Char-Broiled Aluminum Pistons after just 2500 Miles... Why?

[hurst1979olds]

Re: Char-Broiled Aluminum Pistons after just 2500 Miles... W

Does look like your alittle rich. Doesn't look out of the normal. But I don't see why you would need cam2. Unless you have 58cc heads, but with 64cc you will be fine with just regular 91-93 octane. Maybe cam2 for strip only.

 

[online170]

Re: Char-Broiled Aluminum Pistons after just 2500 Miles... W

Why are your cylinder heads off at the mechanic's after 2500 miles?

What cam are you running?

 

[Mistermastamind]

Re: Char-Broiled Aluminum Pistons after just 2500 Miles... W

Why are your cylinder heads off at the mechanic's after 2500 miles?

What cam are you running?

.465in/.488ex Camshaft. My mechanic says it's 292 duration. I don't know about that stuff. I can't remember the brand name of the cam, but I Bought the cam from Northern. The heads are currently off the car in the machine shop getting screw in studs and guide plates installed. The Magnum rocker arms were tapping very badly due to the camshaft ripping the press-in studs out of the heads. in the last 2500 miles my mechanic had adjusted and tightened the rocker arms about 10 times before he finally decided to tell me I needed to have screw in studs installed. Luckily my mechanic is honoring my warranty on all of this stuff. In my opinion he should have known to have the screw in studs and guideplate installed before bolting them to the engine in the first place. I had also previously broken/bent (2) pushrods.

 

[Mistermastamind]

Re: Char-Broiled Aluminum Pistons after just 2500 Miles... W

Does look like your alittle rich. Doesn't look out of the normal. But I don't see why you would need cam2. Unless you have 58cc heads, but with 68cc you will be fine with just regular 91-93 octane. Maybe cam2 for strip only.

I have regular 1997 305 Vortec heads off of a Chevy C1500. I was told that the 305 Vortec heads coupled to the 350 block would provide for better compression. My mechanic says that my motor is 10.5:1 or 11:1 compression. Once again I have no idea what that means. Does that sound about right?

 

[Mistermastamind]

Re: Char-Broiled Aluminum Pistons after just 2500 Miles... W

Looks super rich to me.


10:1 should be fine on 93 with no additives. The carburetor could use some tuning though.

My mechanic has mentioned to me that the 600 CFM carburetor was not big enough for my set up. I am currently having a 750 CFM rebuilt. He says that the Compression may be 10.5 or 11 to 1. He stated that with the 600CFM my engine was starving for gas. Does this sound correct?

 

[Mistermastamind]

Re: Char-Broiled Aluminum Pistons after just 2500 Miles... W

I made a mistake in my introduction and posted the same pics of the passenger side of my engine.
Here is a pic of the Driver side.

 

[jae]

Re: Char-Broiled Aluminum Pistons after just 2500 Miles... W

As others stated it looks as though you have an overly-rich condition, meaning you have too much fuel for the air flow / rate. Is he basing his 600 cfm carb too small on the the compression ratio, which he should be able to determine, from prior experience or the entire engine build?

I would run the 600 cfm carb and try to tune it, use a high-quality premium fuel, keeping the 750 on standby. One thing that would help is determining the actual compression ratio, it could be higher or lower than you think. And as others stated, timing plays a key.

 

[rustyroger]

Re: Char-Broiled Aluminum Pistons after just 2500 Miles... W

[/quote]My mechanic has mentioned to me that the 600 CFM carburetor was not big enough for my set up. I am currently having a 750 CFM rebuilt. He says that the Compression may be 10.5 or 11 to 1. He stated that with the 600CFM my engine was starving for gas. Does this sound correct?[/quote]

Your engine might not be able to take in enough fuel/air mix to make all its potential power, but with your carbon build up it doesn't have fuel starvation. Compression ratios over 10-1 will almost certainly require premium or super premium gas though.

Roger.

 

[Mistermastamind]

Re: Char-Broiled Aluminum Pistons after just 2500 Miles... W

Ok thanks for everyone's input. It seems that my old mechanic did not know what he was talking about. The 600 cfm carb turned out to be the exact carb I needed for my set up. In fact, my old mechanic never had the timing set correctly. A reputable engine building shop went through the engine and got everything straight by setting the timing, adjusting the carb, and adjusting the roller rockers correctly after having the Vortec heads machined. I'm clicking on all cylinders now baby. My new mechanics @ Betz Automotive on Jefferson Ave in Newport News, VA informed me that CAM2 race fuel is not necessary, though 93 octane is definitely neccessary. Below is a picture of my engine with a freshly rebuilt top end. Yellow powdercoated Chevy Vortec intake, Ceramic coated headers and the exact same 600CFM carb. Now that the timing has been set, the car starts as soon as the key is turned (Finally).

 

[81Regal]

Re: Char-Broiled Aluminum Pistons after just 2500 Miles... W

Glad you have it running right but why do you have a mechanical fan and what looks to be an electric fan?