350 chevy engine?

Question

I heard that you can put 305 heads and a 400 crank in a 350 block is this true? and if so what would the HP be?

Answer 1

Music is right. It is a great combination, and has been done for years. I would also suggest a rotating assembly if you've never done this, and there is still block work to be done. There are so many cast (cheap) aftermarket cranks out there today to do this, that it is almost not cost effective to do a 400 crank. the 400 crank will have to have the mains turned down to 2.45 inch to fit the 350 block, and you can buy a new crank for what you can have that one machined for. If this is a low RPM/horsepower engine, great, you can use the 5.565 inch 400 rods with 350 pistons. If you are going to turn it over about 5500, you need to upgrade to a 5.7 or 6 inch rod. Most rotating assemblies you can buy will come with one of the two long rods.

As for the 305 heads, they are good for what they are, but not for a 383. They have a 58cc chamber and with the flat tops most 383 kits come with, you will have WAY too much compression. Just the added stroke of the crank adds compression and so does the flat top over most stock 350s. If this is a street motor, you will be good with a 76cc 350 head and a flat top. The "double hump" heads have 64cc chambers, and will with most pistons cause too high of a compression ratio for pump gas. NO, please don't use 396 heads. They are for the Mark IV big block, a completely different engine.

DON'T forget to use the 400 balancer and flywheel (or an aftermarket bolt on flywheel balancer specifically for the 400). this is an externally balanced engine unlike the other SB Chevys, and will shake itself apart with a 350 balancer and flywheel.

Answer 2

I own a shop, and have built more 350/383 engines than I can recall. Yes you can put 305 heads on a 350 block, but it just doesn't work out. There is such a thing as getting the compression too high, and this is what will happen. You will have an engine that you cannot get a handle on the spark knocking (detionation), and as you may or may not know, spark knock will damage the pistions, and/or ruin them. In order to have an engine that will make power, you must match the bore size on the head to the bore size on the block. A 305 has a much smaller bore than a 350 does, thus this leaves an over hang of a lot of meat that takes up quench area. If you look at a 305 head, and measure the area of the gasket for each (305, and a 350) its easy to see how much over hang you will have. I believe this will move the firing area to one side of the piston, and not allow for an even centered firing of the spark plug. I have seen this done, and believe me, the engine made very poor power, and the ignition timing could not be gotten under control enough to make any power. The 305 valves are much smaller, and flow much less air than the big bore heads. The camel hump 327 heads are different in bore area, and have big valves. Everything about the 305 heads, valves, quench area, and runner size doesn't add up to more power, but an engine that can't be tuned to run good. I have seen this done, and it just didn't work!
As for the 400 crank in the 350, this is called stroking an engine. This is good, but if you have never done this, it is a sure engine that will explode sooner if not later. The block must be ground in many area's to clear without hitting the crank, rods, and cam. You will be moving to an external balanced rotating assembly, and must use a 400 harmonic balancer, and flywheel. The rotatting assembly must be balanced, as in the crank, rods, pistons, damper, and flywheel must be matched, and just won't stay together without this being done. If you intend to build a stroker engine, then it is best to purchase a balanced rotating assembly.
Glad to help out, Good Luck!!!

Answer 3

This can be don if you have a Motor that has been made befor the mid 90'

If you rememner the TV Show Knight Rider that body style for the Pontiac Trans Am and Chevrolet Z28 is about as far you could go with the motor. I want to say 92 or 93 stop there due to the complete overhaul design.

Take the VIN off the block, Stop in at your Local Cevy Dealer ask in Parts and also ask if there are any HotRodder GM Mechanics and see if they can help you out. They also will have other sources or web sites for you to check out.

Chevrolet does have a few Engine Book for Perfermance possible cominations and configurations with multiple parts that will fit.
Any Local HotRod Speed Shop will hel you out if they are in to building and custmizing cars for a living.

http://chevyperformance.com/index.html
www.chevrolet.com
http://edelbrock.com/
www.jegs.com
www.summitracing.com
www.nhra.com
http://nhra.com/Classifieds/Performance_Directory/index.html
www.cranecams.com
www.competitioncams.com
www.knfilters.com
www.lucasoil.com
http://www.jet-hot.com/
http://www.strangeengineering.net/

NHRA Site little easy to get lost on the site there are alot of links to check out. It all depends How DEEP your Pockets are. Scroll Down on the Far Right look and click on where is says
PERFORMANCE DIRECTORY.
www.chipfoose.com
May be some help also.

*** Use a AC Delco Battery!!!

I was a DieHard guy. I had problems Batteries Gurgling and times car not starting in normal weather due to Bad Battery Cells with only about 2years of everyday useage with NO additional electronic additions just the standard stuff from the Chevy dealer installs at the Factory.

Besure to get the correct Distrubitor for the Cam.
Make sure you have the proper Flywheel and Torque Converter and ask about What is the biggest Rear End Gear you can use also what would be the best size so you do over reve the motor.

If you go to the Dragstrip see if a Chevrolet Trailer is there. Chevrolet Does pull out there available crate motors they should beable to help you with your Engine Combo. Other Wise Deffinatly look for a SummitRacing, JEGS, Edelbrock, CraneCams, Competition Cams Trailer. You will also get the correct Lifter Valves Rocker Arms a selection to choose for your combo.

The Maifold a Carborator is going to play a factor on how Much HP you want. If your going to use street Gas Racing Gas or Combo Street Gas Racing Gas with NOS. Play with NOS your Dealing with Dynomite Power and may or may NOT with your Combo dure to the Timing you will have to set up to use NOS.

Have Fun I Hope all this has helped you to aFuture Chvey Rumble.

I hope all this is help

Answer 4

Another VERY IMPORTANT thing to mention here is that if you are going to use the 400 crank in the 350 block, you MUST have machine work done on the block to allow clearance for the connecting rods as the 400 crank has a longer stroke there is not enough clearance on the 350 block, as it is stock, for the con-rods. BTW the combination you are talking about has been done for years, it is called a 383 Stroker! And yes, the 305 heads? scrap-em' Not that they wouldn't work but they have too large a combustion chamber to do this set-up any justice at all. The camel backs or 2.02 heads are definitely the way to go if you can find or afford them

Answer 5

Have the heads ported and with the 400 crank you should get a very good gain. But if you going to have the 305 head re dune why not just have the 350 head re dune. This would make more sense. The swap will work if it's not a late model 90's engine.

Answer 6

Yes you can but with 305 heads, you wont get much HP. With a 350 block and a 400 crank, you need a better CC camber head. If you could find a 396 head thats better. Or, take a 350 double hump head, have it port nd polish and ground to a 64 CC camber, which will produce alot of right compression.

Answer 7

All I can add here is DON'T buy 396 heads like someone suggested. The 396 is a whole different motor. I believe the 396-402-427 (not to be confused with the 427" version of the 409) of the 60's are brothers.

Answer 8

without RV cam 325 hp. with cam 350hp or so, headers and better carb that might climb to 400hp.