Advance/retard cam help
 

Hey guys,

I need some help with a cam install im doing, i was waiting to bolt everything up until i got some advice. So heres some background, ive swapped a 355 with maf tpi into my orginally v6 car, its a non-roller block, i have some brodix ik180 heads and a stock intake (plan to upgrade later). Also the car is a 700r4/ 3.73 posi rear if it helps any. The cam i chose is the lt4 hotcam with 1.6 rr

My questions start with this:
Should i advance my cam a couple degrees to help compliment the ltr intake i have? I want the low end torque, and the heavier cam sound, so would advancing it a couple degrees give it a more lopey sound? A couple horsepower isnt a problem for me losing because its my weekend street car. If anyone would recommend a certain advance or retard degree amount i would appreciate it.

I ordered a double roller timing chain with the adjustable gears and also with the thorington thrust bearing. So does the bearing replace the space of the thrust plate that i would put between the cam and timing chain?

One more question, i have the cloyes timing cover with adjustable cam button, from what ive contacted summit racing and they told me to leave .005-.010 space for the cam to move. But ive also read online that cloyes recommends no space whatsoever because of thermal expansion? So the question is, if i leave the recommended cam space with this cover will the expansion leave too much space and i end up chewing up the dizzy gear? Or should i go with the cloyes recommendation? Can something go wrong with leaving no space and no expansion occurs?

Sorry for the long post, im just looking for some advice from any people with more knowledge than me. Most of the threads ive read were pretty dated. Thanks for the advice in advance!

Re: Advance/retard cam help
 

Poor cam choice for a stock TPI; many cars have gone SLOWER THAN STOCK by putting that in there.

Advancing the cam doesn't affect the "sound". It tends to move the peak torque RPM downward, which is NOT the same thing as "more low end torque".

As far as the cam end play, consider that flat-tappet cams have NOTHING WHATSOEVER restricting cam end play, yet they work JUST FINE. You'll actually find that the force of the dist gear pulling the cam rearward as a result of the oil pump load, is FAR greater than the tiny contribution from the cam/lifter interface that you lose with a roller. Personally, IMO any setting that keeps the cam from hitting the timing cover at the one extreme, but doesn't bind the cam in the block at the other, is fine. Like everything else in a motor you can finesse it to death, but you end up in a situation of "measure with micrometer, mark with chalk, cut with axe"; doesn't matter how much effort you put into tweeeeking it and obsessing over it, the end result is not detectably different.

I'd STRONGLY suggest a different cam. Select it based on how closely it is designed to work with TPI, and above all, NOT for "sound". I'd suggest a Comp "502" grind, which is well and widely known to work well with a slightly modified TPI 350 engine much as you describe yours being, with a stock tune (since you don't even mention that). Then, whenever you get whatever intake you might or might not eventually get "later", pick some other cam appropriate to that, whatever it may happen to be whenever it happens if it happens at all.

Re: Advance/retard cam help
 

Advancing the cam moves the powerband slightly lower which is what a street car needs. Retarding the cam moves the powerband higher for high reving race cars.

Many performance cams already have 2-4* advance built into them so they only need to be installed straight up. Without dyno tuning or using a software dyno to see where the powerband is, install your camshaft straight up. Retarding or advancing a cam changes the timing of when the valves open and close.

Advancing a camshaft opens the intake valve sooner. It builds more low end torque. It decreases the piston to intake valve clearance and it increases the piston to exhaust valve clearance.

Retarding a cam opens the intake valve later. It builds more high end power. It increases piston to intake valve clearance and it decreases piston to exhaust valve clearance.

If piston design and valve lift/duration/timing have very little clearance, advancing or retarding a camshaft may cause interference problems. A proper mock up needs to be done to make sure advancing or retarding a camshaft has enough piston to valve clearance.

My race cam is designed to be installed 4* retarded but I get the powerband where I want it by installing it straight up so technically I advanced it from where the grind says it's supposed to be. The camshaft is designed to make power to 8000 rpm but I only spin my engine to 7400-7600 rpm.

Re: Advance/retard cam help
 

Thanks for the advice.

I know it isnt the best choice for a stock tpi, but im more of planning for the intake I will be getting, either it be the lt1 based mini-ram or the stealth ram. Over the last 8 months ive already spent over 6k in engine/tranny/rear rebuilds and upgrades, exhaust, cooling, wiring, so im short on cash to buy the intake i need. I just didnt feel like spending the $500 to get some slp runners when that wasnt the goal i was trying to achieve.

I dont really mind the lost power now, but i do like the sound everyone gets out of their cars with a stock intake even. Im waiting on Tuned Performance to do a custom tune, but he hasnt replied to me in over a week.

So back to the question, would advancing a couple degrees benefit the stock intake over installing it straight up?

Before spending much more money I would really prefer to drive the car instead of letting it sit while i find an intake. advance yes or no? 2-4 degrees??

Re: Advance/retard cam help
 

Thanks for that. so if i mock up the valve clearance and have enough space in there, would there be an issue with advancing it slightly? Or would even after the mock up would it be best to leave it straight up?

Re: Advance/retard cam help
 

Get the right cam. Install it straight up.

Advancing the cam does not "build more low end torque". Peak torque remains the same. It simply moves the RPM at which that occurs, a few RPM downwards.

P/V clearance won't be an issue in any real-world scenario with any cam anywhere close to anything that will work with TPI, including the HOT cam (or a better one for the application at hand such as the "502"). I wouldn't get too hung up on that.

Re: Advance/retard cam help
 

If you have the Hotcam and are set on using it, advance it about 3 degrees from the 109 ICL where they typically "drop in". That will help crutch the component mismatch.
Even with short runner intakes, the Hotcam makes better average power for a street car when installed at a 106 ICL rather than 109.

Re: Advance/retard cam help
 

I agree

Re: Advance/retard cam help
 

Thanks for the advice, so i dont think i can go 3 degrees advance, the timing kit i have goes in 2 degree increments, so should i run 2 or 4 degrees?

Also lets say i do run a short tube runner, one maybe like the FIRST large tube runners, or slp runners that can be ported/ and siamesed, or an lt1 style intake, what would you recommend as the cam advance then? I would assume 0 degrees for the lt1 style intake, but what would run best with large tube or slp? 2 degrees advanced? I am not sure if they flow as well as the much shorter lt style intake.

Once it comes to like the stealth ram or a mini ram, would i retard it a couple degrees?

Re: Advance/retard cam help
 

For street and strip use, the recommendation for advancing the Hotcam doesn't change, regardless of intake type. Only if you're trying to extract maximum peak hp with a short runner intake and truly making use of it with proper gearing on a roadcourse, would I recommend sticking with the 109 ICL.
Until you get the cam in there and degree it, no use fretting over whether you'll need 2 or 4 degrees advance. They don't drop in precisely enough to make that call right now. If you install it and it measures 109 ICL, I'd advance it 4 degrees. Remember, the timing set will wear in/stretch within the first 1000 or so miles, so you'll lose a slight bit from where you installed it.