rebuilding a 4.3

doyoulikeithere · Post by **doyoulikeithere** » Tue Oct 04, 2011 12:30 pm

how much for a set of tweaked Vortec heads?

1Gary · Post by **1Gary** » Tue Oct 04, 2011 5:11 pm

Rule of thumb for intake runner cc size given a C.I.is C.I. x .5.So for a 262 X .5 = 131 cc.

Brodix still builds a aluminum 23 degree head.

Used parts are limited,but there are deals still out there:

http://www.racingjunk.com/Heads/2255422 ... tion-.html

This link covers all the different style engines and combo's build by Chevy:

http://www.enginebuildermag.com/Article ... y_262.aspx

We yrs ago build a forged common pin crankshaft bowie block 4.3 using the Brodix heads when we bought out one at auction when NASCAR drop the use of V6's in it racing program.The increase C.I. and centering the rods on the bores result in huge output gains.This was installed in a Chevette and on a throttle stop ran like clock work 10.90.It was during that research we found that the offset rods was a major deterrent because given the crank you could mod the rods to center them and then the offset would create pistons that had fiction on the bores or run the rods as is and then the rods would create fiction on the side of rod bearings.But......................As my race partner warned,it is expensive to be different.In fact because I insisted on this project when it was all said and done,it almost cost me my 20 yr partnership costing almost three and a haft times of a sbc.

The saving grace is many of the 4.3's where used in normal rotation for marine applications which has a strong parts source.For EFI's I would think they for tuning react the same as V8's for cam timing.Nothing much above 230 duration and lobe centers 112 better yet 114.As stated a they do respond to a long exhaust event.

The bottom line and the main reason why V8 swaps are more popular is the physics of smaller C.I. engines even with the best computer tunes is the torque curve with all small C.I. engines is higher in the RPM range as the HP output is.Dollar for dollar spent a V8 conversion will out preform the 4.3's for street or race use in a torque curve which using a V8 is key for street.That a V8 will give you the much needed torque in normally driven street RPM ranges to move a 4,000 pound van.

brokenwrench · Post by **brokenwrench** » Tue Oct 04, 2011 8:03 pm

[quote="doyoulikeithere"]how much for a set of tweaked Vortec heads?[/

where are you? i reuse nothing but the castings. All moving parts are new. my material costs are about $30 per assembly, all top quality aftermarket parts.

Rocker Studs ARP 134-7201 (metric base) $85.95
or
Whatever 3/8 by 3/8 stud is available, I prefer to drillout the metric and upgrade to 3/8 or sometimes 7/16 base thread. I have jigs to do both.

Comp Cams 987-12 Valve springs $68.95
611-12 Valve locks $16.25
740-12 Retainer $38.95
503-16 Valve seals $21.95
V8-010-8 Exhaust Valve $58.95
V8-000-8 Intake Valve $58.95

This will shock you but the time to do the guides, seats is about 30 minutes, and about 30 minutes to machine the exhausts oversize and machine the exhaust throat, it is very fast. most of the time is porting the exhaust bowl, machining the spark plug dam in the combustion chamber and general blending of the ports and chamber and this takes about 5 hours. I usually do porting after my work day, go to my small shop at home, turn on the tunes, get the head gear, face sheild and gloves out and do it very casually. I actually do this to relax and unwind at home, wife seems to be supportive, she knows where I am and saunters out with cold drinks (fresca).

Incidently, flow bench shows almost no gains with matching the intake side of the equation, the problem is the intake manifolds, if you can call them that. i would highly advocate full roller after market roller rockers, this is free horsepower which these engines badly need.

I paint the inside of my heads with one of those POR products, looks nice, probably no other reason.

You will have a head that flows very well and gives good low end torque and throttle response.

Usually I charge parts plus parts acquisition (tax and shipping if applicable and 6 hours labour, i do not charge at my shops rates for porting as I do it on my own time. My last pair of these heads all costs, taxes, out the door was $807.00. Cam selection and heads is where power is made. Cranks, rods and pistons are simpletons and other than slight gains, money is best spent on top. These heads will far outlast the factory heads as the guides are more durable.

brokenwrench · Post by **brokenwrench** » Tue Oct 04, 2011 8:30 pm

1Gary wrote:Rule of thumb for intake runner cc size given a C.I.is C.I. x .5.So for a 262 X .5 = 131 cc.

Brodix still builds a aluminum 23 degree head.

