Pirate 4x4 banner

1 - 8 of 8 Posts

·
Registered
Joined
·
60 Posts
Discussion Starter #1
I have run this motor for 5 years - made 456HP on dyno. I had a partner for my rig when we built the motor and he assembled it. I decided to do some upgrades this off-season, and found out that he put the #2 and #8 pistons in the wrong bores - the reliefs for the intake and exhaust valves were switched and the valves were actually hitting the piston!!!

I know I'm lucky the motor lived this long, but I'm looking for guys with a lot of motor experience to estimate how much/if they think that this was costing the motor HP.

I would love to swap the pistons to their rightfull place and dyno the motor again, but it's just not in the financial cards. I'm curious what you have to say about it.
 

Attachments

·
Registered
Joined
·
1,380 Posts
mj said:
you are going to put the pistons where they belong right?

And pull the valves out that have been hitting the pistons and check to see if the are bent.
 

·
Registered
Joined
·
6,017 Posts
Pretty sure that those valves are FUBAR. I would replace them and the guides. And then I would take a dremel or something similiar and grind those valve nicks out of the top of your pistons. They could be creating hot spots causing you some detonation...
 

·
Registered
Joined
·
677 Posts
what are the other specs on the motor? with popups like that are you near 11 to 1?
 

·
Registered
Joined
·
60 Posts
Discussion Starter #7
I brought the heads down to the shop today to get some baseline flow numbers out of them. I was glad to see that the advertised numbers and the actual numbers agreed relatively well.

We also threw one of those intake valves on the grinder. Yep - it's bent alright. It wobbled out the guide a little bit too. The guide is still runnable, but one more thing to add to the list of decisions to make.

The rest of the basic motor specs for those of you that are curious:
350 - 4 bolt block - .060 over. w/6" rods
World Prod. Sportsman II iron heads
64cc chamber w/domed pistons for 13.5:1 compression
Lunati solid cam - 292/.550 Intake & 302/.571 Exhaust w/1.5:1 roller rockers.
Victor Jr. intake w/750 double pumper.
 
1 - 8 of 8 Posts
Top