Merlin Boat Anchors? Help pleze!!!

[Underdog88]

Looks like I've lost a second season of boating unless I'm missing somthing. Please tell me I am... Last year missed due to business but built two fresh short blocks and rerigged the boat this winter/spring.

I have/had 2 sets of Merlin Ovals to work on. Just wanted to gasket match and pocket port them. One set appeared to have been milled down before I got them used. I sent them to a friends machine shop to surface those and take a bit off of the other set to try and match them up. It took him forever but he was doing it for free as a favor so....

He told me he had a problem and cut one head crooked so he had to cut more to straighten it up. Then he cut the same amount from the other 3.

When I finally got them back I freaked out... He had cut well down into the intake seats They were 119cc chambers and my pistons are only 10.5cc domes so I figured more compression wouldn't be a problem.

Being the optimist I am, I continued to work on them. I sank the intake valves enuff to get the seats back, after spending a ton of time on the ports and combustion chambers, replaced a few valves, shimmed the springs and slapped them on the motors. Valve to piston clearance wasn't there and roller rockers not centered on stems at all. Pulled em back off and did what I should have done as soon as I got them back from the shop. Put light springs on a couple valves and check piston to valve. Exhaust ok but intake hitting badly. I had to back off the rocker screws to a point where I ended up w/about 1/8" slop at the stem off lobe to clear pistons. Heavy sigh... Running only 540 lift flat tap cams.

I've drove myself crazy trying to make them work but I cant see it. .100 Thick head gaskets will drop compression to nothing, I don't think I can cut that much off piston pocket as the top feels only 1/4" thick or less. Plus I've paid a good race shop to assemble the short blocks after resizing rods w/new bolts ect... One head has much more off than the other. The intakes only show half a bolt hole w/out gaskets. The other not as bad until gsk are installed. I know I can cut the intake side of the heads but think it will hit the block rails then as well. I've crudely cc'd the comb chambers and one set is way down to @90cc and the others about 110. Blocks done at different times and one is Zero decked and the other -.030 so I'd hoped to compensate there.

I retarded cam 4* just to try and it helped a bit but not enough.

Am I missing anything??? Or do I have 4k worth of boat anchors... New Merlins are 2k per set. I've seen ProComp Aluminum for 1k plus swapping out exhaust valves to inconell. I know they are chineese castings but when assembles with good componets by a good head man they are ok I'm told. That's still 2k I don't have right now.

Any suggestions? Am I missing any way to save these things?
Thanks so much for your time and knowlege in advance.
Mark(who was expecting to be on my way to Loto this week)Underwood
Maybe next year...

[ROGUE]

That sucks. Ok a couple of comments to consider.

I cant imagine cutting this style head down enough to make 90cc chambers. I think those are done. I had to angle cut mine to get down to 110 and still have some intake seat.

Now, Im running some healthy flat tappet cams and i dont have a lot of intake clearance but I do have .050. Since i did'nt have to sink my seats my valves are lower (closer) to my pistons than yours. It just doesnt make sense to me that you are having interference issues with your valves higher than mine. Unless your pistons are that much higher. Are the tops (undomed) of the pistons higher than the block surface at TDC? I zero deck mine and L2399 pistons. I know guys with the same setup as mine who are using bigger pistons and do not have any worse clearance issues. Something just doesnt sound right. Are you sure on cam timing? Use a timing wheel and found true TDC using a piston? If you want Ill find you give you my timing events to compare.

But, it does sound like you might have some anchors there. I take it the machine shop wasnt an engine building shop. I remember the first time I set up a swiss mill to do mine it took a week before I finally felt comfortable enough to put a cutter in it. Even if you get it figured out there is going to be all kinds of geometric issues to deal with. The two with 110 cc chambers might be usable.

[Underdog88]

Thanks for the reply Tom.
The machinist is a Harley guy and general machine shop. Not a car motor guy. Didn't think it would be too tuff to do it right. It's not rocket science. I used to do it all the time back in the day. He swears he didn't take a crazy amount off but...
The pistons(undomed part) are at zero on one motor and negative .030 on the other block.
These are the pistons http://www.summitracing.com/parts/STL-H426CP30

Cam timing... I'm a motorcycle guy and we use slotted sprockets to adjust cam timing. How can you go wrong with a keyed sprocket? I did use a dial indicator to check TDC w/piston but simply bolted on the cam sprocket to the pin on the cam and lined up the dots. Looks non adjustable to me... as stated before I did try and use the 4* retard setting on the crank sprocket with some relief but not near enuff.

While I am more of a motorcycle guy, I used to work as an auto machinist in the 80s for NAPA. They even sent me to Dana Tech Center in MI for lower block school. While I'm obviously no expert. I'm also not totally clueless... well maybe I am...

