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Old 06-10-2012, 10:01 PM
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Completing a 305

First order of business: No, I don't want a 350.

This will be my brother and I's first engine build, a bonding experience!

I got the block/heads/cam/intake for free. All I need are pistons and rods, right? The thing is, I'm new and don't know the voodoo behind matching these things together.

All the guy knew is that it was an 80's model. I know I can look up the heads/block casting numbers, but what about the cam? And once I know what they are, how do I pick the proper pistons?

The idea behind this build is a low-budget learning experience.

I bought How to Rebuild a 350 (I figure it can't be too different) and I'm googling things, but it's nice to hear from a real person.

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Old 06-10-2012, 10:28 PM
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tI rebuilds like any small block. My 305 has the performer cam and intake. Refreshed yard 906 vortec heads. Modded qjet and summit 9006 headers. Really happy with it. The 3.73 rear gear and 3000 dymanic stall help move the full size truck. It is no racecar but fun to drive.

The package makes the whole deal. Pick parts that work together. Everything trades off at some point.

A 350 is much stronger, but if it just for fun..
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Old 06-11-2012, 01:05 AM
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Quote:
Originally Posted by Perkster029
...what about the cam? And once I know what they are, how do I pick the proper pistons?
The cam may have an ID stamped into the end. If it is an aftermarket cam, this may be used to find the specs.

But if the cam is used, do not reuse it- even if it comes w/lifters. The original lifters have to be kept on the same cam lobe they were broken in on, so the chance of them having been mixed up is too great to risk ruining a rebuild by using an old cam and having it fail. And you shouldn't use new lifters on an old cam, either. Besides, the cam is too important to be left to chance, and a new cam (reground, stock specs) can be bought for as little as $14, plus the cost of new lifters. A performance cam and lifter set from Summit is a good buy at $100. More on breaking in a new cam is here.

The pistons are chosen to give the correct compression ratio w/the heads you will be using. Chances are, you will be using cast flat top or possibly dished pistons w/4 valve reliefs- they're the most common budget pistons. They also have to match the cylinder bore diameter.

The pistons also have to provide the correct quench distance. W/the SBC engine using a 3.48" stroke crank and stock length rods (5.7"), the choices are a compression height of 1.56" (stock) or 1.54" ("rebuilder" pistons). More on this in the link above.


Some suggested reading material is here.

Last edited by cobalt327; 06-11-2012 at 01:14 AM.
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Old 06-11-2012, 05:23 AM
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Not long ago I did a post called never say never. I said I'd never hot rod a 305. But I did for my nephew since it was all he had. What we had was a 1985 305 out of a station wagon. It had 80,000 original miles. He had a shoe string budget. THe engine was to go into a 89 Ford ranger 4x4. His mud play thing. We popped the heads and I did a medium port job on it. Stayed with the stock valve size of 1.84 1.50. I also slightly opened up the chambers.
The engine had a nylon geared timing set on it. I had a gear drive that had been given to me and since I was never going to use it I passed it on to him.
I also had a set of head gaskets that I also threw his way. The cam is a summit racing .210 duration @.050 with .440 lift.
Weiand action plus intake, Holley 650 double pumper, Shorty headers that cleared everything nicely. A rebuilt HEI that I did myself plus did a super polish job on the mechanical advance. The plan was to use a Quadrajet which is why we used the action plus, but his Q-jet isn't saveable so we went to a Holley. Saturday he took it to the mud park. I didn't go as I had to much to do at home. He called me saturday and was very excited at the results. many people asked him about as they were all thinking it was a hopped up 350 and they got the shock of their lives when they found it was a 305. My nephew said in low range, he winds it up in 1st gear then goes to 2nd in his own words "It goes crazy! it pulls HARD. I can't believe the power it's got! I've been out here eating up larger small blocks easy!" I didn't bother to tell him he's eating larger small blocks up because the difference is the majority of them don't know how to tune it, which is vital in how one makes power. Pay attention to all the details. Keep everything spotlessly clean, and when you get ready to put it together, wash the bores with very strong soap and scrub them with a brush. Wipe them down with a towel and WD40. If you see gray on the towel the bore isn't clean. Building a small block is a breeze and a great engine to learn building skills on.
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Old 06-11-2012, 10:03 AM
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Quote:
Originally Posted by cobalt327
But if the cam is used, do not reuse it
Thanks!! I remember reading something like this before, but it had crept to the back of my mind and I had forgotten.

