Win some, lose some...

[tRustyK5]

Still scored I think. Picked up some 781 heads for $100 today. I asked the guy if he had anything else big block and he showed me his pile of parts. I see an aluminum manifold, and asked how much. He says $50, so I grab that too. I should have looked a little closer, it's an SP2P Edlebrock...tiny ports and only good to 4000 rpm.

I'll re-list the manifold.

Felt I did good on the heads though!

Rene

 

[4X4HIGH]

Sweet score. Are the heads complete with valves?

 

[bailey9r]

Wouldn't that sp2p be perfect for a crawler? it is great for MPG. just wondering. One thing it doesn't work well with is a mpg cam.

 

[tRustyK5]

Sweet score. Are the heads complete with valves?

Only thing missing is the rockers. I think they're 2.19/1.88 valves. They need to be hot tanked, and a valve job, but they look in decent shape as is. Quick question for you, these are going on my '90 TBI 454 I picked up. Not gonna use the TBI, going Q-jet. I think stock CR was 8:1 and the internals look really clean/low mile. Should I look at milling the heads a little to bump CR some? AFAIK they have the same chamber volume (119cc) as the peanut port heads that are on there right now.

Wouldn't that sp2p be perfect for a crawler? it is great for MPG. just wondering. One thing it doesn't work well with is a mpg cam.

I'm not building a crawler, more of a toy I might take mildly off road now and then. I want fun, bit of a rowdy idle with the performance to back it up now and then. I did a quick comparison of port sizing between the 781 intake ports and the SP2P ports...the SP2P ports are literally 1/2 the size of the heads' ports. If I can squeeze $50 out of it on CL I'll be happy to be rid of it.

Rene

 

[4X4HIGH]

The 781 heads do not have 2.19/1.88 valves. Those ARE the sizes you want to have the heads machined for though so that they flow REALLY well for a cast head.

Trying to surface the heads to raise compression is not the way to go about it. First off it takes ALOT of material to remove to change the CR enough that you'd even notice and second it creates a whole other set of problems like intake manifold no longer fits correctly unless you have it machined and the valve train geometry changes as well and the pushrods become the wrong length. If you want a different CR then you need to change pistons accordingly. The 781 heads are technically a 119cc chamber but i've seen them anywhere from 122-110cc so have the shop CC the heads to see exactly what they are (make sure they do this AFTER installing the 2.19/1.88 valves if that's what you're going to do).

 

[tRustyK5]

OK, good info thanks Scott!

Yes I'm thinking of having the 2.19/1.88 valves installed. Getting the heads CC'd is a good idea too. Anything else I should have done to them?

Rene

 

[4X4HIGH]

OK, good info thanks Scott!

Yes I'm thinking of having the 2.19/1.88 valves installed. Getting the heads CC'd is a good idea too. Anything else I should have done to them?

Rene

I would have them pressure tested (after any guides get changed) as the exhaust guides go through the water jacket and can leak if notinstalled and sealed properly. Other than that just make sure once the large valves are installed that they blend the bowls and unshroud any portion of valve that is shrouded too bad.

 

[tRustyK5]

OK, cool. There is a head shop nearby I'll ask for some pricing etc and see what they say.

Rene

 

[bailey9r]

I'm not building a crawler, more of a toy I might take mildly off road now and then. I want fun, bit of a rowdy idle with the performance to back it up now and then. I did a quick comparison of port sizing between the 781 intake ports and the SP2P ports...the SP2P ports are literally 1/2 the size of the heads' ports. If I can squeeze $50 out of it on CL I'll be happy to be rid of it.

Rene[/quote]


I was just kinda helping you sell it haha

 

[Big Ray]

ahhh, the old sp2p...put one on my v-8 jeep when I was but a wee lad...

 

[tRustyK5]

I was just kinda helping you sell it haha

LOL, apparently it is a great low end tq/mileage manifold. Certainly looks better than the stock POS. I'm sure someone local here will grab it for $50 or so.

Rene

 

[Big Ray]

fwiw, the SP2P evolved into the Performer series.