383 Vortec/TBI Build Thread

[Daveo91Burb]

Starting a thread for my build - just took the bare block, heads, and some other parts to the machinist today!

In a nutshell, it's going to be a 4.030 bore x 3.75 stroke, 383 cid, 4-bolt block from a '90 3/4 ton burb (one piece RMS). Eagle stroker, cast steel crank. Original rods, rebuilt. Speed pro hypereutectic pistons, approx 9.0 CR. Vortec heads, pretty much stock (already have them). GMPP 4 barrel intake for Vortec, with adapter for TBI. Enlarged 46 mm TBI unit, 454 injectors. Also using a complete roller valve train, possibly including cam, from a '96 vortec 350. Already have all that stuff or most of it anyway.

You must be registered for see images attach

You must be registered for see images attach

 

[crazy4offroad]

Sounds like a good tow build although I might have chose TBI heads for a better bottom end. What's your machine shop going to charge? What all are you having done?

 

[Daveo91Burb]

I think total is in the neighborhood of $1600 for the assembled short block. He'll hot tank/block prep, bore, clearance for 383, rebuild rods, order all the parts, etc. Install cam bearings, etc. Balance. Not sure if he'll line bore it or not. Same guy that did my Corvette motor - still runs awesome five years later. Works out of his garage, not much overhead.

 

[crazy4offroad]

See I'm at a crossroads. I could spend the same for my 2-piece rear main oil seal 4-bolt main block to go through the same procedure, or I could order a Summit 383 block, already bored and clearanced, 1-piece rear main seal, 4-bolt mains with caps and bolts, already set up for the roller lifter spider and cam bearings installed, for $699 shipped to my local UPS shipping location about 15 miles away. Then order an Eagle rotating assembly with cast crank for $799 and be in about the same ballpark. Or if I wanted something that would see over 6,000 rpms a lot, go with the Eagle rotating assembly with forged crank for $1,159. Of course that still leaves a lot yet to do, cam, heads, etc but I just don't trust my local machine shop after asking for hot tank/magnaflux for a pair of Vortec heads, then if no cracks 3-angle valve grind, new seals and locks, guides checked and heads decked. When I got them back one head had a big crack right in the middle between cylinders. I called and asked WTF and he said it would be OK. I've had nothing but problems since installing them. Post back how well your shop does their work, but I think I'll be ordering my stuff and go that route.

 

[1987 GMC Jimmy]

Oh, and what are you doing for a fuel pump?

 

[Daveo91Burb]

See I'm at a crossroads. I could spend the same for my 2-piece rear main oil seal 4-bolt main block to go through the same procedure, or I could order a Summit 383 block, already bored and clearanced, 1-piece rear main seal, 4-bolt mains with caps and bolts, already set up for the roller lifter spider and cam bearings installed, for $699 shipped to my local UPS shipping location about 15 miles away. Then order an Eagle rotating assembly with cast crank for $799 and be in about the same ballpark. Or if I wanted something that would see over 6,000 rpms a lot, go with the Eagle rotating assembly with forged crank for $1,159. Of course that still leaves a lot yet to do, cam, heads, etc but I just don't trust my local machine shop after asking for hot tank/magnaflux for a pair of Vortec heads, then if no cracks 3-angle valve grind, new seals and locks, guides checked and heads decked. When I got them back one head had a big crack right in the middle between cylinders. I called and asked WTF and he said it would be OK. I've had nothing but problems since installing them. Post back how well your shop does their work, but I think I'll be ordering my stuff and go that route.

Yeah, I went through a similar thought process. I had good luck with this guy before, so I went with what I know. He even did the Vortecs for my Vette back then and actually found cracks in both heads - one of them he could deal with but the other was too far gone and he found me a better core to use. Yeah, I think you have to be able to trust your shop to feel good about it. I might have done the same thing if I were in your shoes. Good luck.

 

[Daveo91Burb]

Oh, and what are you doing for a fuel pump?

I know it seems weird, but I think I'm going to be able to use stock pump, stock pressure. TBI 454s and 350s used the same pump and pressure, I believe. So with my 454 injectors that flow quite a bit higher than the originals I should be OK. At least that's what the tuner I'm using tells me. He says it's a lot more difficult to get the chip burned right if you're changing both flow and pressure parameters. If he can get enough flow without changing pressure that should make the job easier and hopefully more bulletproof. We'll see!

