400 SBC performance upgrades

[mechanicalman]

Originally Posted by mikeygibson

I thinking it would be wise of me to find out my diff ratio and stall converter so I can make a more informed decision for cam selection. I have to repair a leaking trans seal anyway so I can see what converter ive got and I can remove the cover off the diff and count the teeth. Id hate to rush out and get an unsuitable cam.

I don't know of any way to tell what converter you have by pulling it out unless it has a sticker or some kind of stamping, maybe someone will chime in on that.

I think you may have better luck power braking it and watching a tachometer.
https://www.youtube.com/watch?v=WSmdDX3T1l8
Then use this to help you translate the data:
http://www.superchevy.com/how-to/tra...ter-selection/

You can tell what gear without pulling the cover. If it's a posi, block the front wheels, jack up the rear with a floor jack under the diff and put the axles on jackstands. Turn the driveshaft until both rear wheels make one complete turn and count how many times the driveshaft spins. If it spins just over 3 times, it's a 3.08:1 and so on.

If you have an open diff use the same procedure but only jack up one rear wheel, do the same thing but let the wheel turn 2 times instead of one (because the other wheel is not spinning), and then count the driveshaft turns and that's your ratio. Again, if the driveshaft spins just over 3 times (and that one wheel twice) it's a 3.08:1 and so on.

[mikeygibson]

Legend!

[GRX]

Originally Posted by mikeygibson

Thanks again for your excellent advice

http://www.summitracing.com/parts/cc...39-3/overview/

Any thoughts on this cam... Capt Fab recommended it.

A good cam for your 400. Definitely get new valve springs. No way you will get full potential from a new cam, especially one with higher lift, with worn out springs. The Summit page you linked recommends these:
http://www.summitracing.com/parts/cca-981-16/overview/

And follow mechanicalman's instructions in respect to spring break in. A commonly overlooked step.

[mikeygibson]

Originally Posted by mechanicalman

He's right, if you can afford it. Roller hydraulic will produce more power low and high, smoother idle, all better for your application. This is going to be a torque monster!

You will also need a cam thrust button and a heavy timing cover. If you have a short water pump, you may need to install spacers to clear the thick cover.

"Recommended spark plugs are Champion RC12YC or equivalent 14mm x 3/4" reach with flat gasket seat".

"To use stock rockers on S/B Chevy heads, .100" longer than stock pushrods are required".
http://www.edelbrock.com/automotive/...c-170-sb.shtml

If you run a hydraulic roller cam, you will need to check pushrod length to determine proper rocker arm geometry to match the length whatever roller lifters you end up using.

Also for the hydraulic roller cam, use head part number 60975 (satin) or number 609715 (polished) to get the right valve springs for the heavier roller lifters.

I'd use this one:
http://www.summitracing.com/parts/hr...make/chevrolet

And a nylon thrust button:
http://www.summitracing.com/parts/cc...make/chevrolet

And a stiffer timing cover:
http://www.summitracing.com/parts/mi...make/chevrolet

Of course you will evaluate your timing chain when you take it apart but if it's a stock style link type you should upgrade to double roller:
http://www.summitracing.com/parts/su...make/chevrolet

Morel is a brand name, and as I understand it they make both needle bearing and non-needle bearing roller lifters. To get the non-needle bearing rollers I think is overkill for your application (for very large cams with lots more seat pressure), so if you want to research that and obtain a set go ahead, too much research for me on my end to want to do that. If you do get a set, just get this cam to go with those lifters:
http://www.summitracing.com/parts/hr...make/chevrolet

Keep in mind, those heads require .100" extra long pushrods. So now you are going to use those heads and a hydraulic roller cam so the lifters are longer (longer lifters require shorter pushrods). You could do the math (you will need the spec from whatever roller lifter manufacturer you use), but I'd play it safe and get a pushrod length checker and confirm proper geometry and get the appropriate pushrods.
http://www.summitracing.com/parts/cca-7702-1/overview/
https://www.google.com/search?q=rock...0QsAQ&dpr=0.95

You will need a melonized steel distributor gear to work with the roller cam (it's much harder metal than the flat tappet). Don't know what distributor you have.
http://www.summitracing.com/search/p...rder=Ascending

You will need a composite fuel pump pushrod if you are running a mechanical fuel pump (again because of the hard metal in the roller cam).
http://www.summitracing.com/search/p...9%2B4294887662

Some roller cam cores use a cast iron distributor gear end pressed onto the hard shaft, and those can use a cast iron gear. You can use the steel melonized gear on either/or, although iron is better on iron. If that concerns you, you could call the cam manufacturer and find out for sure but I'd just run the steel melonized. I'm installing a new flat tappet cam on my truck this weekend and I was on the fence on which one to use, but I settled with iron on iron.

If you get hydraulic flat tappet, don't forget break-in procedure. If you get hydraulic roller cam, no cam break-in procedure necessary that I'm aware of just follow manufacturers instructions.

In EITHER event, you MUST break in the springs. That means you have to run the engine at least one full cycle getting the engine up to FULL temp, never exceeding 2,000 RPM and then the engine MUST be allowed to cool off COMPLETELY like overnight. I'd do this a few days just to be certain, then let her rip.

If you break in the cam, and then start doing high revs without letting it cool off completely, the springs will turn to mush. This is the most common reason valve springs fail and also why people then want to over-spring their engines.

You do have headers, right?

I have decided to go hydraulic roller cam now after lots of advice different people. Thanks for the info above its really helped me figure out what I need. I have seen some good kits around with all the gear I need. Cheers

[Canuckvetter]

I have a 400 sbc in my 'vette. I love the power it makes. Edelbrock Performer top end, roller lifter/rocker stroked to 434. 10.75:1 compression. Produced 411RWHP and 480 RWFT.LBS torque.



http://67-72chevytrucks.com/vboard/a...1&d=1428891675