318 xe268 cam 6in vacuum, Timing issue?

[jap901]

318 xe268 cam 6in vacuum, Timing issue?
Hello everyone! I'm new here and hope someone can help me with my issue and I will try my best to explain what's been done and what I think may be the problem.

I have A 87 Chrysler 318 from a 5th avenue. iv installed A eldelbrock street master 318 intake, 1406 600cfm eldelbrock carb, GM Hei style distributor and A compcam xe268 flat hyd cam with 302 heads and adjustable full roller rockers. the engine was originally equipped with a hyd roller cam but I had already bought the cam b4 knowing it was a roller cam engine and had to go with longer push rods to correct for this.... "Note the cam was A open new box from a parts store going out of business I got it for a good price but I'm not so sure if its the correct cam".

Now when installing the cam my friends Dad help me and I remember the DOT on the cam gear was at the top and so was the crank gear and I have notice in videos and manuals it shows the DOT on the cam gear to be line at the bottom with the crank gear DOT lined to the top. I brought this to his attention and he said he does this so after you install the cam chain you drop in the distributor and turns the engine over to where both dots line up as the manual shows and it will start right up and run. he said if you don't do it that way it would be out of time.... I think this is my problem because I cant see the manual telling everyone to do it wrong.

My problem is, I only get 6in of vacuum at idle and 18in vacuum when I rev it, from what I read is that this cam should be getting about 15in to 18in vacuum at idle.

Thanks for any help.

 

[RustyRatRod]

Pull the initial timing up.

 

[67Dart273]

The dots change top to bottom every turn of the crank, IE the crank turns 2x for every 1x the cam turns. Your buddy is absolutely correct IF IF IF he "sighted" the marks right, but putting the cam dot on top increases the possibility that you are "off" timing.

Also, when you install a cam, you should not just "toss" it in there, but check it for "degree" against the manufacturer's cam specs, and in some cases (some older Mopar purple shaft cams) CHANGE the timing for better street performance.

All you have to do when installing "dot to dot" is to rotate the crank 1 turn, or else install the distributor with rotor pointing to no6

AS RUSTY SAYS put more timing into it. What are you running?

Time it with a tach / vacuum gauge with vacuum advance unhooked, and idling as slow as it will go. Time for max RPM / max vacuum. You probably want about 15* initial (idle) timing.

You may have to have the distributor recurved if it's a stocker / smogger.

 

[AJ/FormS]

sounds like that cam might be a little larger than "bargained" for, but yes,more ig timing.

 

[Walker434]

I am with Rusty on more initial timing. When I had 18* of initial timing my cam was only pulling about 8-10 in vacum. Now thanks to the help of cracked back I have installed the 14* bushing and am running 22* of initial timing and my vacum went up to about 14 in.

PS also starts better, runs better and smells better.

 

[krazykuda]

You may want to look at this thread:

http://www.forabodiesonly.com/mopar/showthread.php?t=266863

 

[bad440]

Timing should be 20 -22 to run like it should.and i agree it should be degreed in to make sure its right.

 

[jap901]

Thanks everyone, I ordered a cam degree kit today so once it comes in I get back on the engine and give you all an update.

 

[crackedback]

Where do you have the timing set at idle? IF you set it to factory specs, that's your biggest error.

Cam could definitely be installed retarded. Why not try the initial timing to see what happens.

If you do bump the initial to some of the ranges suggested, Don't drive the car. Verify the total timing number as well and adjust the distributor mechanical advance as required.

 

[jap901]

I havent put A timing light on it but we have moved the distributor all over the place with no increase of vacuum... I get a timming light on it b4 I degree the cam and get back to you with the results. Thanks

 

[my5thmopar]

I havent put A timing light on it but we have moved the distributor all over the place with no increase of vacuum... I get a timming light on it b4 I degree the cam and get back to you with the results. Thanks

Maybe it isn't a timing issue even though it sounds retarded?

Is the plug missing from the back of your...1406 Edlebrock?
What is the idle speed and are you using the left or right vacuum port?
Carb adjustment or intake leak?
Valves too tight?..."adjustable full roller rockers"...seen usually at idle.

Just my 2 cents. Let us know the verdict.

 

[jap901]

I replaced the cam with a 275DEH-10 and the cam removed wasnt the xe268 I measured the cam with dial calipers and with 1.5 rocker arms it has a .510 lift on intake and exh. So lesson learned never buy a open new box cam.

 

[Two7T3Dart]

I replaced the cam with a 275DEH-10 and the cam removed wasnt the xe268 I measured the cam with dial calipers and with 1.5 rocker arms it has a .510 lift on intake and exh. So lesson learned never buy a open new box cam.

How's it running now, with the new cam?

 

[crackedback]

Cam should have numbers etched in the rear of cam.

 

[Rapid Robert]

What RRR said, bump the initial up to 20 (easy to do & will tell you if you are on the right track) & holler what happens. whats your initial now? 20 will likely force to to shorten the slots to get back to the tried and true SB number of 35 (initial+slots & can plugged) but you can take care of that later. Yes 12 o'clock and 12 o'clock is #1 compression which lets you set the dist in to #1 but it is very hard to visually get the dots vertically plumb cuz the crank snout is in the way. You may have retarded it a tooth (I'm thinking no but...) and or as said the tchain/gears may be mismarked (fairly common unfortunately). I'm assuming your lifter preload is in the ballpark (not sure if that would radically affect it but just wondering & it might). Rather than pull the dampener/tcover I would hand turn the crank (1&1/4' socket/breaker bar) till either the #1 or #6 rocker arms are (A) both moving and (B) are at the same level (open same amount) and at that point the crank timing marks should be within a degree or two for a symmetrical cam which I am assuming this cam is. Holler how things turn out.

 

[AJ/FormS]

Calling jap901, where are you?

 

[jap901]

Sorry everyone I work seasonally and dont have no time for nothing else in the work season. So here the up date. Im pulling about 15in vaccum with the 275deh-10 dont have not thumping lope it dont even sound choppy to me but it does make great bottom end torque compared to the other cam.

 

[AJ/FormS]

Well, glad to see it all worked out for you. Torque is awesome!

 

[Abodybomber]

Well, glad to see it all worked out for you. Torque is awesome!

Yes it is! Amazing ,when you tune a little bit: All of a sudden, that throbbing cackling beast,purrs like a kitten. It's a cool learning experience...

 

[AJ/FormS]

Yup. A good tune is killer.
It was an aweful lot of work, but the Mighty 292/508 can be tamed pretty good......mostly..........sorta.......some........a little.Well it idled so no one knew what it was, 'til I hit the loud-pedal. Great cam................. once it got going.

 

[Abodybomber]

Yup. A good tune is killer.
It was an aweful lot of work, but the Mighty 292/508 can be tamed pretty good......mostly..........sorta.......some........a little.Well it idled so no one knew what it was, 'til I hit the loud-pedal. Great cam................. once it got going.

Never messed with Purple Shafts,(I like them,on a budget..) My 408 got an old Comp "Stage 3" hydraulic flat tappet.. Specs were :312 advertised/260@ .050/.525" lift,on a 106 l/c installed at 104 Intake center line. That 4 inch arm, made it streetable..Same as yours,takes time.