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Scott Parkhurst


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Finally - 388 comes together!
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After way too long and waiting on way too many little things, it's almost all in one piece.

As it turns out, not much beyond the crank and heads were salvageable from the previous 383.

The new block is .040-over. I had to get a new cam (old one was bent, not worn), new rods (I only needed 2, but Lunati doesn't make them anymore), pushrods (I chose to upgrade to new shaft rockers, so the pushrods needed to be shorter to work with them), and some other stuff I didn't expect to have to replace.

Going in, I knew I'd need new pistons, oil pump, pan, etc. I knew I wanted to coat more stuff, and I knew I wanted to make a few upgrades (like those shaft rockers) and some other basic things (like zero-decking the block instead of leaving the flat top piston in the hole at all), port-matching the header flanges (they were off a lot more than I was comfortable with) and doing the work necessary to provide improved spark plug access and clearance (they weren't designed for the angle plug AFR heads I've got). So, all of that got done.

I also decided to upgrade the oil pan. I was just going to get another Milodon pan like the one my piston exited through, but after looking over my options, I found a killer Canton road race pan that will work even better.

Anyway, after all these things were addressed and made to work in concert, it's almost all in one piece now. It should make around 550 hp/500 ft-lbs again. It made those numbers before, but that was with really bitchin race headers. I want to make that kind of power through the shorty headers I actually use. I also want to dial in the carb with the actual headers I run in the car so its tuning is right when I drop it in. I know it'll still require some fine tuning, but it'll be really close.



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Scott Parkhurst

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SShink


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Cool Scott!  Should rock with the best of them!  j

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Chris R


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That motor is a pure work of art.

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67ss


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When are you going to dyno it? What kind of compression and what are the specs on the camshaft?

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Chris P
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66 Chevelle 300 deluxe
Scott Parkhurst


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It'll be on the dyno at TPI Specialties in Chaska next Friday.

Compression is now 10:1 (up from 9.7:1 previously)

Cam is a Comp solid roller- XR286R

248/254 @ .050

.576/.582 lift

110 LSA

106 ICL

I'm also swapping out the removable venturi sleeves in my Demon RS carb. I've had the 685 cfm sleeves in there since I first installed it. We'll be slipping the 750 cfm sleeves in on the dyno- doing a back-to-back test to see the differences.

sprint.gif

-- Edited by Scott Parkhurst on Sunday 1st of August 2010 10:52:41 AM

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67ss


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Cool can't wait to hear what it does. But I think you are going to run out of steam with that dual plane intake and will have to swap to a victor Jr to get the numbers you are after. That's just my opinion for what its worth.

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Chris P
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Tony Hoffer


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Thats the same cam I run in my 406.. Installed straight up. with old style AFR 195 competition package straight plug heads.. and around 11 to 1 compression.. made 540HP /520TQ

-- Edited by Tony Hoffer on Sunday 1st of August 2010 04:58:58 PM

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Scott Parkhurst


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67ss wrote:

Cool can't wait to hear what it does. But I think you are going to run out of steam with that dual plane intake and will have to swap to a victor Jr to get the numbers you are after. That's just my opinion for what its worth.



 If the redline was over 6,500 and this was purely a drag effort, I'd agree with you.

This is a street car that I also autocross and road race, so it spends a lot of time in the lower rpm ranges and needs to be crisp and responsive down there. It also lives at around 1,500 rpm in 6th on the freeway, where it regularly delivered more than 20 mpg with the old engine.

For these reasons, I'l stick with the dual-plane for improved low-end and mid-range response vs. a single-plane. As dual-planes go, the Air Gap is one of the best. With a 4-into-1 HVH Super Sucker spacer on top of it, it loses very little to a Victor at 6,500, but owns it in the midrange.

I did a lot of homework in choosing each and every component in this engine. I've run plenty of single planes in the past, and for big-inch engines they were okay on the street and did really well at the drags. That's not what this car is built for, and I'm confident I made the right call on this.



