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454 initial timing questons

Old 02-23-2022, 01:44 PM
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So it ran ok at first but started getting hot, and on shut down, dieseled and popped back through the intake. Then it wouldn’t idle down. I still got money on gasket blown out especially with mix matched ports. Is it leaking vac into the crank case?
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Old 02-23-2022, 04:28 PM
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so as I understand it this has a rectangle port intake and peanut port heads which is way different from each other so when it idles for a while there is probably a pint of fuel sitting at the port of the head. also is this still the net zero lash rockers? if so and the head and block have been cut was that factored in or are the lifters now bottomed out? sorry but this motor seems to be very mismatched in parts for it to perform properly in a cruiser.
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Old 02-23-2022, 04:30 PM
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Originally Posted by CPFITNESS View Post
Yes, it worked fine for 4 hours then motor blew up due to old water damage in one of the cylinders
for the record, they all run fine till they don't. so don't assume anything based on what it used to do.
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Old 02-23-2022, 06:40 PM
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Originally Posted by compedgemarine View Post
so as I understand it this has a rectangle port intake and peanut port heads which is way different from each other so when it idles for a while there is probably a pint of fuel sitting at the port of the head. also is this still the net zero lash rockers? if so and the head and block have been cut was that factored in or are the lifters now bottomed out? sorry but this motor seems to be very mismatched in parts for it to perform properly in a cruiser.
this motor was designed specifically for cruisers.
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Old 02-23-2022, 06:41 PM
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Originally Posted by liberator221 View Post
So it ran ok at first but started getting hot, and on shut down, dieseled and popped back through the intake. Then it wouldn’t idle down. I still got money on gasket blown out especially with mix matched ports. Is it leaking vac into the crank case?
Busy couple days but we haven't seen much indication of vaccum leak when running motor and spraying carb cleaner all around.
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Old 02-23-2022, 06:44 PM
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Originally Posted by articfriends View Post
My understanding IF im reading the information posted correctly: motor was overheated then repaired again
18 cc domed 4.280 bore pistons
113 cc peanut ports, IF motor was overheated they had to have been milled/surfaced at least once
block, again, if bored, rebuilt and overheated at one time deck clearance went closer to zero from its original .022-.028 in hole
I ran thru compression calculator, over 10-1 with iron heads, with a small cam thats design is to build torque by spiking cylinder pressure
we run over 10-1 on aluminum headed motors with 20, 30 dgrees more cam duration , strictly on premium
no knock sensor so no way to hear /tell if its knocking
only way it will live is jetted fat to mask the detonation with good premium
buy a 02 bung, put it in a riser, see what you cruisng afrs are and wot, id jet the hard cruising into mid 12's and the wot in mid to maybe upper 11s with that compression with iron heads
You are close but not quite. The motor didn't overheat when it blew up first time. It just lost compression in one hole and upon tear down we determined it was from rust in that cylinder meaning it had taken in water and sat for quite awhile because there was a serious amount of rust "this didn't happen overnight" were the words of the engine rebuilders.
Big blocks are built like this all the time, I'm not sure why so many think it's some radical build???
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Old 02-23-2022, 06:46 PM
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Originally Posted by SB View Post
I somehow missed/forgot his compression info. Thanks for bringing it up.

10:1 or more in a cruiser no less. Anazing how many times people do this. People are forgetting (or not learning) about old school engines faster then ever it seems.
You act as if the motor can see what kind of boat it's in. Why does it matter if it's a cruiser or a race boat. Air, fuel, spark still applies.
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Old 02-23-2022, 07:15 PM
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Originally Posted by CPFITNESS View Post
You act as if the motor can see what kind of boat it's in. Why does it matter if it's a cruiser or a race boat. Air, fuel, spark still applies.
Funny you should say this.
Air- you have a vacuum leak and mismatched head port styles. Fuel = yours is old and low Octane. Spark = -10 degrees
Engines do not know what type of boat/vehicle it is going to be installed into, BUT, they do know what operating parameters/they perform well/reliably in.
The boat dictated the type of build the engine requires. That is why they make so many cam variations, head runner length, intake manifold designs, carb variations, exhaust manifold styles, etc. etc. etc.
Not being sarcastic just trying to get you to take a objective view of the situation. Some of the most knowledgeable engine builders on the forum are trying to help you.
My suggestion is find a new mechanic so far seems like yours is not making good decisions on your behalf.
Just my .02
Good Luck.
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Old 02-23-2022, 07:34 PM
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Originally Posted by compedgemarine View Post
so as I understand it this has a rectangle port intake and peanut port heads which is way different from each other so when it idles for a while there is probably a pint of fuel sitting at the port of the head. also is this still the net zero lash rockers? if so and the head and block have been cut was that factored in or are the lifters now bottomed out? sorry but this motor seems to be very mismatched in parts for it to perform properly in a cruiser.
I thought of those issues as well, but the intake is OEM on both the 7.4 and 454mag for several years.
Also, the rocker shoulder bolts are the same part number for the both the 7.4 and 454mag.

My thought was the valves were possibly too tight and not fully closing, which could still be the case.
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Old 02-23-2022, 07:40 PM
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Originally Posted by CPFITNESS View Post
this motor was designed specifically for cruisers.
No, it was not. Same engine went in all kinds of boats. The Bravo3 part is for heavier boats.

Originally Posted by CPFITNESS View Post
You act as if the motor can see what kind of boat it's in. Why does it matter if it's a cruiser or a race boat. Air, fuel, spark still applies.
Heavier boats will place more load on the engine and cause detonation more easily.
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