vetteguy75

Is it better to change spark plugs going from the top of the engine? Or would it be easier to jack up the car, place them on jack stands and go underneath the Vette?

4-vettes

I find on my 77. Some of each. Although I can get them all from the top. Much easier to see most of them from underneath.

Bikespace

I had to do a mix in my 79. It's really a chore.

In my 80, with headers, it's easy from the top!

Mr D.

All from the top on my 73 AC car. Just need to get creative with tools. #2 under the AC pump I use a plug socket and box end wrench.

Jud Chapin

Re my '76, all but the 2 backs from the top. Not a fun job.

hdeyong

I agree with most. The easiest way is to have access from above and below.

BKarol

I did the above and below, then installed LTH and switched to short plugs. Tired of underneath so purchased this at Lowes for $8. Just slid over the plug and attack from the side with an open end wrench. Easy now to do plug changes from atop. I insert a small thin piece of rubber on the end that comes in contact with the insulator.
https://www.lowes.com/pd/Kobalt-XTRE...cket/999996262

ctmccloskey

I change all 8 from the top in roughly twenty minutes (when Cool) on my 1968 BB 427 with headers. The only semi-tough one is #7 and it is still easier from the top. I use a standard 3/8" ratchet with the spark plug socket and have no problems with all but #7 and that is because the Power Brake booster gets in the way a little bit.

Cmurray79

Both. Front 4 from the top. Back 4 from the bottom

wwiiavfan

I’ve used just a regular old box end wrench on a few of the plugs. This is with side pipe headers.

augiedoggy

same on my 74. sidepipes help.

Elcransonator

Just did mine ('73 non AC originally, Vintage now). I got all the even number/passenger side from above in about 20 minutes. The odd side I couldn't get any from above. It's so tight on the driver's side I couldn't even get my hand down there to back off those wing nuts that hold that shiny cover (shield) over #'s 5 & 7. The booster, master cylinder, alternator, and the tubing on my car make that side beyond tight.

Speaking of those shields over 5&7, 6&8; what are they there for and do most of y'all **** can them or put em back? I didn't want to be accused of going "bubba" around here so I put them back on. Again the right side was a piece of cake because you can get to it from above. The left side was a different story. I slid under there and took the wing nuts off pulled the shield out of there no sweat (thanks to my new Quick Jack). I had to bend those tabs that the shield attaches to because they were in the way of my spark plug socket-BIG MISTAKE! So I changed those two plugs out chop chop and went to put shield back on. Little did I know that bending those tabs back to their original position was not so easy in such a confined space. It is doubly hard because you are trying to line up the holes in the shield to the tabs via a mirror since you are underneath car and can't see the holes directly. I could get the back one in but not the front one and vice versa, etc etc etc etc. I spent about 8 hours yesterday trying everything I could think of to get that mf'er back on with no luck. I finally got it back on this morning after taking that bolt out that holds front tab to engine block (with wing nut still attached to shield). That gave me enough wiggle room to get that rear wing nut in. The moral to my story is DO NOT BEND THOSE TABS! Use an open end wrench or whatever instead.

67:72

'72 BB with power brakes and A/C...

71 Green 454

I hear ya....on my '71 BB with manual brakes and A/C, 1,3,5,7,6 & 8, easy peasy from the top. But 2 & 4 , remove right front tire and access from under.

calwldlife

mine required from top and bottom with a variety of lengths and tools

Don77

On a 77.either from the wheel weels,or underneath. Several with top access but why bother. If I’m takin a wheel off, might as well get them all…….and check the brakes

kossuth

Ditto except no power booster.

interpon

Great point on plugs..
one of my first lessons on spark plugs and China parts..
NGK all the way as i could not find AC Delco in 'original' length.
Plugs are cake compared to OEM wire replacement... i go top and bottom to access..but can get all from top.
https://www.corvetteforum.com/forums...-question.html

Elcransonator

Update: After changing plugs, the car ran real strong for the first 15-20 minutes then on the way home it developed a miss. It was most noticeable at low rpms like taking off from a stop sign. It sounds like it's not running on all 8. The R44ts plugs (same as new ones I put back in) that were in there didn't look bad so I'm thinking about putting them back in there to see if the miss goes away.

Also, as I was inspecting the old plugs I noticed that one of them was a R45ts. Not sure what if anything that means. Maybe a simple mistake at the parts place where the PO bought the plugs. I know the R45ts is a slightly hotter plug but not by much. Any ideas?

interpon

How old are your spark plug wires? moving them around may have compromised them. if it were me..
- replace wires if older (RA has a very good set of AC Delco ORIGINAL wires still available..)
- find your correct plug and go to NGK not China AC.. mine was UR4.
ac delco says r45TS for a 350 but cross-reference gives both UR4 and UR5
https://ngksparkplugs.com/en/part-finder