[pianoman383]

well first of all i need to get my backstory out of the way

i bought a half finished 69 camaro porject this last weekend... i need to get my bearing on where to go with it set up...

the car has gone on a rotiserre and had all the rusty parts cut out and redone. the front and rear suspensions are also all re-gone through. the guy that sold it to me changd over the front brakes to stock disk brake style. its set up with slapping bars on the back sprngs too. he had a 8.5 10 bolt built up with 456 posi gears. the paint on the car the last thing he did, its a yellow z28 clone with white stripes.

i need to put a motor in and want something that will run good and go with my z28 clone theme. im for sure going to use a 4 speed rock crsuher with this i love their sound.

my idea is to build a 4 bolt 350 as a stroker 383 with a eagle forged crank and forged flat top pstons. i want to run the 140 offroad cam in my z28 clone because i had a real 69 z28 in the 70s and ran this cam then. so i figure i will throw inches and head flow at the motor to improve its manners a tad. i will use good parts and am thinking about using these profiler heads in 210cc runners: http://www.speierracingheads.com/profiler.htm with the "ECONO" port. and a victor jr. and a 750 double pump carb.

will this work or am i on a bad track.

[69z28boy]

guys will chime in and tell you that there are better cams to use, which there probably are..

i however, am on the same page with you..

the 140 cam is great in a 302 (with 4.10s and wide ratio) as a street car...

add 80 cubes and its a whole different story.

but you'll need good heads and intake to make that cam work... which is sounds like you are on the right track..

i think you'll need at least 10 to 1 compression though.. that cam is too big to try on anything lower... i'd actually go for 11 to 1 but thats me

i run my 302 with 11 to 1 with that cam on 93 octane and have ZERO issues.. but the addition of 80 cubes is going to change the way the compression affects that big of a cam.

i think you'll be safe with 10 to 1.... anything less and the bottom will be really spongy.

[DjD]

The reason the 302 worked is matched parts that complement the build and work together. I'm not saying the 140 cam won't work in a stroked 350 but I would think the extra stroke might not get you the workable RPM needed to benefit from the 140. Same with head flow, if your heads can pass more through the large cubic inch air pump than a set of factory Z/28 heads opened up the 140 might become a roadblock. Same with compression, I've heard numbers like 12:1 when running a 140 cam and the stock 302 was 11:1 if I recall. Any less compression and I think you'll be let down with your build.

Why not put a 302 crank in your 4" bore block and build a 302 for your clone?

[69duskblueX33]

if you are going to run flat tops, and 64cc heads, i would run a 30-30 instead. with 5cc valve reliefs you'll have probably 10.9:1. running the dynamic compression using the cam card from a Melling 140 replacement grind cam (P/N 22400) your dynamic compression will come in at about 7.6:1 with the 140.

that'll all work, but with those aluminum heads, you can stand to raise dynamic compression a fair bit. i'd try to find pistons with a very small dome or mill your heads to around 58cc if you want to use the 140.

the other option is to build a flat top 406 with those heads and the 140 cam. That would bring compression up to what you want for the cam.

You'll want to run a forged crank, 6" rods and light pistons if you want this engine to RPM like a factory bottom end 302.

[qwiktripp]

Pianoman, what cam did you use? I am building a 383, ported 461 heads 65 corvette 461 intake 2.5 ramshorn manifolds and wanting to know how you made out with the 140 cam. I can move the head gaskets around to get from 10.8 to 11.35 static, to achieve the dynamic compression suggested.

Anyone with experience using the 140 cam in 383 help me out, and anyone good with computing dynamic compression here are my numbers

65cc heads, .008 in the hole, 4.030 bore 3.750 stroke, 4.200 head gasket bore .027 to .051 thickness 6" rods cam card shows SAE J604d intake closing @84degrees intake c/l 108 duration 257@.050 intake closing @.050 is 58 degrees. Thanks

[Davem]

Originally Posted by 69z28boy

the 140 cam is great in a 302 (with 4.10s and wide ratio) as a street car... add 80 cubes and its a whole different story.

i run my 302 with 11 to 1 with that cam on 93 octane and have ZERO issues.. but the addition of 80 cubes is going to change the way the compression affects that big of a cam. .

I know this is an old post but I thought since it is resurrected I would say X2 - X2 - X2 - X2...
Without BIG $$$$ the 383 is just wrong for a 140 off road cam. If I wanted to run the 140 cam in a bigger cubic motor, I think it would live a lot happier in a 377 rather than a 383.

[cstraub]

Piston speed is critical as it swallows up camshaft. A 3.48 stroke 4.155 bore engine compared to a 3.75 stroke 4.00" bore engine.

[DjD]

Don't expect a reply, Pianoman made one visit here in 2010, posted and has not been back since...

Originally Posted by qwiktripp

Pianoman, what cam did you use? I am building a 383, ported 461 heads 65 corvette 461 intake 2.5 ramshorn manifolds and wanting to know how you made out with the 140 cam. I can move the head gaskets around to get from 10.8 to 11.35 static, to achieve the dynamic compression suggested.

Anyone with experience using the 140 cam in 383 help me out, and anyone good with computing dynamic compression here are my numbers

65cc heads, .008 in the hole, 4.030 bore 3.750 stroke, 4.200 head gasket bore .027 to .051 thickness 6" rods cam card shows SAE J604d intake closing @84degrees intake c/l 108 duration 257@.050 intake closing @.050 is 58 degrees. Thanks

[69z28freak]

This is a good thread as I am planning to build a stroker for my 69 z 28 clone and I want the car to be as correct as possible, but have improved internals for better performance. Pretty well everything else on the car will be as factory correct as possible. I was planning on running a stock intake, carb and air cleaner as well.

