Because my car is garaged 200 miles away from where live and study. Actually going there tonight and will be able to check the ratio and the water pump length tomorrow

 

Fair enough. You may find that the math is a little bit off due to the slippage of an automatic transmission, depending on how much it's slipping. Even a brand new auto tranny will slip a little bit. Good luck with your project, oh, and stock SBC pushrods are 7.8" long, so the 7901 Individual Length Checker Adjustable Range: 7.500" to 8.700 should work for you. here is a link to the pushrod checker I am planning on purchasing, check it out:

http://www.summitracing.com/parts/CCA-7703-1

See ya,


Scott

 

Actually checked today and as it turn out I have got a 3.08 in the rear. indicated by the codes and because the driveshaft turns almost exactly 3.00 turns for each turn the wheel makes. Does that mean my tranny is steeling 400 rpms? No wonder it likes the gas station

Sure that is the stock for oe roller engines too? After reading alot on different pages I found on google it looked like 7.8" what stock on 2pc rear mains while 7.2" was stock length for the 1 pc oe roller.

Anyways. Today I put a few hours into cleaning the new block and taking the old freeze plugs out, all looks good.

I think they already look happy together

 

Oops! Missed the part about the roller cam!! 7.8" is for the flat tappet cam, not sure how long a roller tappet pushrod is, but it is definitely shorter. Still, check out the comp cams pushrod checkers, you don't have to measure the checker, it has a little measuring scale built in. It's pretty cool. I have never actually checked pushrod length, but I will be doing so on my next build, so I have kinda looked into it a bit, and most folks say that it's a pretty good bet that you will need longer pushrods when using aftermarket heads and valvetrain peices, so this pushrod checker should be right up your alley.

http://www.summitracing.com/parts/CCA-7702-1/

And, yeah, an automatic tranny will soak up a couple or three hundred rpm, even when new, that's one of the reasons the newer trannys with the lock-up converters get better gas mileage. If I were you, I would consider a little less cam or a little more gear. Something else to think about is maybe a 700r4 swap, you get the overdive gear with lock-up for low rpm on the highway, and first gear is 3.06, as opposed to 2.52 for the th-350, so you get a little more gear in first. There's no free lunch, tho, you pay for the low first gear with wide spacing between gears, which makes a nice, wide torque curve important with this transmission. Decisions, decisions, huh?


Scott

 

The cam is already ordered and looking at previous dynos of similar combos the torque and hp at low seems pretty good. Now eventually going manual I hope I'll be alright. Otherwise I'll have to recam or regear it to make it right. But at least I'm not all wrong

I now ordered the last parts (I think). It's interesting how expensive it gets when it all ads up. $20 here and $30 here, after a while it becomes quiet alot still. I'm keeping count and I'll post the total when the engine comes together and I know it's all complete. I'm pretty sure I'm doing the right thing by ordering these high quality (all forged) balanced parts for the important things such as valve train and rotating assembly..

Now I would like to buy a book and need advice on which one. I'm looking for a really good book that explains all of the basics and details around engine building, how to go, how to clearence for stroker crank, what to measure, how to measure, what the result should be etc. I do know the basics but newer having built an entire engine before there will be a lot of questions coming up and maybe some of them will be answered by a good book. This is going to be a +500 hp N/A engine and I want to make sure doing it all right. Which book should I get?

 

Ahhh! Well, if you are planning on going with a manual transmission, you can get away with quite a bit more cam, in my opinion. Once it's done, you can drive it around and decide if you want a little more gear. Sounds like a good plan.

edit: Here's what I like to with recommended books: Take the title of any books that people tell you about, go down to your local library, and borrow them for a few weeks. If they don't have the book they can get it from another library. Peruse the books for a few weeks, and then purchase the ones you like.

Scott

 

500+ hp NA small block and 3.08 gears with a manual will not give you what your expecting. Street manners will suck, driving around town will be a chore and you will have to slip the clutch to take off from a stop sign or launch every time you take off. A 3.70 gear will work fine with that engine or upgrade to a TKO 500 trans and keep your 3.08. A smaller cam with your compression is not an option. Been there done that. Check my signature. I have a similar build and went with a T56 6 speed and 4.11 gears to make it all work.

 

Really trying to do the right thing here and have been doing alot of research and learnt alot. Some tell me I can have more cam, others tell me less. In the states many of you have been having thoughts on my high compression, in Sweden everyone thinks I'm spot on. Don't at all know where to stand. I've been trying to see to all your thoughts and learnt alot and of course I would have picked a smaller cam if everyone would have told me so. But now that wasn't the case

I can't see your compression, cam or previous cam in the signature, just that you have a forged 383 with tripower which doesn't really tell me much. What downside (apart from nocking) did you have with the small cam and the high compression? It seems you have a long history in engine building and your thougts are worth alot to me!

