Putting in a new Camshaft...any warnings, words of wisdom etc...

[sscam69]

Well if you guys have been keeping up with the performer vs weiand post you know that I am in the process of purchasing a camshaft. Well I am about to at least. My pops decided to donate a camshaft, instead of heads, to "My Project" fund:L.

This is going to be the first time I do something like this but I have a pretty good idea of what I need to do.

Do you guys with experience have any words of wisdom/warnings of pitfalls/suggestions in tackling something like this?

I am going with the XE268H from Comp Cams. What do you think? Know of a better cam, maybe from Lunati? Pending the size of the springs on the heads (going to check before I order).

I am going to remove the manifold and I think I am going to replace it with a dual plane for better low end especially with a cam like that.

I am going to tackle this job in 3 Phases. Why? because I don't have a garage to work in so I need to have good weather in order to do it. I don't want to leave the engine exposed more than necessary to swap the cam and lifters and throw on that manifold. So....

Phase 1 (Day 1)
Prop up the car on ramps disconnect Battery/ alternator/air compressor (air con.)/radiator/condensor etc. I want to remove everything that is necessary for the swap except the manifold and timing cover. This includes removing the balancer and loosening rockers.

Phase 2(Day 2)
At this point the only thing I have to do is unbolt the oil pan, timing cover and the manifold. Like stated I don't want to expose the engine to the atmo. more than necessary so I will

1. unbolt manifold
2. remove lifters and place manifold back on top (to protect).
3. swap cam, replace rods/lifters (new of course) & replace manifold.
4. put in rockers & set valve lash replace balancer and set distributor

Phase 3(Day 3)
On the final day it will be just a matter of bolting back up all the exterior stuff. Alternator/ Radiator etc etc..... Break in cam for 20 min @2K rpm

Phase 4(Day 3)

BURN RUBBER!!!:L

Questions

1. Kinda worried about that balancer. I had the crank exterior balanced when the rebuild was done. Now the timing mark is off so I am assuming that the balancer has spun. Lining up this balancer with the timing mark at TDC on compression should technically put the balancer back in its original position when it was balanced right? I am thinking that even though it has spun it will still be out of balance because of the two independent masses. Will this inbalance be negligable at 2.5K rpm?

2. What do I have to do for the fuel pump. How is the rod suppose to line up or in what position is it suppose to be in?

Thanks again for any help anybody can provide.

Frank

 

[Jack]

Frank:
If you think the balancer is junk then replace it ... for all intents & purposes a slipped inertia ring is not repairable/re-setable ... a bad balancer WILL cause havoc & $ damage. When #1 piston is at TDC then the timing mark on balancer should be at Zero on timing tab ... if it ain't then the balancer's junk or the tab's bolted on cover wrong. Don't pull the distributor until you're certain you're at true TDC on #1 ... life will be easier this way.

Fully-understand the cam & intake manufacturers' instructions before you begin ... and follow them. Adhere to cam break-in procedure without exception. Most gasket sets contain two rubber ones to place at front & rear of lifter valley rails where intake sets. Many folk, including myself, prefer to not use those and instead use a thick bead of RTV silicone.

The fuel pump rod will get in the way. Unbolt the pump and let rod fall away a bit.

Unless you've got one of those fancy cam-handle tools ... put the old cam timing gear on the cam with one bolt ... it'll help you maneuver the old cam out ... and new cam in. Use plenty of cam lube & take great care not to scar your cam bearings with the sharp edges of cam lobes. Careful not to drop a cam ... they'll snap like glass.
JACK:gap

 

[cruzer99]

Have you thought about replacing the cam bearings? With a new cam I always put in new cam bearings........

 

[sscam69]

Most gasket sets contain two rubber ones to place at front & rear of lifter valley rails where intake sets. Many folk, including myself, prefer to not use those and instead use a thick bead of RTV silicone.

Why not?

 

[JHL]

Have a look at Comp Cams Tech pages, there is a wealth of information that will help you understand all about cam selection and valve trains. It is geared around their product but even so the is some very good info. I would also suggest a quick call to your chosen supplier and run your ideas past their tech guys. I have in the past spoke to Comp and Edelbrock and got a bit of info straight from the horses mouth as it were.

J.

 

[cruzer99]

I agree with Jack....I got tired of checking, double checking, and checking again and still worry about that damn rear gasket popping out when you torque down the intake so I stopped using them years ago and found out that most race engine shops also use "THE RIGHT STUFF" by Permatex. It's not cheap but well worth the $'s.

 

[JHL]

One other consideration if you are running with a standard converter and 3.08 gears is not to be tempted by "TO MUCH CAM" your nice drivable Vette will intantly be turned into a dog over night and you will end up very dissappointed.

J.

 

[3TT3V]

Fuel pump rod: in the older engines there is a threaded plug or bolt in the front of the block which is aligned with the fuel pump rod.This plug or bolt can be removed and then a longer one inserted and barely snugged up against the fuel pump rod to hold it in position. Don't know about your engine tho. If that works for you; don't forget to use a sealing agent when you replace the original plug.
Be extremely careful when you take out the cam shaft and insert the new one as damage to the cam bearings can occur. Do not force it or bump it hard.

 

[fc3]

JHL, Can you explain why it will instantly be a dog? I don't understand. Would a higher RPM stall converter with 3.08 gears be better with agressive cam? Thanks, Fred.

 

[rpounds]

Frank,

In regards to the rubber gasket question, I always use silicone also and throw the rubber gaskets away. The problem is keeping the rubber aligned so as not to leak when you reinstall the intake manifold. Apply about a 1/4 to 5/16" bead of black silicone and you will be assured of a leak free installation . . . at least no leaks from the front and rear of the intake

In my humble opinion, the XE268H is too much cam for your combo. The low end will die completely and the top end will not be all that either. That cam, although touted by many, will not be happy without at least a 2500 RPM stall converter with 3:08 gearing. As I recall, you are running an auto, right? That cam should also be run with a higher static compression ratio than you are probably running. I would not run it with less than 9:1 compression, minimum.

