Clonerunner issues found:
Previous owner used steel shim head gaskets,(no copper coat or anything) was not religious about using coolant and apparently did not retorque many a year ago (10) when motor was built.(some headbolts felt like 30 lbs or so)Pistons look nice, especially the two that were sucking water regularly.Flat tops w/valve reliefs.no P/N yet.
Heads look OK, valves etc, still shows crosshatch in cylinder walls,but it has CAM-ITIS!
One lobe shows tell tale discoloration and graininess.Not 100% sure, but is purple and supposed to bee 284/.484.Loved it!
Comp has XE 274H-10 split pattern (230/236@.050) adv.274/286-.488/.491 110' lobe separation
and I can get amazon free freight, and I think a 25.00 rebate.
Would this be pretty close to, or better for my setup? (383 .030 906s,approx 3000 stall,3.55s,# 3800,eddy rpm intake/850 DP 3" exh w/x pipe)
It ran very strong w/the purple.No complaints, so I almost wanted the same cam, but maybe the split pattern would work better for me?
Thoughts?
Bear

It will be quite a bit milder from an idle standpoint because of the shorter durations.

The 274 is a decent cam and would likely work well.

Would be that noticeable, huh?The specs look sort of close,but I was looking at updating to a more modern grind, maybe pick up a broader power band from the split pattern.IIRC the 'purples' were not?
C

Depends on the combo whether a split pattern really will make more of anything you want. I would skip the comp cam and simply call Bullet cams and get a great grind to replace the MP piece. It's just too easy and you'll be happy with the result. Ask for Tim.

Something with similar duration will or a tad shorter will idle better and have more low end.850 is overkill for that 383 IMO.

Comp does make 'updated' versions of the purple shaft grinds, I run their 509. It is 248/254, .509". The 284 grind is like 240/246 if I recall, .484".

It will idle a bit rougher than the old MP grind, may or may not run stronger. I think possibly not, I read somewhere that with good heads and exhaust there may not be benefit from split grind.

The XE284 grind may work if you have the PV clearance.

Decisions, decisions...
Thanks all, food for thought.Maybe not so simple as a "magic" updated grind will make the sun come out, I'll lose 20 lbs, and the angels will sing.
As for the 850 carb,it was a really clean 4 corner I had that was gathering dust,ran a boatload better than the Mighty D it replaced, and Hot Rod used the same carb for their infamous 383 intake shootout IIRC.Plus I didn't have anything else good at the time.
More to follow, heads are off, time to buy a cam.
Thanks, C

A better Comp cam all around is the XE275HL. It has real Chrysler lobes, the 274 is a Chevy lobe cam. It will surprise you. If you liked the 484 cam the 275 will be better.
R.

My thought also about the .525 lift...traditional wisdom (IIRC) was with a stock 906 head, .500 lift was about it.You could go bigger,but the heads only flow so much in stock form anyway, at least up to that magic #.However,I do like the sound of the testimonial.
Are there less "radical" grinds on a chrysler lobe that are under .500?
This thing had steel shim gaskets,would be .020 compressed, so a 'regular'fel-pro is like .038 compressed, so right there is another "bonus" .018 PV clearance.I have never done the clay the piston deal, ever.Theoretically, if I re-install the purple 284/484 (or equivalent) there should be no clearance issues.If I go bigger, I'm sort of in uncharted territory.This motor had stamped steel rockers also, I am anticipating needing adj. rockers and correct length pushrods, as they will need to be "longer" by .018 with the comp. head gaskets.Yes????

The comp 274 is nothing similar to a 284/484. If you have a good set of headers, I would not worry about a split pattern.
You are going to lose a lot of top end with the 274 compared to the 284. But it would be a good cam choice imo.
It's not going to make more power though if that is what you are looking for.

Also what is your compression ratio?

As far as higher lift than the heads flow, it will still hold the valve open at or above .500 for a longer time, therefore you still gain power. If you catch my drift.

