chevy smallblock 400?

Question

ive got a 400 punched 30 over flat top pistons dart iron eagle heads 202 valves ,edlebrock rpm performer intake holly 750 double pumper carb also matching edlebrock cam .488/510 lift 234/244 duration. Transmission is 350TH WITH A10" 3500 STALL converter &373 gears in my rear end electric holly blue fuelpump& electric radiator fan. I want to go faster

Answer 1

I own a shop, and had almost the same exact build up in mine. I noticed you never said if your cam was a roller cam, or not, and do you have roller rockers? The headers must be looked at with a lot of concern. Use a good set of long tube headers with at least 1 5/8" tubes, and use wrap on them to get the heat out of the engine compartment as these engines run hot anyway. They run their best when the temperature is around 160 degrees, so a good 3-4 row radiator is in order. The headers must breathe, as in they don't do much good if you don't open them up so they can get it out the exhaust. The carburetor can be jetted up to around 800 cfm. Another thing that can get you more power is to go to a shim type head gasket that will get the compression up a little more. Most people use the Fel-Pro that compresses to around .036, and you can just order a set of gaskets that will get it down to around .016- .018" without any interference problems. A good porting job on the heads will always get it going too. The Dart heads make good power, and require very little porting, but I polish out the quench area to where it looks like a mirror. A good ignition system is critical to making good numbers. Gasket match the exhaust ports on the heads to where there is no lip left for the transfer to the headers. Use the gasket you are going to run, lay it on the head, scribe around the gasket, and grind away the over hang on the heads as well as the headers. If you got room, put a 1" aluminum block under the base of the carburetor, and you should feel the difference from it. Using the good spark plugs, and indexing them will help out too. Don't scrimp on the ignition wires you use, or the hangers you run them through. Check out the geometry on your rockers to valve stem, and make sure you are on the center to the outer 3/4 of the valve stem, if not put the right push rods in it to get it there. You wouldn't believe how many engines I have seen that didn't run that good because of this. Remember its the little things that make a differernce on race day. I own a race car and a race truck. I build a lot of engines, and I have learned from experience that the small things will be what counts when it comes to winning or not. You could always stick some juice to it, but if you didn't use a good rotating assembly, you might not want to go with too much. Use the 110 octane, and get the timing in at around 36 degerees over all, if you stick nitrous to it, then you will have to back the timing down. I don't know if you have 2 bolt or 4 bolt mains, but the 2 bolt may not take too much juice. Look very carefully at the clearence on the rotating assembly around the cam. You can get a problem with this, and get a ticking noise that you can't never figure out where its coming from. Also gasket match the intake to head transfer, as this is a good place to pick up a couple of horses. I have also seen some guys use a longer rocker arm on the four corners of the engine since they are the longest distance from the carburetor, and allowing them to stay open just a little longer will make a difference in the numbers. A word of caution on the longer rockers, pay close attention to the clearence, and the geometery of the rocker to valve stem. I use a set of lash caps on mine, because it gives me more area for the rocker to move on, and I don't have to worry about the rocker falling off the valve stem at high rpm's.
Glad to help out, Good Luck!!!

Answer 2

Musiclic... Has given many worth while notes. We built a 400 small block for oval track dirt racing last winter. I'd like to add a few things. You didn't include which size intake runner you chose but a 200 - 210 keeps the incoming velosity high. The camshaft seems to have a little more duration than we used. Ours was 220 - 230 at .050 lift. and .560 I. & E. lift while using flat top pistions. A short duration cam with 112 -114 lobe centers really lift a car out of a hole. The addition of GM's roller lifters would be great. GM makes a new hydraullic lifter the's good to 7,000 rpm. I hope you don't attempt to twist yours this far. Comp. Cams have their version also. We have found that the exhaust ports on the Dart heads need a lot of help to make them breathe right. Stay with your pic of carb. size. Don't be fooled by Barry Grant's advertisements. They run great at wide open throttle but part throttle tip-ins are week and big accelerator pump wells and big nozzles won't help. The main boosters are so high the fuel does not pull over easily. Street performance would suffer. * If you have a Dart block and switch cam and lifters triple check diameter if your new lifters and lifter bore clearance.
If your looking for some nice fire consider the DUI copy of GM's HEI. All high performance Chevrolet dealers stock these. They have a website also. They build their own modules as well as will build any curve in you desire with or without vacuum advance. If possible I'd be looking for a tried and true 400 Turbo Hydramatic. Great luck to you!

Answer 3

excuse me...what type of car is this set up in??? how many of the 750 carbs are mounted? 2, i would hope if you want the power to go fast. first thing i would do is get a manual 5 speed transmission with a 10-12 inch HD clutch set up. automatic trannys seldom operate without some slippage. go to a track to check your speeds before and after the switch. also, make sure your brakes work

Answer 4

Well that sounds likea dam good set up but try a bigger cam, Vortec heads but u'll need to buy a Vortec intake, Try fuel injection it'll get you there quicker i hate F.I. but it makes things faster. Bore and stroke the motor umm then i'd try small things like MSD ignitions that fire better then others.

Answer 5

do u want to get there faster or top out faster, just by changing rearend gears u can accomplish this. I had a Camaro that would only do 110 but it could do this in a 1/4 which made my E/T's good. But, if u want to just go faster, raising the rearend gears would make it top out higher, just take longer to get there.