I have a 351w in my '78 F100 and I'm starting to collect parts for the engine. All of the posts I've seen online seem to favor the AFR 165cc and from everything else I've read about them I agree.

My question is, since I don't need emissions testing on my truck, should I go with the non-legal emission version? Is there an advantage over the legal emission version?

Thanks,

 

The emissions heads probably have the air injection ports in the back of the heads, if u arew not using a air pump i would just get the non emission heads as it would probably run a lot better with them.

 

They probably have an EGR port as well, which compromises the roof of one of the central exhaust ports. The manufacturers have no way of knowing what intake you will use with thier heads(some are integral EGR, some don't) so they have to build this stuff in to get a CARB number. But since the 5.8 uses external EGR plumbing from the factory you can still get the functionality, it's would just be a matter of convincing the smog referee to accept it.

 

So since I don't have a smog referee it would be best to go with the non-legal ones, to not have all the extra air injection and EGR ports and therefore nothing will be compromising the roof of the central exhaust port? Sounds good to me, they're the same price, so I was just confirming the differences. Now I just have to start reading up on cams

 

Yep.. that's the choice I made for my 351 build and I have to pass a sniffer test.. they don't care what parts are being used or even check for CARB numbers though, just measure the tailpipe emissions. I'm going to question why you are not looking at the 185 heads though.. the 5.8 can use the extra airflow and the larger heads won't compromise low rpm TQ like it does on the 5.0.. which is what the 165 heads were built for.

 

Oh, well in that case I'll go to the 185, I thought I had read a post by you that said the 165's were perfect for mild cam/intake/exhaust, but the thread must have been about the 302.

I'm looking for towing power as well as having fun, not daily driven (weekends in summer only)

 

Question for Conanski regarding EGR on a build like this:

Is it possible to use the EGR to allow higher compression in an engine like this? Or does that require computer control, knock sensors etc to meter the EG at the proper time?

Nothing like 11 : 1 compression to bring life out of the old lump....

 

I don't think EGR would make enough difference to allow static compression that high, I don't know how exactly much it does on EFI motors but it's not hugh, probably only worth a few degrees ignition advance in total.

 

Going back to this thread, I found some World Casting Products 200cc bare heads brand new for an extremely cheap price and I was wondering how they compare to the AFR 185's.

WINSOR JR. & SR. Cast Iron Small Block Ford Cylinder Heads (the 200cc bare head model)

 

Not really in the same league as AFR.. though certainly better than the stocks heads.

 

wow very good info im glad you had that flow chart on those cyl heads, since ive been trying to find some for a 331/327 build im doing for a car. the only other ones i was looking for info on was the dart iron eagles which advertise a 180cc runners. im assuming they would be close in performance to the windsor jr? or are they better? id like to find a flow chart on them but i cant seem to find one.

 

 

Thanks Paul, I don't fully know what those numbers mean, but I can see that AFR 185's flow a ton more than the WP Sr. 200's. I guess naming conventions don't always mean they're better (200 vs 185)

How much difference would the AFR 185's vs WP 200'smake with a 351w: Hedman longtubes, Compcam XE262H, Edelbrock Performer RPM intake & 650 Holley 4bbl?

 

The numbers are port airflow in CFM at 100 thou valve lift increments. The bottom line is the more air the heads flow the more power they make. It's a double edged sword though because if the heads are really too big for the motor then low rpm power suffers. These heads are all pretty good matches for the 351.. with the exception of the stock heads which are WAY too small.

Here's a dyno sim of the stock, World, and AFR heads with the same cam, intake and exhaust on all 3. I adjusted the compression ratio and valve sizes(where applicable) to more accurately reflect real world conditions. There's a 55hp difference between the World and AFR heads, while there's only 20hp difference between the AFR and Dart heads mentioned by somebody else(not shown). The AFR's make 385hp at 5500rpm with this setup.

 

Wow, 55hp is quite substantial, well worth the extra couple hundred. I'm still waiting on the exhaust anyway so i'm in no rush. Thanks for all the help!