Go Back  Offshoreonly.com > Technical > General Q & A
500hp upper end maintenance >

500hp upper end maintenance

Notices

500hp upper end maintenance

Thread Tools
 
Old 04-09-2020 | 10:30 AM
  #1  
later's Avatar
Thread Starter
Registered
25 Year Member
 
Joined: Oct 2000
Posts: 1,391
Likes: 22
From: Chesterfield Mo/Loto
Default 500hp upper end maintenance

I was going to do a valve spring replacement this spring and then started thinking about just swapping out the heads, been doing a lot of reading through the different threads on heads, springs, and cams, I'm not looking to squeeze the last HP or Torque number but would like to see some measurable gain. in performance. I have a couple of questions, 1.) is it possible to swap out the heads and cam with motors in the boat, which is a 42 fountain with side by side motors with a lot of room in front of motors. if so what would be any potential problems if any. I was leaning toward the AFR 305 heads but then started reading about the EQ ch454a heads and since I'm not a closed cooling system it seems the iron head might be a better choice. either way, I go I would buy a bare set of heads and have them assembled question #2 I read about valve guide clearance being an issue what would be a good clearance for guides. When looking at bare heads they all seem to already have the seats ground at multiple different angles what would be the preferred seat widths and do you get to choose when ordering bare heads, and the last question the age-old question cam selection, it seems that the 525efi cam is used a lot because of the 14 LSA is there a part number for that cam from crane. and one last question what lifters came in the 525efi motors I'm assuming they are the GM dog bone style. Thanks in advance


Later
later is offline  
Reply
Old 04-09-2020 | 11:00 AM
  #2  
Registered
20 Year Member
 
Joined: Jan 2006
Posts: 3,854
Likes: 786
From: St. Pete Beach, FL
Default

Crane 168741

except it has 2* less LSA

https://www.jegs.com/i/Crane-Cams/271/168741/10002/-1

BB-3 XTRA 327

Has awesome flow at 0.600 lift. The BP RR does as will with only a 298cc runner, but I’ve seen speculation as to whether that head is produced at all.

You should figure out if you can handle raised exhaust ports, AFRs are .375”

Also get a new intake. About 4-5 episodes ago of engine masters they tested all of them.

Last edited by hogie roll; 04-09-2020 at 11:11 AM.
hogie roll is offline  
Reply
Old 04-09-2020 | 12:42 PM
  #3  
Registered
20 Year Member
 
Joined: Jun 2004
Posts: 1,948
Likes: 37
From: Omaha, Nebraska. Boat on the Mighty Mo! Longest river in the USA!
Default

What gen of engines?
1BIGJIM is offline  
Reply
Old 04-09-2020 | 12:47 PM
  #4  
Griff's Avatar
Charter Member # 55
25 Year Member
Charter Member
Super Moderators
 
Joined: Oct 2000
Posts: 20,233
Likes: 2,482
From: Omaha/LOTO
Default

Doing them in the boat is pain in the azz. I did it once that way and it sucked.

You have carbed 500hp's correct??? I would use the regular Crane 168741 cams with carbed 500's.
Griff is offline  
Reply
Old 04-10-2020 | 07:52 AM
  #5  
later's Avatar
Thread Starter
Registered
25 Year Member
 
Joined: Oct 2000
Posts: 1,391
Likes: 22
From: Chesterfield Mo/Loto
Default

Originally Posted by 1BIGJIM
What gen of engines?
I would think I have the Gen VI motors
later is offline  
Reply
Old 04-10-2020 | 02:13 PM
  #6  
Registered
15 Year Member
 
Joined: Jun 2010
Posts: 4,806
Likes: 891
Default

Originally Posted by later
I was going to do a valve spring replacement this spring and then started thinking about just swapping out the heads, been doing a lot of reading through the different threads on heads, springs, and cams, I'm not looking to squeeze the last HP or Torque number but would like to see some measurable gain. in performance. I have a couple of questions, 1.) is it possible to swap out the heads and cam with motors in the boat, which is a 42 fountain with side by side motors with a lot of room in front of motors. if so what would be any potential problems if any. I was leaning toward the AFR 305 heads but then started reading about the EQ ch454a heads and since I'm not a closed cooling system it seems the iron head might be a better choice. either way, I go I would buy a bare set of heads and have them assembled question #2 I read about valve guide clearance being an issue what would be a good clearance for guides. When looking at bare heads they all seem to already have the seats ground at multiple different angles what would be the preferred seat widths and do you get to choose when ordering bare heads, and the last question the age-old question cam selection, it seems that the 525efi cam is used a lot because of the 14 LSA is there a part number for that cam from crane. and one last question what lifters came in the 525efi motors I'm assuming they are the GM dog bone style. Thanks in advance


Later
if this is roller cam setup, I’d go Johnson lifters only. Manton or trend push rods. Rockers is a toss up. Scorpion are nice and lots of people go with steel pieces. Can’t comment on cams...
1MOSES1 is offline  
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.