Stealth heads

[Grip64]

Can i get some feedback from you guy's running 440 source stealth heads ??
Good or bad please 

[aifilaw]

They look exactly like a set of edelbrocks, non-canted plugs, ports are smaller, but on the same flow-bench flow exactly the same. There is more meat inside the ports to make them flow better than the edelbricks if you decide to put the money into a port-job.
fully-assembled heads for me came with 3 things that irritate me.
1. valve seats were not machined out carefully, needed to be redone
2. 7-degree locks and retainers are good for a cam less than 0.499 lift at the valve, and/or something making less than 400HP, anything more and the ones that come with the heads are worthless
3. springs are single-spring with shock absorber... I wouldn't trust them once again for a car making more than 450 HP

It's a good head, especially for the price.... but unless you just don't care, I wouldn't buy them fully assembled.. I would buy them bare, have a machine shop install new seats, do very light port work to open them up to 300CFM, install double-springs, 15-degree comp cams locks and retainers, and do a 30-degree back-cut on both ports(depends on the cam). You will be out the cost of the heads plus $1,000 for the work and parts.

[Musicman]

I agree... a good deal for the money, but like any other head they will require some extra work. As aifilaw has already stated...  the 10 degree locks and keepers from Comp Cams are a good replacement for those cheesy stock ones. A good valve job is always required with any "preassembled" head... and just a little light port work will have them flowing 300 CFM. I don't think you can buy them bare bones anymore however... but who cares... the locks and keepers are the big issue for replacement in my opinion.

[firefighter3931]

The Stealth heads are excellent value for the money....way cheaper than rebuilding a set of stock heads and they come with a nice closed chamber. The aluminum casting is a bonus for lightweight and detonation resistance. As mentioned the locks & retainers are suspect and need replacing. The valvesprings are descent for any flat tappet and most solid cam profiles....basicly the same valvesprings that come on Edelbrock RPM cylinder heads.

As for performance ; the Stealths "as delivered" will flow about the same as a set of bowl ported stock heads. They are not in the same league as an Edelbrock RPM or MP 452 aluminum casting and that is reflected in the price. On a bench they are 15-20 cfm down in flow across the board but with porting can be made to work just as good as any of the other standard port aluminum heads. 


Ron

[lilwendal]

Just purchased a set today.  With the Comp Cams keepers   Cant wait to see what they look like.
Ron... Question??? Do the stealths need much work in the bowl or is it more the ports that need to be opened/matched?

[firefighter3931]

Just purchased a set today.  With the Comp Cams keepers   Cant wait to see what they look like.
Ron... Question??? Do the stealths need much work in the bowl or is it more the ports that need to be opened/matched?

With those heads i would focus on blending the transition into the bowl and do a good valvejob....3 angle with a 30* back cut to the valves. That will perk up the low to mid lift flow nicely. The ports are smaller than an RPM head but that's not necessarily a bad thing....it just depends on the engine combination. For a street 440 i'd be tempted to leave the ports alone (maybe mild cleanup with sand roll) and port match the heads and call it good. This is a 500hp head with a little prep work and the right cam on a 440 cube build. 


Ron

[lilwendal]

Just purchased a set today.  With the Comp Cams keepers   Cant wait to see what they look like.
Ron... Question??? Do the stealths need much work in the bowl or is it more the ports that need to be opened/matched?

With those heads i would focus on blending the transition into the bowl and do a good valvejob....3 angle with a 30* back cut to the valves. That will perk up the low to mid lift flow nicely. The ports are smaller than an RPM head but that's not necessarily a bad thing....it just depends on the engine combination. For a street 440 i'd be tempted to leave the ports alone (maybe mild cleanup with sand roll) and port match the heads and call it good. This is a 500hp head with a little prep work and the right cam on a 440 cube build. 


Ron

Thanks Ron...As always..The man with all the right engine answers:cheers:

[dstryr]

I'll be running my ported 440Source heads with a Comp Cams XS290S, .540" lift on the  Intake side, .558 Exhaust.   I upgraded the retainers and locks.  Point #3 by aifilaw just scared me into thinking maybe I need springs before I put this motor in the car.  I think several months ago a builder here or on moparts didn't think the XS290 was too much for the springs, but...

