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'88 454/350 deck height

Mike29

Contributing Member
Was curious if anyone knows the deck height on our older 454's. I'm shopping motor parts for my next haulout and get asked this when talking to parts people. I know there was a standard height and the truck motors seemed to use the taller deck blocks but not sure about the marine engines. Can anyone verify this for me?
 
Every one I've touched was a standard deck height block with one exception...… that was a custom built big block used in a race boat.....
 
I agree with Makomark. Standard 9.8 deck motors. Should be the same as the same year, or year prior 3/4 truck block. If you're doing a rebuild, get a 4 bolt. Most marine motors are, but some of the 330hp and 350hp Crusaders are not.

Your motor, being a 1988, should be a standard deck hight (9.8), Gen IV, 454.
 
I wanted to know the deck height as I'm thinking about redoing my cylinder heads this winter. I have close to 1600 hrs on my motors and they still are running good but I know its getting time. I can purchase some oval port aluminum heads with SS valves for under 1000.00 per side. I was quoted 600.00 per side to redo my peanut ports which I'm thinking I can save 80-100 Ib's a side with the aluminum heads plus get a little better performance with the larger oval port heads. The 600.00 quote to rebuild my old heads was with new SS valves and new guides. I have to stick with my cast iron intake as I have clearance issues with my motor box unless someone knows of an aluminum one that is the same height as the original Crusader one. Thinking of going with some aluminum exhaust manifolds also....maybe Stainless or Hardin....thinking this will take some major weight off these motors and hopefully improve the efficiency just a little. Would love to hear some thoughts.....
 
$1000 a pair or each, for the aluminum heads?

I think you'd be better off reworking the peanut port heads.....they put the smaller ports in the head for a reason. The "weight savings" will be hard to see.

As far as the exhaust goes, if you have the older log style, the newer 'center riser' style manifolds breathe much better and would be worthy of the effort....especially if you make sure the rest of the exhaust flows well....I've never seen anybody go to stainless with a 'normal' inboard....seen a few offered but very expense.

If your hull is relatively light weight, you can probably get more economy out of getting the carbs custom tuned....takes a good bit of time and effort but will pay dividends as long as you use it....

Finally, if you are going to do a full rebuild, you may want to consider the valvetrain....the flat tappets and factory rockers have a fair amount of friction....roller hardware mitigates that....but with added expense....
 
$1000.00 for the pair. I do have the older log style exhaust. The boat is a 29' Blackfin Flybridge model which probably weighs 15000 fueled up and ready to go...shes not light for a smaller boat. Stainless marine is a brand. They are aluminum center rise but don't know if they are plumbed like the Crusader motors to run coolant thru them. I like the idea of the center rise exhaust and will consider that with Crusader manifolds. Although the motors are running great we did a compression check and I have one cylinder on the starboard motor quite low..we shot some oil in and it didnt come up much which is making me think headwork time. $600.00 per engine to rebuild heads with all new guides and SS valves. I like the roller cam rocker idea but have not found one in the reverse rotation style lol. Comp said they could grind me one if I could find a blank. I don't plan on doing this work until winter so won't know until then if the lower end needs work. Oil pressure is at 40psi and neither motor seems to burn much oil which makes me think the lower end is good. There is a small builder here trying to talk me into putting stroker cranks in and making the motors 489-496 depending on condition of the bores. he seems to think it would be the easiest way to increase the lower end torque where I need it near 3000 RPM. That and as you stated opening up the exhaust. Thanks for your input Mark...its always appreciated..... I did overhaul the carbs with some kits from Cliffs. Had an issue with the idle air bleeds plugged on the port motor but was able to change them out and it made a world of difference. I left the jetting alone but reading the plugs all seems good. Even on the low compression cylinder.
 
sounds like you are where we were back at rebuild time.....

I think the exhaust had the biggest benefit to economy....we opened it up with 4" risers and the hoses into a Y with a 5" outlet...thru the mufflers and then opened the transom hole to 5" as well....it was 3" to the Y and the 4" from there back....

The biggest carb improvement came from changing the power piston springs....there's more to be done in the carbs but I don't expect them to have huge changes.....got it to 12 GPH with a full load at cruise....helluva lot better than 16 GPH...

Another thing to check out is running your props thru a PropScan shop.....another worthwhile investment in my opinion....
 
Thanks for the tip on the springs..I was wondering about that. I'll buy a set and see what I can do. I am planning on having the props looked at and rebalanced also. Thanks again Mark for your input. My boat already has the 5" mufflers and outlet. I'll have to get the Wyes though as mine are currently the 3" variety.
Your right Mark about rebuild time. My thinking is just do the whole shebang at next haulout. These boats are on the borderline as to needing diesels which if the budget allows I would prefer. A couple of Yanmar 4HLA or the 6cylinder STP's are a popular upgrade for these Blackfins but you better really love your boat lol!
 
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on the power piston, make sure you make the measurements to verify which springs you have and also to figure out which ones are optimal.

I'd think out West, the need for diesels would be hard to justify give the distance to the shelf.....back here, the mid-atlantic is on the edge but in the northeast, its a much longer run.

We went thru the math when we got into this boat - it wasn't cost effective to buy the diesels upfront, even charter fishing....I believe I had to run over 100 trips a year to break even in 15 years.....that's assuming nothing broke that required hiring somebody. The complete rebuild on the gasoline engines was much less than the cost of a single new engine and we got the gears overhauled as well.....given that the fuel & oil cost has only increased (much more than I guessed at a few decades ago), I'd expect the breakeven point takes longer to reach...
 
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