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I saw a lot of info on the last cam question, I would like some info. I am 62 years old and this will be my first BB build. I have a standard bore 454 Gen IV. I will be using 366781 mildly ported heads with oversize valves. I also will be using a 69 corvette 427 Tri-Power setup. this will be going in my 68 Chevy pickup. The truck weighs 3600 lbs and has a turbo 400 have not selected a stall converter yet. The truck is just a Saturday night cruiser. Need Cam selection help
Thanks
Well, I'd write down all the information at hand on the engine, transmission, truck itself and give a call to the tech department of my favorite cam company and see what they suggest.... Just be sure to talk to a tech and not some phone bank clown at a mail order catalog!
Though I get ridiculed every time I suggest it, I use Comp Cams free download called Cam Quest. If you put in good, honest, and complete information you will get a a good suggestion. With this information I then follow it up with a call to Comp Cams Tech Department to verify the cam I select is going to do what I want!
Tom, you'll need to know the static compression ratio of the motor before you can intelligently choose a cam for it. Please read through this article I wrote for the Crankshaft Coalition wiki. It has been added to by some very sharp people since I wrote it.....Quote:
Originally Posted by tominiowa
http://www.crankshaftcoalition.com/w..._compatibility
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Thanks for the engine building lesson. Now I am thinking I need to buy a kit to check my CC in my 781 heads. because I have seen them listed as 113cc and 118 cc. Is that just over kill for a street engine or am I just too old school. Please advise
Not overkill, just doing the job like it should be done. Use Vaseline on the spark plug threads, under the valve faces and between the Lexan and the head.
I've always used a 100cc burette, but here's an inexpensive tool that should work fine.....
http://www.steigerperformance.com/products/sp90005.html
http://www.ebay.ca/sch/steiger_perfo...l?_sacat=34998
Once you've done your heads, you could offer to do heads for other fellows and recoup the cost of the tool.
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I'm with Richard, nothing old school about doing it right!!! Doing it right does not require spending a zillion dollars on special tools or trick machining necessarily, it just requires ensuring that the parts you select are compatible and will optimize the performance gained for the money you spend! As a 15 year old kid I remember being totally amazed when Lyle Nelson came over to our "race shop" (aka Dad's garage) and taught us how and why to degree a cam, check bearing clearances, thrust bearing clearance, and a bunch of other little details all of which would (again) maximum the performance and longevity of this engine we had all spent our hard earned money on!!!!
I remember when my youngest kid was in auto shop class at the local high school. I went up there one day and degreed a cam for them, to show them how it was done. They all stood around and looked at me like I had 2 heads.......another time I went up and explained camshaft theory on the blackboard. Same deal, 2 heads.....HAHAHAHAHAHAHA
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Ok I have my heads checked and pistons bought, 781 heads checked out at 115cc after the mill job, oversize valves and a little porting work. The pistons are KB .133 dome which will give me a compression of 9.3:1. I contacted Comp Cams and their tech suggested cam 11-242-3dur@.050 is intake224 and ex is230 lift is 0.515 and 0.520. and LSA at 110. What do you think are they in the ball park? Remember I will be running a 427 tri-power on my .060 over 454.. No racing no towing just a street cruiser 68 C10.
Pat McCarthy, Jerry Clayton and others know more about the BBC than I do, but maybe I can set a foundation to work from.....
A 4.310" bore, 4.000" stroke 454 with a zero deck, KB203-060 pistons having a 12cc dome, 4.380" x 0.041" head gasket and 115cc chambers will result in a 9.45:1 static compression ratio.
I would not use a flat tappet cam in anything these days, and especially not in a BBC. Howards has the best price on retro-fit hydraulic rollers for the street. I might use a Howards CL120245-10
278/284, 225/231
106 IC/114 EC/110 LSA
Operating range 1800-5400
Noticeable idle, street performance
Needs 2000+ stall converter
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OK why not use a flat tappet cam these days, what has changed? This is my first BB rebuild in over 30 years, What happened? I read some where that roller lifters can cause cam walk.
were to start so many things.. and some are only bbc problems. ok i will try to help . roller cam is the only way to go on the bbc chevy there about four things why i use solid or hyd roller cams #1 there not many oils the can hold up to the flat lifter cams. i will call them flat just for this post but there not really flat there ground on a 50inch raidus Crown as this keeps lifter truning in bores and cam lobe is ground with a 0007 to 002 taper to help the lifter to turn . if they stop the cam lobe will start a flat spot and fail . #2 added valve spring lbs can added to wiping of cam lobes lower speed low oil splash and poor oil with no zddp .#3 as bbc do not have all lifter bores on the same plane it s really hard to know were every lobe to lifter bore is were it should be ,so with added spring Lbs this can add to faster wear if something is off . they are more whys to it. i would be happy to go over all this on the phone as i not much for posting fingers hurt to much . as for the roller walking /moving .yes as there is some crown on some roller lifters rollers. lifter has no way of holding the cam on track so can will walk with no stop . so with a roller cam you need a stop ..this can be done two ways buy a mark VI cam and chain set your block should have two 1/4 20 thread holes in front of the cam boss this has allways been there on all older bbc. all 454 are drilled and taped for a cam plate to hold cam ..BUT.. never was used with IV stock cam from 1965to89 .only on rev rotation engines had gear to gear timming and with out plate the cam would walk out this cam plate will not fit or work only on a marine cam for rev rotation . so with the new bbc VI has a cam hold down plate for the oem roller engings . so i done many older 396 /496 old IV blocks if you go this way you need the hold down plate for this can be had at the Gm dealer it is the mark 6 454 part it so happens to work on the older gm blocks . but you need the timming set and step nose cam for VI 454 .the other way is buy a button that fits in front of cam to front timming cover as stock cover can flex .i make up a stop on the back side of water pump to hold it from moving if you go cast alum timming cover there will be no need for a stop but will still need to fit a front thrust button to the front of cam . as for roller cams ..if your thinking of going this way. i used many that were 500/500 lift and 220/"220 and 110 intake center line and round 114 Lsa .there many cams over the years around this size. i used for mild street stuff . othere things come in to play you can run and to No piston to valve room very comon on bbc. intakes if heads have been reworked and bigger valves .your valve seals may not clear new springs and get crushed as some Gm heads have long valve guides need to get cut down . so i use a viton rigid steel chimney valve seal
tominiowa,
OEM auto producers put pressure on oil companies to stop including extreme pressure lubricants in their motor oils because it was costing the OEM's for warranty claims against them as a result of extreme pressure lubes rendering catalytic converters ineffective. This was as the OEM's were moving into roller cams anyway, and extreme pressure lubricants are not needed with a roller cam. As you can imagine, there was an onslaught of cam/lifter failures in motors using the flat tappet technology. Here is a tutorial that will hit all the specifics of the problem.......
http://www.crankshaftcoalition.com/w...ips_and_tricks
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with the setup I have been asking about and with the Howard roller cam with advertised dur @278 and 284 with a lift of .574 and .585. will I need to check my valve clearances? I live in a small Iowa town and the local machine shop thinks I am spending too much time on the internet when I ask them to check valve clearances. They did an awesome job on the last Y-block engine I had rebuilt.
How do you know that? Compared to what? Checking piston to valve clearance is just one of the necessary operations you should perform to insure that you have a good foundation for the build.Quote:
Originally Posted by tominiowa
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