How important are orginal heads on a numbers matching engine?

[AuroraGirl]

Another thing to consider is that the second you rebuild that block and have it decked, the numbers are going to get cleaned off it anyways. Cylinder heads are not stamped at all, so there is no such thing as numbers matching heads. There are several casting numbers that COULD have come on a 305 in 86, and it probably wouldn't be hard at all to find a set if you ended up wanting or needing them.

The problem with any original cylinder heads right now is that the 70's and 80's truck cylinder heads were some of the worst that chevrolet ever made. Not only that, but any that still exist in stock trim are going to need a cleaning, decking, valve guide replacement, and probably new valves with a decent valve job to be worth putting on a new engine. Once you have bothered to do that, you could have just bought a complete set of NEW, better designed, iron cylinder heads from summit.

Even stock Vortec heads aren't really worth much anymore since they need $300-400 worth of work to refresh(if they aren't cracked... which they usually are) and you can buy a brand new set of vortec or non-vortec 350 heads from summit for ~$700 shipped.

how about a 72 and similar pre - smog cylinder heads? Like, sure a 72 350 probably wasnt pushing any boundaries but it was 350 and has like 1 emission device on the whole thing(PCV as far as I can tell).

 

[Grit dog]

^If it’s laying on a shelf or out in the back 40, it doesn’t actually match the car it came from, so I’d say, no not worth much.

 

[AuroraGirl]

^If it’s laying on a shelf or out in the back 40, it doesn’t actually match the car it came from, so I’d say, no not worth much.

My bad I meant value as in use, like, how people like power pack heads and 283s, they can make power(esp relative to the time, original heads wise, etc) but I would not want to use my original 350s heads on my current engine(80 350, 165hp, smog). So like how people want vortec heads, does a 72 stock head (prob a truck engine) have any good use or is it like the previous good point of new head for the same amount of money to refresh an oe head that also works better, negating the point in refreshing for most situations.

 

[Salty Crusty]

And you should be aware that if you decide to use the vortecs, they have no heat crossover, poor manners until the engine gets warmed up a bit. Didn't have to worry about this with fuel injection.

 

[AuroraGirl]

And you should be aware that if you decide to use the vortecs, they have no heat crossover, poor manners until the engine gets warmed up a bit. Didn't have to worry about this with fuel injection.

NOT something I would consider myself, but would a heated carb spacer/adapter that gm made for qjets and the weird half-qjets (versajets I think) help that or would that not do what I think it would

 

[Bextreme04]

how about a 72 and similar pre - smog cylinder heads? Like, sure a 72 350 probably wasnt pushing any boundaries but it was 350 and has like 1 emission device on the whole thing(PCV as far as I can tell).

MOST factory heads weren't great in original trim. The benefit of early heads is that they were made better, so they have more meat on them to resist cracking and allow modifications that will increase power output. The problem with earlier heads is that they usually don't have hardened exhaust seats, so they need more upgrades to make them worthwhile for extended road use. Again, it just ends up not being worthwhile unless you are racing in a class that REQUIRES you to use factory casting number heads. Otherwise you can make more power for less money by just using complete aftermarket aluminum or cast iron heads.

I ended up using a set of 802 casting number heads for my mild 350 in my truck. They have the larger 76cc chambers, but I had the block decked and went to flat top pistons to bring the compression ratio up to around 9:1, so that should be OK. I got them from a guy locally that had them reworked for one of his engines that had a burr on the crank and immediately had spun a main bearing on initial break-in. They had brand new valvetrain and new larger valves and I only paid $150 for them. It would have cost me $500 to have the original heads reworked to a similar condition at a local shop. I still did some mild pocket porting and bowl blending as well as a basic chamber polish to clean up the rough casting flash in the chambers, just to get some experience and feel for it. They should be adequate for my mild build... but definitely not worth it if I was trying to make big power numbers or wasn't willing to burn time to play around with porting, polishing and valve lapping.

 

[SquareRoot]

I pulled my numbers matching engine out of my truck recently becuse it decided to blow up on me. Decided to throw a brand new 350 in it for now, so I can get back to daily driving it.
Anyway... I decided I'm going to keep the original engine, so someday if I ever feel ambitious and want to rebuild it, or if I ever sell the truck and can advertise that it has the original engine. Just planning for "someday".
I just bought a blown up vortec for cheap to use as my core, but I dont want to give away the Vortec heads, because they're gold nowadays, but the company I'm buying the engine from requires the core to have heads. So I was thinking of throwing my old worn out 305 heads on it before I give it away, but I was wondering if it would be important to keep the original heads to go with the engine.
Does that effect the value of a numbers matching engine?

"Someday" That's how hoarders get started. 1 in 100 chance that will never happen, e.g., "It ran when I parked it." Uhh huh

 

[AyWoSch Motors]

"Someday" That's how hoarders get started. 1 in 100 chance that will never happen, e.g., "It ran when I parked it." Uhh huh

Haha. Very true. Chances are, your right, but I just can't bring my self to throw it away and it's too pricey for me to rebuild at this point in time.
Plus there company won't take it Haha.

 

[Rusty Nail]

Voted no.

 

[Ellie Niner]

weird half-qjets (versajets I think)

Varajet or Varajet II

 

[AuroraGirl]

Varajet or Varajet II

i was mistaken myself, I was thinking of Dualjets as opposed to 2jets because the Dualjets were late era front 2 barrels of a qjet cost-reduction while the 2jet was a primary and a secondary(I THINK?) of its own simpler and fruitful, various designs