[BillyJack669]

I'm building a 383 chevy to drop into a 77 GMC 1/2 ton pickup.

The engine is built except for the heads, intake and cam.
I'm planning on using an RPM Air Gap intake, and have been modeling several different heads with CamQuest 6 and DD2003, using flow numbers found on several websites including Weingartner Racing's site (wengines.com) and several other sources (I've been excluding the manufacturers' sites as I figure their numbers are probably optimistic.)

Anyway, I'm in no hurry to finish building the engine, so I can save up for a while so I can afford better heads down the line. I modeled Brodix IK200s, Dart Iron Eagle Platinum 230s, Procomp 210s, RHS Pro Action 220s, and Summit 162111s in CamQuest, which came up with several cams that I then plugged into DD to get a more "realistic" simulation.

Since I'm talking street driving, I figured high torque would be more what I'm looking for than high peak Horsepower. My best torque curve looks like a combination of the Dart heads with a Comp XE268H cam. I'm totally open to suggestions!

Oh yeah, there will be power brakes, steering, and air conditioning in the truck.

Thanks!

BillyJack

[oldbogie]

Originally Posted by BillyJack669

I'm building a 383 chevy to drop into a 77 GMC 1/2 ton pickup.

The engine is built except for the heads, intake and cam.
I'm planning on using an RPM Air Gap intake, and have been modeling several different heads with CamQuest 6 and DD2003, using flow numbers found on several websites including Weingartner Racing's site (wengines.com) and several other sources (I've been excluding the manufacturers' sites as I figure their numbers are probably optimistic.)

Anyway, I'm in no hurry to finish building the engine, so I can save up for a while so I can afford better heads down the line. I modeled Brodix IK200s, Dart Iron Eagle Platinum 230s, Procomp 210s, RHS Pro Action 220s, and Summit 162111s in CamQuest, which came up with several cams that I then plugged into DD to get a more "realistic" simulation.

Since I'm talking street driving, I figured high torque would be more what I'm looking for than high peak Horsepower. My best torque curve looks like a combination of the Dart heads with a Comp XE268H cam. I'm totally open to suggestions!

Oh yeah, there will be power brakes, steering, and air conditioning in the truck.

Thanks!

BillyJack

It really starts with gearing (including tire size) you intend to use and whether or not you intend to drive the speed limit. This establishes the RPMs where the engine will spend most of it's time.

The biggest effect on engine power is the velocity of the mixture inside the ports. An engine that has insufficient port velocity from having large ports and a big cam combined with inadequate compression and tuning at low RPMs would be a real pain at freeway speeds. For highway cruising at or near the speed limit you want the engine to be starting into the upper part of it's torque curve. You can use the torque curve as an indicator of mixture velocity. The torque peak representing that place where mixture flow is as good as can be had. For a street engine that usually more RPMs than the average fellow want to listen to or feed, so designs usually back up to where it's getting into the steep part of the curve.

Pistons make 1/2 of the combustion chamber. They need to be selected to maximize the functionality of the combustion chamber while keeping the compression as high as the fuel octane will permit with reasonable spark advance. Too little compression wastes fuel and costs power, too much leads into detonation. A flat top piston works best for developing good squish and quench, but against a small chamber head may produce excessive compression. Small chamber heads on a normally aspirated engine without nitrous work best for mileage and power, but quickly drive compression to places that the fuel can't stand. The solution lies in D dish pistons where the crown of the piston puts a flat surface against the head's squish/quench deck and puts the dish or cup under the valve pocket. You want a Dynamic Compression Ratio (DCR) on the street of about 8 to 8.5 to 1. To do this the Static Compression Ratio (SCR) which is the measures of the spaces in the cylinder and the head adjusted for the effects the rod length and cam timing have on mixture velocity, a decent formula can be found at http://www.kb-silvolite.com/calc.php . Head gasket selection comes next, you want to keep the distance of the squish/quench area between the piston and head between .040 and .060 inch. Part of the distance will how far the piston is in the bore at TDC. One has to be careful as there are rebuilder pistons that assume the block will be zero decked and the builder will want to retain the original factory dimension usually around .02 inch for most anybody's engine, these type pistons are about .02 inch shorter than factory spec when measured from the edge of the crown to the center of the wrist pin. When used in an undecked block this places the crown .04 or more down the hole before you put a gasket between block and head. All sorts of pistons come this way from grocery getter replacements to full out racing, so you've got to pay careful attention to what you've got before you install them. Chevy stroker 383 builds carry and extra PIA in this area as the pistons move this distance around for different rod length choices.

[BillyJack669]

Ok,

Right now the rear end is geared 2.73 and the tires I'm planning on using on the rear will be 235/75r15 or 255/70r15. The engine is built except for heads, intake and cam. With 64cc heads my comp ratio will be 10:1 on this motor. Oh and I do plan on driving the speed limit (5 over max) under normal conditions.

[BillyJack669]

So, no suggestions yet? (bump)

[techinspector1]

Originally Posted by BillyJack669

The engine is built except for the heads, intake and cam.

Please describe the pistons in detail. Part number would be best. Also, what is the piston deck height?

[cobalt327]

For the parameters you have set for performance for your PU truck, along w/the gear ratio, tall tires, AC, etc. it would seem some of the heads that you've mentioned so far have too large port volume to maximise the power in the range you will find yourself in most often.

The PC 210's are said to run well on a 383 SBC- just be sure to buy them bare and assemble them w/your own components if you go this route. The one brand I notice missing is AFR.

