In-car cam change questions

Discussion in 'Technical' started by im devestatingly handsom, Jul 1, 2008.

  1. So.. I have a mostly stock 1976 Camaro with the original 305 in it ( 150,000 miles ). It was rebuilt at 120,000 miles. I did a horrible job of taking apart the top end, porting the heads, and putting it all back together at around 135,000 miles. Now I have some problems and am hoping you guys could help me out.

    I have a new .48 lift hydraulic cam, springs, and roller rockers to go in. One mistake I made during my 135K idiot build was not putting the little valve seals in. Its burned a lot of oil when starting but now it has gotten a lot worse and will even burn oil during idle. I was fearing the rings were bad but I have a good problem. I got the heads off today and found that basically nothing was left of any of the seals. There is one big seal, one little seal, and an oil shield on each valve all of which are gone and or destroyed. Junks of them are everywhere in the springs. Anyways i was planning on buying a new set of each part, and was curious as to what order to put them back on... because there isn't much of anything to look at.

    Another problem is that when i put the rockers back on at 135K i just bolted them on with no care in the world about lash or how they might be way too tight. well...
  2. some of the valves stem tips are a little warped now and don't want to slide out. I was planning on taking a dremil ( however its spelled ) and very lightly nicking off the part that is inhibiting it. Im just not sure if this is a bad idea or a safe one. I really dont want to spend the money for all new valves.

    If anyone has advice on my problems or anything else it would be awesome. I will probable have more problems to come, since i have yet to even get the cam out. Ill have picture tomorrow as well.
  3. Autozone has a valve seal installation walk through if the kit doesn't include instructions. A .480 cam is pretty big for 1976 305 compression and Camaro weight. If you don't have a 3.23 or stiffer rear gear and/or loose stall converter you'd be better off with an RV style cam that will work with the stock valve springs. If you want those new roller rockers to live you better set the lifter preload right instead of just torquing it all down randomly.

    You don't need to remove the valves to change the seals, so them not coming out is a non-issue.
  4. Ill have to check out the installation kit. I was hoping to pull out the valves to clean them, the intake one have some gunk on the top of them.

    I have worried about the cam being too big but from what I've heard the engine tends to respond well. The rear end could be a different story... I already go 55 mph in first at 5500 rpm, but with the new cam it will be reaching up to 65 mph at 6500 rpm. I'm not building a drag car, I want it to be easy to drive on the street with smooth power when i need it. I'm sure on the stall converter either since for the cam it will be around 2500 rpm...
  5. I'm skeptical on your rpm figures, do you have a real tach or the factory liar?(My Camaro tach said 750rpm at idle and 7500+ rpm shifts when I was really lucky to hit 4500rpm) Your motor was rated at 3800rpm stock. Assuming your right about rpm/mph, a th350 and 26 inch tire means you have a 3.08 rear gear, which isn't really enough for your combo. A smaller cam would idle better, pull harder in daily driving, and get better mileage. I'd go with a 204-214 cam, it would not require new valve springs, ignition upgrades, and a looser stall converter, which the .480 probably would.
  6. I have a 4B carb on now, as well as ported (stock) heads. The pistons are after market but were placed in during the rebuild so I am not sure on the stats. I have a picture of them down below. I was told a new cam was put in as well, but if it was stock or now i couldnt be sure because no one from the shop has a clue. I did find out that it is a hydraulic cam, and I believe stock is solid. The car has peak power at around 4400 (44 mph ) using an actual tach, the car doesn't have one. but because the it's the auto 3 speed, the gears are ridiculously long. the power curve is very flat and keeps a strong amount of power that slowly drops off after the peak. Ive hit 65 mph in first but it's pretty weak at that engine speed. I rarely let it get above 5000 rpm.

    I took your advice on the valve seals and have everything taken car of. Everything went well and is now apart and the cam is out. I am cleaning everything from the block to the valves, and painting the manifolds and heads.

    I've done a decent amount of research and the 305 responds well to being "over-camed". My set-up is very similar to a couple build except one thing, I still have the manifolds because I have yet to find a way to get headers into my car. Im not sure how big of a factor that is.

