454-420: are they full roller?
 

I opened mine and they are regular lifters but roller rockers.
I thought they were full roller!

So what is your guess ? How were they built out from factory?
Roller lifter only ?
Roller rockers only ?
Roller all the way?

Thanks!

Re: 454-420: are they full roller?
 

mine had the crane gold...

Re: 454-420: are they full roller?
 

Flat Tappet Hydraulic Cam, Gold Crane Roller Rockers

Re: 454-420: are they full roller?
 

EXACTLY. :D

Re: 454-420: are they full roller?
 

that's what I have too. So they really are 420's, Thanks guys!

Re: 454-420: are they full roller?
 

I always thought those 420's were good motors! good foundation to build some power on! :cool:

Re: 454-420: are they full roller?
 

They are a good foundation. 990 or 188 casting square port heads. Steel crank, 7/16 rods, and 4 bolt mains.


Cam change, Intake and Carb change, Good exhaust, They will make around 500HP

Re: 454-420: are they full roller?
 

apparently they are...my engine builder will make it 500-520 with only blueprint and full hydraulique cam. they then would be ready for step 2 somedays...blowers.

Re: 454-420: are they full roller?
 

I built a 454 420 clone but I bored mine over .030 and balanced and used large oval port head with big valves that are ported and flowed, an rpm air-gap intake. My machine shop told around 475-500hp. I know it sure runs nice and strong.

Re: 454-420: are they full roller?
 

I opened one and it was roller lifter, but standard rockers, mild dome pistons, and 502 marine heads. ummm, something sounds strange....

Re: 454-420: are they full roller?
 

That is not a Merc 420

Re: 454-420: are they full roller?
 

That's what mine have had done. Punched to 468, Comp 292H cam, Merlin Intakes, I'm not sure of the size Holleys on the engine, but it runs like a skeered haint! :cool:

Re: 454-420: are they full roller?
 

it was a GM crate motor, now I am curious as to what I have...... ummmmm........

454 4 bolt truck block, Gen VI, JE Pistons, roller cam, no specs on it, and the 502 marine heads.....

Casting numbers check out....

Re: 454-420: are they full roller?
 

Btw, mine came stock with Gil exhaust. That may have been part of the Kaama package.

Re: 454-420: are they full roller?
 

i have a 454-HO crate motor from GM. I believe this is the same block that the merc 420 is. GM rates it at 425 hp. Mine has roller lifters but not rockers. All parts have Gm performance parts stamped on them. Big rectangle port heads. Beefy 4- bolt mains and aluminum intake. 7/16 pushrods, etc. Bullet proof motors. I know a lot of guys down here run them in work airboats. 5000 rpm all day long every day with no problems.

Re: 454-420: are they full roller?
 

happy to hear that, I'm a GM dealer ! But, I'm surprised since every body says a marine engine is not a car engine... the eternal question...

Re: 454-420: are they full roller?
 

Camshaft (hydraulic flat tappet) for:

Merc 400 / 420 / 425 / 525SC

Crane Part#132561 Grind # H-228/312-2S-14 T1.2
Duration at .004” : 298, 296
Duration at .050”: 228, 236
Lift with 1.7 rocker: .530”, .551”
LSA 114LSA
ICL 109 ATDC , ECL 119 BTDC

Part Number: 132561 Grind Number: H-228/312-2S-14 T1.2
Engine Identification:
Start Yr. End Yr. Make Cyl Description
1967 Up CHEVROLET 8 FAIR IDLE, STANDARD CAMSHAFT FOR MERCRUISER 400, 405, 420, 425 HP AND 525SC-454 CU. IN. ENGINES, APPLICABLE TO 350, 365, 370 HP MILDLY MODIFIED ENGINES WITH FREE-FLOWING ABOVE WATER EXHAUST SYSTEMS FOR PERFORMANCE APPLICATIONS, 9.5 TO 11.5 COMPRESSION RATIO ADVISED. BASIC RPM 2800-5800
Engine Size Configuration
396-454 C.I. V

Valve Setting: Intake .000 Exhaust .000 HOT

Lift: Intake @Cam 312 @Valve 530 All Lifts are based
on zero lash and theoretical rocker arm ratios.
Exhaust @ Cam 324 @Valve 551
Rocker Arm Ratio 1.7

Cam Timing: TAPPET @.005
Lift: Opens Closes ADV Duration
Intake 35 BTDC 83 ABDC 298 °
Exhaust 87 BBDC 39 ATDC 306 °

Spring Requirements: Triple Dual Outer Inner
Part Number 99893
Loads Closed 130 LBS @ 1.850 or 1 27/32
Open 330 LBS @ 1.320
Recommended RPM range with matching components
Minimum RPM 2800
Maximum RPM 6600
Valve Float 7200

Cam Timing: TAPPET @.050
Lift: Opens Closes Max Lift Duration
Intake 5 BTDC 43 ABDC 109 228 °
Exhaust 57 BBDC (1) BTDC 119 236 °

Re: 454-420: are they full roller?
 

Man!SB! You're an engine Bible!

Re: 454-420: are they full roller?
 

SB,
How would you compare the 241 cam to the 561
Total lift is 0nly .004 more intake and .002 exhaust,but I believe slightly less in the middle. The 241 is what I put in my 454 mags. What would be the difference in how they run?
Holley 800s
Wieand Excelerator intakes
Gil exhaust water mixing 3" before transome.
Crane Gold rollers

Re: 454-420: are they full roller?
 

Payton, to not sidetrack this thread I started one about your question on:
http://www.offshoreonly.com/forums/s...65#post1848165

Re: 454-420: are they full roller?
 

Jeff 32
I am so glad you started this thread. I have a pair of 420's that are due for a rebuild and I am looking to get 500+ out of each for my '89 Formula F311. Lets keep this discussion going.
See link - http://www.offshoreonly.com/forums/s...d.php?t=137967

Re: 454-420: are they full roller?
 

I read your tread and there's good info there too. In fact it seems like my heads (don't know how many though) are cracked. Other than that I know I have a cam with 15 milimetre less than it's supposed to have on a lobe. But I'll keep the info coming here, I guess tomorrow I'll have the whole diagnosis and possible rebuild solutions. Besides, I certainly thought about 2 HP500...

Re: 454-420: are they full roller?
 

Whats the difference between the 400 and 420?

Re: 454-420: are they full roller?
 

The 400 had a dual plane intake and a Quadrajet. Also had those log exhaust manifolds with 3" outlets.