Offshoreonly.com - cam advise for 454 mag

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Quote:

Originally Posted by MILD THUNDER (Post 4534865)

Heres a buddys 454's. Started life as 370's, basically, a 454 Mag. Boat ran upper 50's back when engines were stock. Runs 63-65 now. Rectangle port GM heads, Single Plane Proffessional products "hurricane" intakes, 850 quick fuel marine carbs, stellings headers, roller rockers, and a crane 134561 cam. 236/246 114 LSA, 551/571 lift. Flat tappet. one of the engines expired 4-5 years ago, due to a leaking riser on the stock 454 mag iron exhaust manifolds. Mike Tkach redid that engine for him. The other engine, has been going strong for the last 15 years or so. Believe it or not, they did NOT revert water with those cams, and stock exhaust. But, he got a good deal on the stellings, and put them on. The engine that was recently rebuild, recieved the crower cam saver lifters, that have the groove cut in them. The other engine, still has the standard flat tappets. Boat has close to 2000 hours on it, and has never had a cam lobe or lifter failure. He beats the chit out of this boat, and engines, and they just keep running!

https://www.youtube.com/watch?v=3LriYY1QCtU

that was the last marine engine i installed a hyd flat tappet cam in,glad to hear it is still flying around.

Mild Thunder thank you for the video! I'm just going to use the hydraulic flat tappet cam for now and when I go for a complete overhaul I will do the roller set up. With only 200 hours on the motors I would like to use this up first and then later go with a completely different setup along with the rollers.

Lunati cam looks like a good option but I wonder if the 110 lobe separation might cause too much overlap and potentially suck water in even though I have dry exhaust water still can get into the exhaust because the way the fountains sit there azz in the water

I am leaning towards a lunati voodoo cam number 60204. 233/241 @.50 and .554/.572 lift on a 110 LSA

My question, would the 110 lobe Center be too tight and cause too much overlap in a marine engine with dry to the tip Gil exhaust. My risers are approximately 22 inches long as the motors set way back against the stern wall of the boat.

Quote:

Originally Posted by blownsvt1 (Post 4535010)

Thats the same cam i posted, the 60204 is the old part number i believe.

Its not the LSA thats an issue, its the overlap.

When you say "dry to the tip" , do you mean dry THRU the transom, or dry TO the transom mounted tip? Some guys think dry means, its dry to the actual tip thats screwed on to the transom, and a rubber coupler is used to connect riser to tip. That is not dry/fully jacketed exhaust

My risers are approximately 14 inches to the transom tips the inner stainless steel pipe of the riser carrying the dry exhaust ends at the tips that pass through the transom. so the tips is where the exhaust and water meet!

I love the specs on the lunati I guess im worried about water due to the overlap. There are quite a few post on YouTube of this cam and it sounds fantastic and everyone is very happy with power range

I am thinking I am going to pull the trigger on this Comp 4X4 Cam 11-243-4 cam which is 234/244 @.050 with .564/.570 lift on a 111 lobe center. I really like the numbers that MILD THUNDER suggested on the Lunati cam, however, since I do not have true "dry exhaust" I am afraid of the 110 lobe center with a 233/241 duration. Please chime in and I will leave everyone alone after that....Ha Ha!

Quote:

Originally Posted by blownsvt1 (Post 4535408)

I've posted this many times. Tighter LSA's, don't always mean the camshaft has MORE overlap.

Your 234/244 111 LSA cam, will have more overlap, than the 233/241 110 LSA cam.

At .006, the Lunati cam is 276/284. At .050, its 233/241. Your comp cam, is 278/288, and 234/244. The comp cam , will have roughly 2 degrees more overlap at .050, and 2-3 degrees at .006. I don't have the cam cards for exact numbers, but that should be close.

Cam for cam, going to a narrower LSA closes exhaust later, thus longer after TDC. More'suction' on the exhaust from the piston.

Better words: longer amt of time that the piston is going down while the exhaust valve is still open.

Thanks mild Thunder I am trying to listen. Please correct me if I'm wrong but A good rule of thumb @ .006 staying under six degrees of overlap should keep you fairly safe correct?