another question for ya all

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"He has a point since the 305 heads have 58cc combustion chambers and the 350 heads are most likely 76cc, or at best 64cc before milling..."
Yeah, the L98 heads were milled. I wasn't seeking too high of a compression ratio (which is why I avoided the LB9's) because I'm supercharging it this summer....
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"Also I hope you enjoy a compression ratio of about 7:1 with your 350 heads. If you used the wrong head gaskets, enjoy the damaged bores as well"...
Oh my goodness, didn't mean to rain on you're parade Charles lol. Just to 'elaborate' though, I swapped a set of L98 heads onto my LO3, and tossed it's original swirl port design.
The heads were cut, compression is good, and the block's bores are just fine.
As for different cranks (in reference to 305 vs 350, as opposed to 1987-up one piece & 1986-down two piece, rear main seals), kindly explain yourself...
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snipped-for-privacy@webtv.net wrote:

    First for 350 heads to clear on 305's you have to use the thicker type head gaskets. This allows extra clearance. Yes .010 makes a huge differance in such a case.
    As for the Cranks, not only do they carry different part numbers for the same years of 350 & 305, they are different.
    305 Cranks do not have as thick throws, nor or they as strong as a 350 Crank. Yes 350 cranks come in a few flavors too (large vs small journial, forged vs cast).
    When it comes to making high power with a SBC 4 inch bore blocks with either type (factory or machine shop splayed) 4 bolt mains are perfered. Cost wise it costs less to build up a 350 (from a 'core' long block) then it does a 305.
    I have had people buy both 305 heads and 350 heads for their ideas of swaps. When things go wrong (not a problem with the parts I sold them, which were tested used replacement parts), jad these people come back to me. It's not my fault some 305 heads on some 350's will give you 15:1 compression ratio, or some 350 heads will give you as low as 6:1 on a 305. Nor is it my fault that 350 valves do not always clear the bores on 305.
    So with me, 305 heads are 305 heads, 350 heads are 350 heads. If I want a better then stock flow rate, I call Jegs or Summit and get a set of iron heads (dart & world products both make them). then send them to a machine shop and have the seats cut for the valves I chose, as well as have everything tested and assembled. Even new casting can fail a pressure check (rare yet does happen).
    Im sure if you wanted to spend the right amount of money, you could have a 305 sleaved for sixty over slug (piston) or larger. You could probably have the block and a 400 crank machined to work together, and even get some 2.02 intake valves to clear. (334 CID give or take a few). For that same amount of money Ill build a 383 with aftermaket heads, and a large (almost obseanly over cammed) bumpstick. Charles
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wrote:

guys all I wanted to know was is can I take the tune port off a 89 305 and put it on a 86 350 will the bolt holes line up ?
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Terry wrote:

    Intake wise, Yes a 305 and a 350 use the same stuff. Yet there is a Year difference in Head type. 1986 and previous heads have a different angle to the bolt holes then 1987 and later heads, regaurdless of small block displacement.
    You can angle the holes out and have every thing work. Charles
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oops i guess i forgot to mention it was a big block.
wrote:

and
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Huh? Whacu talkin' bout Willis? 366 (truck), 396, 402, 427, 454, and 502. Which big block were you talking about?
...Ron -- 68' Camaro RS 88' Firebird Formula 00' Mustang GT Vert
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thats just what I have been told I'll start from the beginng
I bought a 1987 firebird was supposed to have a 305 in it but when i went to replace the motor cause of a rod knock I find out it is not a 305 but a 350 so i got a new 350 motor to put in (long block) well when i went to put the oil pan on from other motor it didn't not fit cause it was not wide enough so kragen told me it was a big block...I guess I should have known from experience not to take there word for ___ .. so it is not a big block? why was pan bigger? this motor supposely not one made in mexico .....
1989 iroc 1987 firebird
wrote:

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put
block?
Whoa whoa whoa, let's take a second here.
4 bolts per valve cover = small block. (centerbolt or perimeter, regardless)
More than that, most likely big block Chevy motor.
If it's a big block then the small block stuff WILL NOT fit.
At that point you'll just have to buy big block parts outright. Aside from distributors I can't think of anything that interchanges between big and small block Chevy. There are a couple small pieces that do, but nothing important.
See what you really have, then check back with us.
-Matt- "..."
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went
a
known
regardless)
bigger? or wider then the other 350 that was in it . That and the flywheel didn't not match up to new motor
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pan
There are a couple of other things you need to find out to identify this engine, and we'll need to know a little about the old engine too.
One piece or two piece rear main seal? Dipstick on driver's or passenger side? 153 or 168 tooth flywheel?
It sounds like at least the heads if not the whole engine in both cases are 85-earlier models. If not, then you have a parts interchange problem due to a couple of running changes in small block Chevy over the years. You might have an '87-up block in one case and a pre-'80 block in the other, or some other mismatch that just requires some extra thought to make work.
There are a couple different bolt patterns on flexplates and a couple different pans. It shouldn't be this hard to figure out, but parts stores aren't what they used to be, so you end up with the added confusion of guys talking out their @ss when they don't really know the answer to your tech questions.
Let me know what you find and we'll go from there.
Good luck.
-Matt- "..."
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Terry wrote:

    There is no way you can confuse a Big Block with a 350 Small Block. Especially with the cylinder heads on the engine!
    If you do indead have a BBC, the valve lay-out it's self will look compleatly different from that of the SBC. SBC rocker arms are all in a line, both intake and exhaust. BBC are splaid, intake at one angle, exhaust at another, so the rocker arms sit staggared.
    Not all Small Blocks take the same oil pan. One peice rear seal blocks take a different pan then two peice rear seal block. Drivers side VS Passenger side dipstick makes a huge differance as well. Some aftermaket SBC blocks have a expanded skirt area and take either BBC, Olds, or Aftermarket ONLY oil pans.
Post the casting numbers off both engines. Ill see if I can identify both for you.
Charles
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As Charles said, find and post the casting numbers if you can find them, from the heads and blocks. Many here have decoding books that at least can tell you what the parts were for at the beginning of their life.
...Ron -- 68' Camaro RS 88' Firebird Formula 00' Mustang GT Vert
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