oldchev

I'm generalizing my statement here on what's happening when the highway. If I'm just driving on the highway, if I pull out to pass it may or may not go into passing gear and I am almost never at WOT.

oldchev

Thanks anyway, I'm going to stay away from the EFI and Computer. I don't want to change the car that much.

Buy the way, i want to thank everyone for the help with this build. I really appreciate the input.

REELAV8R, so being a novice engine builder there are MANY things I don't understand. When you say a cam is alittle short, what do you mean? Are you referring to lift or duration?

My TH400 is going to be reworked by a trans shop that the owner races a camaro with a TH400 so I have some confidence in him. He has already told me that he wants to know what my rear gears are and what cam and heads I am going to use among other things. He told me he will pick the Converter.

63 Mako, you mentioned compression ratio, then you mentioned a DCR of 8.00 to 1. What is DCR?
you recommended AFR 195 heads with 75cc chambers, and .040 quench. I assume the 195 means the intake runner size? Correct me if I'm wrong, but then how do I know what the quench will be?

This juggling of parts is going to drive me nuts. I see the AFR heads your talking about, but I would have been scared off by the 75cc chambers. Wouldn't that kill the power?
Right now I'm going to do some research on the Edelbrock web site and look at different Heads. Thanks again for now. Dave.
I am figuring on all my power in at between 5500 - 6000 rpms.

63mako

Flat tops combined with 75CC is preferable to Dish with 65 CC to obtain same compression because the Quench is effective with a flat top, not so much with a dish. The absolute best combo is 64 cc heads and flat tops but that pushes your compression way to high. Quench is the distance from the piston @ TDC to the head surface. Quench is distance piston is "in the hole" or below the deck @ TDC + Head gasket thickness. .040 is ideal. Typical stock piston is .025 below deck. 1094 gasket is .015 thick. DCR is the compression ratio the engine actually sees when intake closing point is figured in. Intake closing point is not at BDC. These pressures need to be below 8 to 1 with iron heads and everything set up perfect or 8.5 to 1 with aluminum heads with everything set up perfect to run on 93 octane without issues. I like a safety margin on a street build, especially with a high gear differential and auto. Everything is not always set up perfect or stays set up perfect. Advantage to a little lower DCR is ability to run lower octane fuel. I have seen well designed builds with 8.2 to 1 DCR that run fine on regular and also seen not so well designed builds that ping at that DCR under certain conditions on premium. Building streetable power with 3.08 gears and auto is tricky. To much compression requires to big of cam. It will be doggy and sluggish bottom end and midrange. To little compression you need a cam that has a low rpm range and leave upper midrange pull and higher rpm power on the table. These are actually heavy cars. Overcamming is very common and generally leaves the owner disappointed saying they need a bigger stall or different rear gears. There are thousands of combinations of possible SBC builds. Don't go too big on your stall!! Racing and street use is way different. To big of stall will run hot. Many racers will go too big on the stall. You have to remember peak HP and absolute best 1/4 mile times do not = a good street car. There is no replacement for the best heads you can afford.

oldchev

[QUOTE=63mako;

I follow you on the points you have just made. But the combinations are endless. To someone who has built a few engines and has done some racing, it no doubt is easier to make choices. Also if I wanted to become a racer and play with some different combinations it would be easier to pick something and then go from there. But I want a fast street car that I don't intend to take apart again. Now my choices are critical. In retrospect, i have not found out just exactly what are the specs in my current original engine. It is a 350/350, hydralic cam, with double hump heads, cast iron intake and Q-Jet. I'd like to compare that to some of the cams I have been looking to buy. Dave.

REELAV8R

Dave, I can tell you that choosing a cam is not an easy task for guys like us. Many many things to learn about how a cam affects all the various aspects of the running of the engine not just peak power.
When I say the cam is a little short I am speaking of duration.
That being said duration is head and application specific. You can get buy with a shorter duration with a better head. The AFR's are excellent heads from all I've read. I don't own one, but it will be on my next engine. I can without doubt say that you probably don not want Dart SHP heads. The quality control is just not there out of the box assembled.
If you got some time yet before building this engine I recommend David Vizard's book.

