i need some fast help from some big block experts!

[scutly]

ok here goes. my boats a 95. s/n OF558164 so i thought. i order a 91-97 merc 454 (or 7.4 for you metric guys) long block. this all is prior to me knowing about GEN V and GEN VI. i got my new block unwrapped and i pulled my old motor today and i got a few confusing differences between the two. my new block is definitely a GEN V. it has round port heads, double roller timing chain and takes a 10 bolt timing cover. Ebay listing. (i paid $2200). the block i yanked out today has a 6 bolt timing cover and i find a tag saying its a Quicksilver Repower part # 807739R5 date 2/23/2001 ser # R091000129 . obviously a GEN VI. here's the kicker. this engine i pulled has the same round port heads as my new GEN V. but the intake manifold has OVAL PORTS!!! the butcher who worked on this boat bolted down this oval manifold with a oval gasket on these round gen V heads that dont belong on this gen VI block???? is this common practice? am i just way confused? it seems i have some hodgepodge slapped together mess. at this point my heads spinning. i got this 40' manlift i rented for $300 till tuesday morning sitting on my driveway and this new engine has to go in by then. what parts are interchangeable and what do i have to buy new? these are the parts i planned to swap
oil pan
harmonic balancer
timing cover (NOT)
bell housing, engine coupler and flywheel
intake manifold (dont think so)
carb
distributor
all the brackets and pulleys with the raw water/fuel pump and power steering pump
all the block sensors
i have new manifolds and risers, alternator, starter, circulating pump, front and rear mounts

 

[picklenjim]

Re: i need some fast help from some big block experts!

Those heads were used on both the gen 5 and gen 6. People have been known to run the oval manifold on the peanut port heads. Granted not for a high performance scenario. Is it an aftermarket aluminum type intake? Your only other option is a stock cast iron type intake for those heads. I would go ahead and put the engine in and worry about the intake later. Do you have a carb or fuel injection? I would think carb with that intake. If carb what does it have for a fuel pump? Electric or one that runs off the water pump? Gen 6 was designed generally for fuel injection as it has no provision for a fuel pump. My thought is this guy had a gen 6 but wanted to run a carb. No one really makes an aftermarket intake for the peanut port heads so he used an oval port intake. Here's a thread that hits on it some.
http://www.nastyz28.com/forum/showthread.php?t=7184

 

[picklenjim]

Re: i need some fast help from some big block experts!

Looks like all you should need is a timing cover. All other parts should work that is if you decide to go with that intake. Going to need a fuel pump block off cover for your block or you could switch the fuel pump to the block and put the cover on the waterpump/fuel pump. Did you add those parts or am I loosing it and didn't see them at first? It answered some of my questions.

Make sure your new circulating pump is exactly the same as the old one or you will have belt alignment problems.

 

[cathken]

Re: i need some fast help from some big block experts!

be careful switching the harmonic balancer and flywheel.i do know from experience that switching gen 5 parts onto a mark 4 long block leads to engine vibration at all rpms.

 

[scutly]

Re: i need some fast help from some big block experts!

yes i edited my post after the fact to include my parts list. so both blocks use the same oil pan and valve covers? good. what about harmonic balancer? my fuel pump runs off the raw water pump. i just checked both blocks and neither have a opening for the fuel pump. ok now this is a big question. what kind of timing cover? plain old tin/stamped steel one? i found an aluminum one on line that clears the double roller chain, but i cant get that today. i searched around at merc dealers yesterday for part # 811570 and no one had it in stock. but will a stock chevy cover fit and is it ok to use for a marine engine? the oil pan is stock gm tin and not aluminum. now the intake is aluminum GM stamped 6269318. i looked that up and its from a 1971 454. but, you say its ok to use this manifold with the different shaped ports on the heads? this has been done before? i found a used gen V round port manifold on craigslist for $75 off a 92 searay that's still for sale so its not like a $500 mistake. my biggest hold up is the timing cover so i can put on the oi pan and set the engine in the boat.

 

[scutly]

Re: i need some fast help from some big block experts!

be careful switching the harmonic balancer and flywheel.i do know from experience that switching gen 5 parts onto a mark 4 long block leads to engine vibration at all rpms.

im going from a gen 6 to a gen 5. i can't assume anything, but ya gotta hope/figure the guy reused some parts off the original gen 5 that came with the boat on the quicksliver gen 6 replacement that was installed in 2001.

 

[FreeBeeTony]

Re: i need some fast help from some big block experts!

Is that a pic of the Robert Moses bridge?

 

[picklenjim]

Re: i need some fast help from some big block experts!

Any chevy gen 5 timing cover will be fine. Don't need to be marine.

 

[scutly]

Re: i need some fast help from some big block experts!

Is that a pic of the Robert Moses bridge?

yup heading east, looking west

 

[joncrisler]

Re: i need some fast help from some big block experts!

Pick up a copy of Mike Mavrigian's Rebuilding Chevy Big Block Gen V and Gen VI engines. It was recently reissued, and is available in Kindle Edition too for about $7 so you can download immediately. It will tell you all about which parts will interchange.
Search Amazon for ISBN 1557885508

 

[scutly]

Re: i need some fast help from some big block experts!

very cool book! for 6 bucks i downloaded it to my laptop and my droid. we got the new block in late yesterday thankfully because its pouring right now! im nicked up, banged up, bleedin a little and smashed a finger, but when im finally floatin that first cold one is gonna be the best tasting coldy i ever drank!

 

[joncrisler]

Re: i need some fast help from some big block experts!

Good luck !! Best 6 bucks you will spend on the entire project. The previous edition was out of print for about 5 years, and used copies commanded $60-150 bucks- I got lucky and found a good one in the UK for about $45, but recently I accidentially stumbled on the Kindle edition.