Reply With QuoteCall me before buying anything Comp. I get exceptional deals.
Wow! What's up with CAT? :squiggle:
For those of us that say the thread about the CMI headers....Check this out. I raised the Bull$hit flag, and they sent me the dyno sheets. I'll post this in that thread too.
WOW. 56 Horsepower. It's not 60, but it's big, and I didn't believe it until I read it myself.
http://www2.***boat.com/image_center...-01-_1dyno.JPG
Call me before buying anything Comp. I get exceptional deals.
Ok Infomaniac, thanks for the offer! Even with shipping to you and to ?, you think it will come out ok pricewise?
Summit=
Rockers, CCA-1128-16: $409.99
Conversion Studs, CCA-4514-16: $72.39
Guide Plates, CCA-4806-8: $46.69
$529.07. I think there is an $8 handling charge, free shipping so:
$537.07 shipped.
Allright gang. The old hot rodder in me says I can swap out my Mag Cam for the HO cam and it'll run.
It's been verified that the only difference between the HO and the std MAG (besides 50 HP) is the cam and the computer. Some S/N's have noted a Throttle-Body difference, but I can't imagine what major differences there could be.
Another point, Raylar puts his cam, heads and intake on the 496 all day and runs stock Mercury programming. What gives? If I pick up an HO cam from a Raylar convertee, why not slap it in? Does the computer control any injector timing that could be tied to the cam grind?
Has anybody tried, considered or even talked about this yet?
The timing is fine for either motor. Raylar has found that the fuel/timing mapping in the ECM is a good match for their entry-level kit. They just up the fuel pressure to around fitty pounds and the a/f ratio come out right.
I can beat that. I will PM you tomorrow. Saying Summit is enough.
Ok Infomaniac, thanks for the offer! Even with shipping to you and to ?, you think it will come out ok pricewise?
Summit=
Rockers, CCA-1128-16: $409.99
Conversion Studs, CCA-4514-16: $72.39
Guide Plates, CCA-4806-8: $46.69
$529.07. I think there is an $8 handling charge, free shipping so:
$537.07 shipped.
Yes I was wrong on the rev limit. I had a relapse back to my 7.4L days.
The 4950 rpm rev limiter should allow you to reap the benefits of the very small increase in duration youll get with the 1.8 rockers.
Just thinking out loud here but what makes the power in a cam is not primarily the lift. The more important factors are the intake and exhaust duration, the aggressiveness of the flanks and lobe separation. The lift pretty much just follows these characteristics and should also follow the head flow numbers. Lift will help if the heads flow much better at those lifts which would not be the case in the stock GM 8.1 head. A more aggressive duration cam (such as the HO or Raylar cam) with quicker ramps and longer durations will open the valve quicker and leave it open longer at the increased lift. This is important due to the long dwell created by the long 496 rods and will allow for much more air to be ingested and gasses exhausted.
Raylar has verified several times a 26 hp max increase in his real world, back to back, dyno testing with the addition of 1.8 rockers. However, this is with his heads, an increase in fuel pressure and another point of compression to work with. Still pretty impressive but then again his heads flow much better than the stockers at the increased lifts. With all that being said and further thought, my guess is your probably looking at a ~15-20hp max increase with the stock heads and much less aggressive cam to start with.
With the slight increase in hp and no fuel pressure increase you might indeed help the soot problem. That may be worth the $$$ itself but for the hp alone it may not be cost effective. If your not afraid of the work, pick up a cheap HO takeout cam and stuff that in there with the new rockers (watch valve to piston clearance), up the FP a bit and you should be ready to rocknroll. Again, just thinking out loud :idea:
If you do add rockers regardless if you change the cam, I would also make sure you closely check you geometry and make sure nothing (such as push rods) hits or rubs on the stock heads.
Im sure Ray could shed some of his experience on this and these are just my thoughts that may or may not realign your thinking.
Let us know how it turns out and good luck.
If you do come out with a 40 hp gain with the rockers Ill be the first to run out and get a couple sets of rockers and a couple sets of the new 60hp CMIs and have me a set of HP525EFIs. Life is good :wink:
Dave
If you do come out with a 40 hp gain with the rockers Ill be the first to run out and get a couple sets of rockers and a couple sets of the new 60hp CMIs and have me a set of HP525EFIs. Life is good :wink:
Dave
Exactly. While your at it, we can go in on a joint venture capital property with some coastal condos in AZ......
I bought this boat as an "unfinished project" The guy who started it, put the std MAG in. If it were the HO, I'd be a happier fella. With a baseline 375, if I could squeeze 50-75 HP TOTAL out of her with just some simple mods like these, then I'd be a happy camper. Unfortunately, 3600 pipes are not in my budget at the time, but I wonder what a set of CMIs behind a Raylar would do for you?
The 1.8's are definatley in my future (next season) and I'll probably try the CAT ones......I have planted some other seeds to try and find more info on CAT. We'll see.
What's the attraction to the stock valve covers? You are digging a ways into the motor, changing out a bunch of stuff, why let the stock valve covers alter your choices?
BJH
:shift: Just to help keep you guys from grenading your 496's do not put any cam or rocker combination in a stock 496 block that takes the intake valve lift over .520!! If you do you will find your intake valve dancing on top of the hypereuctectic pistons and the rest will be history. Also, all other BBC valve covers do not fit 496's, they are drilled in a different pattern. The stock valve covers have no oil drippers underneath and if you put in any roller rocker on stock heads you will have to change the rocker studs to SAE threads and use valve cover spacers to clear the adjustment nuts. Why do ours fit? because we engineered and built our new aluminum heads to accept our special rocker studs, adjustment studs and the like. Just remember guys, be careful who tells you what, unless you know the exact inner parts and workings of a 496 you may get yourself or others in deep do do! "A little bit of knowledge can be a dangerous thing!" :hammer2:
Just some assistance here.
Ray @ Raylar
Well, I was informed by Shadow, who is pretty tight with Ray, that their rockers are designed with the adj nut down inside the body, to fit under stock covers.
I am pretty sure their heads are the same dimensionally as stock, since they are exact replacement heads.
I know for a fact that the Comp Cams stainless rockers, that look exactly like Raylars, will fit. My local engine builder just built a smog-legal 526 gen VI for his 1995 Chev dually. It has GM iron heads, 1.8 CC rockers, and stock valve covers with the drippers ground down.
Cam lift:
496 Mag int = .282 exh = .284
w/ 1.7 = .479 .482
w/ 1.8 = .507 .511
496 HO int/exh = .300
w/ 1.7 = .510
w/ 1.8 = .540
See, by just changing rockers, you put your cam lift a little better than a stock HO. I would imagine there is a little more duration on the HO cam, but it can't be much at all. Much easier to change rockers than cam.
Well.....see Ray's post.
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