hows my heads look?

[pearl91chevy]

i did the 3.1 swap a few months ago and drove it through all spring/summer without any problems.. and im currently tearing apart the motor to paint the block and misc. other things.. im just curious since i have the motor apart should i do anything to it? do i need to check the heads somehow? make sure everythings tight? clean anything up?



Drivers side:



and heres passenger:

[-10below]

if you have the cash,

-install higher ratio roller rockers
- if you're not going to do that, you could re-adjust the valves
- also need to put a rag in the two intake holes before that quarter falls in there

[fishindabay]

as he said... don't lose the quarter... and it looks like your engine coolant temp sensor is broken off in the driver side cylinder head.

[pearl91chevy]

how do i go about re-adjusting the valves? how will i need to know if they even need to be adjusted? and i grabbed the quarter off as soon as i took the picture so no worries lol

and the coolent temp sensor isnt broke, i just unplugged it..

[HappyBuddaBelly]

To adjust the valve lash, you just need the right sized socket on an extension, and a ratchet. Go through your pushrods, starting with the number one cylinder, and wiggle them up and down, if they move freely up and down, or around in a circle, tighten that nut until they don't. The lifters should counter some of the play because they're spring loaded, so don't tighten it too much. When none of you're rods move, you're done. You'll notice improved performance, less noise, AND better timing.

[34blazer]

Quote: Originally Posted by HappyBuddaBelly

To adjust the valve lash, you just need the right sized socket on an extension, and a ratchet. Go through your pushrods, starting with the number one cylinder, and wiggle them up and down, if they move freely up and down, or around in a circle, tighten that nut until they don't. The lifters should counter some of the play because they're spring loaded, so don't tighten it too much. When none of you're rods move, you're done. You'll notice improved performance, less noise, AND better timing.

you forgot to mention that lashing is done on the heel of the lobe, and the socket you will need is a 15mm deepwell 1.5 turns after zero lash

[beaniebmx]

you dont have to check the heads unless the motor has alot of miles on it, my 91 2.5l has 99,000 miles and we replaced the head gasket and every other gasket along the way to it, it wasnt completely blown, but had a rip in the cylinder closings, which is a failure.

its not too hard to pull the heads off in the state your motor is in, just taking the intake off, pulling the rockers off and pushrods, making sure to number them in order they are installed in. that way you dont mix cylinder 4 pushrods with cylinder 1, or exhaust pushrod with intake.

once you do that you can take each one to a peice of flat glass and roll it to make sure its still straight, if its bent, replace them.

youll need 2 head gaskets, and intake gasket, and head bolt set.

it cost me about $150 in parts to do a full head gasket replacement on my 2.5, because i had a $130 exhaust header i had to replace.

if its got low miles on it, id just leave it as it, check the valves and all that.

[pearl91chevy]

the motor itself is around 125,000.. it was 3,000 miles less then my 2.8L when i swapped them out.. the intake has already been taken off during the swap so that shouldnt be hard to get off..

[34blazer]

Quote: Originally Posted by pearl91chevy

the motor itself is around 125,000.. it was 3,000 miles less then my 2.8L when i swapped them out.. the intake has already been taken off during the swap so that shouldnt be hard to get off..

do some port work as long as you have em off and maybe a 4.3 tb

[Z28Camaro]

Do you like the 3.1 more? More power and better gas mileage? What benefits did you get out of it?

[pearl91chevy]

Quote: Originally Posted by 34blazer

do some port work as long as you have em off and maybe a 4.3 tb

do some port work as in what? im sorry, i dont know much about engine performance, i just know the basics.. and luckily i didnt struggle to much during the swap.. and i did hear about doing a 4.3tb swap but wasnt sure on whats involved.. think you could give me a lil more info?

and Z28Camaro:
the main reason i swapped motors was he re-built the internals on his less then 5000 miles before i bought it.. and he is putting a 383 stroker in his car and thats why i snagged it from him.. i bought it complete without trans for 150bucks.. i couldnt pass the deal up.. and i looked into turbo'ing this motor but its kinda on the back burner right now, i have the turbo sitting in my garage but i'd rather get it fully bagged and painted first.. but as in power i did notice a small difference, not alot.. but im fine with it and the gas mileage does seem alot better then the 2.8L..

[34blazer]

porting and polishing the intake and exhaust runners. basically smoothing out the casting irregularities to increase airflow. but if you dont know that much about that, do some research or take it to a machine shop, otherwise you will mess the heads up. a common power gain for the tbi is to swap a 4.3 v6 throttle body for the smaller 2.8 tb. the added airflow increases power output noticeably. you'd get way more out of the 3.1 with the larger 4.3 tb.

[paxter]

If you're pulling the heads, I'd take them to a machine shop and have them pressure tested and checked for warping. Not a big deal but you'll have it apart and be replacing the gaskets anyway. Replace the valve guide seals also. My head gasket blew, so I took them to the shop, had them decked and the valves re-seated and the guide seals replaced and it was around $250. When you set your valve lash (adjust valves) you tighten 1 turn after clearance is removed. Spin the push rod with on hand as you tighten with the other (you'll feel it touch) and then tighten 1 more turn. Once you do a few its actually pretty easy.

