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Author Topic: Anybody have a favorite cam for an Advance?  (Read 531 times)

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Offline Andrew

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Anybody have a favorite cam for an Advance?
« on: September 20, 2019, 12:32:00 PM »
90% sure Iím going to rebuild the motor this year in my Advance. Itís got a 94 Mercruiser 350 Ďmagí motor in there now. Iím not going to go crazy on this thing, but would like to get a bit more torque on the low end. Donít really care about anything over 4,000 rpm.

Iíve got a quadrajet, with the Ďmagí intake, essentially the high rise Chevy z-28 manifold. The guy at my local Ďspeed shopí ( surprisingly there is still one left in my town) tells me I should stick with the intake I have - so guess I will. Itís a pre-vortec motor, so while Iím sure I could pick up some torque by converting to vortec heads and intake - more $$$ than I want to spend.

The oem cam for this motor is pretty mild, 200 / 212 duration, 400 / 410 lifts.

Thinking of going still mild with a 212/218 but might go up one more ( 218/224)  Curious if anyone has been down this path with this hull, and has any advice ? Thanks.

Offline backfoot100

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Re: Anybody have a favorite cam for an Advance?
« Reply #1 on: September 21, 2019, 01:32:13 PM »
Marine cams are mild as far as cams go.
Not sure how much you'll gain with just a cam. Seems like a lot of work for very little reward.
Is the factory intake cast or aluminum? What HP is it
rated at? 260? 285? 300?

An internal combustion engine is an air pump. The bottlenecks are carb, intake, head and then exhaust. You increase the airflow at one point and its only as good as the next bottleneck. As a general rule these engines in stock form have crap intakes and heads.  I really don't know what a cam will do for you with the crap heads. My personal opinion is put new intake and heads before a cam but thats just me. I put heads and intake on a bone stock 351 that bumped it at least 30-40 HP and never touched the cam. That was in a buddies 80 Correct Craft. It was a smokin 53MPH barefoot boat after that.

The QJ carb is good to 750CFM. The factory does a good job of setting them for a specific engine and application. At least in the automotive world. As long as you keep the engine pretty much stock the QJ is fine. Modify the engine and any QJ carb adjustments are a PIA.

I built a 400 HP stroker for my barefoot Advance and it runs strong so the hull and tranny will handle anything you want.
When people run down to the lake to see what is making that noise, you've succeeded.

Offline Andrew

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Re: Anybody have a favorite cam for an Advance?
« Reply #2 on: September 22, 2019, 10:58:15 PM »
Iím not doing the rebuild just for the cam - I bought this motor , used, and ran it in anotherís boat for last 12 years. Itís always run well for me, but there has always been a lot of Ďblowbyí smoke coming up through the valve covers and routed back to the flame arrester. Never bothered me so much when the motor was 10+ feet behind me in an engine room.  But in this boat itís more of a problem, when I get off the boat, I have the smell of burning oil exhaust. 

So while Iím got it torn down for new rings and bearings, doesnít make much sense to reuse the 25 year old cam. I believe my 350 mag is rated at 300 hp.

My machine shop guy is a boater, and seems to know what heís talking about. I told him i want to boost low rpm torque, donít really care much about max rpm or speed. Told him I was thinking about replacing the crank to make it a stroker, upgrading to vortec heads, or perhaps both.  The vortec heads is a good upgrade, but I would have to replace my intake. So far both the local machine shop and speed shop have told me not to dump my intake, which is a cast version of the z28 gm intake; supposedly itís a good one. He told me the stoker upgrade is a nice one, but really pays off in the top end. So probably not a great choice.  He said my best bet is to up my cam a bit, and gave me the name of a guy who will tune my carb to match  the motor. But he didnít have any specifics yet on the cam. And he was more used to building Ďgo fastí motors with performance exhaust.

Offline Andrew

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Re: Anybody have a favorite cam for an Advance?
« Reply #3 on: September 22, 2019, 11:00:49 PM »
What are you doing for exhaust on your stroker?

Offline backfoot100

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Re: Anybody have a favorite cam for an Advance?
« Reply #4 on: September 26, 2019, 06:33:29 AM »
Seeing as you're tearing it down anyway then I agree that a cam couldn't hurt. I think either one your contemplating would work fine. Neither one is radical by any means but going any bigger starts to push the torque curve higher up the RPM scale and you'll start losing your bottom end. Talk with a cam vendor to get help on which one. You have to be a little careful about water inversion when talking marine cams too. I put a Comp marine cam in my stroker and am very happy with it but its also a roller and not a flat tappet.

@Andrew
I have a stock aluminum logs with 4" SS tubes straight out the back, no mufflers.
When people run down to the lake to see what is making that noise, you've succeeded.

Offline Andrew

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Re: Anybody have a favorite cam for an Advance?
« Reply #5 on: September 30, 2019, 08:42:52 PM »
Did you raise your exhaust above the stock Ďbelow the waterlineí location? If so, any pictures?

I was kicking around three ideas for this motor - Stroke it, convert to roller cam, swap to vortec heads and intake. Perhaps one, two, or all three of these.  But real goal was just new rings, bearings, valve job.

For the sake of keeping the rebuild cheap, Stroker is not going to happen. And roller cam is not going to happen. I went with the cam a little over stock (212/218 - lifts under 500.). Compcams told us either of the two I was considering would not take an inch lb of torque off my bottom end.

 I havenít made final decision on heads yet. I can  get mine redone ( need different springs for this cam, probably some porting while they are at it) for about 350. Or my machine shop can set me up with some stock vortecs worked appropriately for about 500. Plus another 200 or so for new intake manifold. Going to the Carlisle swap meet this week, maybe Iíll find cheaper head option, but probably not.


Offline backfoot100

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Re: Anybody have a favorite cam for an Advance?
« Reply #6 on: October 02, 2019, 06:23:27 AM »
No I used the stock outlet. Just put new exhaust tips on it.
https://photos.app.goo.gl/EYTTp82ukGCisJLe9

Reworking stock heads is a waste of time IMO. Stock heads are horrid for anything remotely performance oriented. Vortec heads are the Chevy equivalent of GT40P heads for a Ford. You'll get noticeably increased performance and HP. The only downside as you stated is you need a new intake and valve covers. The intake is a wash as its normally included in any head upgrade over the factory cast iron unit. The valve covers are cheap.

I know its not cheap but you'll never wrong with a quality set of aftermarket heads. By the time you factor in reworking a set a factory heads and putting new vavles and seals in the cost is pretty much a wash and you can literally take them out of a box and bolt them on.
When people run down to the lake to see what is making that noise, you've succeeded.

Offline Andrew

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Re: Anybody have a favorite cam for an Advance?
« Reply #7 on: October 21, 2019, 06:00:45 PM »
I probably should have gone aftermarket heads - but I found a set of vortec, and my machine shop did the valve jobs, and new springs and all to match my cam. All told it was 500. Probably would have been only another 250 or so for some budget aftermarket, but not this year.

Now I just need to get them on, and find an intake manifold. Vortec head bolts are same size as old school heads, right?


 


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