Is this the best way to go or should I go with a more traditional motor combo, ie 302 or Old 350 LT1.

[DjD]

Mike a 383 or other large cubic inch SBC won't rev like the 302 or sound like one for that matter. You might be able to build a 350 that will sound like a 302. Other than that any SBC can be dressed to look correct... All depends on what you want!

[kettbo]

good food for thought
certainly NOT a 140 cam....

I see CSTRAUB is on this thread already and online. He would be a good go-to guy for cam design and grinding....this is what he does. I build inexpensive BBC really not applicable to what you are doing so no recommendation from this kid!

Plenty of good heads out there, some of the iron ones painted in 'Chevy Orange' would be ok to me cosmetically. I'd rather have the manners of a moderate 383 then the BANZAI-only 302

[69z28freak]

Originally Posted by DjD

Mike a 383 or other large cubic inch SBC won't rev like the 302 or sound like one for that matter. You might be able to build a 350 that will sound like a 302. Other than that any SBC can be dressed to look correct... All depends on what you want!

Thanks Dennis I guess I am looking for advise on what would be the best motor option for a 69 Z 28 clone. I am sure different people have different opinions, but I am fishing for ideas. I was originally going to build a 350, then thought a 302 would be the best option, and now I am thinking of the stroker. My engine builder is pushing for the stroker as he says it is the best value for the money in terms of performance. Perhaps I will have to take this back to my original thread and not hi-jack this one.

What I am looking for is a reliable engine that I wont have to work on that much and tune, that will perform with enough power that I wont regret the build thinking that I should have built something else. Obviously I want a motor that will work good with a stick. I am thinking of either a 342 or 373 rear gear so I an still drive short distances on the hi-way. I don't think build a motor with a 488 rear gear is an option to me, which I have been told is what you need to run a 302 to get maximum performance. Of course whicever option I go with, the enture drive train will need to be matched correctly for maximum performance.

[kettbo]

I'll see you on your thread Mike

[SY1]

Like Dennis said the original poster is long gone, so this is for the rest of the guys asking for opinions. A 377 vs 383 has been covered many times by the magazines. Everytime with similar internals they come out even performance wise. I don't think the 140 is a good match for a 3.75 stroke SBC. The cam makes power best 4200-7200 rpm and requires 11:1 or 12:1 to work best depending on who you want to believe. This is due to the late intake valve closing event at 56.5 @.050 ABDC. The dynamic comp calculators will ask you to add 15 degrees to the closing point, so when using the calc use the figure of 71.5.

I was building a 377 destroked 400 for the same reason many of you are, wanted to capture the feel I had in the 302 motors I'd run in the past. With the purchase of a Cola 4340 3.080" crank it's turned into a 334 cid now. It will have a 140 cam but using 1.7 rockers (.545/.571 lift) and carry an offy 2x4 crossram with Pontiac Motorsport heads milled to 55 cc chambers. This yeilds 11:1 compression using forged flat top pistons with -5cc valve reliefs. The deck is cut .025 so the 1.261 comp ht piston will be .001 out of the hole and a .039 gasket leaves the quench at .038. I think the larger bore will help the large valves breath a little better, my only concern is the valves are a bit large at 2.10 and 1.625, as well as the 196 cc intake ports. I expect it to be a little soft on the bottom but advancing the cam 4 degrees should help move the dynamic compression up close to 8.45:1, with 8.5 being the max you'd want to run on a street motor with premium pump gas will help minimize that. The only real challenge to this motor is finding suitable connecting rods at a decent price. A 6.200 rod is needed, like the 408 W Fords ran, same pin sizes as SBC (theres a rod/stroke ratio for you 6.200/3.080 = 2.01:1, Yunick used to say 2:1 was about the best practical ratio you could attempt). Scat has them as well as others, but would rather go with a Callies or Carillo as spinning the motor as high as a 3 inch stroke wants to go puts a lot of stress on the rod. I've damaged GM Bowtie profiled beam capscrew 7/16 rod big ends trying to spin them, but that's because they are way too heavy. So the rod needs to be light, but not so light it sacrifices it's integrity. This drives me back towards an i-beam capscrew rod since most H-beams are significantly heavier.

I'm still tempted to spring for the extra cubes of the 377, but I've damaged a few 3.48 stroke motors trying to spin them like 302s. Also the beehive springs Comp Cams offers are a great choice. With the right shims and valve length and higher ratio rocker you can get the seat and open spring pressures to fall right in where GM wants them. Plus you gain several hundred rpm before valve float over conventional springs and the steel retainers are so small they are lighter than a titanium retainer for a conventional spring.

You can make more power with more cubes and much more torque, but you won't want to do it trying to copy the sound of a 302 by running a 30/30 or the 140 cam, it's just not a good match, much better current grinds I'm sure to run with those motors. We'll see if this 334 runs like a hopped up 302. I'm prepared to change the heads to a small intake port and smaller valves since I'm not sure the motorsports heads are going to be a good match, but certainly wanted the smallest chamber 23 degree aluminum head I could get my hands on to try first.

[69z28freak]

Good information Dave, thanks.