Really a great book for explaining all the reasons behind making certain choices when building an engine.
It also will spec a cam for you that is 98% of the time correct for your application. Much better than calling cam companies

Also these guys are impressing me greatly with the recommends they make on cams. You can give them a call and take their recommend to the bank.
http://www.straubtechnologies.com/

I'm not an engine builder by profession. Just an average Joe who has built his own 350.
On pistons and head chamber volume (64cc vs 75cc) I prefer to have D-dish (reverse dome) pistons with a smaller chamber vs the larger chamber and flat top pistons. I'm of the spherical burn chamber school of thought.
You'll get many opinions on all aspects of your build. Your best bet is to try to understand why those recommends are being made and if and how that applies to your build.
For CR and DCR computations use this calculator, it inputs altitude as well as cam and engine specs for computations.

http://www.jeepstrokers.com/calculator/

oldchev

[QUOTE=REELAV8R;
If you got some time yet before building this engine I recommend David Vizard's book.
[url]http://www.amazon.com/David-Vizards-Performance-Blocks-Budget/

Yep, I've got some time yet. I read one of his books many years ago. I'll get this one too. thanks for the help. Dave.

oldchev

Well I have been studying this stuff. Reading alot here and other places on the Web. Got Dave Vizard's book. (thanks REELAV8R). I've put together a Spec Sheet. See what you think? My goal is about 400 hp, and near 400 lbs-ft torq. Want it streetable, but alittle lumpy to the idle. Have th400 w/3:08:1 rear. These spec are for a 350 or 355ci
My rpms at 65mph is about 2700. So you can imagine where my torq needs to be. And stall. My old 350/350 could get alittle rubber from standing start with no power braking back in its day. So I deffinately want it to better that. Here's my proposed specs:
- Howard's roller cam #180245-10, 225int/231exh@ .050, .500int/.510exh lift at the valve, w/ 1.5 rockers, LSA=110*.
- World Products 180 Heads, Cast Iron, 180cc int runners, 66cc chambers, 2.00int/1.6exh valves.
- Intake.....still looking
- Need Carb.
- Remanufactured, 1996 to 2002 Chevy block w/ mechanical fuel pump
- Scat, balanced rotating assembly, w/nuetral damper, balanced flexplate, forged I-beam rods, Hyperuetectic Flat Top pistons.
- TH-400 Trans, w/2000 stall.
- 3:08:1 rear gears.
Any opinions on how this combination would fit my needs or even work at all? Thanks, Dave.

63mako

Your TH 400 has a 2000 stall convertor stock. You would be dropping compression and increasing cam duration from what you have. Would be soggy on the bottom end with 350 CI and 3.08 auto. This is a lot better cam for you and works with a 2000 stall. http://www.summitracing.com/parts/hr...make/chevrolet
Or this one.
http://www.summitracing.com/parts/hr...make/chevrolet

REELAV8R

Mako63 do you think with iron heads he can get away with the DCR that high?
With .040 quench, 66cc heads and 7cc flat tops he will exceed 8.0 DCR on those cams.
I agree those cams would be better if you could get away with it.

Old chev, the cam you spec'd would be good in that it would keep the DCR down below 8.0 and would extend the top end a bit. However the overlap on that cam is 61*. Look at Vizards book and overlap suggestions to see if that is where you want to be.

