74Runneer

So i think that i did this wrong but heres what i did: Unpluged the positive wire going to the coil, took out the spark plug, cranked it over 5 times. My carb is being rebuilt to i had the fuel going to a bottle. Also i couldnt warm the engine up because i didnt have a carb, but here are my results:
1: 125
2:120
3:
4:
5:125
6:120
7:125
8:118

I couldnt get the 3 and 4 spark plug out because of my stupid headers. there isnt enough room to fit a knuckle bit to my wrench and there is just no room. I tried to use a pliers and just go under and twist it but the steering column was in the way. What do i do here?

Anyways are the numbers i have alright? I have a mild cammed 318

moe7404

normally you should have all the plugs out. the carb should held open. coil disconnected. having an open carb and a loose spark wire might be bad. then crank the engine. any cyl that is 10% less than any other. put some oil in that cyl. this will seal the rings but not the valves. this will tell you where the low compression is. i dont recommend headers for street engines. the horse power made by a header is mostly at high RPM.

Kern Dog

Huh???
That is some faulty logic. ANY engine can benefit from a tubular header. Your advice smacks of the old timer that thinks "ALL engines need backpressure".
Installing headers on even a MILD engine results in a power gain from 2000 rpms and up. WHY? Look at the restriction in factory cast iron manifolds, THEN look at a header. The increase in internal volume of a header is ONE of the benefits. Another factor is that headers "scavenge" the exhaust from the engine. In effect, each tube pulls exhaust gases of the next firing cylinder on that bank. Even a mild cammed 318 can see 10-15 HP from a 1 5/8" header.

To the original point, Your numbers look good so far, but you really need to find a way to remove the other 2 plugs to get all of the numbers. Numbers high or low do tell a story, but what really matters is how close the numbers are to each other. Your numbers are fantastic. Pro engine builders aim for a max variance of 3% on a fresh engine. You are around 5%. Many techs will agree that as long as you are within 10%, the engine is sound.
I recently did a compression check on my Charger and was within 4%.

moe7404

" ANY engine can benefit from a tubular header" i dont disagree. i just dont like having to put up with the disadvantages. yes i HAVE had 2 sets. it IS a trade off. for me generally for every day driving you dont gain as much as you loose. when one makes you spend 2 extra hours to get a starter out it isnt worth the trouble. ian not saying for you to not use one iam just saying that there are disadvantages you dont know about till its 100 drgrees out side and it makes you take 2 extra hours. if you want use one. but remember there ARE trade offs.

pro-tech

Two words Mini Starter or late model starter. I can get the starter out in 15 min. on my 360 Duster.

74Runneer

Yeah, I agree that there are trade offs but I personally think they are worth it on this car. Yeah ill test the other two today. Would warming up the engine bring all the numbers up? I was told it would.

TVLynn

Numbers are good ! The reason they are low is probably due to the mild cam and the fact that you have a low compression engine

74Runneer

So do you think my rings are probably good for another 5000-10000 miles?

74Runneer

I checked the last to cylinders this morning and they were 125 each so it looks like its fairly consistant around the board.

TVLynn

Rings should be fine !! Could be good for another 100K. I would consider a different cam ! One with less over lap to keep compression up. Or maybe just a stock 340 cam

74Runneer

I'm putting on 302 casting heads which wiill raise the cr to around 9 to 1. That should help it out right?