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Old 04-14-2011, 03:23 AM
Dyna Dyna is offline
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SBC 406/421 build advice needed for a 58 Suburban

Hi Folks,

I need some help with our SBC engine build. Iím not new to engines, done several rebuilds but itís been original spec mostly and never a Chevy engine. Itís been Cadillac V8, Ford V8, Volvo, VW etc and the last time we made any serious engine build for power was well nearly twenty years ago, and that was a VW Beetle 2.3liter turbo making the ľ mile in 10.69. It was an all original full body, interior, chrome etc 1958 Beetle except for engine and box, real wolf in sheepís clothing.

Now we have a 58 Suburban and well the 283 aint up for the task of an Autobahn stomper scaring the living daylight out of Beemers, Bimmers and Benzes. Hence I sourced a SBC 400 (2 bolt main), and modded the frame to take a Jag IRS with 2.88 posi final drive. The 400 will be coupled to a overdrive box, but Iím not sure yet which one, the goal is 2000 rpm at 70mph and that it should be able to do 150mph.

This is a sleeper setup, so a few things are more or less set in stone.

1: Will have original Chevy script valve covers which doesnít have oil filler or breather holes
2: The 400 will get machined / tricked at the rear to be able to hookup a 283 breather pipe
3: Intake needs to be able to be machined to take a 283 oil filler pipe. It canít be a super high riser, somebody should be able to get fooled that itís original at a quick glance.
4: It will have a TBI EFI controlled by MegaSquirt II (possibly III), TBI is a 900cfm Holley 4-port, with 4 injectors (12R-11157B) 1 3/4" throttle blades. I have a 670cfm too but my guess is that itís way too small.
5: It will have a dual snorkel Pontiac GTO 455 69-72 air cleaner; big nice stocking looking and it will hide the TBI.
6: Will have short WP since I want to look stock for 58 i.e. dyno/alt mounted with original brackets on the drivers side, A6 compressor* mounted with original (well Corvette/Chevelle 65-66) brackets on passenger side, and finally PS pump mounted low on the drivers side.
7: Likely having 2.5Ē ram horn ala Corvette early sixties, they look the same on the outside as the 58 ram horns on the Burb
8: Will have a small body Megasquirt controlled HEI dist from http://davessmallbodyheis.com/ -- i.e. a stock 58 dist with modern interior and computer controlled ignition map
9: Everything will get painted factory.. .


Iím not building a street and strip engine. Sure I might take a test doing the ľ mile but that is maybe once or twice during the time I will have the Burb. This engine needs to be streetable and produce loads of torque all the way from say 2000 to 6000 rpm, that is kind of why I went for a 400. Want to have that good feeling you get in a big cube engine. A feeling just getting whisked away from standstill effortlessly without really flooring the pedal, but merely touching it. Itís speed as and the ability to overtake like the car was on fire that is of high importance. Remember it will be a highway/Autobahn warrior .

Since itís going to be driven in Europe it can run on 100 octane pump gas (that is about 95 octane in the US due to differences in how octane is measured), I would although prefer to drive on 95 octane (about the same as 91 octane in the US) since that is about 30 cents cheaper per gallon, mind you we pay nearly $8 per US gallon over here Ė and yes it sucks big time!!


If we start with the top end things where a lot easier before simply not much to choose from, Iíve also forgot loads and kind of need your views of what I should go for. Been looking at heads, and if you donít want to go for cheapo ProComp head, the main stuff looks to be costing about 800 Ė 1400 assembled depending if you go iron or alu. This is for non CNC ported, but figure I could light porting, matching etc our self since we done that in the past. Looks like runner of about 210 Ė 225 should be sufficient for a 406 Ė 421 (depending if I stroke or not). Iím interested in hearing your view and arguments of what heads to go for, around the price bracket mentioned above, likewise what intake to match it with.

This assembly aint going to be stressed as an explosive street and strip engine will. Hence is it wrong to think we can go for cheaper parts on non critical parts i.e. lifter and rockers. From experience a breakdown there will not be catastrophic, compared to a breakdown in the rotating assembly. Thinking a retrofit roller cam, with ProComp hydraulic roller lifters (~$120), and ProComp roller rockers, thinking shaft but then there is not much stress on this engine so maybe not warranted to have them. Donít know what ratio to go for although, well itís a cam question and here is where I really need advice. What cam should I go for? Need some god advices of what roller to go for? And if I donít go roller what flat tappet would you recommend?

I know that the 2.5Ē ramhorn might hamper the setup quite severely, but how much will in hamper it? Iím going for a relatively free flowing 3Ē exhaust, dual the whole way back and with a cross over pipe. Iím also contemplating having exhaust dump vales such as the once sold by quicktimeperformance.com. That way I could just dump out the exhaust without any mufflers at ĺ gas or above i.e. overtaking.

Ah yes it would be nice with a good recommendation of what timing gear (type of mechanism) to go for and what model/brand to set for. Here I want good stuff since if this breaks it will get expensive. Well good doesnít mean expensive just reliable and does the job, and if necessary adjustable (depending on cam).

In regards to the rotating assembly I can see us going stock with 0.030/0.040Ē overbore just. Well of course blue printed, good quality stuff and so on but in all essence stock. However I feel that going internally balanced would be of great advantage, likewise getting better stuff would provide for an engine that will last. So Iím thinking going (forged) internally balanced crank, and I think also going from 3.75Ē to 3.875Ē stroke since the price is the same anyways. If I understood it correctly using 6Ē Scat H-beam stroker rods and you can still go with stock cam base circle and it would only require minimal if any modification of the block (correct me if Iím wrong). It would be nice to get your opinion on what crank and rods to use and your view why. Piston wise Iím contemplating forged or hypereutectic, forged is not that much more expensive but all small expensive in an engine build adds up. Reason why I think hypereutectic might be enough is that; we will never shoot it with nos, nor will we rev it like idiots. Anyways what is your thoughts, what to go for and why? Remember we are in recession so as everyone else we arenít made of $$ .


Really big thanks in advance for everyone reading my post and possibly giving advices.

Dyna


*The compressor might be the newish pro6ten. Still kind of like the old A6 better since it looks just massive Ö.
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