Rods 'n' Sods - UK Hot Rod & Street Rod Forums banner
1 - 20 of 44 Posts

·
Registered
Joined
·
78 Posts
Discussion Starter · #1 ·
I'm soon to start building a 383 with a target of 500bhp/500 ft/lbs, and from a fair bit of research I have come across several combinations that should do the trick.

I've got my donor block which is from a '90 GMC Vandura which from last night's investigations is a 2 bolt, non roller block... at least it has a 1 piece seal going for it.

Having bought the donor car, broken it, retained the V5 and trans for BIVA reasons (two major components from the donor and all that malarkee for age related plate and pre '93 emissions etc) I'm pretty committed to using this block, especially as it was low mileage, virginal an ran perfectly before I removed it.

So... a few questions if I may.....?

From my research it seams that the threshold for needing 4 bolt mains is circa 500 bhp to be safe, so I guess I'll need to get it machined for splayed 4 bolt caps??

Who in the UK is experienced and good quality for this type of machining work?

Also, my research also suggests that from about 450 bhp upwards, roller cams tend to be used, which is a problem, as I don't have a roller enabled block.

It seems as if a roller cam is good for about 20bhp gain on a like for like spec motor. Is there any way of equipping a non roller block with a roller cam, or any other suggestions of how I can make up the loss of power from having to use a flat tappet cam without just going for a crazy cam profile which will ruin flexibility?


My intended spec 'was' before I discovered it wasn't a roller block was...

383
ARF 195 heads
10.5 CR
Comp Cams Xtreme Energy (12-433-8)
Forged Eagle Rods
Forged Eagle Crank
KB pistons
Edlebrock Perf RPM manifold
Edlebrock Thunder series 850 Carb
MSD etc, etc.


Thoughts, comments and guidance appreciate. Ta.
 

·
Exceeded sell by date
Joined
·
7,742 Posts
You can buy retro fit roller cams/lifters to fit the early blocks but they work out quite pricey. Your spec will depend upon weight of vehicle, gearing, converter, intended use etc.
 

·
Registered
Joined
·
78 Posts
Discussion Starter · #3 ·
I didn't realise you can retro fit a roller into a non roller block? Any links to these parts as a sample? Does a '90 block fit into the early catagory?? I always saw pre '86 (2 piece seal) as an early block?

The motor will potentially have a dual role.... initially, and primarily, it will be mated to a Porsche G50 manual transmission in a mid engined conversion weighing approx 1100 kgs.

With reference to weight and gearing.... I assume this is to calculate the best combination of torque converter stall versus cam range? If so, on a manual transmission car, this becomes less important...? Or have I got that wrong?

Intended use will be occasional weekend blast + RWYB drag days. Does need a small element of streetability though.
 

·
Registered
Joined
·
423 Posts
This-

Where the Chevy Rollers Are
The original small-block Chevy remained basically unchanged from 1955 through 1985. But in 1986 Chevy finally addressed that leaky two-piece rear main seal by making it one piece, and later added hydraulic roller cams to the 305- and 350ci passenger-car engines that retained the same 0.842-inch lifter diameter. The factory conversion to hydraulic roller cam added slightly taller lifter bosses and three small cast-in perches that mount a stamped-steel spider, along with a two-bolt cam retainer plate located at the nose of the camshaft to limit fore-aft movement in the block. While all passenger-car small-blocks from 1987 on were roller-cammed, light-duty trucks used this same iron block but stuck with a flat-tappet camshaft. This means the block comes with the casting provisions for adapting a factory hydraulic roller camshaft. At the most, you may have to drill and tap a couple of holes. We've even seen four-bolt main hydraulic roller cam blocks.