Used parts are limited,but there are deals still out there:

http://www.racingjunk.com/Heads/2255422 ... tion-.html

This link covers all the different style engines and combo's build by Chevy:

http://www.enginebuildermag.com/Article ... y_262.aspx

We yrs ago build a forged common pin crankshaft bowie block 4.3 using the Brodix heads when we bought out one at auction when NASCAR drop the use of V6's in it racing program.The increase C.I. and centering the rods on the bores result in huge output gains.This was installed in a Chevette and on a throttle stop ran like clock work 10.90.It was during that research we found that the offset rods was a major deterrent because given the crank you could mod the rods to center them and then the offset would create pistons that had fiction on the bores or run the rods as is and then the rods would create fiction on the side of rod bearings.But......................As my race partner warned,it is expensive to be different.In fact because I insisted on this project when it was all said and done,it almost cost me my 20 yr partnership costing almost three and a haft times of a sbc.

The saving grace is many of the 4.3's where used in normal rotation for marine applications which has a strong parts source.For EFI's I would think they for tuning react the same as V8's for cam timing.Nothing much above 230 duration and lobe centers 112 better yet 114.As stated a they do respond to a long exhaust event.

The bottom line and the main reason why V8 swaps are more popular is the physics of smaller C.I. engines even with the best computer tunes is the torque curve with all small C.I. engines is higher in the RPM range as the HP output is.Dollar for dollar spent a V8 conversion will out preform the 4.3's for street or race use in a torque curve which using a V8 is key for street.That a V8 will give you the much needed torque in normally driven street RPM ranges to move a 4,000 pound van.

from a logistics viewpoint your are correct. however, emissions rules vary all over, some places allow no changes, where I am a V8 would automatically fail as it was not original, I get around this with farm plates as I have a farm. the other issue is interfacing the electronics, my personal position that a Safari van is not a race car. It can do everything that you want towing and offroad with 250 hp which can be made easily and with improved gas mileage with original computer and fuel injection. Removing and replacing a Safari motor can take two days of hard work, altering, fitting, customizing, cooling, etc. can take another two days. A good V8 could cost $6,000.00, putting a used one in given the time to install is just not worth it. If you paid a garage to remove and replace twice it would near pay for a new motor. It is easy to spend $10,000 at a garage doing a V8 installation, with electronic management systems for the engine and transmission. Then the 4l60e fails and you have another $2,500.00. one of the biggest conflicts we get is putting used motors in, many garages refuse to do it as buddy always thinks that the used motor he got gets pulled in an out free as many times as is necessary, I have 3 G- body chevrolets sitting in my yard now for this very reason, the customers brought in used warrantied wrecker motors, did not want them tested before install, one has a failed transmission and a rearend with apparently no gears inside, one has a rod knock, one has no compression. for guys who live paycheque to paycheque they will be here for 6 months or more. I digress,

if you want a balls out tire smoking Safari van, get a V8, if you want everything to work reliably, transmission to shift flawlessly and various check lights to work, rebuild your 4.3. I am getting on in years, still have a 9 second Chevelle, for me, my Safari is my daily smile and drive vehicle. I can set the tires on fire with my 265 hp (dynoed) 4.3 and get 25 mpg. my AWD has the exact same setup and I get 22 mpg. best yet is i can pull my chevelle to the drag strip and act like a wildman there.

1Gary · Post by **1Gary** » Tue Oct 04, 2011 8:44 pm

Just be aware we have had guys buy a donor V8,install,and get great gas mileage.They swap harness,V8,and computer easily from the donor.One member from Calli is using a old style Edelbrock EFI on a 355 towing threw the mountains his sand rail/trailer getting 22 mpg.

We have had guys equal or beat 4.3 gas mileage with V8 swaps mainly because more means less gas peddle.

If your V8 is within 10% of OEM and you swap the V8 chip in-it will plug and play.

I am curious.Do you have a flow bench and charted the flow on the mods you have done??.

I do know we have had guys from multi states get pass emissions and a number from Canada with a V8 as well.I don't know what they did one for one through.

I think you need for one reason or another to be committed to a 4.3.When you start looking at the torque numbers at what RPM at the rear wheels..........well that is kind of hard to buy into the 4.3's.Just my two cents worth.

Also just so you know I am in the process of building a 383 for a 1989 Astro that the build plan is in the range of 480lbs of torque@ 3500 RPM and off idle well into 400lbs with hp at 350 at 4250 RPM.I fully expect to get high teens to low twenties for MPG out of it.

brokenwrench · Post by **brokenwrench** » Tue Oct 04, 2011 10:15 pm

brokenwrench wrote:
1Gary wrote:Just be aware we have had guys buy a donor V8,install,and get great gas mileage.They swap harness,V8,and computer easily from the donor.One member from Calli is using a old style Edelbrock EFI on a 355 towing threw the mountains his sand rail/trailer getting 22 mpg.

