This past winter I match ported my intake and had my throttle bodies rebuild and bored out to 53mm, also purchased a pair of new Dart heads put all back together and wow what a Hugh difference, but and there is always a but isn't there ? My 110,000 lower end could not take the increase in compression so now I will be going the direction of a new short block. My question is what would be the best block to go for; I want to keep my crossfire system because I feel very comfortable with it. Feedback is greatly appreciated

 

Why not just take your block to a machine shop?

 

OR... why not diagnose before treatment? The C4 Vette has one great feature that is a throwback to the cars of old. The oil pan comes off easily without having to pull the engine.

Pull the heads and look at the cylinder ridge. If there is very little ridge, then there is probably not a lot of cylinder wear. Pull the pan and the pistons and mic the cylinders and crankshaft. Unless the engine has never seen frequent oil changes or has been driven REALLY crazy, the odds are very good that things will be in tolerance and simply replacing rings and engine bearings will put the short block back in good shape.

In the old days this was called an in frame overhaul and was an accepted maintenance/rebuild method. In those days, with carburetors and the poor oils that were available the cylinders were often toast at 100,000 miles. Today with far superior oil and fuel injection limiting the amount of oil washed of the cylinder walls during cold starts, bottom ends are good for at LEAST twice the mileage as those of old.

The Small Block Chevy is an engine that has always lent itself to reringing. The odds are HIGH that this would get your engine as good as new.

If it turns out for some reason that your engine is indeed worn out requiring a short block, you will not have wasted much work because you will have it to a point where a short block could go in quickly.

Good luck,
Doc

 

I was looking over some of the GM off the shelf short blocks and was thinking that it would be a pretty safe way to go. I am interested in finding out if there is a better match for my crossfire setup, they offer the blocks in horsepower ranging from 290 up ? The differance as far as money is not that much and if you feel it would just be better to re-build what I have then I will do that....

 

GM blocks are fine. You should decide what your goals are first. Do you want some performance gain? Machine shop is cheaper I think... plus you can just have em go 30 over on it. Now you put in a nice set of pistons and rings and you got a better setup than some of these other block. Just remember your block is the same as these other 350 blocks, it all depends on what you want inside of it.

 

Okay guys, we're still putting the cart in front of the horse here. It is VERY likely that this engine could be EASILY, ECONOMICALLY and EFFECTIVELY overhauled in frame.

There are many advantages to taking this approach:

You will keep the factory balance - unless you spring for a really expensive short block it will probably not be balanced.

It will maintain a numbers matching car. Who knows, these cars MIGHT be worth something some day.

There is almost no additional power to be gained from the short block. The vast majority of power is determined by the heads/cam/intake package.

It would save lots of money.

You would have the pride that you know that you made it all like new YOURSELF!

Doing an inframe overhaul in some ways would be easier than changing out the short block. Once the heads are off, which they have to come off anyway, you simply pull the pan (fifteen minutes on these cars,) unhook the rods and push the pistons out. Make sure all pieces are marked so they go back in place in all the same positions. Mike the cylinders and journals which will probably be fine, then put it back together with new rings and rod bearings. If you've had any oil pressure issues, replace the main bearings while it's apart. For peace of mind replace the oil pump. At that point you have a fresh, balanced short block without having to remove and replace it.

In a Vette because of the engine setback and difficulty of reaching bellhousing bolts, reringing the block in frame may very well be no more hassle than changing the short block.

AGAIN, don't put the cart in front of the horse. You guys are already talking about boring the block before you have even MEASURED IT!

Diagnosis before TREATMENT!

Doc

 

There were over 55,000 '84 Corvettes made. They will not go up in value (I'm not knocking them, I have one). Doing your in car rebuild, after the pistons are out, you said mike the cylinders and if ok, just put new rings in. New rings would never seat without honing the cylinders. If honing in the car, oil and metal would get all over the crank and main bearings unless you're talking about a dingle ball hone which is a half a$$ way to hone 8 cylinders. If the heads are off, the op is only a half hour away from pulling the whole motor so why not just do it right?

 

I understand that my 84 will never increase in price but that is fine with me as I have no intentions of selling the car, yes I actually like this car.... Doc I understand your approach and respect your advise but I do plan on keeping this car long term and really would not like to pull her apart again. So with the fine advise I have received so far the best way seems to be sending the origional block out to get it overhauled, is that how everyone feels ?

