[30-A rider]

Gentlemen,

Building my 454 .030 over motor. L2349 pistons should yeild about 10:1 compression. Intake is Edelbrock RPM Air gap. Have not purchased carb yet. Rear end will be 3.73. TH400 trans with approx 3200 stall. Car is 66 Chevelle and will be 90% street and not a daily driver.

Heads are GM 049 castings that have been reworked by a reputable builder who frequents this site. Have 2.19/1.88 SS valves. Flow sheet I was provided with heads reads as follows:

28" 4.350 Bore

Good Port Bad Port
2 162 2 162
3 228 3 222
4 286 4 270
5 311 5 302
5.5 313 5.5 311
6 313 6 318

Im leaning heavy towards a hydraulic roller camshaft but have not made a decision as of yet and want to get the combo correct. My question is how much split should I be looking for in a camshaft? Hope I provided enough information for some insight. Thanks in advance for any replies/recommendations. Always appretiate the expert advice and learning tools I get on this forum.

Thanks again,
Scott

 

[GRN69CHV]

Scott. how big do you want to go?? L2349's may need to be flycut deeper if you go much larger than a 230-236 intake lobe, depending on the ICL. What mannerisms do you want? Personally, I would go 6-8* split. If you can locate one, the Crane 741 cam (236/244, .610/.632 112LSA) works well. A little more knarly- and a bunch less idle vacuum, VooDoo 60213 (241/249, .625/.625 110 LSA).

 

[wildman926]

personally, i would go 6-8* split. If you can locate one, the crane 741 cam (236/244, .610/.632 112lsa) works well. A little more knarly- and a bunch less idle vacuum, voodoo 60213 (241/249, .625/.625 110 lsa).

x2!!

 

[bigjoe1]

Do not loose too much sleep over it. Once you get it togeter , you wont be able to tell the differance anyway.The Exhaust side of a camshaft is not as important as the intake is, neither is the exhaust flow in the heads.


JOE SHERMAN RACING ENGINES

 

[69-CHVL]

Joe, what about a single pattern cams...they work?

 

[bigjoe1]

Single pattern cams work very well if you do not need an extended RPM range above the actual HP peak. In most street engines, a single pattern cam will run right with any dual pattern grind if the lobe design is a good one.The dual pattern will make a differance if the exhaust system is not as good as it could be( poor mufflers and or pipes )

JOE SHERMAN RACING ENGINES

 

[Splitter]

Hey Joe, if you could answer another question: How important is it to install a cam at split overlap? If a cam has 10 degrees more duration on the exhaust side, should it be installed 5 degrees advanced?

 

[69-CHVL]

You would think a dual pattern cam would be a disaster with stock-type heads, but Comp musta knew something when designing the Magnum line. Figure they never would of sold them if they didnt work good.

 

[Bob West]

Harold recommended a solid roller, .725/725 251/261 on a 110lsa for my sons street/strip 80 Malibu running a 150 shot of nitrous. Its a .030 over 454 with 781's w/air gap intake. If all goes well he'll be running it Saturday night. Its gone a best of 11.5x on motor, 10.6x on nitrous,3.90 gears and my old 10" ATI converter, Harold thinks high 10's on motor now.

 

[GRN69CHV]

That does put it in perspective. A 10* split for N2O use. FYI, I still have not duplicated the 117.43 MPH that I got in the fall of 2007 when running the ZZ502 heads (that supposedly need a 10* split) with a cam that only had a 3* split (233/236 on 112LSA).

 

[BillsCamino]

Ran a Jay Allen custom SR cam in my 540...over 16 degrees split duration...with AFR 335 heads.

 

[69-CHVL]

Ran a Jay Allen custom SR cam in my 540...over 16 degrees split duration...with AFR 335 heads.

Bill, 16*...what's up with that ???

I guess its not that important maybe as BigJoe says, but 16* does sound like alot. Does that cam run good?

 

[BillsCamino]

Does that cam run good?

Car/driver weigh 3750 lbs...n/a pump gas motor.

 

[wildman926]

You need the split if you have a poor intake/exhaust ratio head and/or crappy exhaust.

You need the split if you want to make power upstairs in the rpm range.

The exhaust side IS important, if you can not get out what you are putting in, that causes reversion and drop in power.

It is all about the combo and intentions of it.....

 

[3V Performance]

Bill, 16*...what's up with that ???

