The Great Pumpkin - '71 Duster

So yeah, about that intake valve tick I mentioned in my last post. It didn't go away and was pretty loud last time I drove it which makes it hard to ignore. I ran a leak down test and it wasn't looking so hot. I guess I've known about it for a while. I did a compression check at some point in the last year and that cylinder (#5) was the lowest. The leak down confirmed it was the intake, I could hear the air coming through the intake runner and out the carb. Guess the head is coming off at some point soon. Not sure if I am going to pull the whole engine out - I might. Would be easier to check everything over, clean things up and re-seal it for next year.

Really though, the car seems to be running OK otherwise. I did address the lean spike I have at WOT by going 2 steps up on the carb jets and going back to the pink accelerator pump cam from the red one. I have not made any 'runs' since the changes but cruise A/F ratio did not seem to be affected much, maybe slightly richer but for the most part stayed the same. The pump shot was smoother with the red cam though, the pink one is kind of 'right now' then flat whereas the red one seemed to have better coverage. That's exactly how they are designed though so its good to have the experience under my belt and know the difference between the two different cam profiles. Might try a few others, I have a whole assortment of them.

So the valve tick issue got me thinking about the brand new (bare) RHS heads I have sitting on my shelf. Enough that I called Brian at IMM out in CA and talked with him for a bit about the potential of those heads and how putting them on would affect my current combo. I described my current situation and told him what I wanted to accomplish and he seemed to think it would be no problem with the RHS pieces. He even thought the LD 340 I have might work well and could potentially add some torque to the equation. It was good to talk to him, he was helpful and insightful.

I'm pretty much sold on having him prep a set for me but obviously that will entail changing some things around on the current engine. I have some of the parts on hand to do the job but I will need to get new head and intake gaskets, new intake rockers (have W2s now) and probably pushrods. IMM sends you the heads with valves, springs retainers and locks so that's all covered in the price. That also means I will have some checking to do - compression ratio and pushrods specifically. I can see a graduated burrete and a deck bridge in my future.

I'm actually really interested in making this change. I've seen guys with milder combos than mine go pretty deep in the 11s with RHS heads. W2s are great but mine are not ported which makes them sort of pedestrian. I don't zing the engine to 8 grand but that's where W2s really shine. What that means to me is that there's not much advantage to having heads with so much potential only to limit said potential by not porting them or running the rpms up where they make more power than conventional heads.

Thinking about selling some stuff off to finance this venture, namely one of my guitars that I rarely use. I could sell the W2s and probably come out ahead but I think I'm gonna hang on to 'em for now.

More to come.