So i went to smog yesterday with my 1995 Ram 1500 5.2L Gas, Warmed the truck up for about 25-30 driving up the hill and back on the freeway and come to the smog shop and it did Pass the smog.

Now the guy there told me that the HC (PPM) @ 15mph Max was 118 , the Average is 45 and My truck had 82 (Meas), and he suggested to get that number 82 lower, He also mention to make sure i have

original dodge spark plugs and That HC beeing @ 82 is related to fuel,electrical.

Here is a screen shot of the paper received:



What you guys think about improving that number?

Thanks for any advice.
Regards.

 

Since you already passed this is not needed and I'm not sure if it will help with the HC but, I have heard of people driving at high rpms in a low gear to get the cat really heated up, to help with its efficiency. Other than that, yes, a tune up would help. How is your plenum?


P.S. My sister lives in Roseville.

 

Hello,

Yes, a tuneup will do it.

My Plenum, i think some years ago i check and i so some cracking but not major but there was small signs of oil in there but not much i may have to re-look.

Where is a good place to get a cheap set of Hughes plate and screws,gasket,etc everything that's need it? I guess ebay maybe.

Thanks.

Yes, i am in the border with Roseville city only 30 sec driving ), By the Mall.

 

Get the plate, etc direct from Hughes.

 

Ignore the plate, it's not the issue. Crap gasket from Ma Mopar is the issue. Gasket blows, plate gets room to move slightly and vibrate bolts loose. Dissimilar metals is not the problem, if it was it would impossible to put headers on aluminum heads which will reach 1000F vs our MAYBE 500F on the bottom of the intake.

 

So you think that the Aluminium plate will heat up way to much? that the plastic plate thats there now? Hmm, thats not going to be good for the engine i guess going from 500 f to 1000f.

 

What? Stock plate is steel and common belief is that it warps as it heats up where the aluminum doesn't. This is wrong. The 1000f i threw out is temps many performance applications see in the exhaust where it exits the motor. The 500f is an unrealistic number that the stock plate MIGHT reach.

I'm saying a good felpro gasket will fix a plenum leak

 

Yeah, I did the math on the plate movement, and it was in thousandths of an inch, so, no, that certainly isn't the problem. Its the BOLTS that are a hair bit too long, along with a crappy cork gasket. A good fel-pro gasket, new, shorter, bolts, would likely solve the problem as well. The hughes plate IS a good product, if you have the money, go that route, if you wanna go cheap, just to the gaskets and bolts. (or, simply but thin washers under the current bolts.)

 

I don't think the bolts are too long. Tq check pulling mine off showed they were still properly tq'd and gasket wasnt blown. I think it's just as simple as a junk gasket that blows and the space between the plate and aluminium that was normally taken up by the gasket is now free and the plate vibrates in that space causing the bolts to back out.

Again, my own personal theory. I have no solid proof of this or anything. Might as well do the bolts for peace of mind unless you feel like experimenting for me.

 

If memory serves (because I'm too lazy to search this here forum for that copy of the calculation I remember posting) it's right around 60 thousandths of an inch of differential thermal expansion over the long sides of the manifold over a span of a couple hundred degrees. For the don't-grok-physics crowd, that .06" is distributed over the length of the manifold, so between any two (plenum pan mounting) bolts it's more like 0.015" on the long sides. I didn't bother calculating for the perpendicular motion of the short sides just because doing so would be superfluous. There's no problem there that can't be solved by using shorter bolts to overcome the shallow blind bore problem.

As shallow blind bores go, those in our intake manifolds are a lot cheaper than the other kind that you can't get rid of without a divorce lawyer.