New rv cam and timing chain - retard or advance

[mikeginn]

Installing a new rv cam and timing chain. I have read conflicting things about whether to retard or advance the timing chain.

So what do you say?

Thanks again

Mike

 

[beaux312]

retarding it will move the powerband up, advancing it will move the poerband down in the RPM

 

[DirtDonk]

And since trucks spend most of their time at, and need more torque at. the lower rpm range, you don't usually want to retard a cam for a truck. Maybe in a mud-bogging or dune hopping scenario, but even then, only if your engine is built and set up for higher rpm use.
Can you give us the exact specs on the cam? The term "RV" covers a pretty large possible group of cams. Some are just better left at zero, but pending further info on the cam, I'd say that advancing it would net you more benefit by lowering the rpm where the torque peak occurs.

Paul

 

[broncnaz]

install it straight up. most RV type cams are built for lowend- midrange power already advancing it will only lower the powerband and may hurt hiway speeds.
I'd say in most cases you wont see any big differances in lowend power anyhow there's a reason you have a transmission. So just install it straight up and dont worry about the confusion. Later on down the road if you decide that you need more top end or more bottom end then you could try playing with it as at leas tthen you would know if it actually made any real improvement.

 

[Quick & Dirty]

Most of the mild street/RV cams are ground so a straight up chain will be 4° advanced. Adding more advance probably won't be helpful.

Look at lobe separation and intake centerline on the spec card. That will tell you if it is already advanced.

 

[Boss351]

new cams are allready retarded degree cam first or just put it in straight up check cam card or call cam manufactor to varify proper installation. DON't forget the break in additive or YOU WILL be doing the job AGAIN !.

 

[surveyor5]

You paid for the engineering of this cam. Trust the manufacturer. Straight up!
Mike

 

[mikeginn]

it is a summit cam. here are the specs

Summit Racing Part Number SUM-3600

Cam Style Hydraulic flat tappet
Basic Operating RPM Range 1,200-4,800
Intake Duration at 050 inch Lift 204
Exhaust Duration at 050 inch Lift 214
Duration at 050 inch Lift 204 int./214 exh.
Advertised Intake Duration 262
Advertised Exhaust Duration 272
Advertised Duration 262 int./272 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.448 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.472 in.
Valve Lift with Factory Rocker Arm Ratio 0.448 int./0.472 exh.
Lobe Separation (degrees) 112
Computer-Controlled Compatible No
Valve Springs Required Yes
Camshaft Manufacturers Description Smooth idle, excellent low-end torque/horsepower, towing, good fuel economy in stock engines. Good camshaft for turbocharging

Unfortunately, it was installed 2 degrees retarded. only the timing cover and water pump were installed, so, redoing it would not be THAT much of a hassle.

Is it worth it to crack it open and reset it to straight up or advanced?

The gentleman who helped me builds old school hemi race engines. An old timer and wealth of knowledge when it comes to his specialty, so I went with his suggestion. But, it appears I should have consulted the bronco experts first.

So, rip it open or leave it for now?

He also suggested the valvoline 20 /50 racing oil with the zinc and phosphoruous additives. Has not been put in yet, waiting on the oil pan. Is there any other suggestions that may be better?

Thanks
Mike

 

[broncnaz]

Sometimes well meaning old timer race engine builders are not all that helpful as there used to race engines built to go fast. Not only that different brands of engines respond differently. there's a big differance in race and street not saying that the same basic principals dont apply but are usually unneeded.

even 2 degree retarded might not make much a differance the RV type cams are so small that you dont see the differances that race cams see. but I would probably put it back straight up. Thats a common cam that a lot of people run in there bronco and it has good power all around. As for the oil choice well I'd run it for the break in of the cam but 20/50 is a little heavy I'd prefer something a lot lighter for normal use. 10W-30 and just use some zinc additive.