screaming eagle heads
- Thread starter traveller
- Start date
dolt
Well-Known Member
The short answer is yes, Stage IV heads will fit your cylinders. The long answer is a bit more complicated.
There are two Stage IV kits, Street and Race and each includes a different set of heads. The Race kit includes the CNC/MVA heads; 98cc chambers, 2.120" exhaust valves, very stiff springs and will accommodate cams up to .660" lift; the PN is 16925-11. You would not want to run these heads on an 88" motor, even with the 10.5:1 pistons.
The Street kit however, includes the CNC ported heads, stock chamber volume, 1.875 intake valves and will accommodate cams up to .585" lift; the PN is 16500013A. Assuming your current heads are stock or have stock chamber volume of 85-86cc; these heads will work with you current configuration. However, they are about $800 from an online discount dealer and $1000 from a storefront dealer and you could have your heads ported for better results for less.
Unless you are getting a great deal and the heads are the CNC ported heads, you would see better results having a reputable porter work your heads. There are two forum sponsors that could help you with that project.:icon_wink:
J
Jack Klarich
Guest
Not a bad price IMO New Castle list price is $846.94
dolt
Well-Known Member
Tough call.:sd The CNC heads are decent and certainly a step up from the OEM heads but not sure if the step up is worth $600 when, for about the same cost, you could have your heads fully ported with larger valves, etc.
Without seeing the heads, I can't say for sure but I would probably have them broken down, cleaned up and all carbon removed from the chambers, valves lapped in to the seats, new guide seals and I might even have the "high performance" valve springs swapped out for the OEM beehives. I don't recall the seat pressure on the springs in the CNC head but those heavy duty SE springs can be a source of valve train noise.
I am fortunate to live very near one of the best head porters in the country so it would be very easy for me to have a set of OEM heads fully ported heads with 1.94" intake valves and 1.630" exhaust, etc., etc, for $750, so I would pass on purchasing a set of SE CNC heads for $600. However, you may not be as fortunate and, like I said, the CNC heads are a step up from your OEM heads and the price is reasonable. However, I would not just bolt them on without checking them out as outlined above which will add a bit to the cost.
If you haven't done it already, I would suggest that you replace the head gasket with a .030" MLS head gasket like Cometic and yes, the later intake flanges will be required as well as a new set of performance exhaust gaskets.
The only other thing I would suggest is that you do a compression test before the exchange just to verify actual compression. According to my calcs, you should see about 190psi; a good place to be. However, you might also machining the heads for compression releases, installing them and using them. Not a "must do" but will extend battery and starter life at the compression level. Additionally, should you ever increase displacement to 95" or 98", you will likely need compression releases then.
Like I said, tough call but not mine to make. Sounds like you are prepared to spend some money for heads to improve the performance of your build. So, the question for you is whether or not to spend the $600, plus the cleanup cost for the CNC heads or spend a bit $700-$900 for a set of Stage II or III head from a reputable porter. JMHO.:bigsmiley10:
Also, I can't finish without adding that increasing displacement is the most cost effective upgrade to any build. If I were in your situation, I think I would go all in and bore to 98" as part of the upgrade. :s
traveller
Member
thanks dolt, your info has been very informative, I've considered boring to a bigger bore but that would mean different pistons and rings also. I'm a firm believer in more cubic inches but I'm sorta committed to this 88 ci. I really like it and I guess I'm like the army, be the best you can be. but I really appreciate the input. thanks again.
dolt
Well-Known Member
Understood. Just pointing out that $500 will get your cylinders bored/honed, new piston kit fitted to your OEM cylinders and rings gapped. Another 10 cubic inches doesn't sound like much but 115-120TQ/105-10HP numbers are within easy reach; never get there with 88".:coffee
Good luck with your project; let us know how it turns out.:s
If it were my money (its not) I would buy a set of used heads and send them off to a machinist and have them set up to your current build. I would recommend calling a few of the more popular guys and talk to them and ask all the questions you have. Compile the questions first. I would highly recommend Scott Palmer at Hillside. IMO he is really good at what he does and has been doing it for a very long time.
To add to what Dolt has said, I would consider the compression releases as a necessary item. Money well spent IMO.
To add to what Dolt has said, I would consider the compression releases as a necessary item. Money well spent IMO.