chris from ocean performance has 2 drop in 420 blower motors-860-388-6000

Jim V rebuilt and did some porting on my 088 heads and I picked up 2+ mph on my 24 Pantera. It was about $1000 and that included cutting for 2.25 intake valves and new intake valves.

Definitely upgrade the heads and cams.


Wannabe

If i remember that 420 had some weird one off cam numbers and riser -manifold sets
If the roller rockers still have some life to give and the gen 4 heads havent cracked a bob roller cam and a real exhaust manifold with divided runners should wake it up good. Your old exhaust if not corroded will bring suprising almost gil money to the trs boys wanting to stay with cast

That is a good idea. The ones that are on it look new or recently redone. I'll have to wait and see what I find. I'll probably have the heads checked out and decide where to go from there. I could probably sell the heads and manifolds (if in good shape) and go AFR and headers. I ran AFR's on my LS motors in the off road race car and was real happy.

Lots of options for upgrading the 420's. It really depends on what your HP goal is and how much you want to spend.
Pretty much everything posted is possible but the cost range is from probably 5k to 12k per engine depending on what you want.

420's used the same cam as a 525SC and is still an off the shelf Crane part.
They had Gil exhaust.

I thought i remember seeing some 420's with cast stellings knock offs using gil style flanged risers. Looked just like gils but had a weird riser flange and real long tails really heavy.it was only on the 420 ,maybe it was the 440. Sounds like the op's exhaust has been changed anyhow.

I agree with the rest of the guys here. Your money will be best spent, in a new set of heads. All the heads are pretty good nowdays that come from AFR, Brodix, Dart, etc, and will be a nice improvement over the stock heads. The stock heads are too large of a intake runner, poor exhaust port flow, and crappy chamber design. They really arent worth rebuilding imo, when you factor in the cost to rebuild, and performance gain/weight savings, over some new alum heads.

Heres a real basic 454ci , AFR 265 ovals, 950 Holley, 10:1 deal, 609HP at 6000RPM, 575ft lbs at 5000, with a basic off the shelf crane 234/242 hyd roller. I wouldn't be talked into spending 2,000 dollars, to stroke it to a 496ci, that seems so common around here. Your stock crank and rods are fine for that power level. Save that money for heads, cam, lifters, etc.

http://www.airflowresearch.com/engin...-265cc-bbc.php

the little heads do seem stout.

http://www.superchevy.com/how-to/eng...al-port-heads/

Just curious, what is the average cost of AFR heads?