The hydraulic roller-cammed motors also come with a stepped drive face on the cam, which requires a different cam sprocket with a smaller bolt circle. This is the basic difference between a factory-style hydraulic roller cam and the standard early small-block Chevy flat-cam mount. So the idea is to use a later-model, one-piece rear main seal block with the factory hydraulic roller cam configuration. That way you can reuse the factory hydraulic roller lifters and tie-bar arrangement along with the factory-style cam timing gear. It keeps the price down to almost nothing and frees up more money to spend on a good aftermarket hydraulic roller camshaft. This is an especially good idea when stepping up to a budget cast 383-style crank, rod, and piston package

Roller Warning
One area where you must be careful with production-based small-block Chevy hydraulic roller lifters is with high-lift camshafts. According to Crane's Director of Valvetrain Research and Development, Mark Campbell, valve lifts of more than 0.530 inch at the valve with a 1.5:1 rocker can allow the lifter to fall deep enough into the lifter bore (because of the lobe's small base circle) that the steel retainer can lose its grip on the lifter body. This allows the lifter to spin in the bore and destroy the camshaft. In checking a few cam catalogs, it is possible to order a hydraulic roller camshaft with enough lobe lift (in excess of 0.354 inch) to create this situation, so just be careful. This is why Crane created a long-travel hydraulic roller lifter that will allow you to run a high-lift hydraulic roller cam with the stock lifter configuration. These eliminate the problem but are also much more expensive than OE replacement lifters. Another solution would be to run a 1.6:1 rocker ratio with a reduced lobe lift cam to accomplish more valve lift.

Read more: http://www.carcraft.com/techarticles/ccrp_0710_chevy_small_block/viewall.html#ixzz1ahEx2JCm
Read more: Chevy Small Block - Car Craft Magazine

Read more: Chevy Small Block - Car Craft Magazine
 

·
Registered
Joined
·
78 Posts
Discussion Starter · #8 ·
From reading the Chevy High performance article, the retro fit kit solves the problem. I trust that a post '87> non roller block can accept the pre'87 retro fit kit?

If so, we're laughing all the way to the 11's....
 

·
Registered
Joined
·
78 Posts
Discussion Starter · #11 · (Edited)
For the record, here are some pictures taken 7 minutes ago of the block - as shown, it is a 1990, 1 piece main seal, none-roller block with no casting provision whatsoever for factory roller equipment.





So, just to confirm, there is such a thing as a post '87> retro fit kit which will be okay to use in this block despite there being no casting pads etc?

Thanks.... just want to be certain as the parts website are very ambiguous about what a retro kit will or won't fit in terms of '+/- '87 or roller / non-roller block.

Nobody seems to acknowledge that there is such a thing as a post '87 non-roller block.
 

·
Exceeded sell by date
Joined
·
7,742 Posts
I would say ask Comp Cams if you want a certain answer but the retro kit is designed for blocks with no factory provisions so I can't see the problem? It's all about keeping the lifters on track in a non guided block rather than anything else surely? May be worth a quick e mail.
 

·
Registered
Joined
·
2,499 Posts
The factory roller cam lifters were individual so required the fitting kit to ensure that they didn't turn in their respective bores. The aftermarket kits use rollers on link bars to stop this happening. The factory lifters required the longer lifter bores. The aftermarket ones don't (in fact they wouldn't work in the roller blocks). A good set of lifters will cost about £450.00 if your using a solid cam on the street opt for the Hipo ones with pressurised oiling. You can use ARP studs in a 2 block which are as strong as a factory equipped 4 bolt but if you can go splayed go for it but you will require a line bore & hone of the caps afterwards. Bullet cams are excellent I run one in my engine. You can get 383 kits which use the 5.7" rod to avoid clearance issues too.
 

·
Registered
Joined
·
78 Posts
Discussion Starter · #16 · (Edited)
Thanks everyone for your input so far. I e-mailed comp cams today and await their response. I Spoke to Real Steel who suggested a pre'87 retro kit would work but the chap didn't sound 100% convinced.

As I'm new to this, I'm very much in the dark with these engines and feel a little overwhelmed with all the possibilities and combinations available. Some are saying 500bhp is easily achievable with a NA 383 whilst others are saying to get a real world proper UK 500 bhp on a dyno is a tall order whilst retaining any kind of usable bottom end....

I guess much comes down to the use the vehicle is intended for. I'd want to be able to fire it up, enjoy a lumpy 'lub-thub-wobble' idle and racy agressive feel, yet have it at least so it can be driven about at as low as 1500 rpm without dying a death and having some reasonable response without too much fuss, getting smoother and more switched on above 2,000 rpm and starting to come alive after about 2,500.

