Thread: Help Me Pick Some Heads For Christmas Present

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I've gotten through some of the reading regarding cam choices and their relation with regard to CR but I'm still getting hung up on the proverbial "did the chicken or egg come first?". In my case, do I install the heads or cam first?

What's the proper approach here if I want to target a SCR of 9.5:1 (assuming iron heads), do I

a) Choose a cam that best works for 9.5:1 then install heads/shim gaskets (and possibly pistons) to achieve the target SCR?
b) Choose a head to achieve my target SCR first, then install a cam that works best for the new SCR
c) Match, spec and install the cam and heads at the same time

Ideally I would think option 'c' would be the correct answer but because of budget constraints this option is out. If I go with option 'a' do I just use my target set up to make the choice? This puts me back to square one, choosing a set of heads to increase my SCR which after established would help me to choose the proper cam per everyone's advice. Thoughts?

Originally Posted by Nuckingfuts

I've gotten through some of the reading regarding cam choices and their relation with regard to CR but I'm still getting hung up on the proverbial "did the chicken or egg come first?". In my case, do I install the heads or cam first?

What's the proper approach here if I want to target a SCR of 9.5:1 (assuming iron heads), do I

a) Choose a cam that best works for 9.5:1 then install heads/shim gaskets (and possibly pistons) to achieve the target SCR?
b) Choose a head to achieve my target SCR first, then install a cam that works best for the new SCR
c) Match, spec and install the cam and heads at the same time

Ideally I would think option 'c' would be the correct answer but because of constraints, this option is out. If I go with option 'a' do I just use my target set up to make the choice? This puts me back to square one, choosing a set of heads to increase my SCR which after established would help me to choose the proper cam per everyone's advice. Thoughts?

Remember I said earlier that the last two things you buy for a project are the cam and the torque converter?

I was under the impression that you were not going to change pistons. Are you going to leave the stock pistons in the block or change them out? Because that could change the whole complexion of this project. You might begin thinking 383.

It's just a matter of alloting a certain amount of money per month to the project. Few of us have had a lump of cash to build what we wanted to right out of the box. I used to work on a $50/week budget in the early days. Sometimes a project would take 5 or 6 years to fruition, but it was something that I loved doing, so I kept at it. Mama was good with it because it kept me close to home. I remember waiting 10 weeks to buy a set of coilover shocks on a roadster project.

The closer I got to finished on a project, the more interest there was among my friends and their friends and sometimes, someone would offer me more money for the project than I thought it was worth at that point and it would go down the road and that would give me a jump-start on the next project. That's what happened to my 392 hemi in an MGA roadster on a chopped Galaxie chassis and my '27T roadster on a homebuilt 2" X 6" chassis with a 429/C6/9" projects, as well as several others. Some other projects, like the VW bug on a '62 Olds Starfire chassis with a 394 were stillborn and sold off for parts. Not everything turns out like you envision it. For me, it was always about the building it, rather than the driving of it.

I keep thinkin' that there is one more project in me and that's what keeps me going at my age. I would love to do a blown 302 in a Miata with a paddle-shifted 6-speed. That's one that I would want to drive.......
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Originally Posted by techinspector1

Remember I said earlier that the last two things you buy for a project are the cam and the torque converter?

I was under the impression that you were not going to change pistons. Are you going to leave the stock pistons in the block or change them out? Because that could change the whole complexion of this project.
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Ok I got it this time. The details are registering but I just hadn't prioritized them in my head yet. So prioritizing our list,

1. Change rearend gearing
2. Get the compression up by way of an iron head (I had no intentions of swapping pistons unless you suggested otherwise, glad I don't have to)
3. New hydraulic roller cam set with 204 intake duration (your article chart shows a 212 duration cam for a 9.5:1 SCR though??)
4. 10" torque converter

[QUOTE=Nuckingfuts;572955]Ok I got it this time. The details are registering but I just hadn't prioritized them in my head yet. So prioritizing our list,

Originally Posted by Nuckingfuts

1. Change rearend gearing

Unless someone has changed out the differential sometime during the truck's life, I'm pretty sure it came equipped with a 12-bolt GM. Count the bolts holding the rear cover on.....
https://www.ringpinion.com/b2c/DiffD...&DriveType=RWD
We touched briefly on the ratio that would work best. Having been part of many different discussions and witnessing many different builds concerning the proper ratio, I have concluded that a 3.73 ring & pinion will work best with an overdrive transmission. I say discussions and witnessing builds because I never have and never will use an overdrive transmission on a hot rod build and I'll never advise anyone else to do it either. I feel that the only reason to use an overdrive transmission is for fuel mileage and I am not interested in fuel mileage in my hot rod. Fuel mileage is for my daily driver that comes from the factory with an overdrive transmission that I will never touch.

