Your right..... 71 ls6 was open chamber lower compression 425hp. I'm pretty sure 71 was the last year for the ls6. The ls7 was open chamber, rated at 465 hp and was only offered over the counter well into the 80's possibly into the 90's. I know someone who bought several ls7's over the counter throughout the mid to late 80's

yes,my moms 71 vette has a ls6,,i think the tag was like 435 hp and 500 ft lbs of tq..ill have to look at it again..

yep,,i put a ls7 crate motor in my 78 trans am...that thing would carry the rt front tire when you wacked 2nd gear..i hear the engine was way over 500 hp..

I cant see how those pistons, with a 108cc head, and 4.25 stroke in 4.25 bore, would net only 9:1. Without knowing the deck height or gasket thickness, Id say they are probably closer to 10:1.

Actually I believe those pistons had 14cc domes. If the heads been surfaced, and block been surfaced, you might have a 10.25-10.5:1 engine there. That piston was originally meant for the 1971 LS6, but to be used with the open chamber head. The 1970 LS6 used the closed chamber heads, but an even larger dome than the pistons you have, which netted around 11.25:1.

I wouldn't be surprised if you listed those heads on fleabay, and get some good money out of them to a guy doing a restoration on a Chevelle or Vette. Then get some aluminum heads, better modern rods and pistons. Those are some heavy rods and pistons you have there.

I would have to check the number on mine but that piston looks like the same dome (hard to tell exactly) which is an L2349F which has a volume of 30.6cc. depending on if the block is decked, head cut, etc it would run 11.5 to 12:1 or so. the same piston was used in a lot of them with the open chamber head which brings it down to around 10:1 depending on the head used. as we all know chevy head cc is all over the place. mine was probably equiped with open heads when new but had a set of closed heads from a 1965 425hp 396 corvette. I sold the heads and paid for my entire engine rebuild so that worked out pretty good.

I think those are like the 2399 speed pro /trw with smaller dome

What I have found after sifting through a hundred Chevy forums is, a replacement for the LS6 piston (in over sizes too) is like you all said, TRW/Speed Pro 2399 / .095 tall dome. If I remember right they fill something like 13cc.
All I can really say is someone put a lot of time and effort into this motor and then ran the piss out of it so there has to be something there. I spun the motor over a few times before I took it apart and nothing hit. When I got it apart I also inspected to see if anything made contact and couldn’t find anything. Something did happen one time to a valve cover. Looks like one of the pushrods tried to come through it at some point but again there is nothing inside that looks like it did the damage to the valve cover so maybe it was old damage.
Anyone know how far down the oil in the pan is below the pan rail? Need to make a dip stick and need the full level.

M/T, hate to say it but I’m not a fan of aluminum heads in a boat. I see what the water around here does to my intakes and want no part of it when it comes to heads. Not only that but if this motor didn’t come like it was I may have stroked it but I would have not nearly done all the stuff that’s been done to it. The boat is lite and small enough that it doesn’t require the same hp for say an offshore. It’s even a little scary now. But like I said before, I can’t let this motor go. If for just the cool factor alone. I was almost prepared to accept a Hp loss to keep it after just reading the run #’s off the block. If I can get this one together I will then have a Mark IV 454 (496 stroker) and a 427 (stroked to who knows what at the moment) complete roller motors from the floating wrist pins to the roller rocker. This is stuff I dreamed about only 20 years ago.
I know some of you guys have unlimited budgets and this is old news but to me when I started to open up this motor and finding out what was inside it was the best Christmas I ever had. I took 5 years to go from a Mercruiser 330mei 454 to a 420hp 454 then to a 4 bolt main 496 stroker roller motor. After all the rebuilds the only thing left from the original 454/330mie is the oil filter mount. The gen V 454 in the Biese now is a great motor and in perfect condition. I have a note pad in front of me now of all the things I wanted to buy for it over the winter so I could stroke it and a couple other things. After totaling up the money I didn’t think it was going to get done this year. Then to have this motor basically fall in my lap I’m more than happy to get it back together just like it was raced and drop it in the 54 year old drag boat. I’ll just have to accept that the wife will never get in it even if it’s on the trailer. The kids will love it though even though the wife will only let me take one out at a time just in case. LOL.

