mcollinstn

Understood. That makes it much simpler. The 525sc is a "known quantity". Good motor. Stock pulleys should give you right around 5 pounds of boost. If your motor is "stock" and makes less than this, you either have a blower in need of freshening OR you have a slipping belt OR you have a manifold leak.

Are you using a "damped" gauge or at least a liquid filled gauge? Cheapo gauges can not only be inaccurate, but can do everything you describe. Have you checked the gauge against a known calibration, and have you checked it for smooth movement? Internal burrs on the little brass gear rack can cause stick-slip and jumpiness.

This would seem to indicate that your boost pressure was NOT fluctuating as the gauge seemed to show. Erratic boost pressure will show up as erratic output.

Well you sort of called the gauge a vacuum gauge in the first part of your post. Then you said it was showing 2 to 3 pounds of boost. That doesn't exactly jive as I have an Auto Meter vacuum gauge in my middle drawer right now and it don't show no boost. That's why I asked if you were running a combo gauge (I actually like combo gauges). Apparently you are.

Thank goodness. Those guys should be able to provide some good info.

Those can slip, for sure. But if your pulleys are clean and straight, and your belt tensioner is not binding up somewhere, you shouldn't be experiencing much slip.

No need to be sorry. If you were only allowed one post, then you could be sorry, but you get to keep posting all you want.
And there was nothing wrong with your questions, you simply asked questions with no supporting info or basis from which to answer. If I just wanted to rain on your world, I would have done so. But since I want to try to help answer your (good but poorly supported) questions, I told you what info you had omitted. I also threw in some daggers cause I am probably not as tolerant as I could be.

Grumpy? I prefer to call it well-seasoned. Possibly even stinky.

mc

dykstra

iTrader: (1)

well seasoned,,,, that's great!

Thirsty Turtle

[QUOTE=Wildchild212]#1 I have a 525sc all of the components of an sc, would like to know the pulley size.
QUOTE]

I did a search and came up with 5.5" as stock? Those that were looking for more boost were running 2.5"-3.0", but recommended an intercooler.

Bruce

Griff

5.5 lbs of boost is stock.

Top pulley is 3.5" and Bottom pulley is 7.0" stock on 525sc

A 3.0" top pulley will give about 7 lbs of boost.

Wildchild212

That is great news. The pullies we tested with where a 3.5 on the blower and a 4.75 on the crank. I now have the 7.0 on the crank but cannot afford more dyno time.

Griff, Do you know off hand what the belt size is? Obviously my belt is to small for the 7.0 pulley.

Mark.

Thirsty Turtle

They should give you a free pull for the mix-up on the pulley size

Wildchild212

My dyno info is on a floppy disk and my computers floppy drive does not work. However here are the specs of the motor from top to bottom.

stock 525sc flame arrestor. 1050 dominator carb running 93 jets square . a 177 weiand blower w? a 3.5 pulley on top and a 7.0 pulley on crank.( was running wrong pulley @dyno time. pulley was a 4.75) rectangle port heads with 1.900 standard length inconel exhaust valves. 2.190 severe duty intake valves. Crane cam, lift intake @ cam 312 @valve 530 exhaust @cam 324 @ valve 551. cam timing @.005 intake open 5* btdc closes 43* abdc max lift 109 duration 228* exhaust opens 57* bbdc closes 1* btdc duration 236* Ground w? a 112 center lobe. piston are 8-1 compression w/ 4.28 bore. felpro gaskets all the way around and a high volume oil pump.

Wildchild212

That would would be great. probably not going to happen.

Griff

That would definately expalin the low boost reading. They were probably correct.
The specs you posted were almost identical to a 525sc. Is your cam a custom grind on the 112 lobe sep???? All the #'s are the same as the 525sc cam except for that. Stock crane cam is 114 lob sep???
Carb jetting is also on the lean side. Stock jetting is 98's squared. I would go bigger if I were you. Nothing will kill a blower engine faster than being lean.
Other than that, the only differences I see are the .030 overbore and the CR you listed is 8:1. Stock is 7.5:1. Both will only add power. If thre Cr really is 8:1, then you mightwant to keep timing down to 32* Stock is 35*

You should have a solid 525-535hp engine.

Wildchild212

Griff. Yes, the cam was ground to a 112. The dyno was telling us that the motor was running rich, that is why I re jetted. That however was with the smaller pulley. I will put the larger jets in now. I set the timing at 32* total for the higher compression. Thank you for all of your help.

Mark