    Right now I am trying to figure out the exact things your telling me. Im just curious if having the mods on I do now, if those problems will be as prominent? Iv'e taken some "rough" measurements and it appears that my new cam is only .02" higher lift ( that is no where near being a fact though ), but the duration is much more noticable. Thank you for the advice, and any more that you have would be awsome. I will probably have a week before i go puting things together so Im open for anything.
  7. You car came with a hydraulic cam stock. The cam you took out should have a part number on the end so you can at least know what your baseline was. Painting the manifolds won't last long, even if you sandblast them first. No motor wants to be over cammed on the street, part throttle response and mileage will suffer greatly. If your pistons are flattop you'll
    probably be ok, but if you have the dished replacements that cam will want some help moving the car at low speed.(gear/stall/headers)
  8. I painted the manifolds once before and it only lasted a couple of months but it looked a lot better for that time and it wasnt a lot of work.

    The pistons turned out to be 20cc dished pistons. I'm not at the garage but I'll check on the cam.

    I plan on getting headers in, but the space is very hard to find headers that can fit in there. I also hope to get a different rear end sometime, but that most likely won't be for awhile. The stall converter I am looking into.
  9. #9 sbctimh, Jul 3, 2008
    Last edited by a moderator: Apr 25, 2016
    Sounds like you don't have any extra compression to bleed off with that big cam. It isn't the Lunati .480 cam is it? That things 230 duration @.50 and 108 lobe separation would absolutely kill the motor. I doubt you'd be able to run power brakes or steering without turning the idle way up; which you may have to do anyway to keep your converter from stalling the motor altogether while stopped in gear.

    Summit shows lot of headers for you, starting at $90
    Your a lucky bastard, the only bolt in set of headers for me is $500+ and I'd have to run a very small front tire to clear them. I hate the idea of skinny fronts since my car has a fat poly bushed swaybar and super quick steer box on it and I'd like to autocross it eventually. <A BORDER="0" HREF=""><IMG BORDER="0" SRC="pitlane/emoticons/sad.gif"></A>
  10. #10 im devestatingly handsom, Jul 3, 2008
    Last edited by a moderator: Apr 25, 2016
    That's the cam I purchased. 230, 230 duration. Im not sure on the cam that was in it, all Ive gotten on numbers from it were EP1, C8, L7, CWC. I haven't been back to look at it, but that's what my friend was able to find on it.
    Here's someone using a 292H cam with 244 duration .5" lift. They did have headers and flat top pistons though.
    this is a more similar cam to mine, with very similar pistons... but they do have headers.

    Right now I just hope that the engine will run well with my pistons because that's the part that is not a bolt on.

    BTW what is your car?
  11. The cam in Popular Hotrodding has 6 degrees less intake duration and a wider lobe center. This puts you at ~25% more overlap then their cam, 46 degrees for them 60 for you.
    SummitRacings description of your cam: Magnum series cam and lifter kits require a higher compression ratio, rear-end gear ratio, and stall torque converter than stock.
    From Comp Cams site: Needs stall, headers & gears. Rough idle.

    I drive an 81 Cutlass with a 455 Olds big block.
  12. My compression was around 9.2 which isn't a lot, but could be worse.
    The rear end is one thing I won't be able to do for awhile.
    I plan on doing headers, but need to find the right ones. The website you showed me had one set for $90, i've found about 4 or 5 that could do the job, and I have a place does does exhaust very well and will do free labor.

    The stall converter I will have to wait and see how the car runs. That will take some more work to swap out. Even if the car is low on power from 0-25 mph I'm fine with that because the car is not meant to be a drag car but a easy driving camaro.... but if the idle is horrible and power steering don't work then im in trouble.
  13. That 20cc dish piston actually puts your compression just over 8 flat, even if the motor was decked, line honed, and equalized you'd end up with under 8.5
  14. i bought some shorty headers. 1.5 inch tubes, with 2.5 inch outlet. hopefully those will help my case out.

    i have everything cleaned and prepped... i took off probably 10 cc worth of soot on each piston and in each head, but the engine looks brand new. I did slide the cam in tonight. The valves seem to barely overlap at all, but that is with no instrumentation.

