I'm considering do an upgrade to my top end and I'm looking for some advice from some of the more experienced engine guys on here.

First, is it worth doing? Since building my first engine 7 years ago when I was 22 I've second guessed my head choice after talking with some different people. I'm running Edelbrock E-tec 170's which I had bought as part of their "power package" so it came with a matched cam and rpm air gap intake. The motor is a full roller 383 stroker (all the details below).

I've been happy with it, it's great on the street and it's run a best of 12.044 @ 112 with a 1.6s 60'. This wasn't under the best conditions, track prep wasn't great, I'm pretty sure it has more in it.

Alas, with all the nay-sayers saying the 170's are too small for a 383 stroker, I've spent the last 7yrs wondering if I've left a lot of power on the table. I built the short block strong and the engine only has 11k miles on it, so it should easily take more power. What I'm wondering is if it would be that much of a difference to make it worth doing... I'm leaning towards it probably is, I know there's WAY better head/cam combos out there, but I'm in no way an expert.

So, in addition to your thoughts on whether the Etec 170's are sufficient or I should go to something else, I'd also like to hear your recommendation on what heads I should look at.

As a side note, the current setup has developed some little external coolant leaks from the head gaskets and intake gasket... so it gives me a decent reason to justify a head swap to myself

I know head choice depends on a lot, so if you need more info than what's below just ask, I definitely have it.

Thanks for any help!

Specs:

11.0:1 CR

-Bare 1987 hydraulic roller 350 block-Eagle Crank
-6" Forged Eagle Rods -Forged Mahle flat tops
-Aluminum Edelbrock E-tec 170s, 64cc chambers, 1.94" int/1.55" exh valves.
-Edelbrock Roller cam .539/.548
-Crane Cam Gold Race Extruded 1.5 rocker arms
-Comp Cams high energy hyrdaulic roller lifters
-Edelbrock RPM Air Gap intake
-Edelbrock Thunder Series AVS 650cfm
-XSPower Side pipes

-Built 700r4
-Rearend setup out of a '78 with Richmond 3.90 gears.

 

AFR 195's or 210's and a cam to match, what is the duration @.050" of your current cam ? I would also go with 1.6 RR's.

A high 11sec car with 170cc heads on it you must have revved the crap out of it. It just don't compute.

Give me all the specs like how far down in the hole the pistons are and gasket thickness and gasket bore, etc. etc. and I'll run the numbers

Oh yeah, how did you get the '78 rear end into your '80 ?

 

That's along the lines of what I was thinking for heads.

Duration @ .050" is .234/.238.

What would the benefit of the 1.6s be? I do remember reading somewhere a while back about doing 1.5 on the intake and 1.6 on the exhaust. Some old racers trick or something?

I'm not sure, I built planning for the high 11's and that's about what I got. I think it has high 11's in it, but like I said 12.0 is the best to date... track prep was crappy though and traction was a little issue, not too bad but enough. I shift between 5200-5400, rev limiter on my MSD is set to 6k. You can see the number on the windhshield in the video below matches the time slip. That was this past fall.





I had the short block done by a local machine shop, so I'm not a 100% sure on some of those specs. Gasket thickness I believe was .039" compressed.

As far as the rearend, that was fun haha. I actually got the entire rearend (diff, mount, halfshafts, VBP offset TAs, VBP monospring, and bilstein shocks) all complete from a forum member who was going to a straight axle. Then my buddy, who parts and flips cars, had a 78 that he had parted and was going to the junkyard. I cut a portion of the rear frame out of that, then cut the crossmember out of that and had it welded into my car to accommodate the pre-80 iron diff mount.

Donor car:


Frame section:


Cross member:


New parts before cleaning and painting:


Old setup:


Ready for new setup:


All done:

 

I really like my 195 AFR heads.
It is just a very nice US made head, with a lot of flow.

Here is my AFR 195 heads.

 

Something does not add up especially for a C3. A 383 with 11:1 compression (seems high), a high lift cam (539/548 seems very high for an edlelbrock cam that are usually pretty mild), and 170 CC edlebrock heads (pretty mild with small valves no less) and the car did almost the 11's????

I would think that motor would have to make at least 500 GROSS HP, probs more like 550 Gross HP which seems pretty dubious with the combo for high 11's in the 1/4 mile. Anyone else wondering about this outcome?

 

112mph sounds about right making very strong torque
What converter?
OP at this point youll be speding much to gain little and give up manners
Could do some headwork, larger valves etc but gain?? if you can diy play with used intakes then go for it how fast do you really want to go

What can you tolerate or spend?

You can go wth a larger head/solid roller honestly if it were me sell that mill and go 421/427 etc.