Hope I'm not all wrong in my build and I do myself believe that I'm not (for whats little its worth). Lots of articles and crate engines are using much bigger cams for the 4spd manuals and getting some amazing results, they might however have much higher gears and that's a journey I'm well willing to take if so. I might however get a second run at the cam as I'm now on a stock base circle (according to a magazine article I should be alright with this exact rotaring assembly, http://www.chevyhiperformance.com/te...k/viewall.html) but many with other rotating assemblys claim you need a smaller base circle so we will see. Will be back here regularly to report, maybe some others can take advantage from my learnings

Thanks again for all your help
Best Regards Axel

 

Yeah, I think that here in the States, we get used to a certain way of thinking about what a "streetable" compression ratio is, because of the gasoline quality that we are used to. Apparently, you will be running what we here feel is the equivalent of "racing gas", and so, will be able to build accordingly. Racing gas is expensive, and not always readily available here in the states, so we go by the rule of thumb that 8.25:1 dynamic compression ratio is stating to get close to the edge on 93 octane gasoline, so take our advise with that in mind.


Scott

 

My point is that to run higher compression requires a bigger cam to keep your DCR in a range that will run on the fuel available. You have done that but that bigger cam moves your operating RPM range up. Your cam matches your compression and I would not go smaller. Corvettes are fairly heavy cars. With the higher gear ratio rear end this causes the engine RPM to be outside the cams operating range at lower speeds or for example taking off from a stop sign or cruising around town. It will also idle rougher and may not smooth out until 1500 RPM or higher. If you check various cam specs you will see that the bigger duration on the cam you will get notes in the description that 3.70 or 4.11 gears are recommended or a high stall convertor to accomodate the operating range of the cam. This is something many first time builders do not take into account or ignore. It is fine to build at the power level your shooting for but the rule of thumb on a max performance street build is shoot for a 10 to 1 final drive ratio in first gear.
For example if you have 3.08 gears and a 2.20 to 1 first gear in the trans your final drive ratio in first gear is 6.77 to 1. This is ok for a stock cam that pulls from idle to 5000 RPM but will suck in a car whose cam operating range is 2800 to 6500 rpm. If the same build and car has 4.11 gears with a 2.20 first gear in the trans the final drive ratio is 10.04 to 1 which is perfect for that big cam. This allows the heavy car to accelerate from a stop needing about 1/3 less torque at low rpm where that big cam lacks power and gets you into the operating range of the cam much quicker. It will also cruise in the operating range of the cam and fuel mileage will suffer. There is no free lunch. Performance and street manners are greatly improved if the gearing matches the build specs of the engine. You will be able to drive and use the car with the gearing you have but will not see the performance you expect on the street or the track. A TKO 500 will get you real close to that 10 to 1 final drive ratio in first gear. With that trans you would want a .82 overdrive instead of the .64 because again you will be outside the cam operating range at cruise speeds. I am not certain the .82 OD is available in the TKO 500. Or use a 3.70 or lower rear gear and a TKO 600 or a regular 4 speed but then fuel economy becomes an issue.
A richmond 5 speed would probably be an even better choice with your 3.08 as the gear spacing is closer and final drive in 4th gear is 1 to 1 in the trans. I don't know if the Richmond shifter will fit in the stock location. The above information is why the 5 speed upgrade is the most common and useful upgrade for many corvette owners. There are many that have done what your doing and were not happy with the outcome until they do a trans upgrade and match their gearing to the build.
The builds you are refering to with 4 speed manual trans and big cams getting amazing results are not running 3.08 gears.

http://www.5speedtransmissions.com/5sp_comparison.html

 

Very good explination. Often overlooked by personal engine builders. The larger the numbers are not necessarily the better, more powerful and enjoyable combination. To a point of being a pain to drive everyday.
It can get to a point that only the builder and folks who understand the system may effectively drive the car.

 

You can use a 2 piece rear seal crank in that block as I have done that many times with theh correct rear seal adaptor. that way you can use a crank that you can internally balance and more so if you go with a 6.000 rods.

 

Here is a guy with the issues I was talking about. Quite a bit smaller cam and much less compression than yours.
http://forums.corvetteforum.com/c3-t...questions.html

 

Thanks for all comments. Sorry I havn't been in for a while but I'm in the middle of my vecation at San Martin and internet is a luxury.

