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I have a 72 2wd blazer with a stock rebuilt 402 that I am wanting to get a little more powere out of. Here is what I am thinking. I bought a edelbrock pro flo, looking to buy a set of 98cc closed chamber heads, going to get a cam, bought a set of headders and 2.5' stainless dual exhaust. I going to get a 2500 stall and I bought a set of 3:73's and locker. How do you think this combo will perform? What kind of horsepower do you think I will achieve?
Thanks
it will work try a small hyd roller cam gm #12551622 thru www.competitionproducts.com this will work good hp 430? tq 500 with 9.6 cr
That should give you a boost for sure. Pat, do you think he will be at 9.6 c/r just because of the heads? Im thinking no...but the combo will still work pretty good for what it is. John
with the small cc and the 402 piston yes if has the 350hp pistons and o deck it will be that
Quote:
Originally Posted by pat mccarthy
Operating Range: 1600-5800 RPM
Duration Advertised: 270° Intake / 286° Exhaust
Duration @ .050'' Lift: 226° Intake / 236° Exhaust
Valve Lift w/1.7 Rockers: .544'' Intake / .547'' Exhaust
Lobe Separation Angle: 112°
That is what comp cams told me to run.
Operating Range 1500-6500 RPM
Duration Advertised 300° Intake/306° Exhaust
Duration @ .050'' 240° Intake/246° Exhaust
Lift @ Valve .560'' Intake/.573'' Exhaust
Lift @ Cam .330'' Intake/.337'' Exhaust
Lobe Separation Angle 112°
Intake Centerline 110°
Intake Timing @ .050" Open 10° BTDC
Close 50° ABDC
Exhaust Timing @ .050" Open 57° BBDC
Close 9° ATDC
That is what edelbrock told me. Which one will give me the roughest idel and performance? How does the gm cam compare with them? I appreciate the replys.
I probably shouldn't say this, but I'm going to anyway.....
Son, you may not hear from Pat again. Your question about roughest idle nails you as a poser because you're concerned with impressing the geeks at the drive-in with a ratty idle. Pat gave you his best shot, a cam with a very wide power band, reasonable duration for the static compression ratio so that the intake closing point matches up, long lobe separation angle for high manifold vacuum to operate accessories, excellent carb signal and reasonable valve lift for long spring life and easy operation on the rest of the valvetrain. He further estimated 500 ft./lbs. of torque from the motor. Horsepower will be unimportant in moving that big hulk of a Blazer. Pat knows what he's doing with big block Chevys, but I don't think he's too tolerant of youngsters yankin' his chain.
I love it!!;)Quote:
I probably shouldn't say this, but I'm going to anyway.....
Yes, the rough idle. You can have that too, but then your blazer will be a slug, and wont be able to get out of it's own way. What would you rather have? Everyone wants the best of both worlds...and you cant do it. Everything is a compromise.
thanks techinspector1 and 1johnnyO your are both right and did a better job then me telling him so i will not add to it .you both get a A+:3dSMILE: from me :)
I was just asking advice. If I knew all this I wouldn't ask. I thought that was the reason for the question? You guys might not like my ride anyways. the cams mentioned above will supply 10 to 13 lbs vaccum, is that not enough. Sorry to be so young and stupid.:rolleyes:Quote:
Originally Posted by pat mccarthy
Attachment 15784Attachment 15785
"I was just asking advice."
I know, and that's why I almost didn't post. I know you don't know what you're doing. All of us guys have lived through the nasty cam period of our lives. We've put up with the stalling in traffic and not enough vacuum to operate accessories and clunking going into gear and lack of low end torque and being just generally a pain in the ass to drive, just so we could amaze the geeks who don't know any better.
"You guys might not like my ride anyways."
Your ride is gorgeous.
"is that not enough."
No.
do not be to hard on yourself .when you get older there will be plenty of people that will do that for you
You know I am young 26 years old, but if I remember every big block my old man has ever built had a hell of a cam in it and would just about shake the fenders off. They would also run like a raped ape, the last big block he had in a 66 nova with the 871 blower and twin 850's had the ''rough idle'' and the largest mickey thompson tires on back of it that you could put. That cam in that car didn't seem to stop it from spinning both back tires running 55mph down the road when he got on it. Now I know that he had a blower and aluminum heads and didn't need alot of vaccum for this application. Next motor was a ls1 and my brother has a ls1 and both of them have a large cam that is very noticeable for a fuel injestion car and they run like a bat out of hell also. I am not doing this for drag racing but to just pep the motor up a little bit. I will for sure want to show off at the car shows with my rough sounding big block, I think it is cool and do a lot of other people. I guess it is just preference. Sorry for trying to learn a little something!! I guess you might also ask if your old man knows so much about big blocks why are you here asking questions, well I like do things on my own without the help of my old man ( don't like seeming like a youngster that doesn't know a lot about motors and cams). Thanks for the help.Quote:
Originally Posted by techinspector1
You seem to know you stuff and I appreciate the info and cam suggestion. I may go that route. Thanks for your time.Quote:
Originally Posted by pat mccarthy
Couldn't find that cam on there.Quote:
Originally Posted by pat mccarthy
Thanks, Kade
Kade, you seem like a nice young man and I'm sorry I gave you a bit of a hard time.
