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Cam Swap questions

20K views 195 replies 13 participants last post by  Dajerseyrat 
#1 ·
I plan on swapping out my current cam for something a bit less aggressive and was wondering what else i need to purchase besides the cam and assembly lube.

Currently I have a timing belt set up on my motor- so what seals or shims do you think I need to replace at the time?

The current cam is a solid roller cam and will be replaced with a solid roller cam, i have 1.50 ratio roller rockers, the push rods say .780 (if I recall correctly) and I have solid roller lifters.

What other engine parts do I need or would you suggest?



Thanks in advance for your help.
 
#3 ·
The same car from last time 67 Camaro that was a race car that i would like to drive on the street.

Small block Chevy 383 stroker, really pissed off motor. Runs like crap below 3500 rpms currently, way to aggresive cam.
293/297 advertised duration
260/264 actual
.627/.600 lift
107 Lobe seperation


Looking to calm her down to cruise with. But I dont want another thread with all sorts of advice on what to do with the motor, I just want a simple answer of what else I'm gonna need to change doing a cam swap.
 
#5 ·
Intake gaskets, water pump to block gaskets....valvecover gaskets if your not using re-usable's.

Belt drive seal at cam gear, depending on how old current seal is - more than a year old I'd replace it. Shims should stay the same as current set-up.

If the new cam has a different base circle it might mean a different length pushrod, depending on the amount of difference. You'll want to compare base circle diameter between the two cams to verify. More than .040" difference will mean new length pushrods necessary.

That should be the basics.
 
#6 ·
I like to use the bathtub like sealer,that sticky/thick black stuff that keeps the cover sealed forever.get a new timing belt. Inspect the rollers,probably time to replace them with the abuse they have had. Fresh set of springs. Full inspection of the rockers(and shafts). Check the ends of the valve stems. Do a screw driver inspection of the guides. OR,better yet remove a couple retainers and inspect split lock fit and valve guides with the valves at .500. Check rocker studs if you use rocker arms. If in the slightest doubt,replace all of the above.
Plus what Richard posted,,,,
 
#10 ·
Im swapping the cam and rather than pay the quoted $320 to completely rebuild the old Dillman carb I have on there that I know very little about, I decided to purchase this brand new Holly HP 750 in black for $670 brand new from Amazon.I have no clue what was done to that old carb and am not going to sink anymore money in it. I figure at least I got a nice new, unmolested base to start with for only $300 more. Plus i can sell the old carb for at least $300 on Ebay...




 
#14 ·
750 is way too small for that engine
In its current form, I agree..But like I said Im swapping the cam to something in the 2000-6800 rpm range and seeing how I spend more time from 2000-4000 and not much time up near the 6800-7000 rpm range the 750 would cut it. I asked Lunati as well as Holly technicians what they recommend for what i planned on using the motor for and bot recommended a 750 double pumper.

Like I said I would like to drive the car on weekends and cruise to shows and am tired of it in current form and want to tame it down a bit. It should still be fast just not as fast. and I will keel the current cam and carb so if I ever plan on racing it, its an afternoon of labor away..

On a side note, every person that has looked at my car including one of the East Coast sales reps for Manley performance who happens to live in my neighborhood, said that the carb on there was a 750cc main body.
 
#15 ·
I removed the old cam and lifters, just curious as to if this is normal wear patterns? The lifters look good and the bearings sound fine, but I noticed the wear pattern where they were a black color and now look worn on the sides so they look silver. didnt notice any abnormal wear on the cam lobes or roller themselves.
 

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#16 ·
Can you catch your fingernail in the scratches/scuffing on the side of the lifter?? if not it is ok, but if you can feel deep enough scratches to notice with a fingernail then it isn't good.

Second pic almost looks like little flecks of rubbed off steel embedded in the sides of the lifter body...or is it just a trick of light??

Roll the lifter wheel up the inside of your arm, between your wrist and your elbow, the skin there will pick up flaws in the bearings real sensitively. Stuff you won't feel rolling the wheel with your fingers.
 
#18 ·
Heads are Pontiac in name only, just to satisfy a Nascar requirement for when Nascar was using them in Pontiac bodied cars, you would need SBC lifters. Your heads are considered SBC.

If you order Pontiac lifters, they will be for a Pontiac block, and the link bar spacing won't be right.
 
#27 ·
New cam looks larger base circle in the pic (looks standard), you'll have to measure the two cams to know for sure. Measure acrossed the heel of the lobe.

No way to tell looking at the bottom end photos, it is the rod bolts threaded end/rod shoulder area that are toward the cam that is where the clearance issue is, where the rods swing up towards the cam.
 