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Scott Parkhurst

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Scott Parkhurst


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Tony Hoffer wrote:

Thats the same cam I run in my 406.. Installed straight up. with old style AFR 195 competition package straight plug heads.. and around 11 to 1 compression.. made 540HP /535TQ



 Yup- my 210 angle plug AFRs like this cam too. It's a great combo at 383ci or more.

Does yours nose over at 6,500 rpm too? In the 383 it make peak power at 6,400 and peak tq at 4,600. It should be real similar in the 388 with a tiny bit more compression. I've always shifted it at 6,500 and been real happy with it.



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Tony Hoffer


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Scott Parkhurst wrote:

Tony Hoffer wrote:

Thats the same cam I run in my 406.. Installed straight up. with old style AFR 195 competition package straight plug heads.. and around 11 to 1 compression.. made 540HP /535TQ



 Yup- my 210 angle plug AFRs like this cam too. It's a great combo at 383ci or more.

Does yours nose over at 6,500 rpm too? In the 383 it make peak power at 6,400 and peak tq at 4,600. It should be real similar in the 388 with a tiny bit more compression. I've always shifted it at 6,500 and been real happy with it.





Its has pretty flat power curve.. I go through the lights at 6500 with 4.10's and a 28" tall tire. I have T&D shaft rockers and run 1.6's on the intakes. Im running a pro-systems prepped 750 HP.

running 50/50 mix of 91 non-oxy unleaded and 100 race gas.
air bleeds are 35's
jetting is #78's front.. #82's back ( no power valve in back)scan0071.jpg
timing is 40 locked..

-- Edited by Tony Hoffer on Sunday 1st of August 2010 05:04:45 PM

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Scott Parkhurst


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Those are solid results Tony! What intake are you using? What size headers?

Here's my buildup story on the previous engine:
http://www.compcams.com/Community/Articles/Details.asp?ID=1945664039

The dyno chart is in there- Obviously my engine is the 383; the 355 I built alongside it was destined for another project.

The new 388 build is being documented too- I'll let you guys know where it ends up being published.



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Tony Hoffer


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Scott Parkhurst wrote:

Those are solid results Tony! What intake are you using? What size headers?

Here's my buildup story on the previous engine:
http://www.compcams.com/Community/Articles/Details.asp?ID=1945664039

The dyno chart is in there- Obviously my engine is the 383; the 355 I built alongside it was destined for another project.

The new 388 build is being documented too- I'll let you guys know where it ends up being published.





Im using a Vic JR #2900 .. CNC port matched from the factory to a fel pro 1205 gasket.. same as my AFR 195's

The headers are Stahl equal length 1.75 inch long tube with a 3 inch collector into full 3 inch exhaust with an X pipe. 22 inch long case mufflers and torque tech 3 inchtails with turndown..

Best et was an 11.38.

-- Edited by Tony Hoffer on Sunday 1st of August 2010 06:35:48 PM

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Scott Parkhurst


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Gotcha. My stuff is all based on the 1206.

I'd love to have Stahl pipes. They just plain work! I need to drop the dough on that someday. I'm sure they fit nice, too...and probably have decent plug clearance/access.

I've got Hedman shorties. 1.5 inch primaries and I had minimal clearance to plugs/wires. I had to take them off to change plugs. Not ideal.

I had them modified to improved clearance while they were out of the car, and re-coated too. I'm anxious to see how well they'll work in their new state. They do offer a ton of ground clearance, which is critical in a car as low as mine being used to go around corners.

They feed into 2.5 inch tubing with and H-pipe back to Flowmaster 40s, and I'm adding dumps behind the muffs. The tailpipes over the axle are no longer- they didn't want to play nice with the new Watts link setup on the rear axle, so away they went.



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Derek69SS


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Sooo... when will the car be ready for a shakedown run?

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Scott Parkhurst


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If we dyno on Friday and all goes well, I'll start getting it back in over the weekend and should be ready to hit the road by mid-month at the latest.

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