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305

5K views 55 replies 6 participants last post by  Wezz 
#1 ·
hello all!

i have 3 questions

i am reboulding my 305 yes iknow its not a 350 but i hold my 305

i port/matched the heads .. gegrind the valve seat exhaust are new seats , the valves are regrinded specs are:8 58 cc chamber but milled a little intake is 1.88 exhaust is 1,5 will send a pic from that

the block is a 305 rollerblock but im using a edelbrock performerplus cam kit with flat tapped lifters specs are 194° / 214° .398" / .442", 112°, 107°, 16

im using a performer intake and edelbrock 600cfm or holley 600 sfm double pumper not sure wichone

i will use headers a HEI distributor new wires sparkplugs

the question is how much hp and torque can i aspect

question 2 is before i started the project i did a compression test and each cylinder has 159.5418 is that the same als 11:1 ? and is it normal on a 305 tbi rollerblock?

question 3 i read other topics and they talking about piston to valve clearance wil i get in trouble?

sorry for the bad englihs but im from holland haha :)

thankyou
 
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#10 ·
No 160 psi is not 11.1, you need to get all your engine specs and use a compression calculator to figure your compression out. That will come later when all the machine work is done. If it's a basically stock engine rebuild with a cam etc. you may have "around" 8.50 - 9.0 to 1. There are lot of variables involved.... all depends on heads and machine work. ..... and your English is just fine.
 
#11 ·
so if the engine i ready and al the parts are togheter and i do a compression test then i still dont know anything ? haha btw my underblock is still the same i looked @ my cylinderwalls and with the information i could find i think its good enough ,, i post a pic from it .. thnx
 
#14 ·
160psi does not indicate 11:1 compression ratio.
I can't give you the formula to figure out the psi result of 11:1 CR, but I can tell you it has allot to do with when the intake valve closes. If you have a long duration cam the psi will be lower than if you have a short duration cam period. An 8.5:1 CR engine with a short duration cam can have as many psi as a 12:1 CR engine with a long duration cam.
You may want to download the CR calculator near the end of this article. Good article by the way. Dynamic CR
Also you might want to grind out that "swirl vane" next to the intake valve guide to give you a little more performance.
Also IMO a double pumper works better with a manual transmission where a vacuum secondary carb works better with an automatic trans.
ssmonty
 
#24 ·
I can't say how well of a condition your cylinder walls are just by looking at them except that they have lost all of the cross hatch from wear. Can you feel a lip near the top where the piston ring stops it's upward travel and starts to go back down into the cylinder?(Top Dead Center) Commonly refered to as a ring ridge. If you can feel it with your fingernail you need to get an "inside" Micrometer or a bore gauge and take some measurements and refer to an overhaul manual to find out what the acceptable tolerance or wear limit is.
I know you have difficulties getting parts economically, but if you can feel a ridge, it may be time for an overbore and new pistons. If it was measuring 159.5418 POUNDS PER SQUARE INCH I'd say it was in pretty good shape. If you talking about pascals or something else I couldn't say one way or the other. I know they all didn't measure the exact same amount, but generally if they all measure within 10 percent of one another they should be ok.
No the heads I posted a pic of were not swirl port heads. I was just trying to give you an idea of what to get the guides to look like instead of having the big vane. You asked for a pic and thats all I had.
ssmonty
I take too long to type. I see that painted jester beat me to it.
 
#26 ·
hello no i didnt get the pistons out .. like i said its my first project so onley the heads ported and new cam .. and clean up everything.. if you feel on the edge of the cylinder wall you can feel a little ridge on it .. but onley the dark ridge .. its not much and by looking the piston isnt touching it at all..

i looked a few days ago on the internet and I found a few pages that says that an interference fringe an accepted phenomenon .. but what will happen when I let it sit there is not a scratch or feel visible in the cylinder wall .. there was on that edge a little black attack like the pistons .. I HBE and edge gently cleaned the pistons also schooingeborsteld .. I have the pistons leave because this is my first project and I still do not know everything and I piston rings and bearings risky find ..

mn engine has basically always nice run. but had a leaky koppaking. and did only what cylinder machining done and everything cleaned e camshaft replacement for others
 
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