#29 ·
The old cam's BC is .900 the new one is over 1 and will not work. Thank you Eric for pointing out this silly oversight on my part and saving me a major headache. The new can is being shipped back and I'm working with Lunati to see what will work for me with minimal wait time.
 
#30 · (Edited)
. Yes, base circle not a concern with 350" and smaller, and even with '377' type big bore/350 stroke combo, but becomes a concern with strokers and even stock 400's... and with other than stock rods... and the much fatter lobes of roller cams... and rods with nuts and bolts instead of just bolts... and fat aluminum rods...
 
#32 ·
So I just ordered the smaller base circle cam and went a little more aggressive I opted for the :40120733
Solid Roller Cam. Rough idle. Excellent cam for high performance street/strip applications. Excellent mid to upper RPM torque and horsepower in 355-383 cubic inch engines. Needs 3000-3500 RPM stall speed converter, 10:1 or better compression, aftermarket exhaust system and 3.90 rear gear ratio.
Advertised Duration (Int/Exh): 279/285
Duration @ .050 (Int/Exh): 249/255
Gross Valve Lift (Int/Exh): .585/.600
LSA/ICL: 110/106
Valve Lash (Int/Exh): 016/016
RPM Range: 2800-7200
Includes: Cam Only
Part Number: 40120733


Another thing I learned on this simple cam swap that I assumed would be easy as pie, is that I need to run a bronze gear on my distributer. So I learned 2 things in the past 2 days I never knew...
1) stroker motors usually require a smaller base circle cam
2) solid roller cams require a bronze distributor gear

Any more tricks I do not know..:thumbup: I guess this is exactly why I am doing all of this myself, is to learn as I go.
 
#33 ·
Wasn't there a solid roller compatable gear already on your distributor??...you had a solid roller cam in it.

Doesn't have to be bronze, there are melonized steel gears and composite gears available to run on steel roller cams...they last a lot longer than bronze...bronze need to be checked fairly often for wear, they are "sacrificial" material.
 
#38 ·
Gotta give you credit for sticking this out. Most guys would have just bought a 383 crate motor and been done. You're getting a helluva education and keeping a positive outlook over it....very cool indeed.
Use a sharp punch to drive the rollpin out. It should slide right out; I changed one a long time ago that the end of the pin had started to mushroom (previous owners are...awesome). If you drive the car a lot, pull the distributor at the end of the season, before you put it to bed for the winter, and inspect the gear. If you don't like the way it looks, your first order of business in the spring should be a "Melonized' steel drive gear. Don't sell the Dillman if you can help it. You may find a couple hundred bucks at tax time further down the road and decide to give it a shot; or maybe you get involved in a race car etc. It doesn't take much room on a shelf.
 
#41 ·
Im also going to have to change the pushrod length to achieve the proper geometry. My current ones are 7.800 however my new lunati roller lifter appear longer than the the ones I currently have. (brand unknown) I ordered a comp cams pushrod length checker took for $15.
 
#45 ·
hi over there,first a thank´s for much informations and explaining,. i´ve got this camshaft with camcard with all spec´s,the box it came in say´s only "power plus".been lokking at the net but only performer plus exist.can anybody inform who is the maker of that name?
 
#48 · (Edited)
hi over there (from Sweden),first a thank´s for much informations and explaining,. i´ve got this camshaft with camcard with all spec´s,the box it came in say´s only "power plus".been lokking at the net but only performer plus exist.can anybody inform who is the maker of that name?
. Sounds like it was made in China by Communists... what's the spec's? Might also be one of the 20 brand names Federal Mogul makes cams for...

. This is an automobile cam we're talking about? Right? I see Power Plus parts for Indian Motorcycles...
 
#49 ·
. As John Rockefeller used to say, if you have to ask, you can't afford it... LOL!

. It would depend on how much of a 'race car' it was... and what's your idea of a 'street car'... for 'cruisin'...

. I'm still wondering if he went small enough on a cam yet to like it...
 
#50 ·
When we're in our late teens and early 20s, most of us order cams by starting at the bottom of the page LOL
I think you'll be happy with this. It'll have its own growing pains; getting the carb dialed in, the right ignition curve, so on and so on. This is normal until you have experience, and even then, fine tuning can be equal parts art and science. Good job so far!
 
#52 ·
Thank you sir. I did opt for the MDS digital E curve distributor which is fuly digital and easier to adjust the timing curves and vacuum advance with just the turn of a dial. So that's one less time consuming headache. I'm still on the fence about using the carb I bought or just holding out for a nice fuel injection system, since I am more versed with tuning fuel injection systems. By the way the cam shipped and will be here Saturday!! So i can put her together then measure for the push rods and order them up.
 
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