What elevation are you at? And what is the weather like that you'll be driving in? Higher altitude and you could get away with higher DCR computed at sea level and allow a lower duration cam.
If it's 100*+ when driving then cooling the intake charge, and keeping intake manifold cool is going to be very important to avoiding detonation. As well as the engine as a whole running cool.
In order to run a duration such as you are contemplating with that 3.08 out back, I believe that a higher stall such as 2600 or so is going to be necessary to get you in the meat of the power for starting out.
I'm running a 270/270 219@.050 on a 108 LSA with a 2400 advertised stall that brake stalls at 2600 rpm, with a TH-350 and a 3.08 and it still is not amazing at launch. It is much better than stock and can get out of it's own way. Getting about 377 peak hp.
Peak HP and drivability are at odds with each other with less than great heads on the car.
Check out this site and see how your world heads stack up to others such as AFR heads.

http://users.erols.com/srweiss/tablehdc.htm#Chevy

That magic 400 HP with good streetability is going to be in the higher flowing heads.
Poor flowing exhaust ports force a split duration and increase the overlap period.
If you can get 80% or better with a good 2 1/2 exhaust low restriction mufflers or side pipe exhaust you could probably do away with the split duration and not loose much or any performance.

63mako

If he goes with the second cam and you plug in bore, stroke, 66 CC head, 0 deck, .040 x 1.25 gasket, .250 ring to piston, .003 clearance. he is @ 8.07 DCR @ sea level and below 8 to 1 @ 400 ft. With his quench he will be fine. I would go with better flowing Aluminum heads and the first cam but I am betting he got the World heads already on the cheap.
If he goes with this gasket he is under 8 to 1 at sea level.
http://www.summitracing.com/parts/fe...make/chevrolet

REELAV8R

As for the intake, unfortunately it boils down to what fits under the hood. In your case if you are staying below 5500 RPM you're in luck as the Edelbrock Performer would fit that bill just fine or the Air gap Performer has also been known to fit for many people. Kind of depends on what air filter set up you have or are going to have.
If you go with the regular performer and run that 8.0 DCR then I would recommend putting an oil splash shied or similar on the bottom of the intake in addition to blocking off the crossover heat passage. Lot's of heat added to the intake by that exhaust crossover and the oil mist in the lifter valley. Best way to avoid that is with the air gap, if it will fit.

For a carb, if you are willing to rebuild it for your application and tune it once the engine is together, the stock Q-jet is a great carb for that application. Good gas mileage and flows up to 750 CFM.
Cliff Ruggles wrote a book on how to rebuild and tune it.


I knew squat about the Q-jet before I bought his book and followed it. Now I can tune it any way I want and feel comfortable tweeking all the circuits to my liking.
Or you can send it to Lars Griswald and have it rebuilt. At the very least get his papers on tuning the carb to get it done right.
Do a search for for his name here and you'll find the e-mail address for him.

oldchev

Between your post i had typed out a lengthy answer then got called away from the computer, the computer went off line and I lost everything. So here goes again. It is hard for me to relate to what is a big cam or what is a small cam, or high lift, etc. But I am learning. So one of the things I looked at was the specs of my original 350/350hp cam to the best that I could find them. i have the original Service, Shop & Overhaul manuals for this car. or I should say they are for 1969 with supplements for 1970. In the engine spec for the cam it does not list the durations, surprisingly. But it does list lifts. It shows .260 int./ .273" exh. at the lobe. With 1.5 rocker ratio I would see .390" int / .409" exh at the valve. Zip Corvette Products list a cam for a '65 to '69, 350hp, hydralic with 230int/230exh duration and .460/.480 lift. So I stuck with the duration that I was seeing here, but added lift. Now David Vizard in his book, says that if you keep the duration small that a Chevy small block can take all the lift it can get. Now I have a hard time relating to what is a short duration. But then Vizard said at two different points in the Cam chapter, at one time he said "a short duration cam (less than 270 degress)'' now I believe he was talking about 270 advertised degrees, I take that to mean about 220*. Then he also says "we are talking about cam durations less than about 274* seat to seat, I take that to mean around, 224 @ .050. So yes, my choice of cam is pushing it alittle. From Mako's two suggestions I like the 1st one, ( but what do I know), but yes the duration would be more in line with Vizard. But I was afraid of the 108 LSA because of possible loss of vacuum to run the accesories. But another of Vizard's tenets is that long durations don't destroy vacuum and drivability but the OVERLAP does. And with shorter durations, you can have tighter LSAs. See part of my problem so far is that I don't know what, "SHORTER", or LONGER, or TIGHTER means. But I am learning. So yes, maybe with the shorter durations of your 1st suggestion I do not have to be afraid of the 108 LSA. On the second cam you suggested, I am afraid of the Lifts. I have been trying to keep the lift around .500". This is because I believe that is a safe area for long life of the valve train. And this is much higher than the original specification of my original cam.
REELAV8R, I am in the hills of central PA. elevation around 1100'. Yes, the duration I suggested is longer than what I think Vizard would say. I am still guessing at this. The durations from Mako look good but see my other concerns above. I chose the heads because I want Cast Iron. And I believed big valves (2.0/1.6) with smallish 180 runners would help velocity. With a lift of this .500 range I believed all that would be good. and I believed the 66cc chambers instead of the 64 or smaller would ease the CR. I don't mind 91 octane gas. That's what I have to use now. I see you both have posted again since I started this. I haven't digested that yet. I hope this uploads i'm starting to swim. Also I retyped this really fast, I hope it make sense. Having said all this what is your take on my reasoning.

