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Old 26-07-2009, 10:51 AM   #1
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Big Block Chevy help??

Hi All,

I'm shortly going to be building up the 8.2 for the revenger. To be frank, what i know about BBC's could be written on a postage stamp in black marker.

Currently I have the 'bottom half' with pistons etc, crank and cam installed, this has apparently all been balanced etc. The sump's on, but i've got some baffles that i'm not too sure about, so i'm guessing i'd better take the sump back off to see where those go!

I've got a set of hi-perf heads with square ports, they're far from mint but seem fine. I'm currently having the valve seats re-cut in these to remove a bit of pitting before i lap the valves in. I've also got a hi-perf intake manifold ready to go on.

Basically I'm looking for any advice on where i go from here. I'll be having to strip the 7.4 down for bits for the 8.2. I'll be ordering a set of head bolts and a 850cfm holley from real steel.

Any advice on then bolting my collection of bits and bobs together in the hope of creating a semi-reliable engine would be greatly appreciated!

Cheers, James
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Old 26-07-2009, 11:19 AM   #2
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Kerry (AKA Motivator) is your Man on this James
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Old 26-07-2009, 11:22 AM   #3
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Russ said that too... I look forward to his response!

James
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Old 26-07-2009, 03:17 PM   #4
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Have a word with CC, he's almost finished putting his back together.
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Old 26-07-2009, 05:58 PM   #5
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Cool, forgot he's got that 26!

One of the main things i was told was that i need to match my valve springs to my cam... The heads I've got already have double valve springs, but i have no idea what the cam is.
I don't intend to rev the nuts off this engine (i don't see the point if you've got the correct prop, and i want reliability) so does it really matter that much?

James
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Old 26-07-2009, 07:34 PM   #6
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Quote:
Originally Posted by larby View Post
i have no idea what the cam is.

James
I'm pretty sure it's that longish thing with the egg shaped metal pieces on it and it makes the engine go ruppity ruppity.

Example
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Old 26-07-2009, 07:51 PM   #7
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Quote:
Originally Posted by larby View Post
Russ said that too... I look forward to his response!

James
Did you mention a gin in your PM? if not he may not answer James. I had to pour the stuff down his throat to get him to sigh a Contract........
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Old 26-07-2009, 08:07 PM   #8
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Quote:
Originally Posted by larby View Post
Cool, forgot he's got that 26!

One of the main things i was told was that i need to match my valve springs to my cam... The heads I've got already have double valve springs, but i have no idea what the cam is.
I don't intend to rev the nuts off this engine (i don't see the point if you've got the correct prop, and i want reliability) so does it really matter that much?

James
James,

It's not the revs you want to worry about, it's whether you have a cam suitable for marine or not. Where did the block come from? Basically the wrong cam will result in reversion which will do the valves in no time at all.

The standard springs should be fine to 6000 rpm without bounce and you should only be aiming at 5000 as a maximum if you don't want to be pulling it apart every five minutes.

Gen 4, 5 or 6 block? This is important to know if you are using heads from elsewhere as the series had different water routing. See here:

http://www.boatmad.com/forum/f5/big-block-chevrolet-details-very-informative-13235.html

It also makes a difference whether you use an engine mounted or remote fuel pump. (Later blocks have no drive).

Make sure you use inconell valves if you want more than 100 hours out of it. Basically, however well you plumb it and make sure you don't rev it before turning off, you will still get a little sea water coming back to the valves. One tiny little bit of rust on an exhaust valve and the local increase in temperature will blow it to pieces. The only upside when it does happen is that the ports are so large that it will generally spit the valve head out with no damage.

Sump is important to get right. Is it a marine item?

As you'll be using a remote oil filter, make sure you've got a high output oil pump and the correct oil pressure relief valve installed. Also clean out the remote hoses etc if you're knicking them off the 454, You'd be surprised how many people forget and then wonder why the engines turns to sh*t staright away.

Top quality marine gaskets is a must. A big problem you will suffer is pound out on the inlet manifold so make sure the faces are perfic before sticking your felpro set in.