The more modern cam, XE275HL, will probably have more duration at 0.200 lift than the .484. I think you'll see an increase in max horsepower.

As far as rockers go, pick the cam, (mine is best), install it, see if preload is OK. If not, get a set of pushrods the right length. I bet your existing valvegear except for springs will be OK.

The only problem with higher lift is you need springs and retainer-to-guide clearance for it. Piston-to-valve clearance is something to check, but most bigblock Mopars have the pistons down so far that it is a non-issue.
And if you replace a steel shim head gasket with a composition gasket to increase P/V clearance, you deserve whatever loss of performance you get.
R.

Good information, good thoughts, dogdays, viperblue.
Looking at a set of used ductiles, as I am not a gambling man, and these rockers had 'acceptable' preload as far as I can tell,reasonably sure that'll go away.
The pistons do not appear to be KBs,no part number visible,pretty good wedge shaped clearance notch running across them, slightly deeper for the intake valve.Will be checking how far down in the hole they sit,just on GP.
As far as replacing a steel shim gasket with a composition and "deserving" the power loss I get,
sorry, my love affair with 60's technology only goes so far.
Not doing this for the P/V clearance, I am doing this 'cause they FAILED.(whether mis installed, not retorqued, whatever)
Sealing technology has advanced light years since they built these motors.Ditto for cam technology, hence the look at newer grinds.
No steel shims, thanks. Not worth the what is it, .2 potential compression point gain? With what passes for gasoline these days, it is not even a question anymore for me.Got a leftover set of custom detroits from Dan D I'll probably use.
Still deciding if I want to use the 440 source heads I have,too.
Thanks for all the input!Onwards!

The aluminum heads, would really wake it up. 40+ cfm more flow than stock and almost 10cc smaller chamber, will raise your compression almost a point over what you have.
A high lift cam should be fine with your pistons. I would go ahead with the high lift 275 version.

Unfortunately,these are the 1st gen "take your chances" heads.May go ahead anyway, what am I going to save them for?Good opportunity,Will run them by my friendly machine shop to check for the legendary tight guide and general valve job re-check issues.
Interestingly enough, the fellow at 44o source highly recommended the very 274 grind we are discussing for his gen 1 heads with my application.(I didn't even tell him what I was thinking, he popped up with that recommendation.).The Comp cam tech line guy Chris, stated unequivocably (whew, 10$ word) that they use chrysler blanks for chrysler cams, and he wishes the forums would let that one die???
He also likes the 274.Still thinking.

With the comp xe 274 you could run stock stamped rockers. The 275 would negate aftermarket, plus stiffer springs. With the 274, you could use what came on the source heads. Just go for it man.
Let us know how it turns out.

Comp, Comp. Comp, that's all this board ever talks about. What is it about them, and what wrong with Hughes/Engel cams That are made to take advantage of Chrysler .904 lifters? http://www.hughesengines.com/Index/produ...mp;partid=21852
http://www.hughesengines.com/Index/produ...mp;partid=21852
http://www.hughesengines.com/Index/produ...mp;partid=11429

Engle hasn't cut a hughes cam in a long time from what I've known.

Plenty of companies make cams that try to maximize use of the .904 lifter. Not just hughes. Outside the overpriced nature of most hughes cams, have at it.

1. I don't care for the original COMP Xtreme hydraulic cams:
- fast acceleration/deceleration ramps that cause a lot of valve train noise
- those same ramps also result in the valve train not RPM-ing as well as smoother lobe profiles; I've seen more than one dyno of those cams that show premature valve train "crash" compared to other profiles

2. I don't know if Comp resolved those issues w/ their HL Xtreme Chrysler lobes or not.

3. If I ever ran another hydraulic cam, I'd look for something less aggressive that would result in a "happier" valve train.

4. Hughes hasn't had Engle grind their hydraulic or solid flat-tappet cams for years, although I'm not sure who their grind of choice is now.