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-   -   problem with aftermarket cylinder heads. (https://www.offshoreonly.com/forums/general-q/331612-problem-aftermarket-cylinder-heads.html)

mike tkach 10-17-2015 08:59 PM


Originally Posted by offshorexcursion (Post 4367217)
I don't think your theory applies in the high perofrmance offshore world.

People love to brag about their toys. Powerboat owners especially like to impress. Exaggerating how many hours they run in a season, how fast thier boat goes, how long they can get a bravo drive to last, etc. But in reality they are anchored at the sand bar, lost a race to a slower boat then their claimed top speed, all while having the bravo blues. Why would the same not apply to engines?

There's plenty of proof to say that there is a problem, I think the more accurate question is, how much reliability and piece of mind will I gain for the money?

Sure some can bolt on heads without precision setup. Not everyone needs shaft rockers or piston oilers either. But when it comes to Marine High Performance Engines what's the best bang for the buck while trying to achieve ones goals?

IMO spending a few hundred on double checking and setting up heads is priceless compared to other "upgrades" that may be recommended.

looks like you have it all figured out.glad to see that you are in good hands.

sutphen 30 10-17-2015 11:10 PM


Originally Posted by ICDEDPPL (Post 4367207)
Is anything in a production line really ready to just 'bolt on' ?
Can I buy a 'production' short block not check anything bolt my stuff up and go and have a trouble free summer? If so please send me the info I`m ready to buy.

yeah,,1-800-merc

mike tkach 10-21-2015 04:29 PM

ok,i had a set of afr 315 cnc heads that were bought from bob madera checked for valve to guide clearance and got the report today.all intakes ,0015&.0016.all exhaust .0018.these were checked at a very reputable shop that specializes in cylinder heads.these heads were ordered for a 1000 hp supercharged marine engine.just thought i would post my findings.

donzi matt 10-21-2015 06:46 PM

I will have a set of Raylar 496 heads next week, I plan to verify installed height and guide clearance before installing them. I'll report the findings, not that there is a big market for them here, but it will at least give a point of reference.

SB 10-21-2015 07:09 PM

Hey DM - ah forget it, you have closed cooling.

buck35 10-21-2015 08:09 PM

Not too many problems with aftermarket heads it seems, who is ecstatic with the upgrade, or at least very happy they made the move.

14 apache 10-21-2015 08:18 PM

Had one set of brodix heads 2PR that I had to mill all of the jesel stands where the shaft goes through them like .014 from side to side a real pain in the ass. The roller was not flat on the valve. This was 10yrs ago. Intake and exhaust.

articfriends 10-21-2015 10:45 PM


Originally Posted by buck35 (Post 4368676)
Not too many problems with aftermarket heads it seems, who is ecstatic with the upgrade, or at least very happy they made the move.

When i switched from merlins vrs to afr 315 CNC's with a bob madera cam i picked up 200+ hp, later on with a bigger yet cam and those heads with one size smaller blower pulley picked up another 165 hp, very happy and no, did NOT need to open valve guides up even though i boat in "great lakes" water !

turbo2256b 10-22-2015 09:14 PM

I almost hate to think of all the heads I have flowed and ported as well as intakes. Bottom line Brodex and Canfield no matter what stage on my bench flowed + or - 5% of there advertised data and had the least amount of machining issues etc and best valve train components stock.

bobl 10-22-2015 11:26 PM

I'll throw in my 2 cents worth. I've built about 30 engines using aftermarket cylinder heads. Also have bought a few sets of AFRs from Bob Madera. Never had any problem with the AFRs. Most of these were in the 600 HP range with a few being 900-1000 I've used various Edelbrock BBC and SBC heads with the only problem being the exhaust ports sealing with cast aluminum manifolds. A set of SBC Procomps that were customer supplied required a lot of clearancing to get the pushrods to fit. The biggest problem I ever had was with a set of Dart 325's. There was casting flaw that caused a water port to leak into the valley. That was very difficult to find. Dart claimed to have never heard of such a problem. The fix was to weld the port and resurface the heads.

Bob Lloyd

Edit: I forgot to mention the Raylar 496 heads that developed cracks and leaked water. Had 3 sets of those.


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