75vetteman

here's my current setup
350- .30 over
standard pistons
headers, sidepipes
world products sportsman 2 heads
roller tip rockers standard 1.52 ratio
edelbrock performer intake that is going to be replaced with preferably a weiand dual plane high rise if i can find one
holley 650 or 750 carb, whichever i can get working right.
camshaft i'm looking at on craigslist is a crane cam #114201 hydraulic flat tappet.
car is a daily driver.
currently has a comp cam 12-206-2 (hydraulic flat tappet) but i want to go a little bigger

specs of cam are:
basic operating range: 2,200-5,200 rpm
222 duration at 050 inch lift
advertised duration of 284
.45 inch lift with factory rocker arm ratio
lobe separation of 114

specs on heads:
72 cc chambers for a compression ratio of 9:1 with the .30 over according to a computer model
200 cc intake runners (hand ported along with exhaust runners)
2.02 and 1.60 valves

maximum valve lift of .56 inches and the crane cam is well within this limit at .45 inches
does this sound like it would be a decent choice? i can't afford new parts so i end up piecing motors together and hope that it works good lol

75vetteman

starting to second guess my decision. found something that said 11.5:1 comp ratio or higher recommended and auto trans w/ 4000 stall converter etc. etc. is this too big a cam??? then i found something that said 9.5 to 10.75 recommended and cruise rpm of 3200 to 3600 which would suit me fine if i go with flat top pistons.

63mako

Jumping from a 260 duration cam to a 284 duration cam is a huge jump. If your looking for a little more go with a 268 with a 108 lsa. The 108 will increase cylinder pressure to compensate for your 9 to 1 compression running the higher duration, more lope. This one looks good depending on your rear gear and trans. http://www.summitracing.com/parts/CCA-12-319-4/

75vetteman

thanks for the input. found something else that said not legal for street or highway use. i have too much of a need for speed. rebuilding the motor and suffering from a case of while i'm at it, and go big or go home

68post

The cam you have will produce more tq below 4,000 than a larger cam. I'd port the heads with special attention paid to the exhaust porting ,mill them for more compression (complicated), and add 1.6 rockers too.

$0.02 for all it's worth..

oldschoolvette

The biggest issue with cams is that bigger is not better in most cases.

better to be a little on the small side in a street car

jb78L-82

Not a cam expert by any means but thought I comment since I had the Comp Cams 260H in a 350 bored .030 many years ago in a Nova with a turbo 350 auto. Pretty much a standard 350 with the edelbrock SP2P manifold (do they even make that intake anymore?). As others have stated, the engine made good bottom end torque and was well suited to the auto (i recall 3.08 gear).

The specs of the new cam:

specs of cam are:
basic operating range: 2,200-5,200 rpm
222 duration at 050 inch lift
advertised duration of 284
.45 inch lift with factory rocker arm ratio
lobe separation of 114

Looks very similar to the stock cam in my L-82 which I am getting ready to replace.

L-82 cam specs 222@.050, Lift .450/.460 LSA 114. With the World products heads and the 9:1 compression which should flow better, I would assume, than the stock 882 heads (same 2.02/1.60 valves), your setup seems very close to a mildly modified L-82 engine. That cam in my L-82 is very good from about 2,500-5,500 RPM in the L-82 but is not known for its low end torque and is better suited to a 4 speed than an auto for that reason. On the dyno, that cam in my L-82 produced highest torque between 3,500-4,000 (depending on the whether the cam was advanced 4 degrees or not) and highest HP at 5,200 RPM-which btw is dead on with GM specs for the L-82 engine published in 1978 for my car.

Hope that helps.

63mako

The L-82 cam was originally designed for the L-46. It came out in 1969 and was matched with an 11 to 1 compression ratio. It does not trap as much A/F mix due to the late intake closing point. Wide LSA increases intake closing point further, Lazy stock ramp on lobe increases intake closing point further. Result is an engine that does not have desirable cylinder pressure to have good torque at the bottom end. Increase in RPM everything happens faster, retains more A/F and cylinder pressure rises as RPM increase providing the torque characteristics you see. The key is having higher cylinder pressures in the RPM range you operate the engine in. Gearing is important because with a higher operating range cam you need lower gearing to get into the operating range quicker.
Questions to the OP-
1. What trans and rear gear do you have?
2. What characteristics of your present cam are pushing you toward a change?
3. What end result are you trying to accomplish?
4. Is there any way possible you can afford a retro roller conversion???

jb78L-82

63mako, Thanks for the feedback-it helps me learn all the intricacies of cam tech.