I use roller rockers on one set of heads and standard rockers on the other. More for ease than anything as the high performance heads are different heights and you can't just swap the pushrods. And before you ask yes I do keep a spare pair of heads already built up as I have learnt from experience.

If you need anything else ping me an e-mail and you can have my phone number.


Kerry
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Old 26-07-2009, 08:10 PM   #9
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I See you mentioned Gin
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Old 26-07-2009, 08:13 PM   #10
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Quote:
Originally Posted by Ben View Post
I'm pretty sure it's that longish thing with the egg shaped metal pieces on it and it makes the engine go ruppity ruppity.

Example


And I always had it down as the spinny round bit that makes the difference from a street rod engine to one were the torque is actually useable in a marine engine.
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Old 26-07-2009, 08:15 PM   #11
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I See you mentioned Gin
Mine's a large one.

In all fairness you've done well to get me in a fit state to post on a sunday afternoon.
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Old 26-07-2009, 08:34 PM   #12
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Mine's a large one.

In all fairness you've done well to get me in a fit state to post on a sunday afternoon.
Thats a very fair comment mate
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Old 26-07-2009, 10:46 PM   #13
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Ben - Thanks for the description, with that fine nugget of knowledge i feel i'm a veritable master of internal combustion now!

Kerry - Thanks very much for the response, that's just the kinda thing I'm looking for! I'm going to source a manual for the basics on torques etc, but there's nothing like experience when it comes to the little things they never mention which make a big difference!

It's a MK6 penta block, 8.2 written on the side. I got it from Russ as a part of the deal. Being penta I'd imagine the cam is a marine one, and probably fairly stock.

The fuel pump I'll be using (i assume) is the one on the 7.4, which is belt driven, and kinda remote mounted i guess.

Should i throw away the valves i got with the heads then or will they be ok? They're all in very good nick despite being a few years old...

Not a clue on the sump, but it looks the same as the one on the 7.4... how do i tell if it's marine or not? I'd imagine it is as it looks to have come with the engine originally.

Bummer about the pushrods being different, hope they're not too expensive!

I'll have to speak to you further about the oil pump/remote filter thing!

That's about it i think, I'll send you a PM now. If you're happy to have a chat over the phone that'd probably be easiest and would be very much appreciated!

One last thing i probably should've mentioned originally is I've got 3 weeks till the race and a fairly limited budget! Just to make life easy!

Oh, and I'll bring a bottle of Gin with me next time i visit the UK

Cheers, James
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Old 27-07-2009, 08:44 AM   #14
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Oh, and I'll bring a bottle of Gin with me next time i visit the UK

Cheers, James

Do you not drink yourself then

All sound pretty good James, ignore the penta / mercruiser bit the blocks come direct from chevy as a merine base and aren't touched by either unless they are building a bulldog or similar.

Valves are going to depend on where they came from but we need to make sure the exhaust at least are inconnel, i.e. stainless.

The gen 6 means you have non adjustable valve train, hydraulic roller cam followers which makes life easy.

It's going to be worth us looking around for a cool fuel setup which is basically an electric driven fuel pump running through a cooler that slings under the engine next to the sump. It's worth it for the hot days.

Anyway, you have my number now so give me a tinkle. Oh and don't discount JF, Matt and TD for advice, they have a lot of knowledge on these babies too and I'm a firm believer no one person knows it all.
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Old 27-07-2009, 09:26 AM   #15
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carb

850 cfm carb is to big for 502 that will only be rev to 5k max,750 more like it,
merc 502 500hp motor only ran 800 and your way of that with cam ,springs intake etc.
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Old 27-07-2009, 09:30 AM   #16
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Quote:
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850 cfm carb is to big for 502 that will only be rev to 5k max,750 more like it,
merc 502 500hp motor only ran 800 and your way of that with cam ,springs intake etc.

Nice avatar pic. Engine looks as nice as it sounds.
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Old 27-07-2009, 09:35 AM   #17
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850 cfm carb is to big for 502 that will only be rev to 5k max,750 more like it,
merc 502 500hp motor only ran 800 and your way of that with cam ,springs intake etc.
Thats the best bit of news i've had all week, I've already got a 750cfm on the 7.4!

What is the motor in your avatar? Looks great!

James
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