Small Block & Big Block Chevy Specific - straight plug heads vs. angle plug heads

whats the diff. between the straight plug heads and the angle plug heads?? which one is better?? any pics that can show the diff. would be great, thanks

I was going to buy the long tube headers for my 89 trans am but in the description it said that it will only work w/ the angle plug heads, and i wasnt sure which ones i had so i ended up buying shorty headers!

if your spark plugs go straight in, perpendicular to the cylinder head, you have straight plug heads.

if the spark plugs go into the head at an angle, you have angle plug heads.

Not really rocket science

if your spark plugs go straight in, perpendicular to the cylinder head, you have straight plug heads.

if the spark plugs go into the head at an angle, you have angle plug heads.

Not really rocket science

i thought that was it, but whats the adventage of it?? are the straight plug heads newer??

I've heard if you're runnin headers, it's much easier to change plugs with angles plug heads

That depends, when I had my 406 with angle plug dart heads in the 3rd gen car, with headman long tubes it was a b*tch to change the plugs. I think a lot of it just depends on the way the headers are designed for your chassis.

Well, i have headman full lengths, i had the straights on it, it wasnt bad, but when i put theese andled plug heads on it i had to dimple one tube, i had to go out of the way and buy the accell header plugs to make it go the less painful way. There is no gain power wise if that is what you are asking.

so the bolt patter and everything is pretty much the same except for the plugs??

is that why when you go to buy longtube headers some say that will only work w/ angle plug heads??

The plug angle will change with certain combustion chamber layouts. The guys designing the head will try to get the spark in as close to the ideal location as possible. Sometimes that will involve changing the angle relative to the external plane. It isn't a case of one version being better, but more a case of that layout is the best compromise for that chamber design.

so the bolt patter and everything is pretty much the same except for the plugs??

is that why when you go to buy longtube headers some say that will only work w/ angle plug heads??

yes, and yes

Not much difference in performance unless using older heads with large domes then marginal. Look at airflow low to mid lift flow numbers, not plug angles.


If you have a 55 Chevy, angle plug heads seem nicer with most header designs currently available from an access standpoint.