I see fellows using an overdrive transmission with a hot rod cam. Makes no sense to me. Any hot rod cam that you might choose (like the 204 that I like for your truck, has a minimum cruise rpm of 2200-2600 rpm's. Now, I ask you, how are you going to make any fuel mileage if you have to run the motor at 2200-2600 minimum. If you gear the rig to run down the highway at 1600-1800 rpm's, you are out of the range of minimum cruise rpm's that the cam grinder specified for that cam and you are not generating any fuel mileage anyway. Can you see the lunacy in this? You either drive a hot rod or you drive a stock cam rig. You cannot have it both ways, not with a carbureted rig at least. (224 intake cam-3000 to 3400 cruise rpm), (236 intake cam-3800 to 4200 cruise rpm). I hope you can see this, that the wilder the cam, the stupider the idea of an overdrive transmission becomes. If you want to run an overdrive transmission, put a stock cam in the motor, enjoy the ride and leave that hot rod nonsense to someone else.

So, that leaves me (Henry Hotrod) with either a 2-speed Powerglide or a 3-speed TH350 or TH400, or a C4 or C6 if using Ford motivation. With any of these choices, I will still use a 3.73 gear on a street driver. It's good for cruising and it's good for acceleration. If I were to build for a street-strip vehicle, I would gear it up into the 4's. I guess my all time favorite sound would be the fellow from my neighborhood who drove a '57 Chevy with a Rock Crusher Muncie 4-speed running through 4.56 gears and the sound of a Quadrajet opening up. Sounded like 14,000 rpm's if you know what I mean.

I would begin by contacting the differential specialty companies, such as Currie Enterprises or Moser Engineering and talking with the tech guys about the ring and pinion, a limited slip pig of some kind and axles. Sometimes these guys will know of a complete unit that is for sale somewhere. (I like the Auburn Limited Slip units).
Tech Support | Moser Engineering
https://www.currieenterprises.com/contactus-2
https://www.richmondgear.com/contact...ts-components/

Originally Posted by Nuckingfuts

2. Get the compression up by way of an iron head (I had no intentions of swapping pistons unless you suggested otherwise, glad I don't have to)

Pull a valve cover and find the casting number of one of the heads (cast in between the springs or pushrod holes). That's the easiest way to look up your heads and find out the combustion chamber volume. Then I can teach you how to find the static compression ratio through common math. Production heads are generally 64 or 76 cc's, so there may not be a lot of room to arrive at the SCR that you want with a production head.

Originally Posted by Nuckingfuts

3. New hydraulic roller cam set with 204 intake duration (your article chart shows a 212 duration cam for a 9.5:1 SCR though??)

A 204 cam will work all the way through 9.5:1. If I were building your motor, I would not use any more cam than that.
The chart is showing "ideal" and there is a little wiggle room either way.

Originally Posted by Nuckingfuts

4. 10" torque converter

A 10", 2500 stall unit would be just right right in my opinion. Just like with gears, lean on the manufacturers. Call 'em up an yack with 'em. They won't bite.
Contact Us - Hughes Performance
https://www.coanracing.com/contact-us
ATI Tech Support
I've known Jim Hughes for nearly 30 years, so if you can, try to give him your business. He does a lot to support racing and is a good guy. When I teched at Firebird years ago, Jim would always have a hot meal ready at his pit for any of the race crew, not just once in a while, but at every event. I paid him back by teching his car(s) at his pit, saving him time and effort from loading up and going to tech up on the hill. And by the way, I never, ever found anything wrong with Jim's car(s). First class operation all the way.
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Richard I've gotta start by saying, you're good man! You've got 30+ years on me but I can remember even back as a young man gravitating toward the 'old guys' because they were chalked full of knowledge and willing to mentor to any young guys that showed a genuine interest to learn what they had in their noggins. You my friend are one of those inspiring mentors to us younger generations, I appreciate your time sir!

Yes this truck is equipped with a 12 bolt rear end. I've never attempted to change gearing but I'm not afraid to tackle the job if I can't find a 3.73 geared rear end for a reasonable price. The bay area here is a joke with regards to pricing on certain parts, rear ends being one of them. Tare down is straight forward, I just need to get up to speed with the install protocol, setting lash, etc. I'd actually prefer to do it myself as it's one of those things that's still a grey area and as an engineer, I must scratch any itch I don't understand. Either way I'll look into your suggested diff guys to see what the options are before making a decision.

I hear your logic on the OD transmission and will take that into consideration. Transmission change is way down the list so I'm too worried about that anyway. Most of my son's driving will be to/from school, sports and Friday night hops for the next 3 years so a 3.73 3-gear set up would be just fine. My older daughter's Jeep got 12.5 mpg during her high school years and because the drive mileage was so low it didn't hurt my wallet too bad.

I'm almost positive these stock heads are the 76cc's (but I had planned to pull the covers off at some point to confirm) so I'm not sure how much can be gained with these heads. I'm open to suggestions though and can pull a cover this weekend to confirm if it helps.