[I]What I have found after sifting through a hundred Chevy forums is, a replacement for the LS6 piston (in over sizes too) is like you all said, TRW/Speed Pro 2399 / .095 tall dome. If I remember right they fill something like 13cc.[\I]

See, and your answer was right here on oso waiting for you!

True but I'm kind of an information slut and I've been known to slum a little to get what I need. http://www.graphiclayouts.net/smilies/sign/sign0004.gif

Block has been taken off the machine shop. Has to be done. They used gapless rings the last time and it looked like the ring and the support ring under it, the gaps lined up and dug into the cylinder wall is the best I can come up with. I didn’t want to have it cut and damned if I can afford it but now is the time to do it. While there Ken (the owner of the shop I take my blocks to who knows me by name like you know your neighbor ….scary how many times I’ve been there) confirms that one of the cylinders has been sleeved. He also mentions that back in the day the big thing was to have the longest rod you could fit in a motor. Not necessarily for stroke either. Wasn’t positive why else they did it besides getting the piston to the top of the cylinder.
The more and more I get into this motor the more it’s starting to look like it should be a museum piece on old school bad ass.
Today I spent 5 minutes looking over the intake and heads. Everything is ported and polished. Double springs with a damper spring on the valves. Heads have been cut for nylon valve seals (when I have 4 packs of umbrella seals in stock, go figure).
Just when I think I got this motor figured out it throws me another curve ball. I was starting to think that someone built this motor in their garage for a strret rod or race car and they still may have at some point but…. When I took it apart it looked like it has never been taken apart before. Gaskets and RTV were perfect and there was not a single mismatched bolt or nut on the whole motor and for the most part they were all allen heads (intake, oilpan, fuel pump). Even the intake has 7-11-69 (July 11 1969) stamped on the inside. Then ……… I notice the flywheel. It’s an inboard flywheel that the starter mounts to the bellhousing. Thought about flipping the ring gear over on the other side but it’s not cut for a gear and there would be almost nothing left for a shoulder for the ring gear (.024”) to be centered on. And even if done according to the 454’s flywheel (pictured on left) the ring gear still won’t be in the right place.

http://imageshack.us/a/img689/4624/k8tg.jpg

http://imageshack.us/a/img600/3550/cuch.jpg

Also I think we may be on to something about the rods being KIEKHAEFER's.
Just found this flywheel on ebay. Looks just like the one I have.

KIEKHAEFER HAYS FLYWHEEL 396 427 MARINE
http://i.ebayimg.com/t/KIEKHAEFER-HA...Hfw~~60_57.JPG

that flywheel proves the engine was in a boat that uses a rear mount starter,my guess is trs application that is internally balanced.looking more and more like a old 482.did you measure the bore and stroke.

Well the cam has been changed at one point. Original specs are 288/296 and it now has a 290/300 and its all roller.
I guess after thinking about it (the sleeve) I guess it had to been taken apart at some point but man they put it back together right. RTV was only on the pan ends. When you take apart a 40 year old motor and all the gaskets just peel off leaving nothing behind it had to be done right.
Looked up the original head gasket. Hi-pro marine. Another thing that says it was a boat motor. So now I’m leaning toward it’s a boat 482 race motor that someone added a few tricks to.
Bore is 4”, stroke is still up in the air yet being the crank is at the crank shop. I have to call them today so I will ask for it to be measured.
anyone know what years the 482 were built? After looking up the Cyclone I ran across someone who said that the Merc Tornado was also a 482.

the bore can not be 4 in,std bore on a 427 or 454 is 4.250.

sorry, left off the .250 part

just a minor detail!

