I used to prick punch the lines on each end to mark them. then clean them off really good with brake clean and seal with JB weld. if the engine is older the and has high miles its most likely the bearing have damage from the mix of anti freeze in the oil.

I suggest you pull the intake and look under it at the vally if the engine isn't in running condition.

so with that said, what else would you like to know?
 

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broken
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Discussion Starter · #3 ·
well before you buy it let me tell you a few things.
the 305/350 blocks of this vintage are prone to "porosity" as GM called it. the blocks were cast thin and they would pick up sand while being cast and it would get trapped in certain areas of the mold. the 305/350 seem to show signs of this in the lifter vallys . the first signs of it are what lloks like pancake batter in the oil cap & valve covers. I have seen the stuff inchs thick inside the engines. if you suspect you have one of these you can see it as huge globs of slugdy looking goo on the vally walls and the majority have a pattern to them. I used to prick punch the lines on each end to mark them. then clean them off really good with brake clean and seal with JB weld. if the engine is older the and has high miles its most likely the bearing have damage from the mix of anti freeze in the oil.

I suggest you pull the intake and look under it at the vally if the engine isn't in running condition.

so with that said, what else would you like to know?
:rock: every thing!!!!i love this shit!!! it is a running engine but i just want to break somthing open and learn! he said somthing about the 305 has better throttel responcse but uses more fuel is this true? what else should i ask about said engine and trans exc? oh yeah it has not been rebuilt and the donor is getting a big block shoved in it that's why it was removed. thanks:beer:
 

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You know - you could get a 350 block and internals for about $50 too. I personally prefer these blocks. I have 2 TPI 350's that smoke tires pretty nice.

I have a 305 with a wobbly cam - but still like the 350's.
 

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yea, the 305's rev better than the 350 and can be built nicely. As far as using more fuel, that would be compared to the 350 in the same heavy truck. They were rated for less fuel mileage only because it had less HP than the 350 in the same truck.
 

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I guess the best thing about the 305 is the fact everything for a 350 bolts up(except flywheels & balencers). if its a later one the rear main should be a one peice on the underside of the fly wheel. if its an old style(pre `85) it won't have a seal visable under the flexplate/flywheel. the majority of parts are bolt ons like heads & cams and such. the intakes are the same, but the `87 and later intakes don't work on the `86 and earlier heads without modifing the center bolts on either side of center on the intake. for some reason the changed the angle of the bolt holes in `87. if you decide to use the 305 the best mods are bolt ons. doing tons of work in the crank piston area is kinda a waste. they are good reving engines and do good up to 6000 rpm , if you want to go higher then that you would need more money in the engine then its worth.
 

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Discussion Starter · #7 ·
thanks for all the info! ON THE WAY HOME YESTERDAY MY 4 BANGER BLEW UP! now i need to know what this stuff is worth! 305 with a turbomatic 350 and a np203 t case i need a new motor bad so i need to sell this and get another 2.5 for easy install. thanks for all the help.
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i will get the millage later tonight
 
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