Hello all, yes it is another rebuild question. I am wanting to just rebuild my 305 HO motor. I am not looking to bore it over or anything crazy. The only changes it has currently is a fully mechanical quadrajet and Vacuum advance dizzy. I will be keeping these on the new motor.

My question is should i keep the cam I have? I love the sound it gives and it has all the performance i need.
Is there a way to find an exact replacement prior to removing the motor?
If I pull the pistons what is considered acceptable to keep std rings on it? I don't want to bore it over.
Same with the main bearings and the connecting rod bearings. I should be fine with not getting the crank turned correct?

On a side note. I know my harmonic dampener has shifted due to the rubber being loose. I have one off of a 350 I can direct swap them correct? Of course I will make sure they are the same size and width, but I wasn't sure if they are matched to the flywheel. Actually I do have the flywheel. Would it be a good idea to swap as a set?

That is the start to all my questions.

I want to thank anyone who takes the time to answer, I know there are alot of similar posts but none seem to be trying to accomplish my goal.

 

No way of telling right now. You have to pull it apart and start measuring things.

The need to bore and/or hone is not really left up to you wanting to or not.. It depends on the wear on the engine.

You need to measure the cylinders at top, center and bottom on 4 sides of the bore to check for out of round. As the engine wears, the cylinders will wear oblong or egg like.

If you have a cylinder thats not true and round, then it needs to be bored.
If they are true, then you need to look at the cross hatch if no cross hatc or real light cross hatch you will need to hone the cylinders.

Same goes for crank and bearings.. 1st check all journals on crank for any lines, ridges, nicks, etc that you can feel with your fingernail.. If your nail can catch on it or feel it then it needs to be polished, maybe turned.

Measure the journal size with a mic and see what it is at. This will tell you if you need std. or undersized bearings.

Also when putting engine back together, check the bearing clearance and adjust with diff bearings as needed.

 

Well, with no malice intended...NightRider is about 180 degrees off on what to do, after checking anything..as well as how to check a few things.

Here's the deal...you (OP) don't have a machine shop in your back room...so if you think your engine is tired, then pull it and take it in to a machine shop and ask for them to rebuild it...but please call ahead, get prices, et...

Then call about crate motors/shop motors and what you may get from them, versus just having your's rebuilt.

No way to tell what cam you have in the car right now, without pulling it, hoping the numbers can be referenced, or paying dollars to put it on a profilng machine

 

Sorry 8mike9 but I strongly disagree.. Sure what you said is what the common person would do, but not what a gear gear/car guy would do.

Oh BTW 8mike9 you can tell what cam or at least what cam size, duration, lift, centerline is installed if you have a degree wheel and dial-indicator and stand.

You don't need to own a machine shop to check your cylinder taper and trueness nor do you need to own a machine shop to check your crank journal sizes or bearing clearances.

In today's tech age any good do it your self'er type can do a good rebuild on a SBC. The info is out there and free for you. Step by step guides, clearances and specs.. Just got to look them up.

Yes you will need to take your block to machine shop to have it bored, honed, hot tanks, pistons pin fitted, etc.. But if you can and your a gear head why not save $600, 800, 1200, 1500, 2500 bucks and check your clearances, and assemble the engine yourself.

I'm a performance engine builder so maybe I'm biased on the subject. I charge customers $600 just for the assembly labor on a stock or mild SBC.

The tools needed to check these basic items can be had for cheap.. Sure the cheap ones are not as good as the top dollar stuff but no need in that for basic use.

With $135 worth of measuring tools you would be able to measure just about anything on/in a car.. From tire run out, brake run out, setting up a man. trans bellhousing, check heads and block for flatness, piston in bore/deck height, bore dia., journals, valve lash on mech. cams, valve lift, retainer to guide clearance, etc etc.

