I've spent over $5K on building a nice 327 for my 68 Camaro. All professionally built. The motor doesn't come alive until about 5000 rpm. The selected components were to make it a fun low end torque street machine. The motor doesn't want to take the gas. I have dart 202 heads. Keith Black pistons 10.5/1, .030 over. Doug Herbert hydralic roller cam. (c6pj). The rpm range is 1200 to 6200. specs Dur. 278..306, @.050 223..234. Lobe c = 112 deg. The lift using 1.6 rockers is .532..536. The cam was installed at 0 deg. Timing is set at 40 deg adv. Ihave an msd 6a ignition with an msd distributor. The Carb is a speed deamon 750 vacuum sec. The original intake was a victor jr. I replaced it with a dual plane rpm performer. Better results but not good. Doug Herbert said to degree the camshaft to 4 deg advance. Is this a big change? Does it sound like a fix to my problem? The motor seems to be over cam'ed but the cam is not radical. Whats going on ? If i put the 1.5 rockers on I will reduce the lift to .499...502. Please help. jim

Your cam seems like it is way to big. What is the gear ratio in the rear end? Is it a stick or automatic, if it is an automatic what is the stall of the converter? I would call a couple of cam manufacturers with your combination and find out what they recommend. Good luck.

Steve R.

Jim,

This is WAY WAY too much cam for your 327. The HERBERT cam part number PN CC6P with 217/224 duration @ .050 and .483/.502 lift would be a MUCH MUCH better cam. With your 1.6 rockers lift would be .515/.535. You are more than likely with your present cam NOT generating enough vaccum signal in the manifold area to allow your carb with it's vaccuum secondaries to work properly. Generally engines that have that high a duration cam need to use a mechanically operated carb of the double pumper variety. If that were the case, you wouldn't want to use more than a 650CFM double pumper on this combination.

I mentioned HERBERT specifically because maybe they would let you exchange your existing cam for the one I mentioned.

The dual plane manifold is a good idea but you have got to get rid of that CAM!!! Advancing the present CAM 4 degrees would not be a good solution because it is just too far off from where it needs to be spec wise. Your other components should work well with the milder cam.

I would use rear end ratio in the 3.55-3.73 range and maybe a 2200 stall convertor if you are using an auto. Now this car WOULD be fun to drive. HP should be in the 350-375 range and wouldn't be PIGGY at lower RPM's.

Just as refernece the much touted PERFORMANCE PARTS HOT CAM setup specs are: 217/224 @ .050 with .525/.525 lift (1.7 rockers). Now look at these specs and compare them against the HERBERT CAM I am suggesting. Look familiar???? DURATION IS EXACTLY the same!!!




[This message has been edited by sr71bb (edited 09-22-2000).]

Bring timing back to 35 total. Pull plugs to see how they're burning. If they're OK, jet up 2 sizes in secs. Use weaker/ligher spring setup in secs. Might try a 4 hole spacer if hood clerance allows. Will boost vacuum signal.

Cam is slightly large, but should be nice 6500 rpm cam for 327. ( most ranges are quoted for 350 ci, the smaller 327 "sees" more duration.

think you need to fine tune combo is all. But if you go and change cams FORGET THE IDEA OF USING A HYD ROLLER. Damn, use a solid, either flat or roller tappet. I shudder to think of what spring pressure is to keep that cam from floating at 6500 rpm.

Sorry, see below!!!

[This message has been edited by sr71bb (edited 09-22-2000).]

Good suggestions all 427 EXCEPT you and I differ on the solid CAM idea. I think they are too much of a pain in the *** to keep running properly on the street but I know you have a different opinion on this.

Wouldn't it be fun to take this combo and tweak it on a dyno!!! As a matter of fact, let's do it right NOW!!

Here is dyno sheet with both your existing CAM (I will call it BIGCAM) and the MILDER cam I talked about (SMLCAM):

RPM-HP-BIGCAM-TQ-BIGCAM-HP-SMLCAM-TQ-SMLCAM
2000---155------408--------161-------422
2500---201------422--------205-------431
3000---248------433--------252-------441
3500---296------444--------297-------446*
4000---342------449*-------338-------444
4500---382------445--------371-------432
5000---411------431--------390-------410
5500---423*-----404--------395*------377
6000---415------363--------377-------330
6500---394------319--------355-------287

PAST 6500, forget about it, HYDRALIC won't get there!!!

Looking above, there is less difference in these two cams than I initially thought but the milder cam obviously is more torquey at lower RPM levels.

427 has hit on something in regards to your timing. I have always found 36-38 total timimg to be IDEAL. I have seen as much as a 25-35HP loss on the dyno when running outside these parameters. I would also try to borrow a 650 double pumper carb if you could to see if your existing cam is preventing the 750 Demon from operating properly due to a low vaccum situation.



[This message has been edited by sr71bb (edited 09-22-2000).]

Don't ya just HATE it when some unknown comes in here and starts jabbering? Well, here I go...