I guess its not that important maybe as BigJoe says, but 16* does sound like alot. Does that cam run good?

If it's not that important then it would have been ground a single pattern. BUT it wasn't. It is important!!

 

[bigjoe1]

Pro stock engines ( 500 cubic inch ) only have a 58 to 62 percent intake to exhaust ratio. It cant be too important

JOE SHERMAN RACING ENGINES

 

[CDN SS]

FWIW .......I run a Chris Straub solid roller with 16* split .......Brodix ovals approx 61 i-e ratio....big improvement over my old solid roller of similar duration with 8* split ..works for me :0

 

[BillsCamino]

You need the split if you have a poor intake/exhaust ratio head and/or crappy exhaust.

You need the split if you want to make power upstairs in the rpm range.

Old school theory :noway:

Full CNC ported 335cc AFR heads which have one of the best I/E ratios for a mass produced conventional head. Actually bounced this cam choice off Tony Mamo who had great interest in the results.
Intake is a R-M CNC Super Victor.
Exhaust system was 2 1/8" Hooker Super Comps. Over .800" gross lift...engine was shifted/trapped @6500. Gained over 27 mph on the back half of the track.

 

[JOHN WILSON]

The cam in my 440sbc has 22° split and it's an N/A motor. Of couse, so far this discussion has only referred to .050" durations and not looked at the entire lobe or what rockers are being used on which lobe.

 

[wildman926]

Old school theory :noway:

Full CNC ported 335cc AFR heads which have one of the best I/E ratios for a mass produced conventional head. Actually bounced this cam choice off Tony Mamo who had great interest in the results.
Intake is a R-M CNC Super Victor.
Exhaust system was 2 1/8" Hooker Super Comps. Over .800" gross lift...engine was shifted/trapped @6500. Gained over 27 mph on the back half of the track.

Tony may have had great interest, as it should NOT have worked for those heads.

Old School Theory? Tell that to Harold Brookshire -
This can be read HERE
"Of course single pattern cams make more torque. That's why Pro-Stocks use 20* bigger exhaust cams at .050, to kill off ALL the torque in the engine.........
There are all kind of reasons to run single-pattern cams.
There are just as many, or even more, reasons to run dual-pattern cams.
There are even reasons to run reverse-pattern cams.
It all boils down to two things, What the cylinder head flow needs, and what the customer wants the engine to do.
I have made lots of hydraulic cams that are single-pattern. I have made hydraulic cams that are smaller, and bigger, that are dual-pattern cams. Both types worked fine for what they were supposed to do. I even tried to talk Holley into 1 or 2 single-pattern VooDoo cams, but then, Comp didn't make any single-pattern Xtreme Energy cams.
At UltraDyne I had a single-pattern flat tappet finish 2nd in the Winston Amatuer Championship.
There are reasons for everything. The trick is knowing the right reason for any application.
I sold 2 reverse-pattern roller cams to a customer today. About 90% of what he buys, and he buys them 2 to 6 at a time, are reverse-pattern. He also helped me develop the 283/289F6 flat tappet, and he's bought a lot of those.
My most popular flat tappets are 6 to 8 degrees larger on the exhaust than on the intake.
The most popular rollers are mostly 8 degrees larger, some only 4, some 16 to 20.
A cam should always be made for what the customer wants the power band to be like.
All of the above are the correct answers."

You can read the below HERE
"All these facts, or theories, change with RPM. What is true at low RPM is not true at high RPM. All cams are a compromise, until we go to digitally-generated valve lift curves.
The longer you can keep an exhaust valve closed, the longer power stroke you have, and the more torque gets put into the crank. Single-pattern cams keep the exhaust valve shut longer, so more bottom-end torque.
At higher RPMs, past peak torque, the most important thing is getting the exhaust out of the cylnder so a fresh charge can get in. If you can't get the exhaust all out, you can't fill the cylinder as full, because old exhaust is still in it.
You notice this most often when you hit peak power. The Torque/Horsepower curve takes a bigger drop, caused by an inefficient exhaust system or cam.
Single-pattern cams make good bottom-end, but limit the top-end horsepower.
Dual-pattern cams make good top-end, but give up a little bottom-end torque.
Reverse-pattern unblown cams are a special case of type one and type two.
They aren't usable except in very limited carburetion applications, where the carburetor limits the maximum amount of horsepower."


Now, what say you?