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-   -   Why this cam in a 420? (https://www.offshoreonly.com/forums/general-q/310089-why-cam-420-a.html)

MILD THUNDER 03-25-2014 08:28 AM

I'm not positive, but did your boat come from Illinois? If it is the boat I am thinking of, I thought at one point it had small superchargers. Either way, that cam sucks.

Honestly, I had one of those 402 Formulas. They are friggin tanks. I had around 600HP per side, and a 25P 4 blade netted me around 5400RPM, 70mph in some chop and trimmed out. That was full roller engines, Dart aluminum heads, stellings headers, 5lbs of boost.

I think a 23P prop is too much for that boat, even if you had true 420HP engines. Get the engines in good health, and I think you're gonna end up with some 21P, or even 19P 4 blades. With 400HP merc's, those boats ran around 55mph at best. Try some 21P Merc Revolution 4 blades. My 402 liked those props the best. Planed great, good cruise, and good top end.

chris302 03-25-2014 09:14 AM


Originally Posted by MILD THUNDER (Post 4095362)
I'm not positive, but did your boat come from Illinois? If it is the boat I am thinking of, I thought at one point it had small superchargers. Either way, that cam sucks.

Honestly, I had one of those 402 Formulas. They are friggin tanks. I had around 600HP per side, and a 25P 4 blade netted me around 5400RPM, 70mph in some chop and trimmed out. That was full roller engines, Dart aluminum heads, stellings headers, 5lbs of boost.

I think a 23P prop is too much for that boat, even if you had true 420HP engines. Get the engines in good health, and I think you're gonna end up with some 21P, or even 19P 4 blades. With 400HP merc's, those boats ran around 55mph at best. Try some 21P Merc Revolution 4 blades. My 402 liked those props the best. Planed great, good cruise, and good top end.

Hi Mild, yes that is the boat. The engines were changed before I bought it and were supposed to have had the top ends freshly rebuilt. They were in reality thrown together with left over parts, mismatched junk. 41 mph when I got it home. tore into one engine last summer (during boating season at the dock) redid heads worn seals, guides, weak springs. different style rockers ect. threw it back together to salvage the end of the season. Now I'm having the other heads done and replacing everything on both of the top ends. I did get it to 50 mph last fall. I will be happy to see 55-57 once done. Derreberry Performance is doing the heads and once I get them back together I will start playing with the props. I am thinking someone took some mags and threw in whatever they had laying around and threw them in the engines.

mcprodesign 03-25-2014 09:30 AM

Right on!! Takes balls to freshin up a motor at the dock !! (;

f_inscreenname 03-25-2014 11:53 AM


Originally Posted by Griff (Post 4095285)
Real 420 cams are Crane 132561 and are readily available

Griff, you know better. lol. http://www.offshoreonly.com/forums/g...-vs-440-a.html
The original 420 is a Ultradyne cam but you are right the Crane cam is a close substitute and after talking to Bob I was very happy using it in a motor I built a few years ago.
As for the Crane being readily available,
Summit - Estimated Ship Date: 4/15/2014 (3+ weeks)
Amazon - Not available
Jegs - is down now but the last time I checked was weeks also.
and I wouldn't trust any of them to ship when they say they can. I waited a couple months and then canceled my order when I found one on eBay (new in its original box, almost wanted to keep it for nostalgia reasons).

MILD THUNDER 03-25-2014 12:00 PM

The 420 was a crane cam. The 440 was a ultra Dyne.

chris302 03-25-2014 01:35 PM

I Already have the cams and the gold rockers. got them from carshop.com in stock and less than the others but shipping is a little more.

chris302 03-25-2014 01:38 PM


Originally Posted by mcprodesign (Post 4095395)
Right on!! Takes balls to freshin up a motor at the dock !! (;

Not balls just a thin wallet. It was either pay someone to pull the engines or buy parts.

MILD THUNDER 03-26-2014 07:58 AM


Originally Posted by chris302 (Post 4095559)
I Already have the cams and the gold rockers. got them from carshop.com in stock and less than the others but shipping is a little more.

Cool. The carshop seems to have better prices on some stuff than summit and the others.

Do you know if your engines are original to the boat? Wonder what size intake valve they have in the heads?

chris302 03-26-2014 12:24 PM

Mild, they are not original located previous owner and was told he bought a 1989 357 and swapped the motors before he sold the 402 im going to measure the intake valves this weekend whenI get back to the lake

chris302 03-30-2014 10:16 PM

Ok just got back from the lake the intake valves are 2.19


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