We have had guys equal or beat 4.3 gas mileage with V8 swaps mainly because more means less gas peddle.

If your V8 is within 10% of OEM and you swap the V8 chip in-it will plug and play.

I am curious.Do you have a flow bench and charted the flow on the mods you have done??.

I do know we have had guys from multi states get pass emissions and a number from Canada with a V8 as well.I don't know what they did one for one through.

I think you need for one reason or another to be committed to a 4.3.When you start looking at the torque numbers at what RPM at the rear wheels..........well that is kind of hard to buy into the 4.3's.Just my two cents worth.

Also just so you know I am in the process of building a 383 for a 1989 Astro that the build plan is in the range of 480lbs of torque@ 3500 RPM and off idle well into 400lbs with hp at 350 at 4250 RPM.I fully expect to get high teens to low twenties for MPG out of it.

i don't disagree with anything you say, you will get better mileage with a V8, assuming it is not a fire breathing dragon. More low end torque works and a V8 provides that, however, personally, it would be hard for me to rationalize spending $5,000 to $10,000 on a vehicle that I paid $1,000 for so that I could accelerate faster. you will have a whole lot more torque than me but that will not make you arrive faster, safer, perhaps marginally more efficiently. personally, I would not want my daily NA driver to have that much power, I would end up in jail. I am a little bit (a lot) old school, I don't fancy problem solving electronics with diagrams and abbreviations that I do not understand. sure you could swap an entire engine, transmission, electronics into a Safari, why the hell the factory did not offer it i will never understand, shit, that platform went on forever, 20 years,

on the other hand, I have a Safari subframe on my shop floor with aftermarket upper control arms with adjustable camber, coil over shocks with lots of height adjustment and rack and pinion steering with a V8 and a front differential from a V8 pickup truck and a 4L80E transmission, it will soon get bolted into a nice Safari van. that will be one sweet ride.

yes I have a flow bench, it is 30 years old ( i bought it new) and is not digital, has analogue dials and gauges and recording is done with a 2h pencil on a piece of graph paper. any significant heads for high horsepower engines are much cheaper bought than made. however, there are no good aftermarket 4.3 heads for less than $2200.00. I can produce an equally performing head for $800.00.

many people look at the top end of every graph, HP, torque, flow, yet never get there in practice, it is of little use having a head that flows at a lift and rpm that you will never use. I admire how you mention torque and not dwell on HP, torque is the business end of performance. There is no net advantage to building a 4.3 that revs to 6000 rpm, all the power is in long before that, I get a kick out of reading ChevyMaher's ongoing stuff about his race van and his street tuning,

yes, the 4.3 is problematic, it is run too hot so that it pleases emissions performance but there is lots of near free horsepower with simple changes, yes a V8 has many advantages, my advantage with the 4.3 is that i get parts cheap, machining costs me near nothing, and i can make the work happen taking advantage of salaried employees and the cost disappear into the background.

i forgot to mention a few things on my build diatribe, often these engines come in with the cylinder head rear water crossover plugged, when you look at the gasket surface the reason is obvious, I port them out significantly, I also enlarge the water pump ports on the front of the block and use electric water pumps with a pump pulley delete bracket. Getting rid of the water pump, going electric, and getting rid of the fan and going electric is expensive but gives more free power. I also fill the block to the bottom of the frost plugs with Bloc Rock epoxy.

now, what i want to know is what the market would pay for a complete bolt in subframe with a 300 hp plus V8, 4l80e transmission, coil over shocks, rack and pinion steering, heavy duty front differential and manually operated transfer case.

1Gary · Post by **1Gary** » Tue Oct 04, 2011 10:49 pm

Just want to say that with smart shopping for a donor,a V8 could be done from $1,500 to $2,500.Totally my decision to stroke my SBC and use the Howards forged crank just for starters.Yepper I didn't stop there either.$$$$$$$$$$$$$$$$$$$ LOL-everytime I eat $0.88 cents hot dogs over any kind of steak,I remind myself that is the choices I have made.Given you being in the business for 30 yrs,I am sure you know what I am talking about when I say no many people think about the huge investment in tools and equipment to do the job right.And depending on how good you want that shop to be,could be more money in that than in a project.

Maher is a die hard shade tree mechanic with a seat of the pants dyno.I too get a kick out of his mods.

