I have a 55 F-100 with a Mustang II frontend under it and a 429 engine. I have replaced the normal 375 coil springs with the heavier 425 coil springs, but it is still much too low.
I am considering a set of QA-1 Coilover units, but with the length of the coilover springs I am not sure this will solve my problem. I was looking at the 1701-1900 springs with the shocks. Has anyone any experience with this setup or a similar problem?

 

I am no expert on this by any means, hopefully AX will chime in but.... are your lower control arms level to the ground to slightly downhill towards the tire end? If so you have your front suspension set correctly. Though longer/stiffer springs will raise the front it may come at the cost of improper geometry. Sounds like you have dropped spindles and the better solution may be to change to a set of standard spindles. If on the other hand if the lower arms are lower at the frame end and go uphill towards the tires you are on the right track. Hopefully someone will come along with a recommendation.

 

What is the angle on the lower control arms? Are they parallel to the ground? If so your issue is with the spindles and not the springs.

 

I have the standard spindles and the lower arms are point upwards towards the tires rather than parallel to the ground as they should be.

 

So much for the easy fix, sounds like you need more spring

 

Eaton Detroit spring has a good chart for stock style springs, It gives loaded spring heights and they will exchange springs if you get wrong one. As far as the coilover conversion , that would work too but you will probably need new lower control arms. Qa1 has springs up to 700 lbs for the conversion setup.

 

According to the set that I am looking at the lower A-arms and mounting system will work with no issue. And yes looking at the heaviest spring setup with this kit.

 

At least the QA1s will be a quality shock upgrade (single, double adjustables?), should be valving matched to the springs you use, don't go overboard on spring choice tho too heavy a spring will be as bad/worse than too light: ride hard/harsh, throw off handling, get the right ones. Coilover springs are inexpensive. Best thing to do is find a certified scale, truck stops, scrap yards, etc. Get two weights: one with the entire truck on the scale (gross weight), second with only the front wheels on the scale platform (front axle weight), driver included. (You can subtract the front axle weight from the gross weight to get the rear axle weight). Give the weights to QA1 for their spring recommendation.
If the front is a chinese clone MII the front springs are likely to not be the spec strength, sagged badly due to poor quality steel, not properly heat treated.

 

Thanks, yes they are double adjustable. I will run by the scale tomorrow and get both weights and then query QA1.

 

That's great! Singles (rebound only) would have been adequate, but doubles are that much better. I'd be curious to know the weights you get and what they say.