    I am stuck with the cam for the most part because it was part of a complete kit. I talked comp cams and they said the cam would be fine, but that was when i assumed the pistons were stock. Either way is there anything else I can do to have it run better besides stall and gears? I will do them but not for awhile.
  15. The headers will help a lot with scavenging during overlap. Find the thinnest head gasket you can get for your bore size. Install the cam 2 degrees advanced to make up for chain slop. Rhodes lifters reduce the lift/duration at idle, they could help you keep power brakes/steering. A spring/weight kit for the distributer is cheap and comes with several weight/spring setups to replace the worn stockers. If you have a th-350 you can adjust the shift point and firmness using the vaccume modulator on the trans. Just pull the vaccume line going to it(passenger side of trans) and there is a screw inside the tube the line went to. Turn it clockwise to shift higher/harder. Adjust a few turns at a time until your happy with it. If your vaccume advance is hooked up to timed/ported vaccume switch it to full vaccume, your idle will come up, but it will help keep the stall from killing you in traffic. You'll probably want an adjustable vaccume advance because with that low compression and overlap, timing will be everything.

    What carb/intake are you using?
  16. I am running a 600 cfm edlebrock 4B carb. I do have a distributer weight kit. I have very soft springs in the distributer, replacing the stock ones. The car had better response with these, but I have no clue on actual power. I am wondering what distributer springs you'd recommend with the new cam.

    I do have a th-350 trans, and the shift points are not where they should be ( shifts at 3800 ), but i often just use 1 2 and D to go through the gears. I will probably end up adjusting this now that I know it exists.

    Im curious about the vacuum port and where it would be? I have a feeling i don't have one because the vacuum comes straight out of the distributer ( at the cone silver thing ) to the carb.
  17. If you can get away with the light springs without spark knock your set. It only effects low rpms so response is all your looking for, it doesn't change max power at all.

    If your that far off on your shift point adjusting the modulator will give you a real firm shift. I'd start with 10 full 360 degree turns and go from there.

    The silver cone on the distributer is the vaccume advance. If the line off it goes to the passenger side front of your bcarb it is using timed vaccume and should switched to full vaccume from the port on the driver side. Make sure any unused port it capped well.

    To reset your idle with the new combo you'll need to first set desired rpm with the idle screw the throttle rests on. Then turn the left screw on the front of your carb to the right until the rpms rise. Repeat until you can't gain rpm with the left screw and repeat the whole process on the right one. This has no effect on power and only effects idle and response.

    You may want to move your accelerator pump arm to the top position if you experience a bog when you gun it. Don't do it unless you have to. As for jets/rods your already pretty close with that carb.
  18. It does go from the dist to the passenger side of the carb. The line on the driver side goes out to some sort of small round drum in front of the wheel well. Not sure what it is. Did you mean I should be able to adjust the vacuum from the driver side port or thing, or that i need to switch the vacuum hoses?

    also i have the heads all together and did testing with valve clearance. The is more than enough tolerance between the valves and the piston, but the head was barely torqued down.

    Another question, when i first start the engine, should i set the distributer ( either using the best guess i have or a timing light ) to firing cylinder 1 and cylinder 1 at exactly top dead center on the compression stroke? or else advanced, retarded, or something else i can't think of?
  19. You'll need to switch the vac advance line from the passenger side to the driver side and use a T so what was already there still gets vaccume. Then plug the port on the passenger side to avoid a leak.

    The adjustment for the transmission modulator is made on the transmission itself, on the passenger side, where the vaccume line goes to it. The screw is inside the vaccume port, just remove the line, turn the screw clockwise, and put the line back on.

    When you check valve clearance you need to torque the head all the way down. Use the old head gaskets and bolts when doing this. Never reuse head gaskets or head bolts for final assembly.

