Thread: tons of bb questions

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I have a 1985 empress 32 ft motorhome. I bought it and it overheated on my journey home. I bought a 454 bb engine because water is poring into the oil pan so I figure the block is cracked and ruined. The engine I bought is old. It is 1973 but was rebuilt in 1985. It was bored .030 and .010 on the bearings.. I am taking this engine apart. I have found the timing chain is totally sloppy it moves 11/2 inches. The bottom crank gear is worn badly. The piston heads look great. The piston chamber walls look fine. The ridge feels like about 2-3 thous only guessing though. I will be looking at the bearings tomorrow. Heres some of the potential problems.

1.My heads are oval port from this engine and are 781's. The intake manifold isnt the same as my 85 but I will need to use my 85 intake because it feeds air into the exhaust. However the 85 its intake manifold ports are smaller I believe they are called peanut. The question is can I use the 781 heads from my 73 engine with the 85 intake manifold.

2.Also I was told that my crank in the 85 is steel Will the cast crank in the 73 be ok in the motorhome. Will the crank from the 85 fit the 73 block(I gues not because the 73 is .010 over on the bearings)

3. I was told to check the cam I can measure the small dia and then the large diameter with a vernier and the difference will tell if the cam lobe is within spec. I dont have a dial gage.

4. If the cam is worn could I use the cam from my 85 motor if it is still in good shape?

I would like to get away with new rings possible bearings if needed. I have already recontioned the 781 heads. My brother has an edge reamer and a reamer to do the piston walls, and a ring cleaner just need a compressor.

Any insights much appreciated. Thanks

yes you can use your small port intake .on the bigger heads . the iron crank will be fine .the cam . well look at the lifters one at a time if dish there junk .if you mix them up thats not a good thing they should be kept the way they were running in the engine .if your old cam/ lifters are good then you could swap the cam and need to use the lifters that where used on that cam. this would be a good time to look in a better cam RV cam new lifters .rige reamers can cut it the wall and honing will not fix it if more then 003 should be bored with new pistons if there a lot of tapper

That is really good news about the ports. Will the 781 heads change the performance of the engine in the rv or the horsepower???

About the cam does the method I described work. I could see a small amount of dishing on a lifter and I can see wear on the sides of the cam lobe. We will be taking the cam out. If I change the cam I dont have the tool to change the cam bearings. Its like I possible will have to get the shop to do some of this work if I need boring and a new cam. What did you mean by a better cam for the rv. I've read about modifyingt hese bb to give huge hp but honestly dont know what I would be looking for in a different cam and what benefit it will give me. Im a total newbie to the chevy bb and only began to research it recently because I have no option. I need a working engine or my rv is also junk.

About the boring. I was hoping to not need to do this. But with the timing chain being in such poor shape it makes me suspicious that this used engine has a quite few kilometers(miles) on it. So did you mean if the ridge is greater than .003 chances are the chamber is tapered from wear. Is that a fair statement?

Im going to my brothers and borrowing his ridge reamer and honer(correction not reamer) and ring cleaner. I at least need a ridge reamer so I dont damage the pistons when I remove them. Is their special care needed using the ridge reamer so I dont cut the wall as you say?

I'm also going to pick up an engine hoist (a 2 ton for only $199 that is on sale at Canadian Tire - I live in North Bay Ontario Can - I think its a great price and with god willing and some luck will remove the engine from my rv through the side drivers door according to our measurements wish me luck lol) so we can get the old engine out. ans strip it.

Will the flywheel match considering the crank might be steel and I didnt get a flywheel with thew used engine?

Thanks for your advise Pat.

Your not far from Pat---why not take it down to him????or--with the proper shipping, you can send your old junk stuff (all painted up nice) down to him and he can send you back rebilt stuff all painted the same color---beats the high customs fees

Wouldnt it just be easier for me to fix/rebuilt this one. I have most of what I need and can get help from my local engine shop. I know that most members on this site rebuilt the 454 for performance but thats not really what I need for my rv. So cost is a consideration but on the otherhand peace of mind is important when I go travelling so I will do whats necessary and will know soon enough because the engine will be apart by the end of today I suspect.

