Let the fun begin

[old truck guy]

Well the motor is in and running. Dave W sent me my start up bin and I took it for the first spin yesterday. Ran pretty good but rich. Got a new bin today with the first adjustments. My concern is this. In the past I've always relied on the temp gauge to view engine temp. With tunerpro I can now see what the computer see's. The coolant temp window at the bottom of the dash after warmup is registering between 98 and 103 (which Dave said is celsius) and the display is red. The temp gauge on the dash displays between 200 and 220 which if you do C to F conversion coincides with each other. I confirmed with my infra red heat gun last night and warmed up at idle it was registering 205 at the base of the water neck next to sensor. If I shoot it at the head next to my gauge sending unit I'm reading 185-190 which is about what the truck gauge is displaying. I used a new ACdelco 195 deg thermostat during assembly. Should I be concerned with this? Do I have a circulation problem at the neck? I was wondering if the bypass hose might be drawing too much coolant back to the water pump and bypassing the radiator. I used a vortec style water pump. Another possible concern I had during assembly was that I used a heated plenum vortec intake (coolant ports at the back of the intake) and the TBI intake gaskets were restricted as to where the vortec ones are not. Maybe this could be causing a temperature imbalance between the front and the back of the heads. I don't know. Looking for input.

Thx, Mike

[1project2many]

There is always a temperature difference between front and back of the heads. Cool water enters the block from the front, proceeds to the rear, rises into the heads, and proceeds forward. All the while its gaining heat. And the top of the manifold is where everything meets so the hottest water will be found there. The coolant passage under the intake allows water to bypass the heads and proceed directly to the water outlet. Its best to use the smallest ports possible for this passage. If the bypass hose and passage were allowing too much coolant to bypass the radiator you'd see an overheat problem. The hot coolant in the bypass wouldn't be able to give up heat to the radiator and would continue to heat up with each pass through the engine.

I have an intake without the external bypass passage which I want to use with a Vortec style pump. The original Vortec intake had a special thermostat design which would close off the bypass hose as the engine warmed up. I had figured out a method to install the Vortec thermostat in my intake using a thermostat spacer and a sleeve but I haven't gone any further with it. Does your intake have a straight bypass? Is there a restriction in the passage??

[old truck guy]

My intake is a crusader marine intake. It is pretty much identical to the gmpp vortec tbi intake without the egr provisions. It has coolant passage from the rear of the intake and a heated plenum. I noticed that the stock tbi intake gaskets have a heavy restriction in the rear of the gasket at the coolant passage as where the vortec gaskets are the full size of the port (surprised they even have a hole in the gasket at all considering anything other than a tbi intake has no passage in the rear of the intake). I tried pinching off the bypass hose while it was running and it had no effect. The plot thickens. It got hot on me tonight on the the temp gauge as well while sitting in the driveway running. Think the fan clutch may be giving out on me. It is a used vortec one that I got from the salvage yard while picking up some other parts. I think im going to try a 180 deg thermostat and a new fan clutch.

[Roadknee]

My 1995 K1500 runs down the road at 190 with a 180 Tstat in this warm weather. It will run around 183 in cooler weather. This is according to the Tunerpro display. I think your engine running 10 degrees above the thermostat is pretty normal, particularly with a new, tight engine.

I'm not familiar with the vortec bypass hose. Is it like a BBC or Ford that bypasses from the front of the intake to the suction side of the water pump? If so, I don't think you would need it. In the TBI trucks with a heated plenum intake, the hot water travels from the front of the intake to the rear, through the heater hose, heater core and to the suction side of the water pump. It is effectively a bypass hose.

I don't think the small holes in the rear of the TBI intake gaskets serve any cooling purpose. I always thought they were there for drain holes so you don't spill as much coolant into the engine when you pull the intake. Could be wrong though.

The title of your post would suggest you expect to be at this for a while. I think you'll find with the help of a professional the tune whips into shape pretty quick. You probably already experienced a noticeable improvement with the second cut at the VE table.

Could you comment on the valvetrain noise with the XFI cam and comp rockers? I'd sure like to hear a video if you get the chance to post one.

[old truck guy]

Where I live the temps range from below zero sometimes in the winter to 95+ sometimes during summer. I went with the 195 deg thermostat because it was stock and thought it would be better in the winter. I also thought this helped with fuel atomization, same reason to use a heated plenum in tbi.

As for the bypass, yes it is the same as a BBC. What I have learned recently though is that the vortec thermostat and intake arrangement closes the bypass when the thermostat opens. I've read that there are basically three ways to achieve bypass with vortec heads. One is to install the bypass hose which seemed to be the simplest but apparently is letting too much coolant bypass the radiator. The second being drilling holes in the outer ring of the thermostat but this uses the radiator as the bypass and I have read can lead to extended warm up time in cold weather. The third as you mentioned, is letting the heater circuit act as the bypass but from what I've read this only works on vehicles that don't have a heater control valve because it won't circulate when the heat isn't on. Does anybody know if 95 trucks have a heater control valve? I've never investigated.

As for the small holes in the rear of tbi intake gaskets, if I shoot the rear of my intake with my heat gun right now its about 15-20 deg cooler than the front, this is with no restriction. GM made those tbi gaskets that way for a reason and I've come to the conclusion that it is to restrict flow from the back of the heads which would increase flow from the front and equalize the temps.

The valve train noise is minimal. I hear a very slight chatter which I believe is the roller tip rockers. I think its quieter than a typical gen 1 sbc and so far my knock counts have been very low on 87 octane and haven't seen any spark retard. I'll try to get a video posted.