Never heard of the "Tornado" engine. But the 482CI 460HP engine was built from around 1982-1986. I don't think Mercury High Performance had anything off the shelf during that period, that made more power than that. In 1986, the 575 came out.

I agree with Mike Tkach. That flywheel is from a boat that used a transmission, like a TRS or Speedmaster. If someone was in there and installed a roller camshaft, I doubt that was done 40 years ago!. My guess is that engine is from 82-86 era, and has been recently gone thru.

During that era, they made the 370/400/440hp 454CI versions. One thing I see different in my service manual, besides the obvious stuff, is that the 482CI had larger valve seat widths, and larger bearing clearances on both the rod and mains, over the 370/400/440HP engines.

I hear you Mild but ..... hold on this is where we make another unexpected turn ....
The block #'s date it from 68-76
The heads #'s date it from 69-72
The Marine Intake #'s date it from 1969

In my searches the 340220 block shows 427T from 1968 to 1985?

http://www.strokerengine.com/BBCcasting.html

http://www.gmclassicmusclecars.com/bbc-block-s.html

I do agree the closed chamber heads would not have been OE on a mercruiser 482ci/460HP offshore engine.

My merc service manual states the 482/460HP cyclone static compression ratio to be 9.2:1, and use the same cylinder head casting as the 370/400/440HP engine, except those had a 4'' stroke, and were rated at 8.8:1 with the 118-119cc open chamber heads, which makes perfect sense when you calculate it.

It sounds to me someone swapped the original heads out for those closed chamber versions, to get the compression up around 10:1. With some cleaning up of the block decks, head decks, it may be closer to 10.5:1. Only way to know is CC the chambers and measure how far the pistons are in the hole. Im sure its gonna crackle pretty good at idle. I'd run it cool, watch the amount of timing, and use good fuel.

You wouldn't happen to know what this means do ya?

http://img39.imageshack.us/img39/7634/zin8.jpg

Keep finding these Crane stamps all over both heads. This end also has a couple numbers.

not sure on those numbers but I did finally get to check the pistions in mine. yours are the L2399 which is a .095 tall dome, mine are the L2349 which is a .265 tall dome. that is why mine is so high compression with the closed chamber heads. both are a closed chamber style piston so it was not uncommon for people to sway the open for closed to bump up the compression easily.

Hey M/T your book wouldn’t give some other spec’s would it? Like was these motors Roller motors? With floating piston pins? It all just keeps me thinking I’m on to something here. Someone either knew what they were doing or they were just insane.
Took the heads apart today and I don’t think this was a “just slap those heads on there” thing. For off the shelf they picked the right head with the 2.19/1.88 valves and the porting and polishing they have done to all the runners is perfect and the whole chamber is as smooth as glass. Bronze guides. Nylon seals. Shims under the intake springs … wow.
On a sad note the crank is cracked and I had to have the block cut 60 over so new pistons are also in the works. I think I have everything or it’s on the way or it’s at a machine shop. Sooner or later it will all be here and then the fun can begin.

They were flat tappet .I'm not even sure there was a hydraulic roller lifter back then. I belive all the GM rectangle Port heads had 2.19/1.88 valves back then. Not sure on the floating pistons

I'd be sure to have the blocks sonic checked for wall thickness. Older marine blocks have been known to rot out . Had a fresh .060 over 454 split a cylinder wall on me first time out. It was paper thin where it split. Can you just go .030 over?

I've rebuild my share of boat motors and this one is the cleanest I’ve ever seen by far. It came from the great lakes area so it was only run in fresh water and may have been closed cooled being it had a tiny bit of antifreeze in it. Flip the block over on the stand and not even dust came out of it. Even the aluminum intake shows little signs of use.
Also the 427 tall block has thicker cylinder walls and I’ve read that some folks take them .100+ with no worries. I wouldn’t do that to a boat motor but this boat sees little water anyway. It’s not like you are day tripping with it or anything.
Block has already been tested and such and has been cut 60 over. Just waiting on the pistons for the final hone.

why go .060 over,.030 should have been fine.just fyi,.070 over is it for that block in a marine application.