Here's an example of what advancing a cam 4 degrees can do: We just installed a new cam in our 68 Camaro and took it to the track running only 13.80's @ 99MPH and didn't have any low end at all. Like your engine, it didn't start pulling until about 4800RPM. We brought it home and advanced the cam by 4 degrees. Immediately, we noticed an improvement in starting, low end torque and could use less total ignition timing (38 from 44) to get better ET's. We took it to the track and ran 13.0's @ 104 MPH all night long. We did have to lean the jetting down a few sizes to get the 13.0's, but the engine pulled strong from the 2200 stall all the way to 6500 like it was supposed to instead of the narrow 4800 to 6600 powerband.
I'm probably the only one here that will say that the cam is a good combination with your head and compression ratio in a 327. I'd stay with the RPM intake and 1.6 rockers. I'll agree that at least a 3.55 rear gear and 2200 stall minimum converter will make things a whole lot better. Tons of low end is taken away by higher gears and lower converters, especially in performance engines.
The whole process of advancing the cam took us maybe 3.5 hours total, and the results were well more than we expected. I will say that we had a 2 piece timing chain cover and the timing gear had straight up and 4 degree advance keyways in it already which will save some time. I think you have a decent combination, but fine tuning, advancing the cam, checking jetting, timing will get you very good results. Keep us posted.
Alice

If you're looking for a fun, low-end torque street machine, you can help yourself by dropping down to a 600 or 650CFM carb - 750 is way too much for a 327 street engine if you want some driveability and crisp throttle response. Even with a 600, it wouldn't start to starve for air until well over 7500 rpm, which you'll never see anyway. Demon makes a 650 with vacuum secondaries, or you can get a Holley #0-80145 (4150 dual-feed with vacuum secondaries, center-hung floats, electric choke) from Jeg's for about $250 - I've used five or six of them on built 351 Windsors (Cobra replicas) and a couple on 383's I've built, and they're a terrific street combination on dual-plane Edelbrock Performer RPM manifolds. Bigger is always better with hand grenades, but not with carburetors.

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JohnZ
'69 Z28 Fathom Green

Wow, One day later and all the responses. I appreciate all the advice. I am running a 373 gear. I also have a B+M 2400 stall conv. The speed deamon carb is very adjustable. I'm in the process of advancing the cam 4 degs. Will keep you posted. If this doesn't work i'll probably change the cam. What do you think about me going with a 3600 stall conv. I already have the tranny cooler in. What the hell its only $$$$.

I advanced the cam 4 deg. The motor is pulling very hard but still high at 3000 rpms. Much better than 5000 Plus. Its still not what i want. Do I try changing the roller rockers to 1.5 instead of 1.6? This will cost $200 for the parts. Should I advance the cam a little more? Should I go ahead and change the cam? If I do that, what should I go with? Thanks JIM

It appears you should go to a smaller cam since you have a hydralic roller.
I was going to suggest installing a set of Rhodes lifters or something like them for a hydraulic cam to give you some more low end or if a solid cam try opening up the lash to the max spec cam company says is OK. You can't do this with the hydraulic roller lifters though.
You might try something in the 210/218 range at .050" on the intake to get more low end grunt. pdq67

Remember the little solid Duntov in the 327/340hp only had 230 degrees duration at .050".
The 327/350hp hydraulic had 222 degrees at .050".
And the 327/365&375hp had the big Duntov at 254 degrees at .050".

Have a 71 camaro rs with a 350 bored .30 over with 10.5 pistons,edelbrock 3 deuce with rochester 2 carbs (unaware of cfm),4 speed with 373 posi.. looking for the most radial hyd. camshaft in power range of 2-5000rpm that would benefit this engine, any input would be appreciated.

Which Dart heads do you have? What size intake ports? If you have the 215 or 220 cc intake ports that could be compounding you're problem. The reason I say this a friend of mine has that same cam in a 350 in his El Camino, he has ported stock heads and it will pull 6th gear down around 2000 rpm very easily.
Stephen

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67 RS/SS 350 700R4
69 SS clone unfinished
72 454 Weekend Racer

Heres another opionion to consider http://www.camaros.net/forum/biggrin.gif


I dont think the cam is too big...i run a 224/230 hydraulic in a 350 in my way heavy 78 chevy truck with a 2000 rpm convertor and 3.08 gears...this thing pulls hard from idle to a tad under 6000 rpms...and it surely doesnt have as wide of a powerband as the roller your using. I wouldnt advance the cam any more than 4 degrees...your taking too much of a risk with your piston-valve clearance already. I think your carb is a bit too big...but there are a million smallblocks out there with too much carb and they still work ok. Personally, I think your low speed response problems are from those heads...a 200cc intake port on a 3.25" stroke motor is just asking for soft low end response. If youve got the money to blow, a set of edelbrock performer or rpm heads with 170cc runners will crispen up the throttle response...not to mention they flow better anyway and you get the "oooh, ahhh" factor of aluminum http://www.camaros.net/forum/smile.gif The performer rpm is an excellent intake (also what I run) but seems to be very picky about the way the carb is tuned. One thing that may help also (if you havent done it already) is try to bring the advance curve in sooner...try having full advance by 2800-3000 rpm (if not already)...many times this will make an amazing difference in low end power. One last thing...I wouldnt swap to the 1.5 rockers...you might see a very slight improvement in low end power but not enough to justify the $$$.

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375hp 78 Chevy truck
77 Chevy Nova
95 Chevy Lumina 3.4L
and building a 78 Nova

[This message has been edited by travis (edited 02-25-2001).]

Don't put a double pumper on it { I don't know where the idea that a radical cam can't use a vacuum sec carb it is much better idea because the carb will only be as big as the motor requires. If you have ever seen an early L88 car they have a cam that is so radical that they won't work power brakes but they came with a vac sec carb.I would try bringing in the advance quicker with that much cam and head voluum you are not going to have much low speed cylinder pressure so pinging will not be a problem and it will pick up the bottom end horsepower a bunch