 

[yevgenievich]

I have seen recommendation to change the fuel pump if going for more than 300hp or so. Pressure can stay the same, just need a better pump.

 

[Daveo91Burb]

I have seen recommendation to change the fuel pump if going for more than 300hp or so. Pressure can stay the same, just need a better pump.

I think I've seen those recommendations too but from a physics standpoint not sure they make sense. If pressure stays the same, and no other variables change such as pipe cross section and material, bends, etc. then flow rate would also stay the same. Maybe it's a duty cycle thing, though? At any rate, I am thinking about replacing the pump, if nothing more than to just increase reliability. I have no idea how old it is and makes a pretty noticeable whine. I know I've read on here some suggestions for fuel pump brand/model, but can't remember what they are????

 

[1987 GMC Jimmy]

I believe that the late TBI BBC fuel pumps are higher pressure and the earlier ones are the same as an SBC, but I'm not a hundred percent. Word on the street is that the Walbro pump is good. If you could rebuild your current sending unit with a good pump like that, you'd be doing pretty well.

 

[Daveo91Burb]

Ah thanks, Walbro is the brand I was trying to remember. I was thinking Wells, but it was definitely Walbro in the posts I read. Yeah, pretty sure you're right - '94 the BBC TBIs switched to something like 30 psi or so. I'm staying away from all that stuff, the injectors I bought are 90-93, P/N 1708304, 74 lbs/hr, designed for a low pressure of 13 psi-ish.

 

[yevgenievich]

As bigger injectors are installed with higher flow rate and the duty cycle is increased, more fuel is used. The fuel pressure would start dropping if the pump is not able to keep up. Later model vortec ac delco pump or the common walbro 255 can be swapped in.

 

[Derick C.]

Im definitely going to follow this thread.

 

[skysurfer]

Later model vortec ac delco pump or the common walbro 255 can be swapped in.

Walbro's 190lph pump is a better match for a mild 383. They list the 190 as being able to support up to 500 hp and you don't run the risk of overwhelming the return line and building false pressure.

If you're looking for a Walbro, don't trust that good price you found on Ebay. The following is posted on the Walbro site:

"Due to a large volume of Walbro Fuel Pump forgeries now being sold on Ebay, Amazon and other websites, WalbroFuelPumps.com has made a decision to not only wholesale to retailers but to also provide the public with a secure place to obtain authentic Walbro Fuel Pumps.

If you see a lower price elsewhere and wonder if you are getting genuine Walbro, just remember we will price match any Walbro Fuel Pump. If you are looking to purchase a Walbro Fuel Pump you can buy here with confidence. Why buy anywhere else?

(Free ground shipping anywhere in the USA and great express and international rates too!)"

 

[Daveo91Burb]

Walbro's 190lph pump is a better match for a mild 383. They list the 190 as being able to support up to 500 hp and you don't run the risk of overwhelming the return line and building false pressure.

If you're looking for a Walbro, don't trust that good price you found on Ebay. The following is posted on the Walbro site:

"Due to a large volume of Walbro Fuel Pump forgeries now being sold on Ebay, Amazon and other websites, WalbroFuelPumps.com has made a decision to not only wholesale to retailers but to also provide the public with a secure place to obtain authentic Walbro Fuel Pumps.

If you see a lower price elsewhere and wonder if you are getting genuine Walbro, just remember we will price match any Walbro Fuel Pump. If you are looking to purchase a Walbro Fuel Pump you can buy here with confidence. Why buy anywhere else?

(Free ground shipping anywhere in the USA and great express and international rates too!)"

Possibly as you were posting this I was visiting the Walbro site and saw that same message. I'd be glad to buy directly from them, but I cannot figure out which 190 pump to buy and really can't even find any buttons to buy any 190 pumps at all. Their website leaves a little to be desired. I could buy a universal 255 or I can search by vehicle to get an OEM equivalent, but that's only 109 LPH, not sure it would be sufficient for my application. Anyone know exactly which model number of Walbro 190 would work in an in-tank Chevy application?

Thanks for the help, everyone, I think I'm on the right track with this, just need a little more info.