TedH

Are you going with stock stall torque converter? If so, and if you are keeping the 3.07 gearing, I would limit the heads to 180cc intake runner to maintain intake velocity. AFR makes a great 180cc intake runner head with the 2.02/1.60 valves. If you are truly serious about 400hp/400tq, you will need more cam (or cubes) than I am running now (see sig). My combo is probably a conservative 350hp/400tq pkg. I run a near stock Bow-Tie Overdrives converter in range of 1800-2000rpm.

This is a driver that runs like a scalded dog off the line and smokes the tires through 1st into 2nd gear.

Blueprint motors sells a roller cam 355ci engine that is rated right around 390hp/410tq. Take a look at its specs to consider what it may take to reach your power goals short of going stroker:

http://blueprintengines.com/index.ph...ase-bp35513ct1

oldchev

About the stall converter. I don't have a problem changing the converter. As a matter of fact, my TH400 is being rebuilt by a pro shop whose owner races with a TH400. He told me he will pick the converter after I tell him what cam, heads and rear gear ratio I will be using. Some of my concerns are that I don't want to have to rev the engine high everytime I pull away from the stop sign. Also, I am concerned with lock-up while driving. My car is doing about 2700 rpms at 65 mph. On slower roads, I believe I should be running near lock-up or beyond. I have been told that if I never get to lock-up that I will be severly overheating the trans.

oldchev

I'm alittle behind on coordination of my responses since I dropped off line awhile ago. But thanks Ted. But I didn't get the specs on your cam. Where should I find them?
I've had the same Q-Jet for about 20 years. I had it apart a few times. It's got pieces in it from everywhere. Haven't touched it in about 6 or 7 years, but I got to tell you I am tired of the hassle of taking the top off it if you do have to do something. I read Ruggles book about 20 years ago. If i did decide to reuse it, it will definately need retuned. Over the years as my engine kept getting worse and compression kept dropping, I kept leaning out the carb to keep things going. Right now I have the fattest needles in it that GM made. and the power piston springs have been changed a number of times. I'm thinking I need a change. Any suggestions.

oldchev

Ted's comments must have hit a nerve when he talked about power, whether it be hp or torq. I hope I'm not headed down a road where I choose to compromise on the power and the FUN for the sake of easy driving. I've had easy driving, and when my engine was healthier it was more fun than it is now. But I want MORE. Not just more than it is now, but more than it ever had. Just for the record, I have been running headers with 2 1/2" pipes for as long as I have owned the car. For the last 10 years I have been running straight pipes mounted under the car in original locations with NO MUFFLERS. I have inserted about 18" of chambered section in the middle just behind the crossmember. It helps with the fun, it sounds great. Oh, I haven't bought any parts for this combo yet.