Your measurement was very close, the connecting rod is actually 6.405" c to c.

I wouldn’t worry too much about the 60 over. There is enough block there to cut it a couple more times. Also as I said before the water jackets in the block don’t even have surface rust and are in perfect condition. Also the tall block has thicker cylinder walls to start with. Not to mention that I always flush after every use. You can’t use aluminum around here if you don’t.
After a talk with Bob it seems that we were starting to figure out this motor but we were looking in the wrong decade. Apparently it’s a 1970 (pretty sure on the year) Kiekhaefer 482. A very bad, bad motor. 10.33 compression, 4.25 stroke (welded up 3521 crank and reground to 4.25 stroke), rods custom made by Kiekhaefer (6.405), 4291 heads (intentionally chosen closed port head) redone ported and polished by Crane (the cam people), Aluminum intake also ported and polished by Crane, LS6 pistons, 10qt aluminum finned oil pan. All that was missing was the aluminum finned valve covers.
Bob thinks I should put it back together and then hermetically seal it in a glass box for display. I love this historical stuff and a 1969/70 Kiekhaefer 482 race motor will be a great addition to my 1959 Biese 4pt Hydro Drag boat and as much as I would like to have them both sealed in a glass box I’m more Williamsburg then Gettysburg when it comes to history. Williamsburg’s motto, “Where history comes to life”.

I also found this >> http://www.offshoreonly.com/forums/a.../t-148313.html

I have a old set of 461 small block heads with similar markings on them. I was told by an old school engine builder that back in the day Crane would take new GM castings , port them, install upgraded valves and springs then sell them as "Crane heads" since there where no aftermarket castings back then.

Figured they would be over 10:1 . What was that engine rated at power wise? My guess around 500hp? Will you be dynoing it after the rebuild ?

Bob was telling me the same thing and it’s been done to the heads and the intake for sure. It’s all as smooth as a baby’s ass. All the intake valves are shimmed (with a different combination of shims so they were doing some measuring). Super nice valves, Brass guides with cut seats for nylon seals …. And all this was back in 1970.

You know now that I think of it, all the things we talked about (like a kid that just learned how to read “see spot run” trying to read an encyclopedia) I don’t think he did tell me the hp. Maybe he can chime in and tell us when he gets a chance. Also Bob if you have it, the torque specs on the rods if you have them.
I would say it will be in the neighborhood 450/500 (with his fingers crossed). No dyno. I’m not into numbers (well I am but this motor is going in this boat no matter what). It’s either going to be fast or …. it’s going to be fast. I have a full roller (floating pins and the whole 9 yards) Mark IV 454 stroked to a 496 now in another boat. It’s a bigger and heavier boat but I know the motor and what it’s capable of doing. Often though about building a duplicate for the Biese being I stumbled onto combination of parts that works well. Now I have this 427 stroked to a 482 and going 60 over makes it a 495ci that is made in a totally different way that I would never thought of. Kind of stoked to find out the comparison. The best of the best that GM, Kiekhaefer and Crane could come up with in 1970 compared to what I built by doing hours of research and shopping on the internet and putting it together in my garage 5 years ago. Not that I doubt my 496 but I bet I get taught a thing or two before this is all over.
I’m keeping a running build sheet of every part and gasket that made the motor so if anyone wants to build a bad ass they will have the build sheet.

I've got a vintage book here dated around 1971, its about hot rodding the big block chevys. and I think they talk about that engine. I'll check it out tomorrow

Mark,

A very rare piece, one of only 25 built at GM in collaboration with Kiekhaefer. If you get me all the numbers off the heads I may be able to get you the original build sheet for them. Later today i will post all the specs on the engines along with the architecture. That is interesting in how they arrived at the configuration without the benefit of easily moving dimensional placement of pin location etc.