Also, thanks for the links. I'll do some heavy reading.

The cam I have looks in marvelous shape, but that could be oil/gunk/untrained eye. If I clean it up, can I tell for sure if it's used or new? Will the rounded lobes be obvious?

Double Vision: Thanks for giving me hope that it won't just be a 150 hp engine passed by civics!

I'll return with pictures of everything.

Thanks guys
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Old 06-11-2012, 10:34 AM
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my suggestions would be to go onto amazon.com and look up books on how to rebuild chevy small blocks, David Vizard and SA design make some very informational books. then try to find a book that refrences the 305 exactly. give these books a good look, before you go too far.

good luck to the both of you.
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Old 06-12-2012, 12:00 AM
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So, I'm putting the cam aside and just going to get a cheap new one. Maybe I'll even go with that link you posted!

Here is what I have:

Block: 14093627

305, 2 bolt, roller cam, 1-piece rear seal

Crank: 14088526 (I'd swear it says 528, check out the picture, but after extensive googling, a few other guys had the same problem and concluded it was an error in the mold)

305/350, 3.48 inch stroke, 2.45/2.10 journal, cast iron, 1 piece rear main seal

Heads: 14102187

305, 1.84/1.50 Valves, 58cc


Now that I know all of this, what do I do with it? How do I make choices on the pistons/rods/cam. Also, I haven't had the block tested yet, and I'm not sure if it's stock or over-bored. That's on the to-do list
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Old 06-12-2012, 08:14 AM
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If you want to save a buck I have a roller cam that will fit this engine for sale. It's the smallest of the line cam in it's class and it's got great low end torque and it gets better fuel economy than does the stock cam.
If your interested in the cam shoot me a PM.
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Old 06-12-2012, 08:57 AM
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Quote:
Originally Posted by Perkster029
Crank: 14088526 (I'd swear it says 528, check out the picture, but after extensive googling, a few other guys had the same problem and concluded it was an error in the mold)...
IMO, that IS an "8", plain as day. Either the mistake was at the foundry and an 8 was used in the mold instead of a 6, or the records were wrong when they recorded it as a 6.

If this is a budget build and you're not looking for a bunch of HP, look into a master rebuild kit from Northern Auto. Name brand parts, low prices. You can substitute the stock cam for a RV grind, get the moly rings, too.
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Old 06-12-2012, 10:07 AM
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since those heads are the 64cc combustion chamber version of 305 heads i wouldn't go with any more than a 4-5cc flat top piston, cast pistons would be fine. be careful when looking at rebuilder kits as they often sell pistons with a shorter comression height to compensate for any need to deck the block. the factory compression height of a 305 piston is the same as a 350; 1.560", many reuilder pistons are 1.540 (.020" less). make sure you buy pistons that are 1.560", only have the block decked as much is needed in order to get a true flat surface and align everything. if you have access to a die grinder then i think it would be a good idea to buy a head porting book and try to clean up the runners a bit (it can be free hp). the heads will likely need to be plained a little bit as well to get them to a true flat surface, personally i would try to have them take off around .020-.030" to help up the compression ratio a little bit. while this being done i would go ahead and have them rebuild the heads. a simple hyd roller cam around 210 duration at .050 and around .430-.440" lift is what i would be looking to use. a simple performer rpm intake (ditch the factory TBI), then look on ebay for a used/rebuilt holley 600cfm vac secondary carb. also look on ebay for a simple 50-60K volt HEI distributor, should be able to find one for about $60.00. a cheap set of headman headers suited for what ever vehicle the motor is going into. keep you power goal conservitive as with what i have menitioned you might see around 275hp/325tq.

and i still say that you seriously need to read a "how to rebuild a small block chevy" book. SA design makes a very good one, written by David Vizard.
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Old 06-12-2012, 11:01 AM
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Quote:
need to read a "how to rebuild a small block chevy" book
UPS delivered it to my door from Amazon 30 seconds ago

I had planned on getting the block/heads machined, but that advice is more specific and exactly the kind of thing I need, thank you.