 

explain why you think the compression is up, and why your engine short block can't take it.
I put 58 cc heads on my 86, and the compression is almost 10.5:1. it runs just fine if you don't do drag racing. The engine does not burn any oil, and it's the basic same engine you have with a 1 piece rear main seal.
The short blocks you see advertised that go from 290 horse up to 255 horse don't all have compatibility with your fuel injection system.
A 350 block is a 350 block is a 350 block. Some have roller cam provisions and 1 piece rear seal changes, but that's it. You can make yours a roller cam block, it's just more expensive. Less expensive than a new block. But if you want a new block, go for it. IF I were you, I would get a zz4 short block, and put everything you have on it, depending on the size of the head combustion chambers. If you need 58cc for the ZZ4 dished pistons, you have other choices depending on what heads you bought.
your cam is 82 and 84 specific. you will have to have a chip burned for your car if you change cams for big horses.
Your car was designed for cruising 75 mph at 1800 RPM. you are going to get into stall speed changes in a converter, and rebuilding your trans.
Decide what you reallly want to do, because there is a action-reaction going to occur when you start overstressing the original parts, and from now on, it is going to get expensive.
Remember this, you already have about $2000 plus purchase price tied up in a car worth $5000 or less, and no matter what you do, you will receive $100 back on every $1000 you spend when you go to try to sell it.

 

You are missing Docs point....

Why are you "sending it out" when you can do it yourself and obtain the same thing??

Rings not seating? I did a 68 Chevy Truck just as Doc suggested in a single Saturday.

A smoking worn motor ran like a scalded dog afterward. The Truck was sold to another kid ( I was a kid) in that town and I kept up with my rebuild for at least 4 years...then the truck was sold to someone I didn't know and I don't know what happened to it after that.

What was Docs original suggestions?? Check the cylinders to see if they are in or out of tolerance....Key phrase being "and mic the cylinders and crankshaft"

If you send the Block "out".....All they are going to do is check the tolerances themselves anything that is still within spec, they aren't going to touch...they'll slap it back together and "LEGALLY" call it rebuilt.

So some hourly wage kid checking the specs is better than you how??

If you want to punch it out .030" over...then state that.

If you only have a 127 piece tool set from Kragen....state that as well.

If you'd like to pull it and paint the block and shine up all the pieces state that as well.

If you'd like to fix the problem and drive on, You have a good suggestion.

 

Okay, I have done in frame overhauls on at LEAST a couple of hundred engines. MANY years ago, I would indeed hone cylinders with crankshaft in place. You are NOT honing the cylinder to size, you are only breaking the glaze. Taking a few precautions and doing a short oil change or two with a GOOD oil filter, preferably a Baldwin which is a ball of string will prevent any problems.

That said, since the late seventies I have YET to hone a cylinder during an in frame and I have YET to have rings not seat. There is ONE stipulation though, and that is the use of cast iron rings.

RYDER Truck Rental at that time operated one of the largest vehicle fleets in the world, second only to the US Government. Ryder labs did EXTENSIVE research and determined that the best way to in frame was the use of cast iron rings on a glazed, but of course in spec, cylinder wall. THIS WORKS and works WELL!

Reringing an engine without breaking the glaze is against old school wisdom but it WORKS!

I had occasion once to see an engine that had 400 miles since a cast iron ring, glazed cylinder overhaul, be taken apart. It was taken apart for a reason besides piston/cylinder issues. Every ring in the engine had obviously seated well.

Newer design engines are not commonly overhauled for many reasons, but the old SBC is a GREAT candidate for this. And the installation of it in a C4 chassis is one of the few since 1957 on which the pan comes off easily.

If you want to spend thousands of dollars building an engine for a car that is worth not much more than that, then removing the engine and doing some quality machine work, rebalancing and all that, then sure, you SHOULD get a great result, but this is a situation that's a natural for a good old fashioned in frame overhaul.

BTW, a "dingle ball hone" as you call it, originally known as a glaze breaker, is just THAT, a glaze breaker. In the case of an overhaul, the hone is ONLY used to break the glaze, not size the cylinder in any way as you would do with a CK10 or some such. There again, NO HONE or glaze breaker is necessary anyway. Just use cast iron rings.

Doc

 

Here is what I did over the winter, installed new Dart Heads #2021600 (2.02 Exhaust & 1.600 Exhaust), New throttle bodies bored to 51MM & ported the stock intake to match the heads. So with that accomplished maybe I can tackle a re-build myself ? my concern is tools..... what tools besides basic will I need ?

 

If you have enough tools to get the heads and intake off and back on, you have most of what you need to do an in frame overhaul. In addition to your basic hand tools you will need a ring compressor for sure and possibly a ridge reamer.

On the other hand, to change short blocks you will need a Harmonic Balancer puller and a cherry picker or chain hoist for pulling the engine.

It would probably cost less for tools to do an in frame than it would to change the short block.

If you've never done bottom end engine work, you will need to learn a few things, but there is probably no shortage of books named something like "How to Overhaul Your Small Block Chevy" that will give you all that you need to know.