    You'll want to start with 10 degrees advance at the distributer with the vaccume advance unhooked and plugged. Hook the vac advance back up and put the engine under load going up a hill in high gear at speed. If it spark knocks set it back to 8, but I doubt it will.

    edit: if you haven't got the kickdown kit to go with that carb yet, do it. What intake are you using?
  20. the worst small block chevy ever made with the worst flowing heads ever made for it really isnt worth buildig at all. Id just go find a junkyard 350 and build that instead. a .480 cam is way to big for that engine. You'll be lucky if that long stroke engine makes it past 4000rpm
  21. #21 im devestatingly handsom, Jul 9, 2008
    Last edited by a moderator: Apr 25, 2016
    I have a basic 14 inch K&N air filter with a 1 inch spacer.

    I am not sure what a kick back for the carb is?

    Also I ran into a problem today. I was pumping up the lifters when I noticed that only one side was getting oil. The other side ( head ) showed no signs of oil coming up and the lifters are just as soft as ever. I am not sure what to do our what might be causing this...

    Yes the 305 is far from a powerful motor. That is the engine that came with the car that has been in my family since first taken off the lot in 1975 and was given to me by my grandfather for $600. I still feel as though it is his car more than mine. He loved the crappy 305 in it, and sadly so do I. The engine has come a long way and has been my "learning" engine. I also could say the same for the suspension, audio, and interior. The engine sounds amazing above 4000 rpm, the highest I've ever taken it was 6500 rpm, but the belt always broke because the alternator bearings were bad. That alone was enough reason for me to do this.

    Heres a video of it going to 6000 rpm from a couple years ago

    ***finally after trying for a week straight i can add pictures
  22. I meant what kind of intake manifold, not air cleaner.

    The kick down lets your transmission drop a gear when enough throttle is applied, this will be more important now that your cam is to big for your rear gear.

    What do you mean oil only comes out one end? Oil should enter the side of the lifter and come out the top into the pushrod. If you have antipump-up lifters(Rhodes or equivalent) they will soft until they see high oil pressure, this lets the lifter absorb lift/duration at idle to make the car more streetable.

    The 305 isn't the worst small block Chevy, they made a 4.3 version with the same stroke and an even smaller bore in the late 70s and early 80s. I'd never build either, but now that I have a 455 I doubt my 350 and 68 Vette heads will see action either.
  23. on the oil issue:

    the driver side lifters/rods, everythings gets plenty of oil, while the passenger side gets only a little to the first lifter. I took out the lifters and did as much testing as i could with the new as well as the old. The drivers side had tons of flow and the oil came out with much more pressure, while the passenger side was a lot weaker. I have a feeling that the distributor will fix this problem but im not sure. The passenger side hole is up higher and gets less oil because most of it just flows out the top where the drill is. I tried using some kind of washer to hold it in, but it made only a little difference. The holes are perfectly clear, im just hoping that the distributor is designed to get the oil flow up to the passenger side valve train....
    if you know anything about this that would be awesome, because I have been stuck on it since yesterday and can't get anything else done.

    the intake manifold is a performer intake from edelbrock, it has the dual plane which is supposed to help at lower rpms.

    my vacuum advance for the dist is already on the drivers side, and the vacuum going to the gas tank is on the passenger side.
  24. #24 im devestatingly handsom, Jul 10, 2008
    Last edited by a moderator: Apr 25, 2016

    i think i should be safe, from the sound of it i need a distributor to compete the oil circuit. just to be safe when i first start it, i will check the passenger side rockers and if they still don't show any signs of oil after a minute of run time, I'll cut the engine and prob take it to a shop.
  25. I finished building it today and after staring at it for half an hour decided to start it.
    It started perfectly as if i never took it apart. It is insane loud because it has no muffler attached, but the idle is very smooth surprisingly. I have yet to time it or tune the carb as well as do the final adjustments on the rockers. The power steering and brakes work great almost better than before. No leaks after being fun for half an hour except a little radiator fluid from the neck, but got that tightened down better. There was no smoke at all, even after letting it sit for an hour. I have a feeling new valve seals solved that problem.

    I will drive it later today and find out how it really runs, because the exhaust is on the ground. Now I'm heading out to time and tune it, also to check the rpms.

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