Questions from a new driver about 235 L6

[wolffcub]

I just got my truck on the road officially mid this week and i have a few questions as for I am not sure if some stuff is normal or not. Motor is fully rebuilt and has Fenton headers and dual intake. When I aggressively approach around 3000 RPM i get this very loud raspy sound right from the engine area. Its hard to say for sure if its the exhaust sound from under the hood or something mechanical. Its almost ear deafening depending how i approach it. If i work into it slowly its not so bad but still loud.

It could just be what the fenton headers do but im not sure.

I will try to get a video of it today and post it up.

What are most of you guys hanging around for temps?

[wolffcub]

And just to let you know i do have a cross pipe installed between the 2 exhaust runs. That being said the sound is still from the engine bay area. It almost sounds like a exhaust leak on a truck when you pin it. I checked for leaks but found none.

[NEWFISHER]

When this noise happens and you are still on the throttle, does it seem to have additional power? The cam profile may be apart of what you are experiencing. Mine comes on at 4200 rpm and screams like a banshee, but pulls you back in the seat on my 250.

[wolffcub]

lol im scared to go over 3000! Cam is new but a stock grind.

[OrrieG]

Here is the stock 1954 235 dyno figures. What year is the engine, early models had splash oiling, starting in 54 (I think) they went to pressure oiling systems?

[wolffcub]

it is a 1955 engine and does not have the splash design.

When the sound is present there is no change in vibration whatsoever. I cam across a post from 2012 that some people were saying it could be bad mains but i don't think its that.

[wolffcub]

it possibly could just be the tone I am getting from my exhaust design after it leaves the headers. Almost want to swap to a stock exhaust i still have from back in the day to just see if it goes away, but its so much work.

[Dan in Pasadena]

I hate to be a potential party pooper but has this engine even broken in since the rebuild?

[wolffcub]

had it running a bit on the chassis and did a minor break in. Been driving it now for about 5 days. 3 days as a test period prior to my inspection and 2 days after. Been easy on it and have had it out on open roads to accelerate and let it decelerate for lots of miles.

Any other recommendations? Why you asking? Think i might have done something wrong?

[G&R's57GMC]

I hope you used metal timing gears and not the fiber cam gear.

These engines are happier below 3000 rpm as the peak torque occurs between 1600 to 2100 rpm , once past 2500 the torque curve drops off .

On my '56 the pistons sound like they are swapping cylinders above 3000 rpm

The engine temp generally runs around 160*, Hot weather may bring it up to 180* .

[Dan in Pasadena]

All I know is these old straight sixes do not like a lot of RPM in stock condition and there's no point in thrashing them to higher RPM cause you don't get much results from doing so.

I'd have recommended looking up break-in strategies for a freshly rebuilt engines BEFORE you, "aggressively" did anything.

[wolffcub]

guess i should say "more aggressively" not aggressively as in foot to the floor. Got a new proper rpm gauge and it gives me a nice smooth reading. The rasp is at 2800 rpm and as far as i can hear after taking the weekend to hunt it down is coming from the exhaust down pipes. I think it just happens to be a resonance im getting at that rpm. I do have a cross flow pipe installed down the line and i will make some caps and try it with it removed as see what happens

Put about 100 miles on it this weekend and on my way home from a car show it was strange but its almost like someone flicked a switch. The thing pulls much harder now. and seems to run quieter at the higher rpm's.

The fuel consumption seems was high but could be due to it breaking in