6 bolt head 7 bolt block. timing differance??

[shadow001dsm]

k i put a a 6 bolt head on a 7 bolt block with 7 bolt cams? i have 0 compression accross the board but i have fuel and spark is the timing different when i mix the head and block?

 

[LiquidX]

Did you verify your mechanical is set right after rotating the crank at least 6 times to see if everything lines back up? Also, you were better off keeping the 7 bolt head on the block as the 7 bolt flows better. People are even swapping out 6 bolt heads in place of a 7 bolt head on their 6 bolt swaps.

 

[empie1]

Did you verify your mechanical is set right after rotating the crank at least 6 times to see if everything lines back up? Also, you were better off keeping the 7 bolt head on the block as the 7 bolt flows better. People are even swapping out 6 bolt heads in place of a 7 bolt head on their 6 bolt swaps.

Its a 1g 7 bolt not a 2g

 

[shadow001dsm]

it is a 1g 7 bolt, and i swaped the heads because the 7 bolt head bent a valve or 2. and no i have not checked the mecanical yet. but i timed it like you normaly would, but does the 6 bolt head make it different?

 

[empie1]

it is a 1g 7 bolt, and i swaped the heads because the 7 bolt head bent a valve or 2. and no i have not checked the mecanical yet. but i timed it like you normaly would, but does the 6 bolt head make it different?

No it doesnt make a difference. Its still the same setup and procedure. I think you have more problems than the timing being off if you have 0 cmpression on all 4.

 

[LiquidX]

Timing being off a couple teeth can cause 0 compression due to valves being open.

 

[shadow001dsm]

yeah its 0 compression on all 4 cylinders. but the rings are fine and the gaskets are ok. the head was seated properly and torqued in sequence to 72 lbs. any ideas?

i was thinking that, im about to re-time it and see what happens, also i thought that maybe the cam position sensor got rotated 180 deg. not sure how to tell though.

 

[LiquidX]

The sensor won't cause 0 compression, that will just give you a hard time to start if it even starts at all as the signal will be 180* out from what it should be for firing order.

 

[shadow001dsm]

true, do you have any ideas on what would cause 0 compression? other than timing?

 

[19Eclipse90]

That's too much torque for an OEM 7-bolt head bolt. Per the FSM, the torquing procedure is as follows:

• Tighten to 58 ft. lbs in this order:
  
  7 5 2 4 10
  9 3 1 6 8​
• Loosen them fully in the reverse order:
  
  4 6 9 7 1
  2 8 10 5 3​
• Tighten in the order first shown to 14 ft. lbs.
• Apply a 1/4 (90 degree) clockwise turn to each bolt.
• Apply another 1/4 (90 degree) clockwise turn to each bolt.

Did you verify the 6-bolt head was okay before installing it? I would suggest rechecking the timing or performing a leak down test to find out just where the air is escaping to.

 

[shadow001dsm]

The head is perfectly fine i just had it had tanked and port and polished right before the install. and could too much torque cause 0 compression though?

 

[19Eclipse90]

If the head bolts stretched and the head now lifts off the block, yes, it could, though I don't believe it to be the case here. Stop speculating and check your timing as that is the easiest thing to check and the most likely cause -- and I mean that in the most respectful way.

 

[shadow001dsm]

i like your thinking, i already have it jacked up and the timing plate cover off, matter of fact i have the laptop next to me as im working on it right now.

 

[empie1]

Timing being off a couple teeth can cause 0 compression due to valves being open.

If it was off several teeth, and valves were open, wouldnt they be making contact with the pistons? Ive had it off 1 tooth and not had damage but several teeth, i dunno about that

 

[shadow001dsm]

not if the timing was 180* out

 

[empie1]

not if the timing was 180* out

Id really hope you wouldnt post this thread without looking at the cam gears first. I didnt mention being 180 out cause i figured it was a given you checked that already.

 

[shadow001dsm]

i did, i timed it like it should be but it never hurts to double check my work. and checking the timing is faster than any of the other possible problems. accidents happen. i guess we will find out within the hour if it was timing or not.

and i only mentioned the 180* out just to show it is possible for it to not hit valves like the other gentlemen above mentioned.

 

[LiquidX]

If it's off a little the valves can open pre maturely causing a loss in compression without valve to piston contact.

 

[Big Woo]

When setting the mechanical cam timing remember that when all timing marks are lined up that the cam dowel pins are in the 12 o clock posistion.

 

[shadow001dsm]

i think thats the part i might have forgot, i realy cant remember if i did that or not, thats why im second guessing my timing.

 

[ramsack]

There's no such thing as being 180° off in cam timing...

 

[shadow001dsm]

the timing was off at the crank,( i timed it thinking it was a 92 block but it was a 94) so i retimed it and took another comression test, and there is still 0 compression. im thinking that the other gentlemen up there is right and i over torqued the head bolts, so they are streched and i need new ones. any thoughts guys?

it is also blowing gases out of the oil cap hole.

 

[19Eclipse90]

Do a leak down test: http://www.dsmtuners.com/forums/articles-engine-fuel/338152-compression-leak-down-testing.html

 

[shadow001dsm]

did the leak down test and air kept coming out of the oil cap so i took the valve cover off and the air was slipping by the bolts for the head.

 

[empie1]

There's no such thing as being 180° off in cam timing...

Wrong. If you have the cam gears with the dowel pins pointing down, its 180 out.
I def didnt think timing was why you were getting 0 compression though.