Hi guys, and thanks in advance.
I have been having some trouble with low end on my motor. I have Comp Cam XE274H which is factory advanced 4 degrees. I spoke with the cam guy from Comp, and he said I could use one of the other keyways in my timing set to advance the cam another 4 degrees beyond factory setting. Is this OK? Seems like that would be alot of advance. Would the motor run ok, and how much would it affect the top end. Thanks again guys
rj

Advancing the cam increases torque at lower rpm, below 5200.

I personally wouldn't go more than the manf 4* of advance built in. Intake vacuum will drop off considerably.

It will be an interesting read from the engine builders here.

Yeah Im with Everett 2 to 4 degs yes anymore and one can have more issues than its worth, even possble valve pistion issues

If u have low end issues, that because the engine is built for high end and/or a missmatch of components

In my book its best to install the cam/carb/hearders/ etc that the car WILL be used for.
Sure guys like to have big cams and use street, fine, they accept the issues that come with doing so BEFORE the build.
Those who let the old "bigger better ego" thing dominate, end up with something on the street that cost a fortune to run and no down bottom go..

2 degs can make a lot of diff...I have basically a 4500/6800 hi lift blower cam advannced 2 degs this has dropped the rpm range to mid teens to mid 4000. I cdo not suggest using this particular cam...it is a 1 off custom billet and purpose built for car use and fuel.

XE274H lobe sep is 110°
ICL is 106°

diff between LSA and ICL is how much the cam is adv/retard.

if your icl was 110, it would be "straight up". Straight up is when icl=lsa, even though icl is crank degrees and lsa is cam degrees. It's just a term.

What they are saying when they say they grind in 4° advance is that when you line up zero marks, the icl will be 4° less than lsa because they put the lobes there(on the stick) in relationship to the bolt holes and dowel(mainly the dowel). Can't change lsa... it's ground in. Can change ICL. Lotsa ways.

If you went 4 more degrees your icl would be 102. Insert Lurch(Adam's Family) noise here. It's not unheard of but you should be able to get bottom end out of a 360 without that. I thought you were getting an Air-gap intake?

Have you degreed this cam RJ? If you haven't degreed it, that's the first thing you need to check. Might be the gear set is inaccurate. You can drill your dowel hole in your gear and use eccentric dowel adapters(can't think of what they're called) to get as little as 1 degree.

They are called degreeing bushings
http://store.summitracing.com/egnsearch.asp?N=700+4294925232+4294924497+42948129 68+115+400330



When you advance a cam, you open the intake sooner, and close it sooner. Opening sooner is not such a good thing, it allows reversion. Closing sooner is a good thing. That traps your compression sooner and raises your DCR. You still have the same amount of overlap unless you concurrently change rocker ratio, because overlap is built into the cam. You have changed when overlap occurs relative to piston position and this is hand in hand with opening the intake sooner.

ICL is crank degrees from TDC when the intake is max opened. Moveable.

LSA is cam degrees between the noses of the ex lobe and int lobe. Ground in.

You guys amaze me as to how much you know about engines and components. Thanks for the education.
As to your Air Gap question, Yes I am planning to go that route, just haven't had the extra cash. Everyone on the planet has advised getting rid of the Vic JR., even the Edelbrock guy. The Comp Cams guy told me my 197 heads were too big, but they are staying regardless.
I don't feel like I overbuilt the motor, though. It runs great on the street, my issue has just been getting it moving off the line when I run the 28" tall 10.5 wide slicks. That's where there seems to be a lot of differing opinions on the cause.
1. Too tall of tires.
2. Vic Jr.
3. possible 2.2 1st gear.
4. 750 mech secondary Holley dp.

Even with the low end issue, the car runs 12.64, which seems reasonably good for no more than I have in it.

1. RPM Air Gap is going on this week for sure.
2. Trans will stay regardless. (4-speed car)
3. Car runs good off the line with 26" Nitto Drag Radials on the street, no bog. Maybe should have gone with 26" slicks for strip?
4. Does anyone think that the 750 dp Mech secondary Holley will be OK with the change to the RPM Air Gap? or should I definitely go to Vac. secondaries?
This car is predominately a street car. Always will be. Too nice to cut up and tub, or cage. Just want the absolute best at the strip that it can be.
Thanks again guys, You guys rock
RJ

Hmmm....Vac sec I think, would be a better choice do to weight and gearing of car. If you had more gear or a little shorter tire it may be alright. 274 is a really good cam.