75vetteman

63MAKO
auto trans. don't know the rear ends gears
can't afford much
end results- give the camaro that did a burnout in front of my house a run for the money and shut up the little rice burners (hondas with tubas up their a$$es) and trucks that rev their motors going past. it's a small town and 2 vettes in a driveway on the main road just causes a stir.
the cam in it right now, on paper, seemed to be a mild cam and since i just yanked the motor today to rebuild it i wanted to go with something with a little more performance
68POST
i'd like 1.6 rockers, but the motor came with 1.52 roller tip and 1.6 roller tip is just too much money for me to spend right now. yes yes why not normal 1.6 rockers? answer: rollers are better

63mako

You need to know your rear gearing to make an educated decision. Why are you rebuilding the engine? The cam is a relatively mild cam but if you have 3.08 rear end you really don't want a lot bigger cam and definitely not a 284 duration cam. Over camming reduces DCR resulting in a sluggish motor that has no power at the bottom end and reduced cylinder pressure even @ high RPM. Result, poor efficiency, poor fuel mileage and less power everywhere compared to the properly matched smaller cam. You need to figure out your gear ratio before you do anything. If you don't have $ for a new cam you really can't afford a rebuild.

garygnu

comps ex268h would work if you have 3.08-3.55 .

75vetteman

i can afford to rebuild the motor,i just can't really afford to be throwing more aftermarket parts into the motor at the same time, but if i find a good deal on craigslist i'd go for it.

i'm rebuilding it because i got screwed over by a guy down in San Tan Valley. sold me this motor for $600 claiming it was rebuilt 50 miles ago. it was a stalled project car of his that he decided to part out. he'd already pulled the motor out. when i got it i found that the stock heads were garbage, so i replaced them. got it running but it's blowing smoke so i've yanked it to rebuild it. compression is anywhere from 115 in oily #8 up to 135 in others. and that's the story in a nutshell.

boat196

Why did GM changed the cam spec's between the too
motors.

L46 224 @ .050

L82 222 @ .050

Bob

63mako

If you want to do this...............You can't do this.............

You need to educate yourself and this forum is great for that. Sometimes the sum of the parts nets greater than expected results. There are L48 members here that have done vortec head upgrades, cam, intake, exhaust, convertor that are in the 12's. Many times the sum of the "go big or go home" parts nets disappointing results. The difference is educated choices. Need to determine the rear gear ratio, Trans (350 or 400 TH, stock? convertor?) then a budget, then put together a properly matched set of parts to compliment what you have and are keeping because of budget. Fast, cheap, durable.........Pick two.

75vetteman

thanks 63mako i pick fast and cheap if that's possible. trans is a 350 w/ stock converter. have a 400 i built for the car but never the time to put it in. not even now. also have a converter from a th350 that's somewhere between 1500 and 2k. it was bolted to the back of the motor when i bought it and the guy was clueless what it was exactly.
for now i'll leave the cam alone, but eventually i might try the ex268h mentioned.
also found me a weiand stealth to replace the edelbrock performer. happy happy happy

75vetteman

just an update for anyone who's interested. got the motor apart and looked at the numbers on the cam. i was lied to! it's not a 12-206-2 it's a 12-238-2. the guy that i bought the motor from had to go find his all his paperwork for the motor and told me 12-206-2. well anyways i'm much happier with this cam. and it explains why 2 of the rocker arm studs on the original heads were pushed out. i knew that had to have been done by a bigger cam than what i was told.
thanks for all the help everyone
also turns out that i have a double roller timing chain. $600 equals a motor that smokes but has a lot of aftermarket parts on it.

63mako

You have a cam with good specs for an auto with typical rear gear if the cam is still good. The pulled studs have me worried that either the rockers were cranked down to tight or motor was overreved. Did you do a leakdown test or a follow up compression test with a little oil in the cylinders to isolate the compression issue before teardown? Keep your lifters in order as they came out and check the cam lobes carefully especially on the lobes tied to the pulled studs. I had an engine that ran strong but smoked when I was young. I tore it out and bought a used, known good motor and dropped it in. It smoked. After much reflection and testing found my "cool" aftermarket valve covers had no baffles. I was sucking oil mist into the PVC. Moral of the story is I trashed a perfectly good engine and spent a bunch of money I didn't need to and didn't really have because I jumped the gun instead of careful diagnosis of the actual problem. Are you sure the heads you replaced were bad? If so how do you know? Do you know the heads you replaced them with were good? If so how do you know? Are you sure that motor was rebuilt 50 miles ago has a ring sealing issue causing it to smoke and lose compression? If so how do you know? Could be as simple as a ring installed upside down, Bad valve seals, A BAD INTAKE GASKET SEAL SUCKING OIL INTO THE INTAKE PORT FROM THE LIFTER VALLEY (very common)or a poor seal at the head gasket sucking oil into the cylinder from the oil jacket and allowing compression into the same (also a common problem). My point is know the exact cause and what is actually needed to repair the problem before you spend good money after bad rebuilding a shortblock that was rebuilt 50 miles ago that could be fine or replacing a perfectly good rebuilt set of heads with 50 miles on them because they need screw in studs and guideplates to accommodate your cam lift. The price of a rebuild will surpass the price of a new set of heads. You could quite possibly need neither if you did not properly isolate and diagnose the problem when the engine was in the car running.

StraubTech

scottyp99

There is an old rule of thumb that says "Figure out what cam you want, then buy the next one smaller."

Scott