Stong runner low 12s is excellent!
Flow #s are one thing but quality of flow and combo/sorting out suspension :thumbsup:

If you want a killer deal on some new AFRs pm tpi421vette hes running some crazy times on a sbc C4

 

As to 383 cr. Just go to an online CR calculator. Mine is 11.2 decked block -7cc pistons. 015 gaskets 64cc heads

The problem I had with big heads and cam 383 and 700r4. 4.11 rear end is that I had to use crutches to help out the lack of lower end power

I went with a 3500 stall 9.5 inch

 

I did a litttle research on the Chevellle forums with guys running 383's with 4.11-4.56 gears in 3400-3500 lbs cars and the consensus is 550 Gross HP would be required for 11.9-12 sec 1/4's and a few said 383 400 gross hp is easy (which we know) but a streetable 550 Gross HP SBC 383 not so easy. That a pretty stout 383 running those times with Edelbrock heads and a relatively moderate cam.....impressive!

 

Seems like you know what you are doing. A 12sec car with those engine specs and a 600cfm carb turning low 12's must be a well designed piece.

If you want to bump it up a few notches a Holley 750cfm, AFR heads and XR274R solid roller will net you a lower timeslip but how much lower I can't say,maybe only a few tenths for $2000, is it worth it ?

If you want to go faster like low 11's then the 383ci engine will need parts that will give you drivability issues.

The comment above is a good one, sell that engine and build a 427ci and you will have an engine that will knock a second or more off your timeslip without breaking a sweat

1.6 RR are used to give a little more lift without changing the duration (it does change a bit but not enough to worry about)

For example if the head flow is maxxed out at .600" lift and the cam only lifts the the valve to .570" then 1.6 RR's will get the lift over .600" .

 

Here's how I got there. I have all the slips, but I'm not home right now, so the older times are off memory but should be close. I started with this motor/trans, but with a stock converter and my BFG Radial T/As (because I was afraid my old rearend wouldn't hold up to stickier tires) and ran a best of around 13.1 @ 110ish. Needless to say 60' was terrible, 2.2ish I think.

After swapping in the '78 rearend setup I switched over to M/T Radials on a pair of my stock wheels. After a lot of tuning and bumping up the timing a little more I ran a best of 12.6 @ around the same trap, 60' down to 1.9.

Next I went to Art Carr and got a 3400 stall. I also did some more tuning, carb spacer, some other little things. The converter was the real improvement though. This is where I stand now with the 12.0.

Thanks. That's basically where I'm at now, figuring out if it's worth doing or not. Money I can come up with, I like to work haha. I'd be doing the work myself, aside from the actually machine work if I went the way of redoing the Eddy heads. At this point I would be leaning towards just selling the heads I have and getting new ones rather than working with the smaller ones, so that would make it more of a quick straight forward swap.

The other catch is I plan on doing an LSx somewhere, probably FAR, down the road. So, I have to figure out if it's worth spending more on this motor or just riding it out until I go to the LS (but that could be a while). Plus, I feel like with the money I put into this motor to begin with it might be worth it to improve it and keep it for a while.

Eh, I'm learning and I put a lot of work into it, but I'm sure a good chunk of it has come down to luck!

 

I just finished my LS-5 454 build. I used Brodix heads, a roller cam, new pistons, GM Performance Parts intake, FAST fuel injection, Hooker Super Comp headers, and Pypes full exhaust.


I can tell you this thing has more horsepower than I thought, when I built it on paper, before starting work (as I always do). I can roll the throttle at just about any speed and break the BFG's loose.


Off the top of my head I don't remember cam specs, but I got it because it's range is idle to 5500 RPM's. That fit my idea of what I wanted from the car. My CR is about 9.18:1 with pistons, heads, and gasket.


I now have just over 100 miles on the motor after cars and coffee yesterday. I've been building engines since I was about 12 or so with my neighbor. I built VW motors, go-carts, 4 cylinder, 6 and 8 cylinders also. The reason I'm telling you this is because this engine has more power than I thought it would. I'm pretty happy!!

 

It takes about 350 HP to run a 12.0 with a 3500# ride weight!

If the same ride had 500 HP it would be in the area of 10.80's or so!

(Add) We have a number of fairly simple "bolt-together" 470/480 HP pump-gas 383's running around town here! None have expensive heads either, most are off-shores actually!

Thanks, Gary in N.Y.

P.S. The ride would need to be somewhat "efficient" for these numbers above but they are correct. We have a 3600# (406"/580 HP) pump-gas ride doing 10.30's at 128/129.