Bob

Yes, the book I have here does mention they built about 25 of these engines. But, they also were talking about the Turbo Version of it. They made mention of getting the parts for it, with no luck. Book is dated 1971.

The only numbers I could find I post in this picture. 416X and C (or G) 2357

http://img39.imageshack.us/img39/7634/zin8.jpg

Casting # 3964291

Thanks again for your help.

And Bob this is the boat it's going in.

http://www.supernova19.com/resurrect...e/1c4b3fe0.jpg

I think it's worthy. :D

http://www.supernova19.com/resurrect...oint_hydro.htm

Rod and packaging
 

Attached is a photo of your connecting rod. (Credit unknown).The parting line on the forging is hand ground smooth the full length of the rod. Areas around the bolt seats are given a generous radius to reduce the potential for stress risers. GM had a design sheet for race preparation of the dimple rod. The Kiekhaefer rods are prepped in identical fashion.

You inquired about the rod bolt torque spec for the engine. I would recommend, given the unknown history and relative certainty of a very high cycle value on the rods (due to age and application) that you magnaflux and recondition the rod with high quality, current spec rod bolts.

There were 25 of these engines assembled at GM in cooperation with Kiekhaefer. At that time all production Chevy big block packages were designated “Turbo Jet” engines. These development engines were designated 482 Chevrolet “Turbo-Marine” engines even though none were ever turbocharged.

The architecture of packaging a 4.25” stroke into a Std. deck block was much more challenging in the late 60’s, early 70’s than today. There were no aftermarket 4.250” cranks or shelf stock piston pin heights raised .125” or 6.385” connecting rods available at that time. That left two choices for an engine builder. Sourcing a costly custom crank from Moldex or Hank the Crank, or welding and offset grinding a OEM crankshaft, using a Std, piston pin height, a long rod, and a raised deck block. Kiekhaefer , had semi finished rod forgings made that would accommodate the necessary 6.405” c to c length of the rod to package the assembly. The packaging of the assembly is why a tall deck block had to be utilized, in spite of its inherent design disadvantage.
What is a routine 482/489/496 build today, utilizing parts sourced from the aftermarket, was considerably more difficult in 1969.

Block deck dimension Std Deck (454)____ 9.800”
½ stroke/stroke radius_______2.00”
Rod C to C________________6.135”
Piston Compression Ht._____1.645”
Piston to Deck_____________.020”
Total_____________________9.800”


Block deck dimension Tall Deck (482)____ 10.200”
½ stroke/stroke radius_______2.125”
Rod C to C________________6.405”
Piston Compression Ht.______1.645”
Piston to Deck_____________.025”
Total_____________________10.200”


[ATTACH=CONFIG]515555[/ATTACH]

Any updates

Took forever for the crank guy to flux the crank and then it was found to be cracked around the 1st journal. Had to source a forged crank and then get it here. Didn’t work out to bad but still sucked. About $450.00 for a reground Eagle forged crank. Then there was the block and such. Had to get pistons 60 over. Got a good deal on them also but when you throw in the holidays everything moved at a snail’s pace. Finally got them here and to the shop for the final hone and finally they turned the block and pistons loose on Friday the 3rd. Loaded everything from their shop into the truck that already had the other pieces in it ready to go to the “House of Balance” so when we crank it over for the first time it don’t shake itself apart. And there it’s been. At least I have the block back and prepped.
Also, figured how much the oil pan holds and marked the dipstick. Locked out the vacuum advance and rebuilt the distributer. I don’t think they used it anyway and it’s better locked down if not used. Rebuilt the heads. What a fine piece of work they are. Rebuilt and plumbed up the carb also and anything else I could come up with. What’s here is just sitting until the rest of it comes back. Then hopefully I can get this pile of parts built into something.