With a fairly stock engine with an auto, stock stall converter in an auto and 3:08 gears, look for a cam that develops tons of torque. Run some of them through Desktop Dyno and see what they look like. If you want good off-idle performance, you'll be more happy with a cam that develops a lot of torque low down than you will be with a cam that develops HP at 5500 RPM.

Again, humble opinions from a guy that's BTDT more times than he cares to remember . . .

 

[fc3]

My 3.08 runs 2700 RPM at 70 mph... will that converter slip at 55mph? Fred.

 

[rpounds]

There are a couple of different torque converter configurations that I know of. I don't know enough about converters to explain all of the differences. I know that the turbine blades are shaped differently in some than in others. I also know that a well designed and built torque converter with a higher stall doesn't feel any different than driving a stock converter . . . until you stomp on the loud pedal. Cheap converters feel 'mushy' and make everyday driving a pain in the tukus. There are a number of articles on the 'net that go into the differences.

 

[rpounds]

By the way Frank, I hate to sound like a salesman from Summit, but check out their 1100 series cams. They are inexpensive (although made by a reputable manufacturer) and the lower numbers make GREAT torque in basically stock engines.

 

[JHL]

Fred,

If you put in to much cam with the standard drive train you will end up with a car that is unpleasant to drive maily due to big cams have poor low speed drivability. Most of the action is in the 3000rpm plus bracket and with the stock set up you cant take proper advantage of a bigger cam. Torque at lower revs is also sacrificed as is vacum for brakes and accesories. Now it is a matter of opinion what is to much but I have paid the price on two occasions for having to big a cam.

Even a high stall converter will not help if you keep the 3.08`s it might mask the problem but not solve it entirely.

J.

 

[sscam69]

I have a manual 4 speed

Thanks for the suggestion guys. The other cam I had in mind was the dual energy cam from Comp cams. I ran a sim on it and it has more low end torque available than the XE cam. I can use the same springs as well.

I am going to check out some grinds from Lunati. Any suggestions. I would like to order this stuff by tommorow so that I can have it by Thur. or Fri.

The weather outside is almost perfect for doing something like this outside. Little to no wind and temps are like at 85 or so.Nice.

Keep in mind that I do race this thing and the car is not a daily driver

 

[rpounds]

Well . . . here comes the guy that sounds like a Summit salesman again . . .

Run the numbers on a Summit 1101 or 1102 with your combo. I have the DD2000 files for them if you need them.

Ron

 

[sscam69]

I took some preliminary measurements of the springs late this afternoon. I got readings anywhere from 1.26X to 1.23X. It was getting late and the sun was setting already so tommorow me and my fiance are going to take a look at the springs and I am going to take better measurements.

If I cannot get consistant readings from the springs I am just going to replace them with the proper springs to avoid any complications. Its is definitely not something that I want to gamble with.

I am going to check out those cams that you suggested Ron.

Thanks everybody for the info/headsup.

Frank P.

 

[anips]

No matter what cam you use make sure to add a can of G.M.OIL SUPPLEMENT to your oil before start up!! It is a high pressure oil additive that helps make a good lobe to lifter base break-in for those first critical 20 to 30 mins.a 2k rpm. Many cam mfgs. recommend it in there inst. Good Luck Anips

 

[GerryLP]

Scam,

I spoke previously with mike (Stingray6974) about cams and he recommended the Crane 272. I had already ordered a Comp 268, so I retained it. Nevertheless, these two cams lift , lobe separation, and duration are similar; however, I must tell you that I am not familiar with the rest of your engine to give you my humble opinion.

Nontheless, keep an eye on your lift limitations for your cylinder heads, and don't forget that the rocker ratio multiplies your lobe lift. So if you choose a particular cam and later you desire a little more lift, then just change from 1.52 rockers to 1.6 rockers and you'll gain approximately 0.030" lift. Allow that possibility on your head's lift limitation.

 

[sscam69]

Thanks for the tips well noted.

To let you guys know my setup and future plans this is what I know about my engine.

-Stock heads -ported (and I think the milled a bit off of them, not sure)
-Stock crank (externally balanced)
-Cast pistons w/ valve reliefs (not sure on CC's)
-Rods-(dunno but would assume stock to)
-Single plane intake (old school Edelbrock)
-Holley 670 CFM carb
-355c.i. .03 over
-True dual exhaust w/ headers
-Manual 4spd
-3.08 in the rear

Ok I have been doing some thinking and I don't think that I will rest at night not knowing what kind of springs are in the heads so I am going to swap them out irregardless.

Another thing I have a 3.73 gear that I can swap back into the rear. I have talked to a person who will knows how to do differentials (backyard mechanic/drag racer, he is good trust me) all I have to do is drop the pumpkin and give it to him. Keep in mind that I do race this car and as soon as I can put all this together I will be taking it to the track to see what it can do.

That brought me to a second conslusion, why put a cam like that and not have good flowing heads to complement the setup? There really isn't a point because all I am doing is killing the flow with those heads. Not good IMO. But.........

So I have been doing some more thinking. I am going to replace the intake and put a new cam the only thing left are the heads so why not just buy some kind of package deal....hint hint. Going to discuss it with my pops and work some kind of deal with him and see if he'll go with it

IF NOT..... I am going to go with the original plan cam/intake &springs. I am going to have to remove the heads anyways so......thats where the "plan B" came from.

I'll let you guys know

I appreciate all the info, thanks again

Frank P.