In fact after your basic hand tools and power tools I recommend every car hobbyist to have these tools in their box.
http://www.harborfreight.com/1-2-hal...rench-239.html
http://www.harborfreight.com/3-piece...set-66512.html
http://www.harborfreight.com/6-inch-...per-66541.html
http://www.harborfreight.com/32-piec...uge-32214.html
http://www.harborfreight.com/6-piece...-set-5649.html
http://www.harborfreight.com/1-inch-...cator-623.html
http://www.harborfreight.com/multipo...ment-5645.html

 

What I was saying is...

Measuring to find out how much taper a bore may have, won't change the fact the the engine will most likely be going .030 over anyways, (as usually is the case with factory Al pistons) most of the wear is evident by ring groove at the top of the cylinder...I've never seen a bore that the honing patch was still evident, that had a ring groove.

In effect if the cross hatch is still present, then not much to measure there.

The issue with just micing the journals and say you get lucky and none have a taper, but are worn an additional .0015...is anyone making over sized bearings any more?...even if they are, you still have to take the crank in to be polished for the new bearings...more than likely though it would need to be ground to get the right clearances.

Shop's generally don't check any fit when you take them a pile of parts, they just do what you ask them to do...so yes, having some tools to measure prior to assembly is critical.

You can't get the complete profile of a cam via a degree wheel...so unless the cam has markings that can be id'ed, it could be one of many with a similar lift and duration...of course if it's a stock cam, the point is moot.

I think my initial reply was a bit harsh, but in general when a person posts a thread such as the op did, they don't have a full understanding of things, and shouldn't be dictating to the shop what needs to be done.

Most small machine shops will let you bring in all your parts, measure things in front of you and let you watch...then tell you what needs to be done...it's a fairly quick process and normally no charge involved...the decision then is do you want the shop to machine the parts and hand everything back to you for assembly, or have them put it together...I'd strongly advise if this is to be the first assy for a person, they shouldn't rely on a book/etc, at a minimum, they need someone with them that has done it before.

 

I truly appreciate everyone's insight. This is not my first build and I am fairly strong when it comes to assembling motors and checking endplay and clearances.

My understanding is I should take them the block have it checked and worked as well as the crank. Then have them test fit and double check the main clearances.

Related to that. I know my existing harmonic dampener has slipped due to the rubber seperator. I have a matching flywheel and dampener off of a 350 block, should I just swap them as a set? Should i get the assembly balanced after that or since the flywheel and dampener are matched not worry about it?

 

Stock cam on that engine is 202/206 duration and 403/415 lift. This is still very mild. Summit has cam kits cheap and with around 214-218 duration and 440-460 lift it will be more powerful and have a little lope to it I think you would be a lot happier with. I did a similar cam swap, intake and carb upgrade on an LG4 and had a pretty peppy little 305 years ago.

 

Pretty sure the balancers are the same for 305 and 350, you won't need to balance because of changing the balancer, if the rods are resized, ask the shop to check them and bring them in tight-ask to be sure...the shop I use only does it when they assemble an engine or if asked to.

If the crank didn't have issue before it will be fine as well.

If you stick to a brand name piston, you should also be fine there.

Of course if you were to change plans and start thinking of a higher output and revving engine, you'd want the rotating assy balanced.

 

All but the 400 small block harmonic dampers are the same. Some will be bigger than others, some will be thicker than others.. That does not matter though as long as it's a neutral balanced damper from an internally balanced engine. (283, 302, 305, 307, 327, 350)

The dampers will all stop at same point. The thicker ones will not change pulley location as the thickness goes towards timing cover, not out front.

For a stock-ish build like your doing, no need in having the engine balanced really unless you go with super light weight or overly heavy pistons.

 

Thank you for the insight. I actually just acquired a 350 that I can slowly rebuild and keep the 305 in the car and the car on the road. High Nickel block as well as many other goodies all for free!

 

Good deal. That's the best route. I have one in my shop im slowly building also for the day my lil 5.0 gives up the ghost or I get tired of it. Good luck with your project