|
Originally Posted by JoeBro
(Post 2671777)
Comp Ratio,...after all my super precise cc'ing :rolleyes:,...I calclulated an avg static of 9.23 to 1. From what I recall, I think information on the pistons assume at 119cc and 0.00 deck height 10 to 1. But I didn't have zero deck height, and I smoothed the edges of the domes to help control any pre-ignition problems the engine might have.
Again thanks for the help. Good luck |
The cam used in the 454-420HP is made by Crane. It's specs are about 226-236 duration and .530-.550 lift. It would proably be a better all around cam in this application and it works with stock exhaust. I can't remember the grind no. but it's in their catalog under marine cams.
|
Be carefull with your cast buttom end! I wouldn´t rew it more than 5200 rpm. I have very good experience with the Part Number: 132561 Grind Number: H-228/312-2S-14 T1.2 (mercruiser 420 cam) You can use your stock exhaust with this cam.
With your small valve size, stock exhaust and cast crank the 134561 cam will be too large and your low end power will suffer. |
Originally Posted by fbh-velocity
(Post 2674417)
Be carefull with your cast buttom end! I wouldn´t rew it more than 5200 rpm. I have very good experience with the Part Number: 132561 Grind Number: H-228/312-2S-14 T1.2 (mercruiser 420 cam) You can use your stock exhaust with this cam.
With your small valve size, stock exhaust and cast crank the 134561 cam will be too large and your low end power will suffer. ....MODIFIED ENGINES WITH FREE-FLOWING ABOVE WATER EXHAUST SYSTEMS,.... My exhaust outlets on the hull are below the waterline at idle. |
Good grief!!
Crane p/n 132561 = $272.39 from Summit. This is a hydraulic flat tappet. Might as well go roller with a price like that. |
Originally Posted by JoeBro
(Post 2674507)
I noticed on the Crane website it said:
....MODIFIED ENGINES WITH FREE-FLOWING ABOVE WATER EXHAUST SYSTEMS,.... My exhaust outlets on the hull are below the waterline at idle. Exhaust under the water line, stock manifolds, all recipie for breaking an engine when you modify it to much. Save your money until you can get a good exhaust, then you can afford to do it right. No sense in buying cams twice. You will alos be able to re- use the piston upgrade and the head upgrade you are using when you upgrade the cam later in life anyway. |
Originally Posted by JoeBro
(Post 2674509)
Good grief!!
Crane p/n 132561 = $272.39 from Summit. This is a hydraulic flat tappet. Might as well go roller with a price like that. |
I do not have the stock cam. I bought this boat with a grenaded 502 engine that had been modded. I think the standard engine for this style of boat was a 454 365HP Mag? However, I don't know what the spec are for the stock cam.
FYI,.. I asked Dennis Moore about using his Manifolds on my combo and he suggested a cam with 224/230 @ .050 with a 110 lsa. and IMCO risers. Everything exiting below the waterline at idle. |
the cam will cost you 400 the lifters are 400 plus a set of springs . But if you are not going to change the exhaust why bother changing the cam at all ?????????? :ernaehrung004:
|
Originally Posted by JoeBro
(Post 2674766)
I do not have the stock cam. I bought this boat with a grenaded 502 engine that had been modded. I think the standard engine for this style of boat was a 454 365HP Mag? However, I don't know what the spec are for the stock cam.
FYI,.. I asked Dennis Moore about using his Manifolds on my combo and he suggested a cam with 224/230 @ .050 with a 110 lsa. and IMCO risers. Everything exiting below the waterline at idle. that 110 ccenter is going to hit pretty hard. There aren't a lot of through hulls that can take a 110 center. You might want to ask around a little more. :cool: |
| All times are GMT -5. The time now is 07:19 PM. |
Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.