[pearl91chevy]

when i was adjusting the valve lash earlier i must have not tightened them down good enough.. i would tighten them till no more movement, then go back no more then 3 min later and they would be loose again..

[pearl91chevy]

and about the 4.3 throttle body, could i also add a spacer on there to get a lil more out of it?

[34blazer]

Quote: Originally Posted by pearl91chevy

when i was adjusting the valve lash earlier i must have not tightened them down good enough.. i would tighten them till no more movement, then go back no more then 3 min later and they would be loose again..

thats because the lifter bled down. if you go too tight you'll wipe the cam, id relash them

[34blazer]

Quote: Originally Posted by pearl91chevy

and about the 4.3 throttle body, could i also add a spacer on there to get a lil more out of it?

it didnt really do anything for me. it will cause the airfilter assembly to hit the hood, and its a pain to adjust the fuel lines up 2in more

[pearl91chevy]

Quote: Originally Posted by 34blazer

thats because the lifter bled down. if you go too tight you'll wipe the cam, id relash them

so lossen them all down again till theres play and tighten them back down till no play?

[34blazer]

Quote: Originally Posted by pearl91chevy

so lossen them all down again till theres play and tighten them back down till no play?

tighten them down until zero lash, which means thats theres no play between the pushrod and the lifter/rocker. then preload 3/4 turn.

[pearl91chevy]

ok im really confused but becasue i dont know what ur talking about..
when u said i could wipe the cam, that means destroy the cam correct? and i dont wanna go to tight when tightening them?..

but in other words tighten till no play left, and then tighten another 3/4...

[34blazer]

Quote: Originally Posted by pearl91chevy

ok im really confused but becasue i dont know what ur talking about..
when u said i could wipe the cam, that means destroy the cam correct? and i dont wanna go to tight when tightening them?..

but in other words tighten till no play left, and then tighten another 3/4...

basically when you wipe the cam, all or most of the lobes are wiped off and the bottoms of the lifters are concave

yes

[1988S10]

wipping a cam out sucks trust me. i learned about setting valve lash the hard way.

[booeman]

do some port work as long as you have em off and maybe a 4.3 tb

Ive got my heads off and noticed a cast fin running towards the valves from the intake manifold, I'd like to do some porting on the intake and I'm wondering if I should leave the fin alone. I was also thinking about maybe increasing the valve sizes, what I have now measure 1.72 " intake and 1.425" exhaust. is it worth the time and trouble to go with larger valves? I'm going with a 4.3 tb and a 260 or maybe a272 cam and 1.6:1 rockers. sorry about hijacking the thread.

[34blazer]

Quote: Originally Posted by booeman

do some port work as long as you have em off and maybe a 4.3 tb

Ive got my heads off and noticed a cast fin running towards the valves from the intake manifold, I'd like to do some porting on the intake and I'm wondering if I should leave the fin alone. I was also thinking about maybe increasing the valve sizes, what I have now measure 1.72 " intake and 1.425" exhaust. is it worth the time and trouble to go with larger valves? I'm going with a 4.3 tb and a 260 or maybe a272 cam and 1.6:1 rockers. sorry about hijacking the thread.

dont grind the bulge down too much, as it helps steer the airflow into the combustion chamber. if anything "shark fin" it, and blend the bowls. remove the casting marks and that should yield some decent flow. you're not going to be able to go much bigger on the valves, it might be a waste of money.

[pearl91chevy]

now im scared i f'ed my cam up..

[34blazer]

Quote: Originally Posted by pearl91chevy

now im scared i f'ed my cam up..

did you run the engine like that?

[pearl91chevy]

run the engine like that when? i have ran the motor in probly 2 monthes, but when it ran it was fine..

[34blazer]

Quote: Originally Posted by pearl91chevy

run the engine like that when? i have ran the motor in probly 2 monthes, but when it ran it was fine..

when you lashed your valves too tight is what i meant.

[pearl91chevy]

i decided to pull the whole intake off..

[fordktpjoe]

You know, I never did understand that "valve lash" thing myself. I was told to adjust them in my old 307 with the engine running, back them off until they started ticking, them tighten them until they stopped, then go another three quarters turn (maybe it was a quarter turn, been a LONG time!)...well the engine wouldn't even run at that adjustment, so I backed 'em off, tightened them until they stopped ticking, and left it at that. She ran like a Swiss watch after that, maybe 60 v6's are different, don't know.
Please don't flame an old man, this was YEARS ago. I just remember it clearly because I was pissed that what everyone told me didn't work!

[seafarer12]

Thats how I always adjusted them on the small blocks I had. 3/4 turn after they stopped ticking. I never had a problem doing it like that. Anyway you do it its a lot easier than adjusting valves on a solid lifter cam.

[34blazer]

Quote: Originally Posted by seafarer12

Thats how I always adjusted them on the small blocks I had. 3/4 turn after they stopped ticking. I never had a problem doing it like that. Anyway you do it its a lot easier than adjusting valves on a solid lifter cam.

i guess it takes years of experience and a keen ear to lash valves with the engine running. ive done it that way, it worked but the preload was a little off when a checked it later on. hydraulic lifters are more forgiving than solids, so i agree with ya there