Installed new heads and cam in my 1990 C3500 farm truck 7.4L

[Yamaben]

These are the stock 14092360 heads. The combustion chamber volume measures 117cc. Although my speed shop guy said he has seen these heads vary up to 120cc. I measured the used (compressed) head gasket with calipers. The head gasket measurement is the least accurate measurement in the math problem, but The compressed gasket is pretty close to .029" and 4.34" diameter. Close enough for me anyway, and I calculated the stock CR of this engine at 7.78:1

I didn't get a picture of checking volume of the new chambers, but it would have looked the same only cleaner.

 

[Yamaben]

Anyhoo, the forums are right when they say stock CR is about 7.8:1. I guess I just needed to be sure.

For reference:

Stock deck height/piston dish = 13cc
Stock combustion chamber size = 117cc
Stock compressed gask thicknes = .029"
Stock head gasket diameter = 4.34

TL;DR Stock CR is very close to 7.8:1

 

[Yamaben]

My new 3931063 heads had a combustion chamber of 99cc. Mortec said they should be 101cc, but after truing them at the machine shop the chambers must have gotten a little smaller. Also, I have had more than one person tell me the Chamber volume can vary even on heads of the same casting number due to production tolerances, and I have no problem believing that.

I had the machine shop pressure test, reman the valves, install hardened exhaust seats, teflon valve seals, and true them on the mill. Mac Weld in Carbondale, Illinois is the only machine shop I trust.

Assuming my compressed gasket thickness will be the same, the smaller chambers put my CR at 8.81:1. I was shooting for 9:1, and this is close enough and probably perfect for running cheap 87 octane fuel. I was hesitant to go over 9:1 CR for fear of spark knock on cheap fuel.

 

[Yamaben]

Good luck finding the lift, duration, and centerline specs of the stock 1990 454 truck cam. I wanted to measure it for myself so I would have a baseline to compare the new cam to.

 

[Yamaben]

I am apparently unorganized enough that I managed to throw away the scrap of paper that I wrote it all down on, but at the time I realized that the Comp cams specs were almost identical to the stock specs.

I knew I was ordering a Comp cams stock replacement cam, but I really thought it would be a little hotter than the stock cam. It turned out it really is pretty much a stock replacement cam though, but I had already bought it, and I didn't want to wait to send it back, so I just decided to use it. I REALLY wish I would have used this cam though. Brian Harris from TBIchips.com was trying to tell me to order the hotter cam, but I thought I knew better because I'm so fcking smart and I don't trust anybody and I never listen to good advice. There. I said it.

I will run it on the Dyno and see what kind of torque curve I get. I'll probably be happy with it, but if I ever decide to change it I will get a roller cam next time.

 

[Yamaben]

Removed the other head and dropped the oil pan. The rear main seal and oil pan gasket were both leaking bad. You can see I removed one of the coolant plugs on the new head in the background. The older casting number didn't have the threaded boss for the auxiliary fan switch, which I was going to use for electric cooling fans. I couldn't get that front plug out so I had the machine shop drill it out for me.

 

[Yamaben]

This is just a shot of the 4 bolt mains as I was changing the rear main seal and oil pan gasket. 10069286 block. It has "pass hi perf" cast into it. The knock sensor and oil pressure sender are sticking out on the sides. I really feel proud of myself whenever I get an older Chevy engine to seal up without leaking.

This really is a pretty stupid arrangement for getting an engine to seal oil. I work on Japanese motorcycles for a living, and these engine covers and 2 piece main seal would just be heresy to the Japanese. Some little Japanese engineer would have to kill himself if he ever designed this mess. Was awesome when designed in 1965, but jeez this was 1990 for heavens sake.

 

[Yamaben]

Got the rear seal and oil pan installed. Installing the new cam with lots of assembly lube on the lobes and journals.

 

[Yamaben]

Checking the lift, duration, and center line of the new cam. It was spot on what the cam card claimed. Comp cams is great company, and they make great products. Buy Comp cams.

My wife sent me that post card of a naked woman from Hawaii when she visited one time. I treasure it.

 

[Yamaben]

Here is a shot of the gasket surfaces and the piston crowns cleaned and ready to go. I ball honed the upper cylinders to enhance the cross hatch even though that is not really super effective without removing the pistons (figured it couldn't hurt). I also ran a tap down each head bolt hole to clean the sealer out of the threads.