I would think more along the lines of a 200cc head or thereabouts, rather than 230cc. An RPM intake and a 750 CFM carb and cam of your choice.

You need a zero deck, 64cc chambers, 0.041 gaskets, a 14cc dish volume and 0.030" overbore to have 10:1 CR. Is this about what you have, or what?

[BillyJack669]

Thanks so far for all the help!

My pistons are Arias flat tops with 2 valve reliefs.
I took the pan off tonight so I could find out the piston brand from looking at the bottom of them. The other marking on the pistons said 400 (i think). The guy who actually built the bottom end says he "figured" the compression ratio (with 64cc heads and a .039 gasket) at "around 10.6:1." He also planned on using ProComps on the engine when he built it originally; the 190cc runner version. It currently has a Comp Cams 305H in it. He said he built it originally for a friend to install it in a Monza drag car. His friend died, then he sold the engine to me.


BTW apologies for me stating on my first post that I'm "building" the 383. I'm more like "bolting on the heads, intake, accessories, etc", "replacing the 305H comp cam", and installing it in my truck.


I've got the .030 overbore, and the stroke is 3.75", 5.7" rods were used.

Any more questions? I'll figure it out as we go, but I may not post for a day or so between (engine isn't in my garage.)


THANKS SO MUCH GUYS!

[383NovaMan]

Originally Posted by BillyJack669

So, no suggestions yet? (bump)

Hey you are exactly at the point i am on my 383. I literally talked to the guy in this video (click the guy top right) Very cool guy

He knows his stuff! not just from the converter back, but he will suggest cam-intake-carb-tranny so theres no wasted power.

hope this helps

[my87Z]

since you are building a truck with a cam made for tq then you will want to use a smaller runner head, the 220-230cc is too large. you should be looking into a head with around 180-200cc. if you have the money then look in to AFR-195's, the Dart iron eagle platinum 200's are nice, the Brodix IK 180's or 200's are also good.

[my87Z]

Originally Posted by BillyJack669

Thanks so far for all the help!

My pistons are Arias flat tops with 2 valve reliefs.
I took the pan off tonight so I could find out the piston brand from looking at the bottom of them. The other marking on the pistons said 400 (i think). The guy who actually built the bottom end says he "figured" the compression ratio (with 64cc heads and a .039 gasket) at "around 10.6:1." He also planned on using ProComps on the engine when he built it originally; the 190cc runner version. It currently has a Comp Cams 305H in it. He said he built it originally for a friend to install it in a Monza drag car. His friend died, then he sold the engine to me.


BTW apologies for me stating on my first post that I'm "building" the 383. I'm more like "bolting on the heads, intake, accessories, etc", "replacing the 305H comp cam", and installing it in my truck.


I've got the .030 overbore, and the stroke is 3.75", 5.7" rods were used.

Any more questions? I'll figure it out as we go, but I may not post for a day or so between (engine isn't in my garage.)


THANKS SO MUCH GUYS!

deffinatly get that 305H out of there, i wouldn't use the ProComp 190's (i wouldn't use the 210's either) but i have heard of some using the 210's with sucess. with all i have read on this site it sounds like Cobalt was right in saying that you should by them bare, have them checked out by a machinest and then have them assembled with quality parts. the parts ProComp has put in there heads is where the main problem is.

[454C10]

I would use the 180cc afr head with 76cc chambers and a compcam 260H. this will make 9.5-9.9:1 cr depending on deck height.

I would use the regular rpm intake with a holley 750 3310.

avoid the air gap intake. you need exhaust crossovers when temperatures drop below 50 degrees. use restrictors but exhaust under the carb is a good thing for a daily driven truck. engine will stumble in cold weather for the first 30 minutes if you use the airgap intake.

also avoid the "extreme" cams, as they are extremely likely to go flat.

2.73 gear in a truck with tall tires needs a small cam with compression to match (low compression). With aluminum heads the cr cam be 0.5 to 1.0 higher than with iron heads.

[BillyJack669]

Thanks for the tips. The XE268h cam is just what I'm leaning toward. If you have a better suggestion, I'm all ears.
I am wanting to build it as a torque monster though. Is that the right cam for the job? Streetable, power brakes, torque.

I can change the rear gears; the tires are just what I like when I look at other trucks like mine. (Right now there's 205/75/15s or something on there.)
I am even ok with a higher stall converter. At this point in my build, everything's up in the air.

As far as the PC210s, does skip white assemble bare heads with good parts or is he selling the assembled from china version? That's where I'm leaning toward getting them from if I go w/assembled procomps. Otherwise I'll take your suggestions and run to the machine shop with them (if I go procomp).

[454C10]

compcam 260H (see above).

will make a little less power but more likely to live a long and quiet life.

[BillyJack669]

Hey sorry about that, posted before I saw your reply. Thanks bud!

[454C10]

here are the heads. 75cc chambers (not 76).

http://www.summitracing.com/parts/AFR-0911/

these heads don't require more exhaust duration than intake on the cam, due to very good intake/exhaust flow ratio. (another reason to use the 260H cam).

again, use the regular rpm intake. for much better street manors in the cooler months. Plus things don't fall under the carb with the regular rpm intake, a problem with the airgap.

if you plan to do lots of driving on the highway, then stay with the 2.73's and the smaller cam set up. But if you decide to change the gears and stall, then a bigger cam and smaller chambers (more compression) can be used.