Hydrocruiser

Cam...advance...maybe compression?

SB

iTrader: (1)

In my notes (copied from other sources) I have the Gen V 502 MPI cam listed as Part#431-850478

I have the following info for this cam:

Hydraulic flat tappet

.004” 296°, 296°
.006” 286°, 286°
.050” 224°, 224°
.200” 130°, 130°
Valve lift with 1.7 .510”, .510”
LSA 115.5°

Part#431-850478 ground with 5°advance
ICL 109° ATDC
ECL 122° BTDC

JIMG

the problem could be the timing if you didn't set it with a scan tool or shunt the timing somehow. with an efi engine it will run fine but short on rpm.

hunster

Tend to agree with the cam after my experience with crate motors. Try to get a build sheet from the seller. If he cant give you one, you can get it from gm but you will have to pay them. They can be traced by the metal tag on the block. There is a reason mercs cost more other than the warranty. I just went through this with a pair of small blocks. I think there a few scabs out there selling regular heavy duty car/truck blocks and calling them marine. I had to drop from 23 laser 2's to 19 mirage to get any power out of them, still I lost 8 mph. This dealer kept promising to make good and never did once he saw he'd have to pull the motors to change the cams. Let you know how that goes in court on the 11th . Back to merc blocks this year. Just a little more for the quicksilver platinum rebuilds w/2 yr warranty. Power is right back out of the box. Bolted on all my accessories got them installed in the boat and it's back to new, got my rpm's power and speed back with the orig props . Expensive lesson but I'll stick with merc.

LAXBAJA

I've contacted marine Engines INC. in Holliston, MA 1-800-786-7639. They wont tell me any thing. were they got the motor from, cam specs, compression ratio, heads, nothing. The tag on the block says
Manufactured for GM
Part # 12568780

Ser# 00047533

Manufacture Date: 04-2006

1113

I called Crane Cams and they said they have no match for those block #s. Its like they don't exist.
Maybe some of you guys can use these #s to get me the right info.

Crane Cams will not recommend a cam, of cut me a cam with the engine specs. They told me that there is a few different 502 long blocks and the heads, compression, and cams are different.

I bought this engine from this company because they had one, not because its cheap. shipped to the door for $5619.00.

LAXBAJA

Timing is at 8 deg advance, 35 deg at 4000 rpm
and yes i have my own merc scan tool. NO Codes

LAXBAJA

ive talked to Tyler Crockett he has a cam and springs that they use in mpi upgrades.
Lift 575 in, 557 ex
I can still use my stock roller lifters.
so this is one option im looking at. but still would like to know what I bought.

SB

iTrader: (1)

I have the Mercruiser (black motors) factory Gen VI roller cams noted with the following specs:

Merc Std BB Roller
.004” 280,299
.006” 266*/284*
.050” 204*/209*
.200” 113*/114*
Lift .480”/. 483”
ICL 115.5*
ECL 120.5
LSA 118*

………………
Merc Mag Roller
.004 300*/ 300*
.006 288*/288*
.050” 225*/225*
.200” 125*/125*
Lift .483”/. 483”
ICL 109*
LSA 115.5*

LAXBAJA

I ran a 25P labbed high five 4600 RPM at 64 MPH

I ran a 25P -3 blade that has big cup in it and i ran 63.9 MPH at 4000 RPM

I ran a 23p Labbed mirage and spun the motor to 5200 RPM at 64.1 MPH

So this is strange. Its like when this motor hits 4000 RPM it falls on its face.

SB

iTrader: (1)

Edited: was for another thread. Sorry.