defiant1

Need to know what size threads the Edelbrock performer intake has to install a fitting to hook the transmission modulator line to and for the brake booster as well.

I am not 100% sure on NPT sizes and how they translate to other dimensions.

d1

JamesPDX

I'm working on this also. I'll share what I found. I’m using the Performer Olds 350 (EGR) #3711 manifold and my own EGR setup because the engine is in a 1987 Caddi. The threads are 1/8 NPT in the port runners of this manifold.

The carb (#3711) base has a port in the rear for the main brake assist input and the brake assist may need another port for the assist switch on some models. It is not clear, but the trans uses a manifold vacuum port near the carb base. I’m also, installing EPA components to pass the DEQ requirements. I’ve modified these to improve the clean air output. It worked like a charm on the 350 engine before I installed a 403 with additional improvements (where I am now). Everything is running better than expected.

I’ll share what I find on this shortly. I need to complete the DEQ inspection ASAP. I attach a photo in progress from last week.

Olds 403 in progress-800x600pix.JPG

TripDeuces

Most NPT sizes are roughly 1/8 to 3/16 larger in size then the corresponding NPT size when looking at the threaded hole. So a 1/8 NPT has a threaded hole size that is roughly 1/4 or slightly larger in diameter. 1/4 NPT has a 3/8 threaded hole, 3/8 NPT has a 1/2 hole, etc, etc. These are rough estimates only so take it for what it's worth.

defiant1

I believe I wound up using an 1/4 NPT (3/8" threads) adapter. I used the old 90 degree barbed fitting and attached it to the adapter, as I could not find an 90 degree 1/4 NPT fitting locally.

d1

JamesPDX

The information given above is correct. Because the pipe thickness can vary somewhat, the size description (i.e. ¼” NPT) may require one of a couple of different taps for the actual hole size to allow for the fitting. Adapters are also, available to allow smaller NPT connections to be installed in larger size taped holes. Engineering is not a simple read for what to do or to use in a specific situation, as there are so many variables involved. However, any one of the following links should provide good information concerning pipe threads that you might review.

http://www.engineersedge.com/hardwar...pe-threads.htm
http://www.plumbingstore.com/sizing-...pe-thread.html
http://www.engineeringtoolbox.com/np...ads-d_750.html
http://www.fairburyfastener.com/xdims_pipe_threads.htm

Additional information on the top side vacuum connections can be found at

https://classicoldsmobile.com/forums...n-diagram.html

This has been a very big help to me. It includes a link to AutoZone technical information as well. You would be further ahead to read these, if you are not clear on the connections or the purpose of each.

wally74

hello Defiant1,
Can yoy tell/show me witch 1/4 NPT (3/8" threads) adapter you used. On my new edelbrock perf. intake I have the same promblem with fixing the transmission modulator line. Maybe I can get this adapter in Holland, otherwise I've to order it in the States.
Grtz,
wally

defiant1

I went to my local NAPA auto parts store and pick up basically what is in the attached link:

http://www.amazon.com/gp/product/B00...XB1080DSAS6T6G

Hope that helps.
d1

wally74

D1,

Thanks !!!!!!

wally