stingr69

Engine has been overhauled twice at minimum. It has had an overbore and at least one hone and rearing job after that. Ring wear at top shows where bore was reused. Looks like a good deal to me.

augiedoggy

Thanks,
Yes thats exactly how it was described to me and what I see with the ring at the top... It was rebuilt in 2004 and in 2008 (with only 12-13,000 miles since ) he decided he wanted a bigger cam so he had a shop "refresh it when installing the new roller cam to replace a smaller roller cam. He thought it was .030 over but it appears to be .020 over which is a plus.
Turns out the heads and lifters have that 12-13,000 miles on them too. I may use my retro lifters out of my 355 unless my better pushrods are the correct length for the lifters in this engine.

augiedoggy

Yeah im still confused.. took a look with another caliper today and also looked at the bottom of the pistons. They certainly have ".030" stamped into the bottom and they look to be very tight in the bores compared to the std bore 400 I had bought the first time around. The most I measure is 4.152 and mostly 4.150 I realize some of this variance is likely my cheap calipers.

* Edit* Clearly my calipers are either junk or something else is amiss because I can fit a .018 feeler gauge between the cylinder and the piston so it cant be that bad afterall.

augiedoggy

I am going to be swapping the pistons to the 18cc Keith black dished version to get the compression up to 10:1 which is worth 20hp and almost 20lbs of additional torque according to my dyno software.

I have a cam question.

Currently the engine has the comp xr270hr-10 cam
https://www.compcams.com/xtreme-ener...all-block.html

I am considering this cam https://www.summitracing.com/parts/sum-1223

for a couple reasons.
One being the hp gain and very small torque loss.(another 20hp gain and 3lbs of torque loss)
Also I feel like since I have the same xr270hr-10 cam in my 355 that it will be like going a step down in a 400? Doesnt the rpm power band move down like 500-700rpm when installing in a 400 vs 350? ive always read that you want to go one step up on the cam choice for a 400 vs 350.
I would actually like a little more lope at idle than I currently have if anything. But at the same time I dont want that to be the deciding factor as it is still function over form here driving the thought process. I have read a little about how the ls firing order was developed to reduce the stress wear on the crankshaft and bearings and that it will help slightly with cylinder cooling though these benefits are likely small.

I have a 1800-2200 rpm stall converter in the 2004r transmission ill be installing with this as well as the 3.55 rear end. Will this be ok for the summit cam being that the 2500+ stall recommendation is likely for a 350 application or am I wrong in this thought process.

These two changes should increase the HP by about 40 and torque by 20 while still keeping the powerband under 6000 rpm. I may not race the car but I do recognize the difference in neck snapping power on the street vs "OK" power... I am honestly starting to worry about the new 2004r holding up with all the additional potential torque.