Just to further your education, a very narrow Lobe Separation Angle (LSA), also called Lobe Displacement Angle (LDA) will give you the rough idle you're looking for, although a cam ground in this manner will peak early and have a very short field of power. 104 degrees is absolutely nasty with very little vacuum (won't operate power brakes), 106 is fairly nasty with little vacuum, 108 and 110 are lopey with low vacuum, 112 is fairly smooth (with decent vacuum) and 114-116 would be a factory (grandma goes to the grocery) kind of a cam that would get you 22 inches of mercury easily.
The cam that Pat suggested is 224 degrees @0.050, 0.483" lift and ground on 115.5 degree lobe centers for a smooth idle and outstanding vacuum. I'm sure he has run this cam before and that's why he recommended it because he knew it would do the best job for you.
You say your father ran a blower, yeah, well, a blower will cover up a multitude of sins in the choice of parts. It's a little more difficult when you're running naturally aspirated.
You may have to call those guys to inquire about the cam.
Again young man, my apologies.
Kade, nice ride! Dont worry about asking questions...You're right, that's how you learn. We have all been there! I guess you have to have a bit of a thick skin sometimes in the forums. Please dont take it personally. Richard has done a big thing by apologizing too. See, we're not such bad guys!:D I was going to mention the LSA thing...you can have that idle that you talk about, but remember, you will give up a little in performance in some areas. Maybe you will notice the small losses, maybe you wont. Call Howard's Cams (owned by same guy as Competition Products) and speak with John or Scott 920-233-5228. Tell them exactly what you're after, and they'll advise you. They grind their own cams, so they have first hand info. Keep on learning, and hopefully you'll still visit us and ask questions from time to time. And keep the pictures coming! As long as they're not of an Eclipse or Honda!!!:p :p (Unless it has a BBC in it) John
No big deal, like I said i appreciate the help. You guys haven't scared me off yet.Quote:
Originally Posted by 1JohnnyO
Well I ended up with some 97cc closed chamber heads off ebay. I hope these will be good also.
That's cool...post the numbers so we can ALL see what you bought!! Small chambers will be good for your compression.
3856206....65-66...oval..CLOSED..396, 97cc chamber
That be them.
Basic Operating RPM Range: 1,500-6,500 RPM
Intake Duration at 050 inch Lift: 240
Exhaust Duration at 050 inch Lift: 246
Duration at 050 inch Lift: 240 int./246 exh.
Advertised Intake Duration: 300
Advertised Exhaust Duration: 306
Advertised Duration: 300 int./306 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.560 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.573 in.
Valve Lift with Factory Rocker Arm Ratio: 0.560 int./0.573 exh. lift
Lobe Separation (degrees): 112
That is the cam I bought.
Kade, those are good heads, a friend of mine is running in the 10's with them!! He had the bigger valves installed, and just mild porting and unshrouding, very minor. That cam should be OK I think. What brand did you end up getting? I dont know what you're going to do with the heads, but make sure your machinist knows what the lift of the cam is that you're going to use, and he can see that you wont have any interference with the top of the valve guide. Thats not a huge lift, but you have to check anyway. Also, dont forget to check your piston/valve clearance too. Keep us posted on your progress. John
The heads have been hot tanked and fluxed with new guides and seals and they checked the stock springs and they were supposed to be good. The cam is a edelbrock. I went with the edelbrock because I figured they had tested the cam with the pro flow system and knew if it would work or not. This is just a street motor and I will not be drag racing, just cruising and going to car shows. I hope this combo turns out good. Reckon the heads will perform ok with stock valves and springs?Quote:
Originally Posted by 1JohnnyO
no it will not . good springs are not that much .buy some springs that you know that can take the lift. if you use them and do not have them to check bad things will happen .coil bind . is one thing that will follow$$$. you will be running the spring at the max and if you shims the old springs then you are past the safety factor. less they are new and will set up for the lift. trash them they are junk . if you machine shop can not do this for you take you heads and run aLOT OF YOU VALVE TRAIN PARTS may not take the lift guilds may need to be cut down steel stock rocker may not work they can hit the stud and you may not have much piston to valve not one thing i posted can past up not to be check. or have some fool tell you it is fine with out checking it
Pat I appreciate that info I will get me a set of good springs and I was thinking of some roller tip rockers.Quote:
Originally Posted by pat mccarthy
not a big fan of roller tips .a full roller or stock type for $80 . more you can get some harland sharps or crane builders roller rockers . with the roller tip you still have the rocker balls and in time they groove the rockers bodys if they have grooved balls for more oil ??? grooved balls are junk .stock ones work better in the long run. if you buy the roller tip, you do not loose the friction of the fulcrum ball of the stock rocker with the roller tip or stock type rocker so the tip will not see much with a roller on the tip ? i think. where you need the roller is at the fulcrum and you do not get it with a roller tip so i think stock or full roller if you go to stock type rockers get a set of long slots
Sounds good, and once again thanks for the vitial info.