Cams
Cam Style Hydraulic flat tappet
Basic Operating RPM Range 3,000-6,500
Intake Duration at 050 inch Lift 238
Exhaust Duration at 050 inch Lift 248
Duration at 050 inch Lift 238 int./248 exh.
Advertised Intake Duration 296
Advertised Exhaust Duration 306
Advertised Duration 296 int./306 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.540 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.540 in.
Valve Lift with Factory Rocker Arm Ratio 0.540 int./0.540 exh.
Lobe Separation (degrees) 114

I was running these for several years prior
Cam Style Hydraulic flat tappet
Basic Operating RPM Range 2,500-6,000
Intake Duration at 050 inch Lift 228
Exhaust Duration at 050 inch Lift 238
Duration at 050 inch Lift 228 int./238 exh.
Advertised Intake Duration 286
Advertised Exhaust Duration 296
Advertised Duration 286 int./296 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.540 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.540 in.
Valve Lift with Factory Rocker Arm Ratio 0.540 int./0.540 exh.
Lobe Separation (degrees) 114

[ROGUE]

No expert by any means but that cam is going to be a real problem in a flat tappet version. That duration will require the ramps to start real early and are likely causing the interference problem, not to mention you better have dry exhaust or reversion will kill you. If you can get the cam card list all the timing events. Then you can determine the overlap. Im running 75 degrees overlap and its very close to reversion and my cams are way smaller than the one you are trying. Keep on mind roller cams can do this much duration without so much reversion as they can rise and fall much quicker.

[ROGUE]

Its the timing events at .006 that will determine the overlap and help you figure how it compares to mine. The bottom numbers on my card. I think those pistons you listed are fine. As far as timing, no its hard to be off much but it happens, I use a large wheel on the crank, indicate tdc on #1 and set pointer to zero, then install cam. a solid lifter and indicate its movement (going the right way of course) There are a bunch of ways to get it more acurate but that gets it close. I like to set intake center around 106 and have tried 110 also. I still like 106 for my setup.

[Underdog88]

I still have one of the second cam listed left. I never sucked any water w/it. I only added 10* duration. shrug. I'll stick the old cam back in and see where I'm at. Going to the shop today... I'll also grab the cam card.
I have a stock head I could clean up and compair P to Valve clearance too.
Thanks for your input.

[ROGUE]

Im sure there will be plenty of people to argue this but Ive always gone by some old school rules that may not apply to roller cams but I think they did to flat tappet. For best torque (boat motors), keep the duration low. Lots of duration can work with compression and high rpm but for the typical 5000 rpm boat motor, low duration is the ticket. Duration numbers on most Merc flat tappet engines are really low. You can get away with higher durations (at .050) on roller cams but the numbers at .006 are much closer than a flat tappet and then interference and overlap (reversion) are much less of a problem too. I hope things look better with the old cam. Those pistons are pretty much a hyper version of my forged ones. By the way, what size intakes are you using. A few years back I went from 2.19 to 2.30 and lost some power. And yea, I am bore notched. I figured maybe I lost some velocity and ram charging with the bigger valves. Engines do like 5600 better though.

[Underdog88]

Put the old cam in with little change but noticed the valves are hitting on the top edge of the relief and not flat in the notch. I suppose this is due to the excessive milling.

Valves are 2.19 on one set and 2.25 on the other. I think I'm giving up on these heads...
Selling all my vacation days and buying 2 sets of these w/inconell ex valves. Screw it...
http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT
frustrated and fed up

Cam card shows at .05 Intake 10btdc close 109 atdc Ex 63 bbdc close 5 atdc
don't know how to figure at .006

My old cam had only 10*less duration and seemed to work well but...
I could get another like my old one or make my pipes dry. These are supposed to be marine cams.

[FastDonzi]

Depending on your Exhaust pipe type you should be about 222* @.050, inducing water at the elbow, then for every 1* @.050 you need to induce water 1" farther downstream.

[Underdog88]

Fast... Thanks for your input. Intake or Exhaust duration? 238 Intake 248 Ex= 26" pipes? I should have close to that. Have to measure them. They are dry almost to the transom.

[FastDonzi]

Looks like with the rise of your pipes and the fact you inducing water towards the end of the pipes you'll be fine.

[BUIZILLA]

Depending on your Exhaust pipe type you should be about 222* @.050, inducing water at the elbow, then for every 1* @.050 you need to induce water 1" farther downstream.

good words to live by...

[Underdog88]

Thanks Buizilla.
What do you guys think of these heads? I'm sure not top of the line but have read good reviews on Skip White Performance assembled ones. I'm selling all my vacation days and these I could swing financially... and be running yet this year.
Thanks for your input guys!

http://cgi.ebay.com/ebaymotors/BIG-B...Q5fAccessories

[FastDonzi]

They seem like a pretty good deal to me, But when it comes to Motor Setup & Tuning Buiz is the Man. His level of common sense and knowledge is second to none.

[ROGUE]

Wow that is cheap fully assembled. Wish I could get .610 out of them but they seem pretty sure .580 is the max lift. I might try a pair of them myself on the smaller motors.

[speedfreak2030]

Buy them and get to the dock!!

[Underdog88]

As long as the City gives up my vacation money I'm on it! They hate when you ask for a couple hundred hours in cash... whaaaa

[ElvisAaron]

hahaha. nice work. very funny yet i find them fantastic hahaha
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[speedfreak2030]

hahaha. nice work. very funny yet i find them fantastic hahaha
__________________________________________________
Cadillac shocks and struts
Chevrolet shocks and struts
Shock absorber

What the fukc do you mean funny? funny like a clown?

[FastDonzi]

What the fukc do you mean funny? funny like a clown?

Hopefully he means Funny "Ha-Ha" and Not the other Funny (wheres the darn Rainbow smiley)