63mako

Lift above .500 is fine with a hydraulic roller cam. Not so with flat tappet hydraulic. Aluminum heads allow more compression or a smaller cam than Iron heads, lighter weight, no negatives to running aluminum. This is almost an exact copy of your stock cam.
http://www.summitracing.com/parts/HRS-117091-14/
This is really designed for the L46, iron head, 11 to 1 engine with good gears, 3.70, 4.11 and better suited to a manual trans. A smaller roller cam matches your gearing better, tighter LSA will make more torque and noticeably more midrange and give it more lope at idle. I would probably go with AFR 180 65 CC heads, 5 CC flat tops and this howards cam. It matches your gearing well and a 2000 stall convertor will work great with it on the street. Should make 400-425 HP, be very streetable with a nice lope, run on 91 octane, possibly regular top tier gas and pull to 6000 RPM.
http://www.summitracing.com/parts/hr...make/chevrolet
It is very close to Ted's cam with a little more lift.
This is almost the same build I am talking about. PM him on his thoughts.
https://www.corvetteforum.com/forums...isaster-5.html

oldchev

Ok, Mako, I was leaning towards the other cam you talked about. This is the 2nd one. This has the higher LSA and the higher (.525) lift.
I noticed REELAV8R is running a 108 LSA. I was wondering how his vacuum is working. I'm going to guess that you like the AFR head because what? Does is flow better? It seems to be the same spec as the one I suggested. i suppose the alum gets rid of the heat faster. Do these Alum. heads cause gasket problems with iron blocks?

63mako

The AFR 180 flows what almost any other manufacturers 200 CC head flows through a smaller port.
The World S/R torquer flows 205 intake 156 exhaust @ .400 lift,
AFR 180 flows 240 intake 190 exhaust @ .400 lift.
Higher port velocity increases bottom end, midrange power and the flow feeds it up top. It is the best bolt on head you can buy, is priced within a few hundred of anything else made in USA and can come with the correct springs for your cam. Head flow determine power potential. Lift increases flow. Cam duration @ .050 determines what RPM the power is made. Compression determines what your intake valve closing point (advertised duration) needs to be to run pump gas. No problem running a Felpro MLS gasket with aluminum heads and Iron block. The link I gave you above he is running a felpro steel shim gasket.
Edit: This is all assuming your going with a 355, .030 overbore 350.

jb78L-82

I have been watching ths discussion for a while but since I am not an engine builder and certainly not a head cam expert, I resisted commenting. So here is my story with a lot of help from 63Mako on the head and cam choice. I had an original L-82 4 speed 3.70 66,000 mile car that i was going to change heads and cam. At teardown, discovered a chipped piston (suspected something was wrong) and was forced into a total engine rebuild going for a lot more power than the stock L-82 BUT keeping as much L-82 as possible. I enlisted a local engine builder with tremendous experience and reputation for the short block rebuild:

I removed the engine and disasssembled the top end and the builder came to my house for the short block pickup. Thee builder cleaned the block, checked the deck (no milling since I wanted to retain the block build numbers), Felpro 1094 .015 head gasket, bored .030, new bearings, oil pump, JE Forged 9:1 flat top pistons/rings, reconditioned the L-82 forged rods, reconditioned the L-82 crankshaft, new harmonic balancer, engine assembly balanced separately and along with clutch assembly, Felpro oil pan gasket, new fuel pump etc.

After much deliberation and advice from 63Mako, DucatiDon and others I went with the AFR 180 CC 65 CC aluminum heads and the Howards Roller cam .525/.525, duration 219/225, LSA 110 since I wanted to make strong mid range power with decent bottom end and decent top end-cam operating range is 1,500-5,600 RPM with good idle (similar to the L-82) and good vacuum. Compression is about 10-10.2:1 and runs easily on 89 octane. The engine is a marvel.....very good bottom end, great mid range, and pulls VERY strong to 6,000 RPM-most of the time the engine lives in the 2,500-5,5000 RPM range. Smooth as glass revving and lots of HP stilll on the table...running Shorty headers, L-82 aluminum intake and the Holley 4175 650 vacuum carb needs dialing in. I know what FAST is with my 10Z06.....not the Z but a giant boost over the old L-82 and if you look under the hood, it looks like a stock L-82...one of my goals.

Hope that helps!