BronsonA2150 Posted 12 hours ago Share Posted 12 hours ago Have a 350 Mack with Jacob’s engine brake and doing overhead. Didn’t realize these are done differently than most I’ve done as you do one cylinder at a time. Couple questions, assume you adjust the stud above pushrod like normal correct? Started to do that but the goofy Jake stud threw me off. And would assume you rotate to each mark on the flywheel and adjust whichever has both pushrods loose, move to the next then adjust the other number at each mark on the next rotation around? Quote Link to comment https://www.bigmacktrucks.com/topic/75902-adjusting-valves-94-e7/ Share on other sites More sharing options...
Joey Mack Posted 10 hours ago Share Posted 10 hours ago Rotate the engine clockwise looking from the front. Do you have a barring tool to put in the flywheel housing... I am very particular about this topic... 1 Quote Link to comment https://www.bigmacktrucks.com/topic/75902-adjusting-valves-94-e7/#findComment-581546 Share on other sites More sharing options...
BronsonA2150 Posted 10 hours ago Author Share Posted 10 hours ago 35 minutes ago, Joey Mack said: Rotate the engine clockwise looking from the front. Do you have a barring tool to put in the flywheel housing... I am very particular about this topic... I do Quote Link to comment https://www.bigmacktrucks.com/topic/75902-adjusting-valves-94-e7/#findComment-581547 Share on other sites More sharing options...
Joey Mack Posted 10 hours ago Share Posted 10 hours ago Great. Pull the ratchet towards the oil pan for proper rotation. Bring it to 1&6. Look at #2 exh. Rocker. It will be rocked when you are up on #1.. then you can start checking adjustment. If #2 exh. Is not rocked, you are up on #6. Roll the engine 360 and come back to 1&6 and start the lash check. You do the bridges first. .010" on both sides. I have a trimmed feeler gauge to fit in the gap at the engine brake reset screw. After the bridge is set, then do the Int. Then exh. And last is the engine brake lash. I assume you have Jacobs 680 heads. The jake lash is based on the HP and turbo model. Do you have that info, and the book ? 1 Quote Link to comment https://www.bigmacktrucks.com/topic/75902-adjusting-valves-94-e7/#findComment-581548 Share on other sites More sharing options...
BronsonA2150 Posted 9 hours ago Author Share Posted 9 hours ago 4 minutes ago, Joey Mack said: Great. Pull the ratchet towards the oil pan for proper rotation. Bring it to 1&6. Look at #2 exh. Rocker. It will be rocked when you are up on #1.. then you can start checking adjustment. If #2 exh. Is not rocked, you are up on #6. Roll the engine 360 and come back to 1&6 and start the lash check. You do the bridges first. .010" on both sides. I have a trimmed feeler gauge to fit in the gap at the engine brake reset screw. After the bridge is set, then do the Int. Then exh. And last is the engine brake lash. I assume you have Jacobs 680 heads. The jake lash is based on the HP and turbo model. Do you have that info, and the book ? I had a guy send me the procedure from the book. Sounds like .080” for mine if that sounds right? Mine is a 94 e7 350 horsepower. And yes mine is the 680. While we’re on that subject, these are horrendously poor performing. That’s part of the reason I’m tearing into it as it kinda sounded like only half were working. Haven’t gotten that far to troubleshoot that yet but noticed this gap between rocker stud and the trigger piston. This rocker is at full motion. Is that large of a gap normal? Only other one I’ve messed with is one on a 3406 mechanical and if I recall it has a lot closer contact. Like it would push the trigger piston in flush with the housing. If that’s not normal I could see that affecting performance Quote Link to comment https://www.bigmacktrucks.com/topic/75902-adjusting-valves-94-e7/#findComment-581549 Share on other sites More sharing options...
Joey Mack Posted 9 hours ago Share Posted 9 hours ago The gap looks large, but likely correct. The E-7 on into the E-TECH series have terrible engine brakes. They Suck!!! Dont loosen any of the set screws before checking lash. Make sure the engine is under 100 degrees or just plain cold. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/75902-adjusting-valves-94-e7/#findComment-581551 Share on other sites More sharing options...
Mark T Posted 9 hours ago Share Posted 9 hours ago That big gap between the Jake and the valve adjustment doesn't mean anything. When the Jake is activated the master piston comes way out of the bore and closes that gap , so sitting there without the engine running.....it looks kinda like it might be a problem. The Jake may need a tune-up kit. Lots of times when they get older the little control valves in the Jake are worn. A 350 ? I wouldn't be afraid to open the Jake's lash to 90 thousandths ( or a little more even ). This is all of course after determining you don't have a bad solenoid or wire off or oil bleeding off somewhere else. 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/75902-adjusting-valves-94-e7/#findComment-581552 Share on other sites More sharing options...
Joey Mack Posted 9 hours ago Share Posted 9 hours ago A rebuild would be good, but at what price. The last one i did was 4 years ago and it was a thousand dollars for the kit. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/75902-adjusting-valves-94-e7/#findComment-581553 Share on other sites More sharing options...
Mark T Posted 9 hours ago Share Posted 9 hours ago 30 year old engine brake, likely a tune-up won't hurt. They are expensive, and that's assuming they're available still. Everything is a fortune anymore. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/75902-adjusting-valves-94-e7/#findComment-581555 Share on other sites More sharing options...
Joey Mack Posted 9 hours ago Share Posted 9 hours ago Sure is on all counts. Screw it, check lash, add the .010" like you said Mark, and down shift more.. it ain't worth taking it apart.. i have a pair of 680 heads in my shop. There might be some usable parts for him when he takes them apart and says ,,Ohh Sh!t... Now what do I do? Quote Link to comment https://www.bigmacktrucks.com/topic/75902-adjusting-valves-94-e7/#findComment-581557 Share on other sites More sharing options...
BronsonA2150 Posted 9 hours ago Author Share Posted 9 hours ago 7 minutes ago, Joey Mack said: A rebuild would be good, but at what price. The last one i did was 4 years ago and it was a thousand dollars for the kit. wow. One for my cat was $2-$300 I’m pretty sure. It looks like nearly identical to this one 1 hour ago, Joey Mack said: Rotate the engine clockwise looking from the front. Do you have a barring tool to put in the flywheel housing... I am very particular about this topic... I do Quote Link to comment https://www.bigmacktrucks.com/topic/75902-adjusting-valves-94-e7/#findComment-581558 Share on other sites More sharing options...
Mark T Posted 8 hours ago Share Posted 8 hours ago 11 minutes ago, BronsonA2150 said: wow. One for my cat was $2-$300 I’m pretty sure. It looks like nearly identical to this one I do The control valves might be the same. Sometimes when you go to change them you discover broken springs holding them. Sometimes the broken springs sneak out under the cover too. But ??? they're a problem if those valves are bad. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/75902-adjusting-valves-94-e7/#findComment-581560 Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.