Best of luck with it,
Doc

 

As much as I can appreicate the opinion of doing a rebuild while the engines is still in the car, IMO this would be the wrong way for a non mechanic to go about it. For someone that has never gotten into clerances and placement of piston rings I wouldn't think this would be a good idea. I know I wouldn't do it that way. I'd go ahead pull the engine and get it on a stand. Some you guys make it sound like a 20 min job.
If he wants the bottom end done then so be it. Don't throw a job at him that he may not be ready for. Sorry but your not gonna do this job with a ratchet set and screwdriver.
By the time you remove the top end, oil pan and everything else, you could have just pulled the engine and already have it at a machine shop and half done, or after you remove all that found out you needed to pull it anyways.
Sorry guys but not everyone is equiped with everything needed to do a rebuild. Remember they would have to buy tools ontop of what they want done and could be down twice as long.

 

If youve never torn an engine down safest route imo

http://www.paceparts.com/

new/cheap/warranty


Sure you can do a poormans hone and use cast rings..it will help, but really...Your motor is 25 yrs old, I bet the cyls have gone slightly out of round by this point and honing wont bring that back. Pulling a motor in a C4 is a lot of work...Hate to see you go through that only to find somethign went wrong with your rebuild. Unless youre a real good wrench and have done motors before get a new one and eliminate the varaibles.

 

I am definitely not a "Super Wrench" sure I did my heads and that was a pretty big job for me. I understand Doc's point but Doc you are most likely much more capable than I am. Right now I am confused and need to digest all the information. If I try to rebuild on my own I will need to buy a special tool to see if the old engine block is out of round, What to do..... need to think this over guys.

 

qws,

He is pulling the heads ANYWAY! If he is capable of doing the heads and intake, pulling the pan, disconnecting 8 rods, pushing out 8 pistons and getting everything back together properly is doable for him IF he feels comfortable with what he has to learn.

cuisinart,

Yes indeed this is a 25 year old engine, but it is an INJECTED engine! Cylinder and piston life were RADICALLY improved with the advent of fuel injection. The old carburetors were dumping raw fuel into the cylinders at every cold start, washing the oil off the cylinder walls. FI probably extends piston/cylinder life by a multiple of at least three. UNLESS the engine has not seen a reasonable oil change interval or has been driven REALLY crazy, at this mileage the odds of in spec cylinders are quite high as are the odds of a reusable crank.

All,

No, this is not a 20 minute job done with a pair of pliers and a screwdriver, but it doesn't require a big, full Snap On box either.

inex1 needs to make his own decision. If he is drawn toward a challenging, but rewarding DIY project and has someone to ask questions and is able to digest information in an overhaul book, this is a good solution for him.

I am trying to encourage him to look into it and challenge himself. He's not trying to build a Pro Stocker. He's ambitiously trying to improve his somewhat modest, but fun car. He has shown that he's up to a challenge by doing the top. That's easily more than half of the work of an in frame on one of these cars.

For an in frame, you're not pulling anything off the front or the back of the engine. The C4 Vette leaves the block quite accessible once the heads and intake are off.

Keep researching this inex!

Doc

 

The op bought a Corvette for performance. If he wanted a truck with "old school" cast iron rings he would have bought the truck. He is starting to mod the car. Modern chrome moly rings can take more heat and abuse than cast iron rings. It may see track use eventually. Maybe even some nitrous. If he is going to rebuild the bottom end, he should be encouraged to do it right. If he wants to assemble the motor himself, he should at least pull the motor, get the thing tanked, a machine shop could take .0005 of the cylinder walls to hone for the new MOLY rings. Better yet, buy a new rotating assembly .030 over and essentially have a new motor, not a patch. He said he wants to keep the car for a long time. Not have another 2 year rebuild hanging over his head.

 

A nice crate motor OVER AND DONE WITH IT. Just enjoy the car , and have fun. Before you know it, you'll wish you had done this or that. Be realistic in what you want, and more importantly who you are. If you like fun, and performance cars, you'll need to steer clear of anything stock on it, unlesss it has the z51 pacakge which might need new bushings at this point anyways.
good luck.

 

Where did he say he's pulling his heads off? You told him too...but other than that I don't believe he was pulling them.


Personally I understand the point that your trying to make and I don't disagree with your point. And I do agree that he needs to research it before making is mind up. I'm being just as truthful as you but I'm on the other side of the fence.
Would I like to learn how to tear my internal apart ...yes. Do I have a book that tells me how to do it...yes. But when push comes to shove I really don't have the time. So for me I either send it to a machinist or buy a new block. Those options have warrentees, my workmanship with zero experience as none. So I'd be pretty upset it I had to tear it down a second time. Anything else on the car I don't have a problem with.

To the op, if you do it Docs way that great, but just know that your not gonna do it in a day, and at times you will be frusterated. Then come back to the forum and pm all the guys that told you to do it yourself...