 

Good to know Gary...Thanks

So Gary would you say/guess that my lightened 78 4 Speed (3,300 lbs) with 3.70 gears with the 10.2:1 compression 355 with a roller cam (.525/.525 lift, duration 219/225, LSA 110, cam operating range 1,500-5,600 RPM) and AFR heads built for Max mid range torque (2-5,000 RPM) would run in the 12's with 255/45/17 ZR sticky tires and 1 3/4 inch LTH's if optimally tuned? Guessing the engine makes 425-430 Gross HP @5,200 RPM

 

I've never had my car on a dyno but I do have a lot of quarter mile time slip data. My best runs are in the 12.1s at 110 mph. Using several of the on line HP calculators, with a car weight of 3,600 (including me), they show around 370 HP. I assume that is the net, flywheel HP. Pretty close to what GOSFAST said.

 

The 170cc intake runners and smaller valves are strangling that motor. I wouldn't go less than 180cc with 2.02 intake valves. 190 or 195 might even be better. That's a pretty high lift cam with short duration and looks like it is suited well for the low end torque of the 383. Like many have always said, the power is made in the heads. I think you have left a little on the table TBH.

 

Leave the cam....I just looked it up on Edelbrocks site......not a bad unit....it is the Rollin' Thunder series (eyeroll) LOL!
Anyhoo....switch to 1.6 will net you 574/584 and a couple of degrees of duration........not sure I would do that.....539/548 is plenty......
I like Dart Pro 1 heads....they are wet flowed and flow very well at lower lifts.....which is what you need. A 200cc Dart would be ideal......
Ditch the 650 AVS carb......you will need at least a 750hp Holley to feeds this......
The Air Gap becomes a restriction at the 540-550 horse level......Dart also makes a nice single plane that flat out works.......
AFR are premium pieces but you need to buy them CNC ported and this adds a lot of $$$$ to the build.......but they do work.
A third option is the Brodix IK200.......they work well too but not quite as well as the Dart or AFR.....
Good luck and have fun.....

Jebby

 

I've got a lot of thinking to do. Part of me says just keep driving it as is... the other part wants to slap on some new heads and wake the motor up some more. I put a lot into the short block, so I feel like it's worth it.

The other thing is like I said the head gaskets are leaking a little coolant externally which will drive me nuts, so if I'm going to pull them and seal everything back up it seems like a good time to swap heads.

Those saying my current cam isn't bad, do you think it would go good with the bigger heads? I know it's a pretty good cam, I didn't want to go overly radical initially because I was still running a lot of vacuum accessories. I've since converted to electric actuated headlight motors, my only vacuum accessory now is the brakes. I was under the assumption that new heads should be matched to a new cam... could I keep the cam I have?

 

Make sure if you replace the heads that you PTFE the threads for the head bolts......most common mistake when assembling and they seep coolant up past the head of the bolt.......
I feel a Pro 1 Dart head, Dart single plane intake and 750 hp would be worth north of 50 horsepower here......you need to let that cam do its work......

Jebby

 

Your car runs pretty good for what you have, but there is definitely room for improvement if you want to spend some money. Your car is showing about 375-400hp depending on how heavy the car is.

A head/cam swap would go a long way. I'd bet you could gain 50-75hp with real good stuff installed. 170cc heads are choking that engine at higher rpms.


On a budget, I would keep the cam, change the heads, AFR 195s CNC ported are always a good option on a 383. Personally, I'd go with at least a 210cc if not even a 227cc (if you change cams). There are lots of other head options as well, you may should look to some of the import heads out there that are ported, machined, assembled by experienced head people like Slick Rick, Chad Speir, Scott Foxwell etc. You can get a better performing head then an AFR for around the same money or less.

I'd keep the RPM air gap intake, port match it and maybe cut the divider down a bit. Add a 1" spacer if you can fit it under the hood.

Lastly, change to a Holley 750 double pumper carb...(#4779 or the HP series)


And more importantly, get rid of the side pipes, that or do some serious modifications to them as they are VERY restrictive if they have baffles in them. Maybe look to Classic Chambered for some of their 3.5" chambered side pipes (2.5" ID).. Without addressing your side pipe issue, there is no point in spending money else where. You are likely restricted with what you have.

 

x2 dont be afraid of a good 195 -210 head esp on a 383
The 210 comp port (not the street head) is a fantastic piece, same with the 195 comp
Leave the cam for now do the heads see where you sit do the 750dp youll like it. You should be in the 11s for sure;hp series, AED one or two others are pretty nice
You know even finding 2-3 tenths gets tougher as you get faster;doesnt sound like much but it is...definitaly will feel it

Maybe this will help you out. Huge gains

https://www.corvetteforum.com/forums...afr-220-a.html