New 350!

Ok well I am going to be picking up a 1992 350 engine from a Z71 pickup from a buddy in the next few days (maybe tonight if he gets off of work) and the only thing missing is the manifold and TBI. Would I be better off finding another TBI setup from a junkyard and use it or go ahead and get the Edelbrock Air Gap and 625 Speed Demon Jr carb? I want it to get more power than stock but still maintain good gas milage. This is going to be replacing the stock messed up 305 that is in my K10 right now.
The motor has 92,000 miles on it or so and needs new valve seals. My father says that since it's out that I might as well rebuild the thing with a plain but nice rebuild kit and then put it back together and into the truck up to TH350 tranny....
Any oppinions here? I want it to have good power but nothing like 450 HP or anything just something around 350, 365, somewhere around there the most. Well actually my father is the one that want's this. I am just doing the work for him because this truck is the one that is supposedly a "father son" project where both our money and time goes into it. :D

Thanks for any oppinions, info.

well your gonna have to do a good rebuild to get the 350 horse you want, that motor comes stock with around 290-300 horse, depending on the output, being a Z71, you might find it is a 300 horse engine, putting on a carb and getting rid of most of the NOX stuff you do not need won't get much more, and there not exactly good on gas, my friend has a '94 GMC Sierra GTw/ 350 3spd auto, and he gets between 12-14MPG, if the '92's trans is still available and is a 4L60E or a 700R4, you might want to consider trying to get that and the '92's driveshaft ( I think the chassies are the same, so the driveshaft would fit your '85 w/ the overdrive trans ).

I don't think the tranny is available Matt. I mean heck, I think 320 HP will do fine. It will only be taken to the strip a few times and that's it. I think I will do a simple rebuild kit on it, put the intake manifold on it with the 625 carb or even a plain 600 Edelbrock and then plain headers and glasspacks. The engine in it now is the 305, the valve seals are wasted I know that for a fact, the rings are worn because it's burning oil, smoking, it has a smog pump on it which is taking power away and the catalytic converter is so old that when you gas it it pops and then let of it pops and rattles because it's all broken up inside so I will take that out. I was going to not even put a cat back on it because a guy said that he knows places I can go to get it passed anyways but to be on the safe side I will just put one of those glass pack looking kind that aren't restrictive even though they are like 150 each.... I have the HEI distributor in the 305 now that I think will be fine because I have a new MSD upgrade kit in it, new wires that are Taylor 8mm. With all that on there I think it will breath and exhale good enough and be better on gas. All I know is that either way I will get better gas milage out of it than this restricted and old 305.

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Originally posted by FMXhellraiser
I don't think the tranny is available Matt. I mean heck, I think 320 HP will do fine. It will only be taken to the strip a few times and that's it. I think I will do a simple rebuild kit on it, put the intake manifold on it with the 625 carb or even a plain 600 Edelbrock and then plain headers and glasspacks. The engine in it now is the 305, the valve seals are wasted I know that for a fact, the rings are worn because it's burning oil, smoking, it has a smog pump on it which is taking power away and the catalytic converter is so old that when you gas it it pops and then let of it pops and rattles because it's all broken up inside so I will take that out. I was going to not even put a cat back on it because a guy said that he knows places I can go to get it passed anyways but to be on the safe side I will just put one of those glass pack looking kind that aren't restrictive even though they are like 150 each.... I have the HEI distributor in the 305 now that I think will be fine because I have a new MSD upgrade kit in it, new wires that are Taylor 8mm. With all that on there I think it will breath and exhale good enough and be better on gas. All I know is that either way I will get better gas milage out of it than this restricted and old 305.

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Don't go without a cat, just spruce up the old 1 or get a cheapo new 1, and drill it out and run a pipe through the middle of it, won't need any expensive cat, '85 is non emmisions, the emmisions crap has to be there. The 305 will be more efficent even with the smog pump, you might get OK mialage out of it by toying with the jetting timing and converting it to a carb but I doubt you will pull any more than 18 out of it. Your also going to have to get a manifold to fit the '87 up heads, because there diffrent I belive ( they are centerbolt, I know that for fact ). get a 600 carb, holley or edle, you could get a quadrajet as an option.

Matt, yeah I have to get the Edelbrock Air Gap for 87 and up, your exactly right. The 305 is leaking all over the place and needs a rebuild, the amound of money I would spend rebuilding it would be more than this 350. Plus the heads on the 350 are better, flow better. I will do a little gasket matching and smoothing the heads on this 350 up. I need to just go pick the engine up and start cleaning it up and tearing it apart when I get the parts in but yeah, the 350 will get better gas. If you saw the 305 in the truck now and seen how it ran you would under stand. I would waste my time messing and tuning the 305. Your right I think what I may do is get the old cat and tear everything out and put the pipe through it, but only thing is I think they do the emmissions test and check the exhaust gasses (the numbers or whatever they call it).... But yeah if they do this and it doesn't pass I will have to run a cat to help. Other than that I dont't know what else to do.

Here they just make shure you got the emissions stuff, until OBD1 vehicles ( early 1990's ) , then they do a smog test and OBD2 ( 1996 up ) gets the computerized emmisions scan through the OBD2 port. the smog test that uses a sniffer measures in grams per mile of hydrocarbons. I wouldn't bother with a rebuild kit, if it has 92,000 miles, those Chevy's go forever, put a hotter thermostat in it and it is not only going to run cleaner but it will help with nox testing, of course you will also need a higher LBS rad cap ( your '85 should have a 7-10 LBS cap ) like a 13-15 LBS so you don't boil over and overheat ( because 1 LBS of preassure/ 3* added to boiling temp, which at 15 LBS of preassure would make 357* ). I'd have the heads rebuilt, put the air gap on it and change the oil pump or inspect the current for damage. also, I don't know if the '92 motor has the provision for a mech fuel pump so you might need a electric fuel pump.

