[SIX8YAK]

I have a freshly redone 428 stroker that I've had in my Grand Prix for a few months. The car is seemingly testing my resolve in every way. This is the third time a motor has been in the car since 2017. Long story.

Notable specs:
428 stroked to 460
10.4 compression
AED 950 carb
Performer RPM intake
KRE D port 85cc
Bullet Ultra Dyne HFT 288/296 @ .006, 231/239 @ .050, .485/.507 @ 1.5 on a 112
Pertonix HEI dizzy
Long Branch manifolds

Anyway, the car was delivered to me after dyno and was running lean and low on timing. The dyno showed 32 total but I believe we found the light to read 29 total before we started messing with the timing and carb. The car wouldnt idle until about four minutes of throttle play, needed to be at about 1100 or so just to stay running and it sounded chaotic. Once it was driving well enough, it would heat up quickly during intermittent stops at lights or idling, jumping from 190 up to 210 in a matter of minutes. Had the off idle stumble then the surging pull after you hit the gas, plugs showed lean as well.

After timing light and carb adjustments, we now sit at 34 total timing with 14 initial. I havent hooked up vacuum advance yet.

After adjusting the timing the car was noticeably better in every way. Starts easy, idles right away with minimal peddle play (non choke carb) at about 650-700 and has very good throttle response. These positive steps are countered by a very cold running engine and a rich exhaust scent.

I have a 160 t stat, and today driving from a shop I went about 8-10 minutes before the water gauge moved off 150 degrees. That is insane to me, and when I finally got to my house I grabbed my infrared meter and aimed it at the heads, intake crossover, exhaust manifolds, and radiator. The intake was about 165-167, the exhaust manifold off the head 174, and the rest was even cooler than that. This is very difficult for me to understand and pretty nerve wracking to possibly be incurring all of this extra wear on something that I havent even been able to truly enjoy.

Admittedly I'm a novice and while I understand well plenty of engine workings, my experience and tuned eye to adjust things correctly is lacking, and I'm already concerned about the 150 or so miles I've put on the car with it being in various stages of unhappy, not enough fuel, now seemingly too much, trying to listen for detonation, etc. So while adjustments need to be made, I dont want to start swinging in every direction if I dont have to.

So I come looking for some hard advice on which way to move. Timing, increase it further if able, or decrease it? I'm aware of retarding the timing to get temps to increase, but the motor seems to really like the bump up.

I was concerned with the t stat but if it was stuck open wouldnt I end up getting more heat than this after driving a bit? It seems to never get above 175 no matter if I'm around town or on a county road. Ambient temp today was probably just shy of 80 degrees.

I'm not dumping raw fuel out of my exhaust but like I mentioned the gas smell is strong. Cam overlap is nothing radical IMO, it's a UD grind 231/239 @ .050 and the lift is just a touch over .500. On my AED carb the float level looks good (centered), there doesnt seem to be anything that jumps out at me under the hood, no outside leaks or "loading up" after I shut the car off.

I'm in the process of wiring up a AFR gauge as well.

Thanks!

AR

[JLMounce]

You've got a couple things working against you that you need to take care of.

First order of business is the vacuum advance. A street car needs that extra advance at idle and cruise operations for efficiency and cooling. Get that hooked up properly with between 10-12 degrees of additional advance.

Second is the carb. Street cars need a choke. If it's cold blooded now in the middle of the summer, what happens on a nice fall day when it's 50 degrees? Wire up a choke

I don't really understand your statement regarding how the engine is operating temps wise. It sounds as if you've got that under control if everything is running around 170 degrees or so. Remember, that the thermostat rating is the minimum temperature, not the maximum. Most thermostats are not completely open by that minimum rated temp, so it's not unheard of to see a car with a 160 degree stat to run around 170 degrees. If that's where your engine is running, that's great. If you have a standard 50/50 coolant to water ratio, you're not boiling that until around 240. In fact, I run the same heads you have and I find that they like more heat, in the 195 range to make best power. You might consider running a 180 degree thermostat, especially if your drives are short. That'll help with moisture in the oil. If your drives tend to be 20+ minutes at a time, it seems like you're in good shape.

Your total timing with the KRE d-port head is in the ball park. Engines with tight quench may want as little as 30 degrees of total advance, while engines with poor quench may want more than 32 degrees. Your statements about the timing being off however are somewhat concerning. Do you have a balancer that is not accurate or possible slipped?

[SIX8YAK]

Thanks for the response.

The car had a few things in disarray and that included the vacuum lines, so that's why it hasn't been messed with yet. I do have the T fittings and extra hose to get it done, but I wanted to get the AFR in first so I can log the differences while I tune instead of doing it twice.

If I wasnt clear, I want the car to run warmer than it is. I do have a 180 t stat I can put in but seeing as it had no problem soaring above 160 prior, I was hoping there was room to tune it into running a little warmer without taking the stat out. Seems 160 t stat is a pretty common thing yet I dont hear of many people running this cool..