Opinions??

Edit: I also have 1.5 ratio roller rockers.

[aifilaw]

In my professional opinion I think the springs will not do the job for that cam in the long term, they may last for 5,000 miles of lightly spirited driving, but I would not trust them beyond.

[dstryr]

Thank you, that's the kind of insight a newb like me needs to understand and once the engine is broken in I don't want to be shy about dropping the hammer.  I've already done the retainer and lock upgrade.  Do the Source heads have spring cups installed?  I don't have my engine at home to check. 

The XS290S calls for their #925 spring;  do you know if the Comp springs will work with the Source seals?  Their site says they should work with most dual valve springs.


I want to get the loose ends tied up in the next week or two so I can finish putting this thing together when the weather turns a little warmer.  I called a local shop today to get some info on dynoing the motor when it is ready to go.  $475 for a half day.  We'll break it in on the stand then do some pulls to get the numbers. 

[firefighter3931]

I'll be running my ported 440Source heads with a Comp Cams XS290S, .540" lift on the  Intake side, .558 Exhaust.   I upgraded the retainers and locks.  Point #3 by aifilaw just scared me into thinking maybe I need springs before I put this motor in the car.  I think several months ago a builder here or on moparts didn't think the XS290 was too much for the springs, but...

Opinions??

Edit: I also have 1.5 ratio roller rockers.

Before buying any new springs why not have your Stealth springs checked. 

The Stealth springs appear to be identical to the Eddy RPM valvesprings and if that is the case they will work with that cam. I have the stock RPM valvesprings on mine with a bigger cam 264@.050 & .580 lift and they were fine. Multiple passes on the dyno to 6500 rpm and no valve float issues. If the springs show 130lbs seat pressure/ 340-350 lbs open pressure they will be OK, inmo. There's allways the option to add an inner spring for increased stability should it be required. 



Ron

[aifilaw]

firefighter,
   one thing you mentioned makes me curious as to where you got the idea. When I got the stealth head and took it to the machine shop to be checked out he had a set of edelbricks and we ran them side-by-side at 25" and 28" and obtained nearly the same cfm out of each within 5cfm at each lift. The ports were noticeably smaller on the stealth. Then he ran a set of completely worked over edelbricks that flowed 310, but that's with a 3-way valve job, back-cuts, and some serious porting.
After looking at the amount of wall we had to work with we both felt the stealth could probably be pushed into a minimum of 325 range with the same amount of effort. I'm going to sonic-check the depth to verify that theory, but that's the instinct.

I think when you measure the pressure on the spring you will find the stock stealth springs lacking... but then again I always over-compensate to avoid engine failure.

[firefighter3931]

I'm going to sonic-check the depth to verify that theory, but that's the instinct.

That's probably a good idea....last thing you want to do it hit water when trying to max port the head. The critical dimension is the pushrod pinch....a stock port head can only go so big before you run into problems.

As for the flow numbers, my buddy Dwayne had a set of Stealths on his bench awhile back and they went 255cfm before maxing out. The typical "stock" RPM/MP 452 (aluminum) head goes 275-280 on his bench depending on core shift, casting flash etc...My "Stage 1" prepped RPM's went 293@.550 and just shy of 300cfm @.600 valve lift. Headwork was focused on low/midlift to fatten up the curve where the cam we selected would be working (Under .600 at the valve) The final intake port volume after porting ended up at 228 cc

There aren't that many spring manufacturers around...it wouldn't be a big surprise if Edelbrock and 440 Source are purchasing their valvesprings from the same supplier. 


Ron

[Mick70RR]

I'll be running my ported 440Source heads with a Comp Cams XS290S, .540" lift on the  Intake side, .558 Exhaust.   I upgraded the retainers and locks.  Point #3 by aifilaw just scared me into thinking maybe I need springs before I put this motor in the car.  I think several months ago a builder here or on moparts didn't think the XS290 was too much for the springs, but...

Opinions??

Edit: I also have 1.5 ratio roller rockers.

I have been using that cam with Edelbrock heads with the stock springs for about 18 months. No problems so far and I regularly see 6200 RPM.