RV cam & 502 HO head compatibility

[80goldenburb]

When i bought my C20 Burb it came with a 502 HO (confused block casting 10237300) which came up as a Gen VI. I call this "confused" as this is NOT a VI but actually a Gen V (no mech pump provision and flat tappet cam). The 502 has since been replaced by a low mileage (37k) '78 RV 454 due to multiple spun bearings that developed in late sept 2016. The heads were still good and I decided to keep them (casting #1497088) when i sold the block after coming across a few Ebay ads with big price tag ($900+, i only paid $670 for the entire truck!). I would like to eventually swap these 088's in place of the 781's that are on it now. What are the differences betwen MK IV RV cam and Gen V 502 cam ?

 

[vkh]

Aren't those rectangular port heads? If so I'd suggest sticking with your 781s. Rectangular ports will kill your low end torque. Less your gonna build an RPM screamer I think oval ports will give you the best overall performance. Also it sounds like you may have to drill holes to run gen 5 heads on a mark 4, though that's just from a quick Google, so take it at what it's worth.

 

[74 Shortbed]

Yep, rectangular heads, 781's are ovals best factory heads for the street, put the big valves in and do a clean up and it'll be a torque monster..

 

[80goldenburb]

Also it sounds like you may have to drill holes to run gen 5 heads on a mark 4, though that's just from a quick Google, so take it at what it's worth.

Drilling isnt mandatory, its an option for extra cooling capacity of the Gen V and VI blocks. I would just need MK IV head gaskets and they would bolt right up.