suggest 305 engine

[fabioblazer]

Hi guys, very good forum and nice to meet you.
i'm Fabio from north Italy and i have a 1981 Chevy Blazer k5 305 engine.
it has just 100.000 km but i'd like to rebuild just the part above (valves, spring, roller arm, etc...) 'cause i think something about a valve, maybe a seal or spring, doesn't run good.
truck runs enough good, not particular problems, just this little hissing about valve probably, confirmed by mechanic.

i'd like use OE stuff, 'cause i don't want necessarily a performance engine, after almost 30 years it need a check and i think changing parts surely it will run good as the past, unless there are some particular products that improve performance without having to change everything else.

could you help me please?
some suggest about parts?
thanks for attention
fabio

[VileZambonie]

You need to find out exactly what is wrong with the engine. If the lower end is tired and worn out there's no point in doing a valve job. What exactly did your mechanic determine was wrong with the engine?

[fabioblazer]

thanks for answer!
he told me hissing is about valve seal.
a piston compressor is a bit lower than others.
decimal of PSI

[VileZambonie]

Not following you but my advice would be to take it to a different mechanic and get a pinpoint diagnosis.

[fabioblazer]

but about valves job? is it a good job?
i think i can get an OE valves train kit and replace

many people advised me to change directly with a 350 engine but here in Italy is difficult to find it a good price, but especially Italian law prohibits this kind of thing.

so, until now i changed parts with OE replacement parts, aware it will not run like a dragstar but at least i can sure to drive always and everywhere.

what kind of kit you can suggest me? surely you will know all about aftermarket world!
thanks again
Fabio

[VileZambonie]

Valves unless they are damaged can be re-used once cleaned and resurfaced. You can buy them individually or in sets. It would be less expensive to replace the cylinder heads by the time you are done paying someone to rebuild your 305 heads.

[team39763]

Wouldn't hissing in the valvecovers be something like a valve guide seal?  I'm no expert, but would that make sense?

[fabioblazer]

no it's not important to find someone else.
i can do the job.
i'd like to know if there is some partular kit to use for 305 engine.

"for team39763":
the hissing noise is similar to a turbo:)
ehy but it's impercetible. there 'for a year and have always gone on the road without problems.

[VileZambonie]

I have no idea what you are talking about at this point I know you are from Italy and communication is an issue but you'll have to try and better explain. You are hearing a hissing noise? So now you want to replace your valves?

[joesgarage71]

thanks for answer!
he told me hissing is about valve seal.
a piston compressor is a bit lower than others.
decimal of PSI

 What I understand is that one of the cylinders are weaker than the others(compression check) and there is a hissing through the intake from a leaking valve.
Fabio,
   You can remove the heads and have the valve job done by your machinist and reinstall them. Valve grind gasket set
http://store.summitracing.com/partdetail.asp?autofilter=1&part=MRG%2D3953&N=700+115&autoview=sku
If you need more parts than this summit can supply them for you.
 Steve

[fabioblazer]

no, i'd like to know if you think it's a valid job rebuild valvetrain after 100.000 km or there is no need.
if you said yes, i'd like to know what i can use as replacement.

OE replacement parts or something other? There are better parts to use?
i could use, for example, different type of roller arms with same specification. maybe original equipment may be replaced with something else, but not to increase performance, just because it's not very good, i don't know! you are the experts
I hope to be clear

fabio

[roadrage41]

youre definitely ok to use aftermarket parts, if youre just wanting to freshen up the heads, the kit listed above is pretty much what you want. OE will be pretty much the same quality, but for quite a bit more money id bet, though i dont know how hard it will be to get those exact parts to italy.

its not necessarily the 100,000 kms thats the sole cause, the engine is almost 30 years old after all.

[choptop]

Its hard to determine if you need to rebuild the valve train without examining it ourselves. If you have low compression in one cylinder, then that is a good sign that one of the valve guides or valves is bad. In that case, yes, have the valves and heads reworked. Unless you are racing or need high performance from you engine, the OEM parts are good enough for your application. In some cases, the OEM parts are higher here, which is why alot of people go to aftermarket parts.

   Briefly, have the cylinder heads rebuilt, have valve guides replaced, and only replace the valves that cannot be reused. You will need the head gaskets and intake gaskets. Pushrods can be reused if they are not bent, but usually are cheap, so I normally replace them.
   The validity of this job depends on the history of the engine. If the engine was well taken are of, then its unusual to have to rebuild the heads. If the engine didnt recieve the maintenance it needed and the fuel was lean, then valvetrain damage is going to occur. Hopefully this helps.

[fabioblazer]

ok! wonderful! thanks guys!
i'm 4° owner but i know just the previous owner.
he used Blazer offroad too but not extremly and the only problems were carburator adjustement and electric system, the truck was parked for years under the weather, so when i get truck, i replaced carb, electric system, alternator, body parts works, etc....many parties were blocked from humidity and rust.

unluckly, in italy is not so easy to find mechanic who knows amercian engine. i found one 90 km away.
i bought parts through internet and he replaced everything and checked all, there was just hissing i told you.

luckly there are sites like this with capable people who can help people overseas
a question... 1981 305 LE9 engine valves are 1.84/1.50? correct
thanks again
fabio


 

[Blue 82]

If you are getting a hissing sound, i would think it would be a vacuum leak.