Please look at the bottom of page where it says FINALLY about ignition system.
When looking at crate engines on line be sure to ask if their engine power numbers are SAE GROSS or SAE NET. A lot of engine builders list engines as Sae gross power which is how factory rated motors prior to 1972. In 1972 car manufacturers switched to sae net numbers which is easily half the reason power numbers listed for vehicles in 1972 were dramatically less than 1971. The difference is sae gross is power engine makes with no accessories (not even water pump), no air filter and no exhaust off their very large long tune headers that would never fit in a vehicle and no exhaust. Sae net is power at flywheel with all those components on engine as it would be in vehicle. This typically yields a number about 20-25% lower than those gross numbers. Multiply their advertised number by .75 and it’s much closer to what I estimate power at in the vehicle. Very misleading in my opinion. A 180hp 350 tbi motor makes a good 230-240hp using Sae gross math. Very few places advertise Sae net numbers. SAE NET numbers are what I will give you when calculating engine power from the specs provided so make sure you also look at the build of any engine online your looking at. if they are promising 300hp or more and using TBI 350 heads then they are either just lying or using SAE GROSS which you can never replicate in a vehicle.
Its hard to keep all the links good since stuff changes so much and parts so difficult to find in stock so I have changed my recommendations some.
NOTE: ANY ENGINE making over 230hp needs to have a fuel pump upgrade. The pump I used to recommend was https://www.summitracing.com/parts/ado-ep381 will support up to 450hp or pretty much the max engine you can run with TBI. But its near impossible to find anywhere. so I have changed recommendation to the Delphi equivalent which is FE0114
So here is my SBC recommendations for TBI.
- if you must have EGR for emissions testing then an ATK HP31 or HP05 motor. just deduct about 50hp from the power numbers they advertise for that engine. several sites sell the ATK engines.
- if you dont need EGR for emissions testing then ATK HP74 or HP90 using vortec heads they are capable of the power numbers advertised if you setup the throttle body and exhaust
with https://www.jegs.com/i/JEGS/555/513002K/10002/-1 and https://www.jegs.com/i/Edelbrock/350/8032/10002/-1 with Distributor https://www.summitracing.com/parts/aaz-84-1830 with coil http://www.summitracing.com/parts/pnx-d3002/overview/ with Accel plug wires http://www.summitracing.com/parts/acc-5114k/ and 8x https://www.jegs.com/i/ACDelco/065/R44LTS/10002/-1 using the bored 46mm TBI unit and adapter combination from sprperformance.com with upgraded fuel pump https://www.amazon.com/Delphi-FE0114-Electric-Fuel-Motor/dp/B000CGFUFW
This setup with custom chip and good exhaust is capable of 300hp and 360tq for a vast improvement over the stock 180hp 265tq 350 TBI motor.
I myself would upgrade the camshaft to https://www.summitracing.com/parts/sum-8800 without changing valve springs or https://www.summitracing.com/parts/sum-8801 with a set of LS3 valve springs, locks and retainers. https://www.ebay.com/itm/143652056384 which will get around the lift issue with GM iron heads. Which 8800adds 20hp and 10tq over that stock vortec 350 and the 8801 another 20hp and 10tq but it does shift the powerband a 1000 rpms higher so gearing and stall converter become more important but it does sound much better.
Custom chip is $360+$10shipping+6% sales tax https://harristuning.com/product/custom-tbi-chip/ or use discounts page https://harristuning.com/discounts/ and mail stock chip with a $300 money order to me and I will reprogram chip with new programming.
The reason is that TBI heads are awful. The vortec heads flow 25% more air through a smaller 170cc intake runner which builds air velocity faster than the larger poor flowing 182cc intake runner on TBI heads so vortec heads will make 25% more power than TBI heads at all rpms. Since a 383 is only 10% larger engine than 383 a vortec 350 will make more power than a TBI head 383. Next, TBI motors use a flat tappet cam and flat tappet cams are problematic at best and if you even want a 30k mile life span from one you have to add zddp to your motor oil. http://www.jegs.com/i/Eastwood/352/12269Z/10002/-1 for that old obsolete cam technology as modern motor oil no longer has zinc phosphate added to it. no such thing as a good flat tappet cam as they are problematic, obsolete technology that requires using ZDDP additive https://www.summitracing.com/parts/isk-zddp if you want that cam to last more than 30k miles. Case 1 of http://www.kirbanperformance.com/product_images/customer_support_item-_pdf-35.pdf is the important one. The only reason the stock camshaft lasted as well as it did was the very low duration and lift of the cam as well as the very weak valve springs. Once decent valve springs and decent cam are used the zinc issue becomes an issue.