BTW-user names are great for site use.What's yours Bud??.

brokenwrench · Post by **brokenwrench** » Tue Oct 04, 2011 11:35 pm

1Gary wrote:Just want to say that with smart shopping for a donor,a V8 could be done from $1,500 to $2,500.Totally my decision to stroke my SBC and use the Howards forged crank just for starters.Yepper I didn't stop there either.$$$$$$$$$$$$$$$$$$$ LOL-everytime I eat $0.88 cents hot dogs over any kind of steak,I remind myself that is the choices I have made.Given you being in the business for 30 yrs,I am sure you know what I am talking about when I say no many people think about the huge investment in tools and equipment to do the job right.And depending on how good you want that shop to be,could be more money in that than in a project.

Maher is a die hard shade tree mechanic with a seat of the pants dyno.I too get a kick out of his mods.

BTW-user names are great for site use.What's yours Bud??.

do you mean my real name?? michael, no fame or fortune.

more money in the shop!!!!, lord knows, about 10 times as much as my house.

Post by **MountainManJoe** » Wed Oct 05, 2011 8:15 am

brokenwrench wrote:the 4.3 is problematic, it is run too hot so that it pleases emissions performance...

From what I've read, high combustion temps produce more NOx emissions. Hence using EGR to bring it down.

Cobra · Post by **Cobra** » Wed Oct 05, 2011 8:17 am

brokenwrench wrote: more money in the shop!!!!, lord knows, about 10 times as much as my house.

oh that sounds like my dream garage

brokenwrench · Post by **brokenwrench** » Wed Oct 05, 2011 8:13 pm

timelessbeing wrote:
brokenwrench wrote:the 4.3 is problematic, it is run too hot so that it pleases emissions performance...
From what I've read, high combustion temps produce more NOx emissions. Hence using EGR to bring it down.

umm, not sure of the actual equation but hot exhaust gas recirculated brings NOx emissions down. I do not lose sleep at night eliminating it.

brokenwrench · Post by **brokenwrench** » Wed Oct 05, 2011 8:14 pm

Cobra wrote:
brokenwrench wrote: more money in the shop!!!!, lord knows, about 10 times as much as my house.

oh that sounds like my dream garage

I have a 5000 square foot Roberstson Steel shop, 50 by 100, if i can figure out how to post pictures i will

Post by **MountainManJoe** » Wed Oct 05, 2011 9:50 pm

brokenwrench wrote:umm, not sure of the actual equation but hot exhaust gas recirculated brings NOx emissions down. I do not lose sleep at night eliminating it.

EGR brings emissions down by decreasing combustion temps. Equation is simple. Less air/fuel mixture = less combustion.

1Gary · Post by **1Gary** » Wed Oct 05, 2011 10:27 pm

brokenwrench wrote:
timelessbeing wrote:
brokenwrench wrote:the 4.3 is problematic, it is run too hot so that it pleases emissions performance...
From what I've read, high combustion temps produce more NOx emissions. Hence using EGR to bring it down.

umm, not sure of the actual equation but hot exhaust gas recirculated brings NOx emissions down. I do not lose sleep at night eliminating it.

Yeah-I'm not worried about my grand kids either.I too sleep pretty good.

brokenwrench · Post by **brokenwrench** » Thu Oct 06, 2011 5:03 pm

timelessbeing wrote:
brokenwrench wrote:umm, not sure of the actual equation but hot exhaust gas recirculated brings NOx emissions down. I do not lose sleep at night eliminating it.
EGR brings emissions down by decreasing combustion temps. Equation is simple. Less air/fuel mixture = less combustion.

mmmmmm, hmmm, the mixture is inert, combustion procedes as usual, the net energy of the combustion chamber charge volume is decreased. less energy is spent in the dissociation of the intake charge from the change of state that occurs when compression occurs as the incoming EGR charge heats the air fuel mixture more or less for free and increases the kinetic molecular energy. there is not as such less combustion, it is just that the energy equation is more favourable as less energy has to be put in to reach the point of combustion hence less energy goes into heating the combustion chamber, which is lost as heat transfer and not pushing the piston down, for any given amount of power output, an EGR engine needs more volume going past the throttle plates manifested by putting your foot further into the throttle,this results in less vacuum or more "pressure" in the manifold and there are less "throttling losses". the vacuum pulses in the induction side, between combustion cycles reduce the efficiency dramatically, this is why direct port injection is so much more efficient. the overall combustion mass temperature is lower and this results in less NOx produced,

hope that helps

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