CJ exhaust port EGR humps

[ksquared 13]

Has anyone determined the value (if any) of removing the EGR protrusions in the 428 CJ head exhaust ports. Looks like it would be worthwhile but I don't have a flow bench and a stack of heads to experiment with.

[Fordrevhead 29]

First, have you ever ported heads? I have and it is a lot of work. Second, you dont want to do all of that work and actually make things worse. ie: Some humps are necessary. It can be done but do yourself a favor and pay $30 to the RHP site for a membership.

 

http://reincarnation-automotive.com/bbf_technical_index

 

I am in no way affiliated but they get some amazing numbers from their iron heads and have excellent instructions, measurements and photos. They are highly regarded on the big block forums.

 

"RHP's ported D0VE heads are making a dyno proven 730 + HP and our ported Iron CJ's are making a dyno proven 846 HP best to date."

Edited April 2, 2012 by Fordrevhead

[ksquared 13]

Yep. I've ported a number of heads (mostly Chevy). Yep, it's lots of work. I'm just doing a light cleanup of flashing & mild blending. Removal of those EGR ports is tempting but if the results are small, I'll pass. I'll check out the link. Thanks.

[LindenBruce 27]

Removal? I'm not sure what the goal is. You can use a good intake gasket that doesn't have the cross-over passage to block them off if that is a concern. Other wise a good bowl blending should give great results. Un-shrouding the intake valve with a fly cutter would also be something to consider. Bruce

[ksquared 13]

The goal is to improve the exhaust port. The EGR ports on 428 CJ heads have a rather large "hump" extending into the port. I suppose this was to get the Thermactor air well into the exhaust stream. I'm not using EGR. These "humps" look rather large. Do they cause much restriction? Don't know. I don't yet have a flow bench or scrap heads to experiment with. Was hoping someone on this forum had experience with these heads. I'm calling DOVE tomorrow to see if they have an idea.

[LindenBruce 27]

Ah, the thermactor ports got it. There is that "wall" right at the thermactor port hole that runs from side to side inside of the exhaust port. Is that the one your are talking about? You can knock that wall down flush and blend it with the top of the exhaust port no problem.

 

There is also that "ridge" on the bottom inside radius of the exhaust port too. You can knock that down some and blend as well.

 

I just cleaned mine up a little, maybe .050 - .070 thousandths off the top and blended them. The one thing I did do on the exhaust ports was to smooth them as much as possible including polishing. That will really help flow and help prevent carbon build up. This was on my set of C8EO-N heads. Here's a few pics. Bruce

[Fordrevhead 29]

I hear to be careful on the bottom side there is typically a ridge there already due to the slope of the port. I would start by doing a port match/ gasket match to the headers then have at it. A LOT of the hump can be removed for sure. The issue is that you want them all to match so if you are over ambitious on the first one you have a lot of work ahead. I tend to do it in stages... so if I get sick of grinding I just stop at the eigth port and then go back and polish, lol. I only ever personally did one set of thermactor era heads, they performed nicely but were 302.