I like the cam alot. I think it will compliment the heads and the Air Gap, roller rockers, etc.
I do have 4.10 gear, but can't really go more and still live with it on the street.
Decided against advancing the can any more, and am going with the factory 4* built in advance.
Hope to have it back together and at the 1/8 mile this weekend. If I can get it to roar out of the hole, I think it will knock on the door of 11.99.
My hope anyway.
rj

pull out anything that doesnt need to be there for the strip to shave weight and hope for the best...Good luck.

12.64 is nothing to be ashamed of. Buncha big blocks out there not doing that well RJ.Making one change at a time is where it's at. You learn what helps/hurts thataway.When you have that intake off is a good opportunity to check your degreeing on your cam as it sits now. You can also check it later too.

Don't forget that if your piston-valve clearance is critical, advancing/retarding has a impact. I have gone to the exstreame of installing 8° bushing to the point the cam bolt threads were cutting into the gear but that was because of the stroker mcgurk syndrome as mentioned above. I got into too big of a cam. That was a total of 12°! , cam already had 4° , many years ago.

Drilling and bushing to advance a cam is a pain in the butt

I have a steel slotted gear...one slips the gear on keyways milled at 2 deg increments

Drilling and bushing to advance a cam is a pain in the butt

I have a steel slotted gear...one slips the gear on keyways milled at 2 deg increments

Not really, I usally drill from the back, leaving a safety lip so bushing wont fall out. Drill the depth according to the thickness of the bushing. Set it where you want it, and its done. But now days I use the Cloyes Hex adjust gear and cover.

Drilling and bushing to advance a cam is a pain in the butt

I have a steel slotted gear...one slips the gear on keyways milled at 2 deg increments


Haven't put a bushing in backwards have you Steps?:)

Ask me how I know:)

That's the fun of it, to me.... "Awright which way does it turn and what is it any how I am wanting, more that way or less?". hehe. Big side of the bushing facing down when the dowel is at 3 oclock advances. Unless I got it backerds. Hehe:)

I've never had one come out. I drill them through full. Put loctite blue, and then peen the outside.

You can get 1 degree with a bushing. And I have a 1° in service right now on my 283.(soon to be a 312 w/ vortec heads and a hyd roller)

Anyway, I think they are easy.

Don, 10-4 on the Hex adjust. I've got one on the way plus the Cloyes 2-piece cover. Never had one before.

Remember, CC does their's on 110/106, Crane on 110/105, ERSON, some on 111/111 and Isky some on 108/108.....

GENERALLY.......

I wouldn't go past 110/104 if it was mine..

pdq67

Haven't put a bushing in backwards have you Steps?:)

Ask me how I know:)

That's the fun of it, to me.... "Awright which way does it turn and what is it any how I am wanting, more that way or less?". hehe. Big side of the bushing facing down when the dowel is at 3 oclock advances. Unless I got it backerds. Hehe:)

I've never had one come out. I drill them through full. Put loctite blue, and then peen the outside.

You can get 1 degree with a bushing. And I have a 1° in service right now on my 283.(soon to be a 312 w/ vortec heads and a hyd roller)

Anyway, I think they are easy.

Don, 10-4 on the Hex adjust. I've got one on the way plus the Cloyes 2-piece cover. Never had one before.

Big side of bushing facing up, thin side down, Think of it as cam pin ahead of orginal 3 Oclock position, advances.

I usually have trouble splitting 1°

What do you mean by 'splitting' Don?

What do you mean by 'splitting' Don?

when you are 1° off, but i guess you hope for the slack in the new chain to take care of that. With the hex adjust , you can get between the dots and probably take care of that?.

Oh, I gotcha. I was remembering the set I just opened awhile back, of the degree bushings...it was an old package or had cosmoline on it Idunno, and I couldn't get the 1° to 'split' from whichever one it was stuck to!!!!:)

You're talking about Cloyes hex adjust tho. I almost bought the set above the hex adjust(Quick Adjust?) and a Comp 3 pc cover, but decided nahhh. If I get that desperate the engine's coming out again anyway. I won't try a cam in car any more, not with my back.

With the hex adjust and cloyes rigid two piece cover , its easy to dial in. Just remove the water pump. The timing gear set has a encapsulated bearing facing the block. The cover has a small cam thrust button.. finger tight against cam and lock it down. Calls for 0 clearance. I have used it twice, got one of UDharolds "billet" (calm down) rollers with the everwear gear. thats what I am working on now.

Zero clearance? Not even a couple thou? I think I was at 5 or 6 on my button. Wow

Any machining necessary for that bearing on the backside?

