semoorma

On my 88 5.0 rebuild I got the GP40P heads installed and a Summit shorty exhaust headers SUM-G9072 (what a bear to install) hook-up. Now I just tried to install what my NAPA shop recommended AutoLite spark plugs AP25's and I can't get them started in the holes. The plugs look the same size as the old ones. What am I doing wrong, is there a special technique?

wbrockstar

When you try to screw one in,is the header tube or flange too close to the spark plug hole or is it positioning the plug at an angle thats making the spark plug contact the header as soon as you begin inserting the plug into the head?? I know gt40p's have a different spark plug angle compared to E7,gt40 & aftermarket heads.The heads listed above have a spark plug hole thats angled away from each header tube whereas gt40p heads have a plug hole that comes straight out which usually requires 90° boots on the plug wires.The following was a question someone asked at Summit Racing.

Q: Will these headers work with Ford GT 40- P heads ?
Asked by JANICE on January 14, 2018

A:Thank you for your question. The Summit G9072 Short Off-Road Headers for Mustang are not compatible with Ford GT 40-P Heads.

This could be the reason why they're not fitting??


The following link has alot of gt40p head information.
http://forums.corral.net/forums/5-0-...1014187?page=1

semoorma

Thanks, about killed myself getting them on. Not to mention it look impossible to put the plugs in. Soooo, after church today its off to Summit I go - about a 60 mile ride. Thanks again. ps. people at Summit said they'd work as I specifically said they were going on the GP50p's. Beware of know it all clerks.

Can you recommend a set of reasonable exhaust heads?