i just built a 500" lowdeack and i have 3 cyliders that are running hotter than the rest.they are cylinders 2,5,7. the oher five are running between 480 and 520. but 2 is over 600 and 5 and 7 are 700+.i have no idea what could be making them 3 hot like that?let me give you a little back ground on the engine.it's a 400 block over bored to 4.380.it has a 4.150 crank.440 h beam rods with ross flat top pistons.it has a hughe engines hydraulic cam with .584/.592 lift with my 1.6 hughes roller tip rockers.237/242 duration @ .050" 108 lobe seperation and comp cams magnum lifters.it has edelbrock rpm heads ported by modern cylinder heads.edelbrock rpm intake with a holley 9831 830 cfm carb.an msd 6al ignition with an msd 8545 distributor.and it has headman headers.oh and it has a pro gear 4000 series timing chain set with a 9 keyway crank gear.any ideas would be very helpful.ive already burned up a starter and it's starting to melt stuff.

 

Welcome!


I think taking over a 1/4" out of each cylinder may be the problem. (I'm thinking you have a typo).

I'm not very good with running numbers like that through my head, I'm more of a hands on fix-it kind of guy but there are some great people here who I'm sure wil be able to help you.

How are you able to measure the temperture of each cylinder? Just wondering.

 

Too much timing, too lean jetting, air leak causing an over-lean condition. How does it idle and run?

 

did you have the block sonic checked? to see if the cylenders were thick enough? .030 shouldnt hurt, im not talkn about the "thin wall" myth, but ive had block that rust had ate away the inside of the cylinder

 

i have 84 jets in front,86 in the rear.it fires right up and idles awesome.if it was lean,why are'nt all the cylinders hot.i checked the plugs,and they actually looked rich,not lean.my timing is 15 inital,36 total.

 

had my blocked checked,it was all good

 

buddy of mine has a laser temp gauge.the block is only bored .040".stock bore is 4.34

 

was the block "decked"? How easy was the manifold install? Bolts drop right in? I'v had lots of sealing problems with my 383 and an Edelbrock Performer RPM.

 

went on like a glove,bolts dropped right in.block was not decked

 

Just thinking out loud here. What if you try an 89 jet in the drivers side rear and an 87 jet in the pass side front. Then check your temps and see what happens. Mark

 

what type of headers are you running? you might want to try some equal length headers, this could be a back pressure issue. If the back pressure is different for those cylinders it might cause a different temp reading.

 

i really dont think it's a lean condition.i pulled the plugs after 100 miles and they actually looked rich.

 

i ran these same header on this engine with 2 other top end configurations and never had a heat problem like this.