454 Rebuild

[jacksubc20]

I need some help and opinions.  I am planning to rebuild my 454 in a 78 C20 Suburban.  I will use the truck to pull a trailer and car (approx 7,000 lbs).  It's got a TH400 with mild shift kit behind it.  Other than that it appears to be stock.  There are oil and trans coolers on it also in addition to the 4 core radiator.  I have a few questions after reading a bunch of the posts here.

The engine will be bored (as little as possible) and plan on using flat pistons so I can continue to use 87 octane.  My plan is to put and Edelbrock Performer Intake and 800 cfm carb.  My first question is will the 800 cfm be too much?  I have also planned to replace stock exhaust manifolds with headers and a completely new exhaust on it.  Should I use 1 3/4" primaries or 2".  Second, what size exhaust pipe would maximize tourque throughout RPM band--I think 3" should work?  I don't think the truck came with cats and I don't plan on using any after rebuild (currently not on it).  Third question, what cam will give me most torque gains at all RMP levels.  I've seen a lot of posts about the Comp Cams Extreme 250, but what lift and duration would fit situation best?  Finally, should I consider replacing the stock torque converter with a TCI High Torque Towing Converter?  Is there anything esle I am missing or should consider?  Again, thanks for all your help in advance!!

Cheers,
Jack

[stepside454]

Obviously flat tops is the right choice, youll want to stay under 9.0:1 compression. The performer intake is a good choice, but for carb Id personally stay with a Qjet, find someone in your area who is good with tuning em. Qjets are perfect for your application if set up right.If you decide to go with an aftermarket Carb Id suggest a 750 CFM Vac. Sec., I personally prefer Holley over Edelbrock, your choice. Also a 4 hole spacer under the carb will help low end torque if you choose to go with an aftermarket carb.
 As far as headers & exhaust, full length headers will help your low end some & maybe even some MPG, stay small tube, as far as exhaust, no bigger than 2.5"
Yes a RV type convertor can help MPG also.
My choice for a cam for this application would be an Erson RV15H part #E120201
 214/214 .492/.492  112 LSA it has an advertised operating range to 4250 RPMs but itll run to 4600 RPMs with out a problem especially with matched springs. John

[jacksubc20]

Thanks for the info.  I have another cam question...I called the Comp Cams help line to ask their opinion of which cam would best fit my application--predominantly used for towing 7K lb trailer w/car, sometimes driven daily so good mileage and driveabilty are important also.  Other info I was asked for is as follows:

454 bored .030 over
Edelbrock Performer Intake
750 cfm carb
Headers no cats
TH400 w/mild shift kit
TCI High Torque Towing Torque Converter
9:1 Compression
4.10 rear gears
28-30" tire

I called 3 times and got 3 different answers.  Not too far off base from eachother, but still 3 different answers.  

11-238-3 Xtreme Energy 262 in/270 ex, .50 dur, cam lift 218 in/ 224 ex, valve lift .504 in/.510 ex, lob sep 110, 1300-5600 RPM

11-231-3 Xtreme Energy 254 in/262 ex, .50 dur, cam lift 210 in/ 218 ex, valve lift .505 in/ex, lob sep 111, 1000-5000 RPM

11-235-3 Xtreme Energy 262 in/270 ex, .50 dur, cam lift 218 in/ 226 ex, valve lift .505 in/.515 ex, lob sep 111, 1400-5400 RPM

Can anyone shed some light on this for me.  I am by no means a cam expert.  Thanks again for any help!

Cheers,
Jack

[TORQUERULES]

with flat top 2 valve relief pistons 119cc heads .030 over 454.

yur lookin at 7.8:1scr.

dual 2.5" or single 3" exhaust.

with 7.8:1scr. A XE250H cam will be best.

If you have extra money ($500.00US extra) hyd roller cam like comp XE252HR
the hyd roller cam is worth avg 48 more lb ft from 2000-3500rpm.

494 bft @2000rpm vs 538 bft @2000rpm

had a 305
have a 357
want a Big Block