Engine Rebuild/Enhancing Tips

[dave84gn]

Popped the motor out of my 84 GN today, looking to basically fix her up and rebuild her. So, I'm all ears to suggestions. I'm working on a fairly limited budget, but here's the deal:

My goal is basically this: I don't plan to race the he11 out of my engine, but I do want it to be able to put out more-or-less stock power when I ask it to... maybe make a few passes at the track once or twice a season, do a little street racing now and then. The second part of my goal is to make the engine strong enough (i.e. rebuild it) so it will last fine while using it as I just described.

Basically, I don't want the damn thing to start knocking or clanging on me 5000k down the road!

So I guess my question is, what sorts of internal engine upgrades/fixes should I be SURE to do? e.g. Would new pistons be of any need if the current ones are fine? What parts should I be concerned about making sure they are in good condition, etc?

Oh and what sort of machine work should I think about getting done? boring; porting; three angle valve job; etc?

Thx guys!

Dave

 

[cool 84]

For what you want, a stock rebuild is fine. A 13 sec car is not putting any real stress on the motor.

I would go with the wide rod bearings that are as wide as the rod. I'm going to experiment with the Total Seal gapless rings. Stock pistons are plenty strong. Stay with the steel shim headgaskets, align hone, have the block decked but just enough to clean it. Double roller timing set, oil control cam bearings, new oil pump, get the gears bead blasted (it really helps), ARP rod and main bolts would be nice insurance although not necessary. I'm sure there are a ton of thing I'm missing but it's late and I'm tired.

 

[Lee Thompson]

Eng. rebuild

OIL PRESSURE-- Should be your main concern with the type of engine you described.
Keep rod and main bearing clearance to .0015 max. (measured)
If your crank is standard and good you can use .001 under bearings to tighten clearance
If your front cover is not scored in the gear pocket, and the shaft bore is good, reuse with new Melling gears and a booster plate
Bead blast the gears, MAKE SURE THEY ARE CLEAN

You shouldn/t need line boring or line honing.
Stock pistons are very good.
If cyl. bore is no more than .002 over sized, don/t bore, use file to fit rings.
I have had some bad experiences with machine shops, some of them try to sell you work you realy don/t need. (this has happened to me more than once, but no more)
If you are dealing with a shop, and they try to tell you these clearances are to tight or they say we build all our Chevys with .003 clearance, gather up all your parts, thank the man for his time and get the hell out of there.
It is no fun to spend $1500, install the eng. and drive down the road with 25 psi oil pressure (hot).
If you are upgrading cams, I prefer GM lifters (some people have good luck with others, no me )
Keep spring pressure to 90 Psi. max. closed.
GOOD LUCK

 

[REDS HOT AIR]

i agree with Lee on the most part

you didnt mention if anything was wrong with it to start with or what kind of mileage is on it.

i went in my 85 motor at 182,000 miles and everything in it looked good other than the cam was wore out and the cyl. walls had some pretty good scratches in them so i bored it to remove the scratches other than that the cyl. walls were in good shape .

im with the others if it dont absolutly need bored then dont i wish i could have left mine standard.

i recomend you spend the extra savings from machine work and get some good file fit total seal rings...tho a pain to sit there and get fitted they will be well worth it in the long run..

both my turbo motors ive been able to just polish the crank and use .001 under bearings to get within speck.

if your going for the long haul it would be best to opt. for a new timing cover so your oil pump will be up to par....i bought a new cover from gm for mine and the melling oil pump kit and a piece of glass with a piece of D.A sand paper stuck to it to machine the cover plate for the pump to remove to ware off it and insure it was flat.

definatly stick with a stock style timing chain and new tensioner
the double rollers are noisy and get even noisier as you get some milage on them.

on a cam if you want stock idle, vacuum, and gas mileage with a little more performance id recomend a speed pro cs1112r you cant tell its in there but will pull from idle to rev. limiter thats the cam in my car now.

the sealed power HT 969 lifters on this cam are quite. also what is in mine.
main thing ..make sure when the machine shop cleans the block make sure they dont hone the lifter bores

also get you a roller cam button/spring so you dont grind down your new timing cover...

keep in mind a little head/port work helps these lil motors out so if its in the budget or you can do it yourself go for it..

while your at it spend some time with a die grinder matching things up like where the t/b and turbo housing bolt together...etc..

good luck....RED

 

[dave84gn]

Thanks cool84, Lee, and Red. Appreciate it. Most of the stuff you've all said is over my head right now, but I'm hoping once I get the engine apart and start doing some quick-learning I'll have tons of questions

Oh and I think I mentioned this in my engine removal thread, but I should have repeated it: Engine overheated on the way home from the track last weekend and was making a terrible knocking and screaching sound from the bottom end of the engine. So I'm not simply doing a rebuilt, but fixing whatever caused this problem.

105 miles on the engine.

Thanks guys, I'll certainly revive this thread once I start tearing apart the engine.

Dave

 

[cool 84]

Let us know what that sound was. I'm betting a spun rod bearing.

 

[dave84gn]

Yup, spun rod bearing (cyl 5). I have basically ripped apart the whole engine except for all the rods and pistons and the crank. So there could be more spun bearings.

Head gaskets looked ok.

Cam looks like it's in bad shape... one lobe was pretty well flattened out (and the corresponding lifter was rounded inward a little), this was on #1 cyl I think.

Timing gear: chain in terrible shape, a lot of general play and very flexible. Larger timing gear had 3 broken teeth!

Here's one for you guys: Cyl2: Piston and valves were gray in color, where the other Cyl's were a crisp brown. Also: cyl #2 intake hole in the heads and intake manifold looked a dry/powdery gray, where the other ones were a black greasy color. And also, the exhaust valve (the inside of the valve) looked shiny brown where the other ones were crisp/burnt brown.

This has got me thinking... what caused these cyl #2 symptoms? I had been experiencing powerloss for the 2 months I drove w/this engine (even after I replaced the valve springs)... adding a fuel pump & hotwiring woke the car up, but not completely. Any thoughts on what would cause these symptoms? Injector not flowing/firing? Ideas?

Oh yea, plugs looked pretty good, except the #2 one looked just *slightly* a bit darker... I'd say it was a dark & crisp brown.

Thx!

Dave

 

[mike85gn]

Well, if you buy Terry's motor, most of the guesswork is taken care of for you. I am somewhat suspect, however, as he was only running 14.2's without NOS. 11.8's with. Makes you wonder how much of a beating that engine took. That and the fact that it is chock-full of Kenne-Bell junk parts, you may want to change the cam out for something that is actually good, Lunati 200/200 club cam, or maybe a Comp 206/206. Do the timing chain as well. Headwork has been done. A performance engine like his should be in the 12's no problem, I am leary of why he only got 14.2's out of it.

What is everyone else's opinion of the appropriate cam profile for performance street and mild strip?

 

[dave84gn]

12's seems a little optimistic, but I don't yet really know all of what he's got done to it. Anyway, I guess there isn't much more to say, as we're having a nice discussion about this over at TBs.com

Dave