Those risers will be fine, but you have to watch out when you idle for extended periods of time. You must clear it out ,,,, meaning put it in neutral and rev it up every five minutes or less. this keeps water from walking up the the tail pipes. I would jet that thing on the FAT side. And as for timing ,,,, well I would go no more the 28* , But MT can help you with what his buddy ran for timing. But remember each motor is different in that aspect due to alot of variables. Oh and it sure looks nice in the boat, motor and bilge

Summit racing lists the same springs for both the 132561 and 134561 cams. Does that mean I could re-use my springs?

Yes. Just make sure they are set up correctly. As far as timing goes, i can tell you this. Back when i had 177 blowers on my 454s, they had dart aluminum heads, in the area of 8.75 :1 compression. The way the previous owner set them up, was with an 18 degree advance bushing in the distributor, with 34 or 35 deg total timing, no water stats. They ran great that way. Never hurt them.

I have spent some time on the dyno with various timing curves on supercharged stuff with mike tkach. What we learned, was the engines liked timing at high rpm, and didnt like it at low rpm. Basically, different than what most NA engines like for timing down low, at least at full throttle.

We first ran this particular engine with timing locked at 34 deg. That setup has worked for us in past. Then we played with programmable curve. We removed nearly 10 degrees of timing in the 3000-5000 range. What we found, was actually an increase in torque numbers, as well as a reduction in exhaust temperature. Once we started bringing the timing back in, in the upper rpm range, the engine loved it. Going from 34 to 35 deg at 6500, netted about a 20hp gain, as well as cooler egts.

Too much timing down low, esp with a roots or whipple, capable of full boost at any rpm, can get you in trouble. Engines are more likely to detonate at peak torque, than wot.

Would it be wise to run the engine on the hose and make a chart of the timing in 500rpm increments? Then I could get my DUI recurved at Davis if need be.

Put the boat in the water if your going to do that, or at least back it into a boat ramp. Problem with leaving it on the trailer in the ramp is the angle the boat is at for the carb. The water hose is ok to idle but will NOT supply enough water for High RPM.

The octane of the fuel has alot to do with it as well as far as timing. Higher octane, slower burn, more timing needed, as you need to initiate the combustion process, earlier, due to the slower burning fuel. And of course, the higher octane, is more resistant to knock. It can withstand more cylinder pressure before detonation happens. Theres really a ton of factors that come into play, but its all about lighting the spark at the right time, and again depends on many variables. The dyno is where this comes in handy tuning this area, and thats actually what dyno's are meant for. Not bragging rights, or to compare others build combinations.

I'm sure back in the days before knock control, map sensors, and modern engine management, these engines had to be setup, that if in fact, the customer ran lesser grade of fuel, the engine wouldn't self destruct, so they played it safe on timing. Usually giving up a good amount of power/effieciency, to prevent immediate failure. Today, most modern engines, will adjust timing, based on things like IAT temps, map vs throttle position, coolant temp, knock sensors, and so on.

I'm not familiar with DUI setups, and how they are curved, or can be curved. Generally, you'll find you want a good amount of timing at idle, at least around 18*, with a fairly "stiff"' curve up until max timing/rpm. This is an engine combo, you really don't want to "bring it all in at 3000" type of setup. Here is a 525 timing graph. It doesnt bring max timing in until 4000. I would even consider delaying that another 500 rpm on your combo.

26 childish back and forth posts out of 40 posts have been removed. No value to the thread and just a rehash of the same bickering.

Its terrible that somebody posts looking for advice and then has to sift through all the BS to get to any technical opinions.

STOP or be prepared to be stopped by the Mods


Oooops. This was supposed to go in the other thread.

I think you posted on the wrong thread.

Don't mean to derail the thread but does the OP have offshore engine mounts? If not might want to look into that while engines are being swapped.

I run 91 octane, ethanol free fuel. No ifs, ands, or buts. The DUI people will re-curve the distributor to whatever curve I want for a small fee. I really want to make sure this thing runs properly.