Well all of this makes me a bit confused, not because I don't understand what you're pointing at (thanks for the nice article and thread) but because my parts are already ordered and I will have to make a decision which way to go before I start putting it all together. Really would have liked to have all of this figured out before I ordered but well..

Routes as I understand it:
1. Kinder camshaft, would probably put me on the limit of pump gas compression even in Swedish conditions (fuel, temp, humidity). Could mean I would have to start mixing e85 and upgrading the fuel system for that to work.
2. Steeper gearing
3. Planning for an OD swap
4. Letting everything be and upgrade one of the above as time goes..

Will have to think about this for a bit. I'm however still confident that my bottom end, heads, intake and carb are the right choices. Cam and gears are resonable things to be laborating with compared to the other stuff

Anyway, for now I'm going to enjoy my vecation. I was in Florida for a few days before flying here and going back the 5th, drove down to key west and had a great time. Will update here when I get a look at all the parts.

Have a great new years eve everyone!
Best Regards
Axel

 

Typically about the most expen$ive lesson in engine building.

Not having a completed design before ordering parts usually means build compromises or buying parts twice

 

I tried before you ordered any parts.

 

63mako,

I put alot of value in all the post that you've made in my thread. I understand that you have a lot more experiance in these areas then me and I have therefore taken everything that you've said into consideration and read all articles posted carefully.

I understand that you've been trying to push my compression down (and my cam with it) and I have read alot about the choice of compression because of this. After all the only disadvantage with having to much of it seems to be detonation.

If you can avoid that there is as I understand it only positive things with having a higher compression. It gives you effectiveness, better low and mid range given no matter what cam and the ability to benefit fully from a long duration cam in the high RPMs if you wish to have that. The 2.5% gain in peak HP is according to many considered a bonus to the previous mentioned on a street build.

After having read alot on Swedish websites and forums about guys using 11:1+ with pump gas and much milder camshafts I started investigating it. According to a few engine builders around town, a professor at my school (vehicule engineering college) and many guys on different forums I should be alright with 11:1 SCR no matter choice of camshaft in the conditions where I plan on driving the car. That was the complete thinking behind the decision of compression.

I would have loved to go 10:7 - 10.9:1 but as you may know given my dispacement and head brand that wasn't an option without extecive machine work (milling) or having too much quench. I did not however intend to use the full capacity of that compression when it comes to cam choice. I though I picked a cam that would pick up heavy at about 2.3k RPM peaking at about 6.3k RPM which according to me sound like a pretty stout street engine.

The rotating assembly in now all forged so at this power level and these RPMs it should be a childs game to make it last.

A second cam is $250. The one I have will be worth more then that in Sweden. Should I get a kinder cam now when I have the chance? I think I'll be alright anyhow compression wise and if I'm proved wrong I'll have to figure that out then.

Given that my auto trans is steeling 350 highway RPM atm I'm open to going 3.70 rear end giving me about the same highway RPM with the manual as I have today with 3.08 and auto. I would love to have an OD trans installed in the future but that's alot of money and untill that day comes I want to be able to enjoy the engines full potential.

I don't want a 7500 rpm strip engine but I want a nice stout and powerfull smallblock reving a bit over 6k. With this kind of displacement, compression and a full roller setup I don't think it should be impossible to get promising numbers up top and a good low/mid range??

 

The compression ratio will limit how small of cam duration you can run without detonation issues. Your present cam is at the very lowest limit for that even with the octane you have available. Go for .040 quench even if it bumps your compression a bit. I have found tight quench is better to avoid detonation than a little less compression and big quench. If your willing to make the needed changes in your gearing I would build what you have. It will be a fun motor with a 3.70 and a 4 speed. My original intention was to help you to use the gearing you have with the build you were planning. Have a Happy New Year!

 

http://www.ehow.com/list_7713046_sup...fications.html
Here is a link for Super T-10 4 speeds. If you want to keep your rear end you could go with the 1980-1982 trans. This will give you a 10.6 to 1 first gear final drive ratio and still have the 3.08 in high gear. The only drawback would be wide ratios between gears but it will get you a useable setup for your build specs with the least extra cost and still perform well in drag racing and cruising economy.

 

I think 63Mako is spot on. He is an expert, I am not. But that 3.08 rear with a hot cam is going to be a dog off the line. Remember that dyno pulls usually start from 2000 rpm or more and quote peak numbers, but you don't want to be launching with a lot (yes, 2 words) of rpm to compenstae for the 3.08. It willl get tedious fast.