TN454Monte Posted June 21, 2008 Posted June 21, 2008 There is an auction on E-bay for a set of GM Hi-Perf Heads. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=320263026556&ssPageName=MERC_BC_RCRX_Pr3_PcY_BIN_W0_IT&refitem=320263026976&itemcount=3&refwidgetloc=bid_confirm&usedrule1=CrossSell_LogicX&refwidgettype=cross_promot_widget&_trksid=p167.m184&_trkparms=algo%3DCRX%26its%3DS%252BI%26itu%3DUCI%252BSI%26otn%3D3 They are for a 1970 454. Will these also fit a 1978 Block ? Are the bolt patterns the same? Thanks in advance!
Heckeng Posted June 21, 2008 Posted June 21, 2008 Bolt patterns should be the same. Those heads won't work with Gen V or VI blocks though due to water passage differences. You should be fine with a 78 block though.
TN454Monte Posted June 21, 2008 Author Posted June 21, 2008 Thanks Scott, I might pick those up. Anythings got to be better than those oval port smog heads that is on there now.
TN454Monte Posted June 21, 2008 Author Posted June 21, 2008 Somethings not right here.... This E-bay seller claims these heads to be: Quote: 1970 454 GM PERFORMANCE RECT. PORT HI-PERF PAIR-NEW He then lists the casting number on the heads as Quote: # ON HEADS 14096188-GM HI-PERF. However one website I came across looking for that head casting number says these heads are: Casting number 14096188 Year 1987-94 Engine 454 Intake 2.19 Exhaust 1.88 Chamber Open CC 118 Any-one have other information that could shed some light on this Casting number??
Sam (Bones) Posted June 21, 2008 Posted June 21, 2008 they are over the counter replacement heads, I would stick to some oval port, 049 or 781 castings, you'll be MUCH happier
TN454Monte Posted June 21, 2008 Author Posted June 21, 2008 Much happier as in 049 / 781 casting vs these on E-bay or a set of early 70's rectangle ports? I've always thought the rectangle ports are better suited to make HP...didn't the LS5's run Rec. Port heads? Am I mistaken? Regardless these heads are out this guy is either trying to scam or just doesn't know what he's talking about.
Heckeng Posted June 21, 2008 Posted June 21, 2008 I am personally starting to NOT believe any of the stuff we've heard about Oval vs. Rectangular port heads for street or strip. I have 325cc rectangular port heads on an 8.75:1 motor (454HO) and that is supposed to be HORRIBLE on the street. It actually has very good street manners. Rectangular port heads are supposed to be more for high rpm hp since they can flow so much more due to larger ports. BUT and I think Sam will vouge for this one, there have been several engine builds using smaller port oval heads that make awesome power throughout the rpm range as well. I think either head will work for either purpose. Just don't go with a tiny port smog head and you'll be good with whichever style head you go with. Also, I think, but don't know for sure, that ALL BBC heads have Hi-perf cast into them? Anybody back that up or prove it wrong? Just my opinion.
Sam (Bones) Posted June 21, 2008 Posted June 21, 2008 LS5's came with the large oval port heads, the only 454's that used rectangle port heads are the LS6 & LS7 Scott...pop a set of 049 or 781 oval ports w/ 2.19 intake valves on there, your low end torque will amaze you, I'm not saying the rec are bad, but for a street car the oval's can't be beat
Heckeng Posted June 21, 2008 Posted June 21, 2008 I can't really compare as I've never run them, so that could be interesting.
TN454Monte Posted June 21, 2008 Author Posted June 21, 2008 Okay thanks for clearing that up for me Sam.
Sam (Bones) Posted June 21, 2008 Posted June 21, 2008 I have a set of 781 castings, but they need to be completely built....free if you want to come get them there are many aftermarket head companies they are producing ovals now, by the time you spend the money on building a set, you could probably buy a new set, I'd take a look and do some research
Heckeng Posted June 21, 2008 Posted June 21, 2008 When I win the lottery, I plan on getting some AFR 315cc heads. Thanks for the offer though. Until then, I'll just keep my current ones (I guess I'll have mine for a long time!)
TN454Monte Posted June 21, 2008 Author Posted June 21, 2008 Bones, I'd be willing to pay shipping and kick you a few bucks your way if you'd send them up to TN for me. Alls I know is these heads on the 1978 bite and I want to stay cast iron for the time being because I just got those front springs done, if I go to aluminum, I most likely will have to switch out my springs again.
Sam (Bones) Posted June 21, 2008 Posted June 21, 2008 what is the casting number of the heads you have? these 781's I have are off a '78 go to http://www.chevelles.com/forums/index.php and do a search, there's a TON of great info on factory iron heads
TN454Monte Posted June 22, 2008 Author Posted June 22, 2008 I'm not sure to be honest. I was planning on having a better set built and just pulling the set on there and putting them aside. I'd like to have an original numbers matching set to go back on the 454 if I ever decide to sell it. Not that a 1978 454 is in big demand, but if I ever decided to go OEM restoration on a Chevy Truck I would already have a set of correct heads.
Sam (Bones) Posted June 22, 2008 Posted June 22, 2008 you might already have a good set of heads, get the casting numbers for me
cudax Posted June 22, 2008 Posted June 22, 2008 Sam, Do you have a good site to cross reference the casting numbers? Mike
Sam (Bones) Posted June 22, 2008 Posted June 22, 2008 http://www.mortec.com/ the 353049 & 336781 seem to be the most sort after for street performance
cudax Posted June 22, 2008 Posted June 22, 2008 Thanks Sam, Believe it or not I have the 336781's. What do you know, something actually worked out for me! Mike
Sam (Bones) Posted June 22, 2008 Posted June 22, 2008 those are decent heads, have 2.19 valves put in them, spring pockets enlarged and you're good to go, they work well with stock size valves too for a street engine
cudax Posted June 22, 2008 Posted June 22, 2008 Eventually, I just might do that. I am still working on the interrior and transmission. When I bought the car the heads were recently worked and I really don't know what all has been done. The guy I bought it from only had the car for like 4 months and didn't do any of the work or know anything about it. I removed the valve covers and there were all new springs and seals plus the heads were the only part of the engine not painted. Thanks Again, Mike
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