Alright thanks for the help Matt. I will definetely take what you said into concideration. Yeah I think new lifters, valves, etc would be nice if I am going to go ahead and replace the seals. I told my father to just not rebuild it but he said it's pointless not to since it's already out of the truck and he wants to just tear it down, repaint the block all nice, nice aluminum water pump, etc. I did work on the 305 a bit today. Took the belt off the smog pump, tightened the valve covers, etc since everything is loose on it. Next I have to get rid of that cat, it's all rattling and that is making things worse. One thing that is bugging me about it is that it is smelling very bad out of the exhaust like a little rich but it is like something burning and melting. That is why my dad thinks it's the rings....

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Originally posted by Matt167
... that motor comes stock with around 290-300 horse, depending on the output, being a Z71, you might find it is a 300 horse engine, ...

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That engine is not CLOSE to 300 hp.

If it was a 92 TBI 350 from a truck, then it's a 200-210 fwhp and 300 ftlb engine with a flat tappet cam.

There is a very nice, but very long, Father-Son engine build project on Thirdgen.org:

http://thirdgen.org/techbb2/showthre...hreadid=279581

If you plan to keep the TBI than aim a lot lower than 360 fwhp. The truck will run very well with 260 fwhp (it'll run 15.0 in the quarter) and more importantly it will run forever with very low maintenance, it'll have awesome off-idle torque, and it will still get "decent" mpg for a truck with a 350.

The most imporant thing you can do for that 92 TBI engine is to remove the heads and port them.

http://thirdgen.org/techbb2/showthre...ght=garage+193

The second most important thing to do is add dual exhaust (with cats) and with low restriction mufflers to the truck -- even if you have to keep the iron exh manifolds (if you do, port them too).

Those two modification will bump the engine output to 240+ with no other changes than raising the fuel pressure.

Do a port cleanup on the factory aluminum TBI intake manifold and pay more attention to the outlets at the top of each runner, and do more porting work on the lower plenum runners because they are more flow-impaired than the upper plenum is. Also port the base of the intake under the TBI.

Remove the heavy rotators on the exhaust valves and replace them with Caprice/Impala LT1 350 retainers/locks and you may as well use the springs from that engine too, to replace the valve springs on your engine. All GM parts, all inexpensive.

On the cam: you have a choice here -- either keep the stock cam which means you will give up 20+ fwhp but have an immensely pleasureable engine to drive with, or do a cam swap to gain more power but give up something on the lower end and on part-throttle driveability. If it were me, I'd keep the stock cam and use a set of $80 1.6 ratio self-aligning stamped steel rocker arms from Scoggin-Dickey..... and then let dad see how he likes the engine. If he wants more, you can always do the cam swap later.

The last item is that depending on how far you go and IF you keep the TBI, you will probably want a custom chip (EPROM) to go into the ECM (computer). So you would need the entire wiring harness + ECM + TBI to use. Carb-to-TBI swaps can consume an entire thread, so I won't detail it here. There are posts on Thirdgen.org that do a better job covering the subject than I could. HTH.

The guy is dropping the engine off at my house today!!! res ipsa, thanks a lot for the advice! Actually it doesn't have the harness or TBI. The kid bought the engine to use that for his 400 I think he said so it doesn't have the intake manifold, wiring harness or the TBI itself. I will put a Air Gap manifold from Edelbrock and a 625 BG Speed Demon Jr on it with headers and glass packs. It's a good thing me and my father like the same parts and exhaust or else things would not go so well. Me and him already DO NOT work well together, my friends said that me and him are much worse than Orange County Chopper guys and our fights are real haha. Thanks for the site too I will check that out right now.
Oh and on that cam I am sure my father will want to upgrade it a tad. I can't go too big so probably just a plain Edelbrock performer one or something small like that. I am guessing the stock compression on these are 8.5:1?

I keep forgetting to ask about this. I am trying to wait and find it out myself but I have no clue where to start or anything.... Around how much should I look into spending on machine work if I rebuild? Since it only has 92,000 miles on it then should everything be fine with minimal machine work to keep cost down or what? I am guessing if I bring it to a machine shop then they can recommend what I do right? Also what about a full bottom end kit with EVERYTHING? Summit has a few Forged kits without con rods and a few other things but they are like 9.5:1 compression and higher I'd like to stay at around 8.5 or 9:1 compression. Any suggestions on the kit and the price for the machining?
Thanks again guys!

IMO you need to do a lot of reading (in books and on the web), and buy a book on rebuilding a sbc by David Vizard. You should do those things first before you start blowing money at the machine shop. Many shops might view the inexperienced newbie as a source of money.... money that you don't always have to spend.

Ok the guy just left my house. I got the engine. It's in pretty nice shape and a total steal for 100 bucks! Turns over and all, took the valve covers off, a bit dirty but not bad.

Yeah I will look into some books thanks. I will go to my local speed shop and ask the guy there what he thinks I should do. I was going to have him build it but now that I am in a local hot rod club there are guys (even though it's for old Ford trucks) in it that will help me out. So I will go to the speed shop and ask him what he thinks I should have done at the machine shop.

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Originally posted by res ipsa
IMO you need to do a lot of reading (in books and on the web), and buy a book on rebuilding a sbc by David Vizard. You should do those things first before you start blowing money at the machine shop. Many shops might view the inexperienced newbie as a source of money.... money that you don't always have to spend.

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HEY,I HAVE THAT SAME BOOK I THINK IT IS OVER 20 YEARS OLD NOW.KEEP IN MIND THIS IS A WRITTER WITH A LOT OF DIFFERENT OPINIONS.