compression test results? please interprit them for me

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79elky454ss

Greasemonkey
Sep 30, 2007
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ohio
I just compression tested my donor 1988 suburban 454, wide open throttle, all plugs removed and got readings consistently 155-165 psi this car ran well despite setting 5+years. It did not smoke on start-up or driving. Carried 50+psi oil pressure. My idea is to clean, paint, desmog, put a torquey cam intake and carb combo, hi-vol oil pump and roll in new rod and main bearings. My ? is based upon the comp test and other observations. Is this gameplan seem logical for this engine? Also please suggest cam grinds if you dont like my choice of truck/rv type shaft.
Thanks Greg
 
compression looks very good !
id check the mains & rods but if clearance is ok , why change?
put a good true roller timing chain, a decent cam, get the carb tuned youll have plenty of torque with that 454 . I woulndt pull the heads for now .see how it runs after those mods ,i'm quite assured youll like it as is !
Dan
 
Sounds ok to me. I would recommend staying with a mild cam with a wide lobe separation angle. That engine probably has between an 8:1 and 9:1 compression ratio and a wide LSA will help trap low RPM cylinder pressure. Plus, the peanut port heads will not breathe well at a higher RPM anyways, so a bigger cam will be down on power everywhere compared to a large one. Look at Comp's Xtreme Energy line or similar fast ramp cams offered by the other major cam companies. You want a LSA number higher than 110 degrees. For example, my XE262 has a LSA of 114 degrees and the low end is unbelievable, plus it has a good idle too.
 
454

i looked up comps xe 262 cams and they have the norm street one with the 110* ,112*, 114* the later 2 are for computer controlled engines and 4x4 trucks. thats what i found out by browsing their catalog.
 
Yeah, but the computer controlled cams will work fine without a computer. This is only from my own experience as my 355 has had 2 different cams in it, both with the 114 degree LSA and I have been very happy with them. The 280h Magnum cam in my AMC 360 has been less than streetable and not as fun to drive on the street as the xe262 in the 355. It may be a parts combination problem in the 360, but it does not make the same kind of power the smaller cam 355 does. I am not a fan of the Big Block in a street application, so I only have experience with the small block. Hopefully someone else here who knows more about them will chime in with more information. Just remember that too much cam will probably make less power than stock, not more. You need to take into consideration your compression ratio, peak cylinder pressure ( a product of cam timing and static compression), and head flow. Remember that cylinder pressure varies with RPM, and a lower peak pressure at lower RPM's will make it sluggish on the bottom end. Picking a cam designed for a higher RPM range than the heads can support will only result in trading off low rpm pressure ( where the heads are most efficient) for high rpm air flow ( that the heads cannot support). Try getting a hold of a good dyno sim program for your PC to help you with your cam choice. I did this and wound up with a very good combination of parts for my car. It's only around $100, which is cheap compared with the cost of doing multiple cam swaps.
 
Thanks guys, I think we are on the same page, low rpm, high torque, very streetable. any manifold suggestions? hood clearance maybe an issue.
Greg P.S. the suburban made the ultimate sacrifice saturday, the 454 is on the stand 😀
 
me again,just checked out compcams site the xe series cams all have 110 LSA in durations from 250, and good price at summitracing(30 miles to the store). Also lifters timing set etc... Summit brand stuff is some cheaper, Is it good quality? thanks Greg
 
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