What I don't want is something that needs the clutch slipping at 2k rpm just to pull away without it throwing a wobbler. However, I am attracted to an LT-5 style top end screamer that's happy to rev it's nuts off, sound glorious in the process and pull like a train all the way up.

I don't understand the pros and cons (except clearancing) between 5.7" or 6" rods for example, other than the pistons would need to be matched etc. What are the pros and cons of either configuration?

I look at cam grinds and whilst I'm capable of comparing numbers, I've no clue as to what the real world affect with be with this duration, or that lift, or that separation etc. Would I want to use roller rockers too?

I guess I fall into the trap of not knowing enough to spec from experience therefore look at all the magazine and engine builder articles where 'this and that' motor was built and produced this and that results and trying to copy that, which I guess is a potential mistake.

How many revs do I need to shoot for at the top end? Do I say 6,200 rpm is fine and stick with torquier manifolds, greater low end flexability and hydraulic lifters etc, or do I get sucked into the attraction of pulling 7500 rpm with big cams, runners and solid rollers etc but risk an edgy motor below 2,500rpm?

Am I right to think carb, or should I be looking into some kind of fuel injection system, whether it be tpi or direct injection (?) etc.

Could really do with an arm round the shoulder. Thanks to everyone who has offered help on the phone and via pm so far, really appreciated - I want to do this right first time.
 

·
Administrator
Joined
·
9,855 Posts
For a street engine, go for big torque at low revs as this is where the engine will be 90% of the time.
7500 rpm screamers are ok for the track but any engine that revs high will always drink more too.

I'm no expert, but my 2p worth is;
Roller top rockers, yes.
Roller cam, yes but less essential.
Fi? yes if you can afford it, much more tunable, bigger torque, more mpg & easier starting.

500 bhp is easy if you spend plenty, turbo or super charger will get you there very quickly and be more streetable I think.

Adam Sayers is a font of info, so what he says is usually pretty good.
 

·
fat rotbox rodder
Joined
·
5,805 Posts
my 383 was built by ice.it has a flat tappet hydrolic cam dart, pro1 heads, victor junior inlet and 750 double pumper carb.it made 490 [email protected] revs and 465ftlb of torque at 4600.it has a lumpy tick over but is driveable around town and on a run returns 16-18 to a gallon at 70-mph in a 2700 lb car.i don`t know if this is of any help to you.
 

·
Registered
Joined
·
78 Posts
Discussion Starter · #19 ·
For a street engine, go for big torque at low revs as this is where the engine will be 90% of the time.
7500 rpm screamers are ok for the track but any engine that revs high will always drink more too.

I'm no expert, but my 2p worth is;
Roller top rockers, yes.
Roller cam, yes but less essential.
Fi? yes if you can afford it, much more tunable, bigger torque, more mpg & easier starting.

500 bhp is easy if you spend plenty, turbo or super charger will get you there very quickly and be more streetable I think.

Adam Sayers is a font of info, so what he says is usually pretty good.
Thanks - but what parts to spend the money on.....?

I know what'll happen... I'll get the hang of driving if, pull some solid 11's etc and get bitten by the bug and want more and more - you know how it goes.

As I'm likely to want to upgrade in the future, I'm concious that the foundations shouldn't be compromised at the initial build up stage, hence my thoughts towards forged crank, rods and pistons etc and the best fasteners money can buy etc.

I looked at NOS systems for a bit of fun research, but it would seam that to get efficient returns on them, you either need to build a motor that is compromised when off gas but great on, or vice versa in terms of cam choice, intake volumes/velocities etc.

What's the score with blowers in a cost versus gain war compare to other tuning items?

Any good resources for me to go and research and learn from?

What style of Fi is commonly used.... I'm guessing TPi as direct injection doesn't fit will with gen 1 head technology etc?

Just hungry for knowledge really about how to build the best bang for buck super strong motor with upgrade potential without having to buy everything again because I was at the limit already for the base components.
 

·
richard rawlplug
Joined
·
8,132 Posts


had this set up on my non roller cammed (1968) roller cam equipped small block..
 
1 - 20 of 44 Posts
Top