Ok so the 204 cam, I'm gathering that the 3.73 gearing, 3-speed, and a compression bump to 9.5:1 from heads is all meant to optimize low end, off the line performance and the 204 cam with 112 LSA to compliment and balance out the system for a wider power band and better drivability. Question, since higher valve lifts produce more hp, what's the highest lift I can get or want?

On the TC, I still have to get through your earlier links but I intend to this weekend then I'll follow up on your lead and contact Jim's group to get some input.

Thanks again Richard!

Originally Posted by Nuckingfuts

Richard I've gotta start by saying, you're good man! You've got 30+ years on me but I can remember even back as a young man gravitating toward the 'old guys' because they were chalked full of knowledge and willing to mentor to any young guys that showed a genuine interest to learn what they had in their noggins. You my friend are one of those inspiring mentors to us younger generations, I appreciate your time sir!

Thanks very much Nuck. I had quite a few fellows help me along the way and I see it as a responsibility to pass on what I have learned because I love it so and would like others to feel the same way about it.

Originally Posted by Nuckingfuts

Yes this truck is equipped with a 12 bolt rear end. I've never attempted to change gearing but I'm not afraid to tackle the job if I can't find a 3.73 geared rear end for a reasonable price. The bay area here is a joke with regards to pricing on certain parts, rear ends being one of them. Tare down is straight forward, I just need to get up to speed with the install protocol, setting lash, etc. I'd actually prefer to do it myself as it's one of those things that's still a grey area and as an engineer, I must scratch any itch I don't understand. Either way I'll look into your suggested diff guys to see what the options are before making a decision.

All these years, whenever I took on a new project, I would contact Faxon Auto Literature for a complete set of service manuals on the car or truck that I was intending to modify. Chilton and Motors manuals basically say "disassemble" and re-assemble in reverse. I have found them worthless, so was very happy to find Faxon years ago and be able to purchase the original manuals from the manufacturers.
Search

Looking at the offerings, first up is a 957 page Service Manual. Very good would be almost like new and good would be perfectly acceptable and serviceable. You'll want the 510 page Overhaul Manual, as overhauls are not included in the Service Manual. Or you can get both Service Manual and Overhaul Manual together on a CD if you have access to a printer and would rather not buy the books.

The wiring diagram is offered as a reprint or original.

If it were my truck, I would want an Owner's Manual to put in the glovebox. This is a nice addition when you go to sell the truck. Never say never.

Finishing off the original GM stuff is a CD-ROM parts illustration and a printed parts interchange manual 1973 to 1987. This is where you'll find the stouter sway bars. The remainder of literature shown is all aftermarket and is available from many different outlets.

Originally Posted by Nuckingfuts

I hear your logic on the OD transmission and will take that into consideration. Transmission change is way down the list so I'm too worried about that anyway. Most of my son's driving will be to/from school, sports and Friday night hops for the next 3 years so a 3.73 3-gear set up would be just fine. My older daughter's Jeep got 12.5 mpg during her high school years and because the drive mileage was so low it didn't hurt my wallet too bad.

Simpler is better.

Originally Posted by Nuckingfuts

I'm almost positive these stock heads are the 76cc's (but I had planned to pull the covers off at some point to confirm) so I'm not sure how much can be gained with these heads. I'm open to suggestions though and can pull a cover this weekend to confirm if it helps.

Yes, with an 8.5:1 SCR, I would bet they're 76 cc's. When we find out what they are for sure, we'll be able to look around for some replacements with smaller chambers.

Originally Posted by Nuckingfuts

Ok so the 204 cam, I'm gathering that the 3.73 gearing, 3-speed, and a compression bump to 9.5:1 from heads is all meant to optimize low end, off the line performance and the 204 cam with 112 LSA to compliment and balance out the system for a wider power band and better drivability. Question, since higher valve lifts produce more hp, what's the highest lift I can get or want?

Lift will be dictated by the duration of the lobe and whether or not the cam is ground on a full diameter blank or a reduced diameter blank. (Smaller base circle). Reduced diameter blanks are used to prevent interference with a few cam lobes and the big end of the connecting rod on a stroker motor such as the 383 Chevy. (4.030" X 3.750")

If this were a drag race vehicle and you were 2/10ths of a second off the National Record in your class, I would advise you to go to 1.6:1 ratio rocker arms. For any other situation, I would advise keeping the stock 1.5:1 ratio rockers. The valvetrain is probably the most highly stressed system in the motor and there is no use in asking more of it than it can produce, trouble-free, over a long period of time. I have seen an average of a 10-12 horsepower gain in a 500 hp motor by changing to 1.6 rockers.

Originally Posted by Nuckingfuts

On the TC, I still have to get through your earlier links but I intend to this weekend then I'll follow up on your lead and contact Jim's group to get some input. Thanks again Richard!

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