Some of my favorite sayings include-----

Whether its on a top fueler, pro-stocker, Indy car,farm tractor, etc----you need astraight round hole----now I'll probably be adding---motorhome, rv---

If your engine is worn enough that you need a ridge reamer to get the pistons out, it will be junk at the very area of the cylinder that needs it to be perfect

You don't want the pistons rattling around like rocks in a tin can. You should at least have the bores checked. Then make an educated decision. If your changing block using the other pistons I'd say new rings were in order but if your not checking anything then it won't mater your build will not in my estimation last very long. If you cut corners now you'll pay later. Somewhere out on the road????

a cast piston master kits are not to bad on price thats the way i would go then one part at a time yes i like nice strait round bores to. it is not hard to get HP out of a bbc block but they make Low Rpm Hi TQ cams .. RV cams look at Competition Products there in Fond dulac Wi there great on price and can build you a price up on a master with the parts you just need

Thanks for the help guys. I had the two end main bearings off to-day and I had one piston out. The 3 bearings were all pretty well wiped but the crank was in excellent condition. The rings on the piston were all intact and the top ring groove was almost clean very little carbon. The ridge cleaned up easily and wasnt really that deep. So I figure rings and bearings at this point. I will be measuring the bore tomorrow to see how much wear their is to be sure its within toerance.

I took the cam out and had a second opinion on the lifters. They have minimal wear and from what I can tell the cam looks good. But I guess what I realize now from this board is this particular cam might not be the best choice. The front of the engine was stamped high performance passenger and I believe it is a 73 block casting. So this cam is meant for an off the lot muscle car in 1973 is my guess. Even if I dont buy a new cam like you suggest I look into Pat, It would make sense if the cam from my rv motor is a cam suited for the rv/truck chassis. The cam has a no. stamped on the end 59G F4 I'm thinking that this no. can identify the cam?

Thanks for your help and suggestions guys much appreciated. I pulled the two end main bearings and I edge reamed one piston and pulled it for inspection. The bearing surfaces have worn away the tin overlay but the crankshaft is in excellent shape. I removed the top piston ring and the their is very little carbon so cleaning the piston will be easy. The piston looks to be fine no scoring of it or the cyllinder walls. I am going to do a measurement of the bore to see what the taper is. I had a second opinion and they felt the ridge was small and the wear on the lifters minimal. I pulled the cam shaft and It doesn't show any major wear. I will look into another cam. Perhaps Im better with the cam from my rv engine since it would be the right one for an rv/truck chassis. We took of the timing chain and cam sprocket and underneath its stamped High performance pass so Im guessing the engine was which we think is a 73 is originally from a car, another reason why the cam is not best for my rv. Im surprised that the engine is in such good shape considering the timing chain and crank sprocket were so loose and worn. This engine has a rebuilt tag from 1985 perhaps they never changed the timing chain then?? I know Im neededing new bearings and rings, timing chain and gears, oil pump and a different cam at this point. What is the tolerence on the bore its .030 over from the 85 overhaul?

Do the rebuild now to avoid the inevitable breakdown on the road that goes to nowhere when it WILL happen! Like Pat says, you can get a decent cast piston kit for reasonable money and also invest in a good low end torque cam and lifters. Go with Hydralic roller if possible but they may be too high perf orientated for your RV cruising needs

you can get smaller hyd roller cams and is really the only way to go on a bbc engine

When you speak of measuring the taper,you are talking about using a dial bore gauge,right??.

The question of a re-bore/rebuild now or not,you should call around for pricing of a tow off a interstate for your size M/H.That even with AAA is about a 1/3 to 1/2 the costs of the rebuild.You have it apart now and I could only wish I was as close to Pat as you are.Going that route you couldn't go wrong.There are rebuilders and then there are guys like Pat that will tailor a engine towards your needs.The long term is really what you need to look at.Spending extra for that at first might feel the pinch,but over all well worth the money.

030 over is not bad for a older block 060 over bores is not to big of a deal for a bbc they can take thats ez on older blocks . what is casted in the block really is nothing all bbc say hi per and some say truck hi per /pass marine the 454 in many of gm line up was not stock it was special order and was there top line cid engine hi per engine even in the later years when they were low on power as for the year of block should be on the back of the bell some of the blocks were used for many years gm did not change any thing. check the casting number that will tell you more on the break off for the block casting years .i never worry about casting numbers just happy to get a good sound block. now days there getting hard to find if thats all on the cam i am thinking i can not help you. if you want a new RV cam i can point you to some cams to look at

Originally Posted by MOOVERMAN

It is 1973 but was rebuilt in 1985. It was bored .030 and .010 on the bearings.. I am taking this engine apart. I have found the timing chain is totally sloppy it moves 11/2 inches. Thanks

There's a chance that when the motor was rebuilt, the shop align honed or align bored the main bearing bore for some reason. This will move the crankshaft centerline up towards the camshaft centerline, shortening the distance between the two and making a stock timing set chain too long, so that it is very loose like you are describing. If the shop did the work and then the fellow who put the motor together maybe used a stock timing set, that could explain it. Most timing set manufacturers make a shorter set to compensate for the shortening of the centerlines. Pat could tell you what the measurement should be for a stock block, or you could carry it to him for measuring. Just trying to pitch in and give you a hand.