For exhaust something like https://www.jegs.com/i/JEGS/555/31102/10002/-1 with
https://www.jegs.com/i/JEGS/555/31006/10002/-1 which needs 3x https://www.jegs.com/i/Walker-Products/948/90-204SS/10002/-1 as the exhaust is designed for a vortec truck which has 4 o2 sensors and we just use 1 with TBI and so the other holes need to be plugged.
SEE IGNITION NOTES AT BOTTOM OF THIS PAGE.
Big blocks are harder as no one really creates a good TRUCK version that I have found. most are more race oriented and the GMPP options have gone crazy on pricing.
So with Big blocks,
, I fix the 2 key issues facing those engines. 1. Compression ratio is stupid low at 7.75:1 and 2. Camshaft is equally horrible. So mainly for heavy duty trucks I clone the GMPP HT502 crate engine https://www.jegs.com/i/Chevrolet-Performance/809/88890534/10002/-1 which uses the same peanut port heads and makes 406hp at 4200rpms and 540lbs of torque with 500 available right off idle. I use a balanced 496 stroker kit.
https://www.summitracing.com/parts/esp-b18021060/make/chevrolet for GEN 4 blocks up to 1990
https://www.summitracing.com/parts/esp-b18020l060/make/chevrolet for the GEN 5 and 6 blocks 1991+
does need adjustable valve train
http://www.summitracing.com/parts/cca-1401b-16/overview/ for ball pivots
http://www.summitracing.com/parts/cca-4514-16 rocker studs.
http://www.summitracing.com/parts/cca-1401n-16/overview/ rocker nuts
this gives a compression ratio 8.75 to 9.0 depending on deck height and if anything is taken off the head to clean up the surfaces.
Then I run a little more camshaft than GM ran in the HT502
https://www.summitracing.com/parts/cca-k11-412-8 for the 1 ton trucks looking for that low rpm grunt. Cam will peak about 4500 rpms and pull another 5-10hp over the GMPP engine and same gain in torque.
https://www.summitracing.com/parts/cca-k11-445-8 is what I run in the 454 SS trucks or those looking to run them on out to about 5200 rpms and good for about 45hp and 20tq over the HT502 motor and pretty much the maximum you can run on the 2 injector TBI system. I run dual 2.5” exhaust on both setups. Stock manifolds seem to do just fine as many prefer that reliability on the 1 ton trucks that are towing and such.
https://www.summitracing.com/parts/slp-h426cp big block 10cc domed pistons for just keeping it as a 454.
The camshafts are difficult to find something TBI compatible and in stock. for a while now customers have had to contact comp cams directluy for those full cam kits that I have linked to from summit racing.
Finally, if you spending this kind of money for a new engine. Don’t skimp out on the ignition system. Don’t go using your 200k mile stock distributor and don’t get the chinese crap off ebay or even your local auto parts store. Currently only recommending Recommended ignition setup: Best brand Distributor from local autoparts store for a 1992 Camaro 350 TPI z28 which has roller cam from factory and coil http://www.summitracing.com/parts/pnx-d3002/overview/ with Accel plug wires http://www.summitracing.com/parts/acc-5114k/ as they have a tough outer covering and good low resistance to get that spark energy to the plugs for a strong fire. For spark plugs AC Delco R44TS for 1/2″ reach TBI style heads or R44LTS for 3/4″ reach aluminum or vortec style heads and with this ignition configuration .040″ plug gap. Skimping on this stuff typically just winds up giving us both headaches trying to figure problems out. Most of your stock sensors will be just fine but if you do replace them USE AC DELCO replacements. I can get them through my local advance auto. Typically takes a couple days to come in and doesn’t cost that much more. PLEASE PLEASE don’t complicate TBI with MSD or any other ignition boxes. They do not work well with TBI and can possibly cause a LOT of issues. Best just to avoid that type upgrade altogether. I don’t like working on my stuff more than once for the same thing and doubt you do either so do it right the first time.