I have a 1985 z28 305 engine. What's the rear main seal? 2 piece or that rope style kind? I want to really get a 2 piece 350 because I've heard those are better. What years did they come on? Also, what ratio are my rocker arms too on the 305? 1.5 or 1.6? Do you also know the size of my pushrods? How about the head specs? Also, can I stroke my 305 up any with using a crank from something else? Sorry for all the questions but I've been reading about how to rebuild a SBC and I don't know anything about mine! THanks.

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1984 Firebird SE
1985 Camaro z28 305 engine T-5 Five Speed Tranny, 92 Camaro Leather Seats Console, carpet everything. Soon to put in 700R4 and 427CI. (Hopefully.
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The 85 is more than likely just a 2 piece seal motor. Nothing special. The only thing "better" about a 2pc seal 350 is there are more flywheels available if you convert to a manual(on a budget though, forget about a T56) The difference in strength on a 350 is 2bolt to 4bolt mains, in which case the 4bolt is more desirable. For a mild street motor though, the 2bolt sohuld work just fine. If you get a forged crank, and go all out, and plan on spinning the motor to 6500+ rpm, find a 4 bolt. Your stock rockers are going to be 1.5, and I dont know the length on pushrods. if the 305 is the LG4, you have 58cc cast Iron heads, pretty restrictive and prone to cracking. I know I am treading lightly here, but it takes serious work to get them to perform on a 350. Not really worth it to me. Search the boards for the 335 stroker kit. You still run a small bore and restrictive heads though, and I think the kit runs around $2k. Mike

 

Since you plan on switching to a 700, I'd use the 1-pc seal block, hands down. A 1-pc seal block will rarelt leak, as opposed to the older 2-pc ones. Only reason I could assume that someone may think the 2-pc is better is that there used to be high nickel content blocks, and also the ability to use a 400 crank to stroke it with less hassle.

 

The only reason I could think that a 2-piece seal is more desireable is like what was mentioned before, the cranks are a dime a dozen, vs the 1-pc cranks. Go shopping for a stroker crank 2-pc, then price the 1-pc.

But if you can't stand a leaker, get the 1-pc

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1987 Trans Am 305
14.88 @ 92.81

 

are the 2 piece seal hard to replace? i heard you have you to drop the oil pan and replace it that way instead of dropping the tranny. is that true?

 

Really the 4 bolt block isnt all that much better for high winding. The configuration more supports truck useage.

 

Yes, that is true.

Dropping the pan is easier than dropping the tranny, though.

 

Keep an eye on original post date here....

 

Well it's a new member's first post, and maybe we should give him credit for using the "search" button....

Although, more likely, it's just that he's got the forum "options" set to display "oldest first" instead of "newest first".

Personally, I don't have any leakage trouble with the 2-pc seals; I suspect that most of the problems are due to improper installation. Either just jamming them straight on instead of sliding them around the circumference, or using sealer on the back side of them, or letting the ends line up with the joint between the cap and the block, or putting them in backwards so that they clear any oil that gets on them OUTWARDS instead of INWARDS, or not putting sealer between the cap and the block.

But to answer CMan's question, I find it easiest BY FAR, to just pull the motor. I fail to understand why people make such a big deal out of that, since a WHOLE motor R&R, even with a different motor, is only about a 1-afternoon job. It's simply not tha tbig of a deal, if you approach it from the point of view that "this is what it takes" and just jump in there and DO IT, and not try to pussyfoot around trying to "get out of doing work". This is DEFINITELY one of those jobs where you can easily do three times as much work by trying to get out of doing the work, than the amount of work you're trying to get out of doing. I think that's where most people probably bone themselves on it.