As for rebuilding the heads, is this something I might be able to tackle myself? "How to rebuild your small-block chevy" has some stuff in it.

Quote:
a simple hyd roller cam around 210 duration at .050 and around .430-.440" lift
How did you pick these numbers? The degrees changes where the power will be, either high or low RPM, right?

From hotrod.com:
Quote:
The rocker arms have a direct effect on lift because they don't have a 1:1 lever ratio. A cam that has .318 inch of lobe lift (that's how far it lifts the lifter) will open the valve .477 inch with 1.5:1 rocker arms (.318 x 1.5 = .477) and .508 inch with 1.6:1 rockers.
Quote:
Generally, a stock engine will tolerate .500-inch lift before the valves hit the pistons or the valvesprings hit coil bind
Are these quotes accurate? If a typical rocker arm would be 1.4-1.5, I'd want somewhere around 0.30"-ish cam lift to come close to without hitting the 0.5" mark.

Quote:
i wouldn't go with any more than a 4-5cc flat top piston, cast pistons would be fine
How did you reach those conclusions, why not more than 4-5 cc?

Boy, that was alot of writing/questions. Sorry if I am bothersome, I'd just like to learn so that one day I'll know how to make these choices myself

Last edited by Perkster029; 06-12-2012 at 11:08 AM.
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Old 06-12-2012, 02:33 PM
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Your engine probably came out of a Camaro or Firebird. Only the cars used roller cams in the 80s. It probably won't take much to get 250hp out of it. There was a factory rated 230hp on some 305s. You can put a used cam from a IROC in there, roller cams are reuseable. Look for a used aluminum 80s 305 quadrajet intake and file out the center bolt holes, it will fit those heads perfect.
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Old 06-12-2012, 02:48 PM
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The first thing you want to get rid of is those exhaust manifolds. The tuned port engines used 2.5 inch dumps on the exhaust manifolds. There are better exhaust manifolds than what was used in the Camaros. The engine will run better if you don't have to run cat converters and restricted exhaust.
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Old 06-12-2012, 04:02 PM
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Quote:
Originally Posted by Perkster029
Thanks!! I remember reading something like this before, but it had crept to the back of my mind and I had forgotten.

Also, thanks for the links. I'll do some heavy reading.

The cam I have looks in marvelous shape, but that could be oil/gunk/untrained eye. If I clean it up, can I tell for sure if it's used or new? Will the rounded lobes be obvious?

Double Vision: Thanks for giving me hope that it won't just be a 150 hp engine passed by civics!

I'll return with pictures of everything.

Thanks guys
The lobes on a roller cam are more rounded than a flat tappet cam. Roller cams use a harder metal than a flat tappet cam, that is one of the reasons most of them can be reused. Stick with a roller cam, you won't have to go looking for special oil that contains zinc.
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Old 06-12-2012, 05:48 PM
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Quote:
Originally Posted by Perkster029
Thanks!! I remember reading something like this before, but it had crept to the back of my mind and I had forgotten.

Also, thanks for the links. I'll do some heavy reading.

The cam I have looks in marvelous shape, but that could be oil/gunk/untrained eye. If I clean it up, can I tell for sure if it's used or new? Will the rounded lobes be obvious?
A new flat tappet cam will be a dark gray color due to the treatment they're given to help them wear better. The dark gray color will be all over except the bearing journals, the lobes the same uniform dark gray, if it has been used it will be readily apparent. More here.

Breaking in a cam right is VERY important. More on that here.

You can use the Comp Cams CamQuest software to see how different cams affect the powerband. Pay special attention to the changes in RPM where the peaks occur as the cam gets more radical.
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