I am completely disassembled and just happen to be going to my buddies next week(the one that has 2 machine shops) I am hauling my freeby 305 along to rip the heads off it so he can get them ready for my 312. I could stick my 412 in the cab with me or clear out a toolbox for it(it ain't ridin in back:D) and get him to mill the face for the torrington bearing if I need to. ????????????????

Chain slack is not a problem because the chain itself will attempt to take on a circular shape as it spins.

There is spring tension all the time whether the cam follower is going up the ramp or going down the ramp on the other side of the lobe. Multiply this action 16 times and increase the rpm's, chain becomes a circle, all slack is gone.

Zero clearance? Not even a couple thou? I think I was at 5 or 6 on my button. Wow

Any machining necessary for that bearing on the backside?

I am completely disassembled and just happen to be going to my buddies next week(the one that has 2 machine shops) I am hauling my freeby 305 along to rip the heads off it so he can get them ready for my 312. I could stick my 412 in the cab with me or clear out a toolbox for it(it ain't ridin in back:D) and get him to mill the face for the torrington bearing if I need to. ????????????????

Instructions say 0 clearance, but I would bet that when the engine gets up to operating temp, they may be a little. No block machine work. Bearing is set in a slot in the timing tear (hexadjust) , bearing is like a torrington but encapsulated with oil holes. The center oil galley plug i have , has a .030 hole in it, this helps too although Cloyes did not mention adding it, I always do. Just follow instruction within.

http://www.cloyes.com/HighPerformance/Products/HexAJustTrueRollerSets/tabid/180/Default.aspx

[QUOTE=77wolf10.85;871759]Haven't put a bushing in backwards have you Steps?:)

Ask me how I know:)

That's the fun of it, to me.... QUOTE]

No m8 other than watching it been done, never drilled
simpler to get adjustable keyway gear in the 1st place

I might get slammed here, but I think even UDHarold has said that +/- 1 or EVEN 2 degree's isn't all that far off if the combination is CLOSE..

110/106, 108/108, 111/111 or whatever..

I personally like what the "Camfather" himself said years ago and that was that the RIGHT cam installed "straight-up" will make more power than a split cam!!

And UDHarold say's different, but his cams are designed w/ split LCA and asymetrically designed lobe's, intake AND exhaust, so are truely SOTA..

But old Ed wasn't all that far off even today, imho for what little I admit to knowing about this..

pdq67

http://speedtalk.com/forum/viewtopic.php?t=7626&postdays=0&postorder=asc&highlight=degreeing&start=15

Replaced cam at Comp factory settings. Installed Performer RPM intake. Didn't get the Air Gap. Wondered if I should reuse my 1" open spacer with the dual plane intake and 750 double pumper. Drove around the block, but started raining, couldn't really tell if any improvement in bottom end. Anyone think going from the Vic Jr to Performer RPM will now allow me to use my 750 dp with mechanical secondaries, or will that still be too much carb? Couldn't get to the track due to rain.
Also my Quick Fuel 750 has a port on the back for PVC or brake booster connection, and the intake has a port for the same, Which combo of connections would be best, and doesn't the loss of vacuum from the PVC affect performance? Thanks in advance.
rj

When I play around town I have PCV, but at the track I plug it. Just cuz.

Re the spacer and 750DP mec sec.... I just put wolf's ZZ4 350 back in while I play with the 412. Decided to leave the 675/775 Race Demon RS as a 775 and run it(had to plug an air bleed in the base) just as a speriment...and it did awesome. I've got all kind of other carbs I coulda put. Has a 3/4" spacer, hell maybe it's 1" I didn't measure:) and an RPM Air Gap, Etec 200 heads and the GM hot cam.

It just runs it's arse off:D. Cold out today and it wouldn't make any heat. Had to cycle my electric water pump. First couple times I hammered it, it bogged. Then after I remembered my ZZ likes heat, I got out of town and let it get up to 160 on the way....oh yeah it remembered how to run:D, spun my 18 1/2" slicks about a foot before enough weight transferred:)

Also my Quick Fuel 750 has a port on the back for PVC or brake booster connection, and the intake has a port for the same, Which combo of connections would be best, and doesn't the loss of vacuum from the PVC affect performance? Thanks in advance.
rjThe carb port would be for the PCV valve. The intake port would be for the brake booster.

Only at WOT, there is no vacuum, PCV will not be working. All other rpm's, there is some vacuum depending upon throttle position. You might get a PCV for an OE SHP engine as it would have a stronger spring to keep it closed during idle, then opens at cruise rpm due to higher vacuum.