Thread: Rebirth of my 99 GPGT

Well the time has come to rebuild my motor (due to a broken rod) and would like to throw my ideas out there for you all to see and comment on.

My plans as of right now are:

1) Getting a top swap setup from Morad.
2) Taking everyting to my local machine shop having everything looked at, all needed machine work done, internals balanced with my existing flexplate and new balancer from Morad
3) Port polish heads, LIM, Supercharger rebuild
4) Going to use my existing internals. I have two motors now so the best 6 pistons and rods and nicest crank. I assume all are equally great, just which ever ones clean up best.
5) Comp Cam's XP cam with springs and retainers
6) Remove the balance shaft gear and use a double roller timing set
7) Machined Oil pump cover
8) 3.5 pulley

I guess my initial questions are; will the 105# springs be ok or should I go a little stiffer? Will the 33# injectors that will come with the top swap be ok or should I go with the 42# since I will be running the XPcam on a L36 bottom end? I want efficent boost, not just to build it. Any other comments would be appreciated. I have been talking to ZZP and want all my stats before I send in my PCM.

I have searched the forum, but want to keep everything within this thread as well because I'll do a build thread.

105's will be fine. Don't bother messing with 33's go 42's or higher.

series 3 pm rods

Sorry, PM rods?? LOL

About to order XP cam, retainers, 105's, double roller timing set, machined oil pump cover.. :-D

dont order a machined cover. that's a super waste of money. any shop with the capability to mill off 20 thou from the pump cover will charge you like $10.

Originally Posted by dbextreme

Sorry, PM rods?? LOL

I believe hes talking about powdered metal connecting rods...

GM ACDelco - 3800 Powdered Metal Connecting Rods #GM-12593375

Thanks for the info bio!!! I'll talk to my machine shop about it.

I was wondering about the rods.. I asked and looked around some and got mixed signals regarding them... Was under the impression if I use those rods I'll have to use the supercharged pistons due to offset or length??? Not 100% sure though and I thought the N/A ones were not as strong... Since I had a rod fail I was going to upgrade them, but I also heard the L36 rods are good up to like 400hp or something like that. Rods I am torn on... If I am doing it might might as well get them I guess.

rods should measure 5.638-5.642 center to center for s/c 5.740-5.744 center to center for n/a 9.4 might want a intercooler you should go 8.5 with new pistons/fresh bore

JP Performance vs Rollmaster Timing set difference other then twice the amount of money for the Rollmaster (double roller)... Opinions?

Valve Springs, I have heard great things about Crow Cams stuff... Opinions?

I want to get the XP cam, springs, retainers, and timing set ordered within the week and right now I am comparing prices between Intense and ZZP.. Other good sites?

for your springs, what is your install height

comp 26915 is a beehive 105@1.8 should do the trick,

if your worried about quality, comp 26918 125@1.8. These springs have a "super finish" which makes them a little more stout if you wanna beat the crap outta them.
sidenote, you dont want valvefloat, but more spring pressure = more wear

retainers comp 774-12 steel

also talk to your local speed shop and see what they can do for pricing, if the machine shop your dealing with cant get these parts, FIND A NEW SHOP!!! cause they probly dont do the quality work your looking for

I haven't talked to them yet about the parts, just the machine work. My machine guy has been doing this forever here locally, built many a race car in his day. I'll take the cam part number and the numbers listed above to him tomorrow and talk it over and see what he can do on pricing, I was just looking at the sites first and was like wow.. big differences in prices with the timing set and springs... Bad part is, here in town, there's only two machine shops and one speed shop. The speed shop I lost faith in cause they are only in for the $$$ not the "sport"... They mark up all their stuff tons targeting rich kids wanting to build there cars on mommy and daddy's checkbook... Ervin Hickman, my machine guy, is awesome and this is nothing but a hobby to him. I've seen everything from an Opal to a prostreet funny car on his dyno.. :-D

But I don't plan on beating the car to death, just the occasional getting on it every now and then. I just want this personally. I didn't know if springs were like lifters. One manafacture makes lifters and puts them in different boxes, thought springs and timing sets might be similar and want opinions.

yea..... sorry if i came off as a dick. i know what your talkin about in regards to that speed shop. i feel most, if not all the shops here are like that. the quality of work is quite poor out here. So if you can trust a builder then by all means use him.


being here in canada if i got a part number, its usally cheaper for me to buy off summit and have it shipped here. very poor supply in westeren canada unless you own a diesel truck.

dont be shy to spend your money on machining, id rather have a low powered turd that will run for another 4000 hours then a hi perf engine that every bore is egg shaped and seems good untill your tenth hard pull only to leave you where you are now.

what compression you runing,, the n/a is 9.4 right??? the cam will help but your can tune might not be ideal

You didn't come across anyway!! lol Just not a big market for performance around here... Unless you have a Honda or 4x4...

Yes, 9.4.. I've been talking to ZZP about my tune. Also Intense offers custom tuning. When I get ready to send them a PCM I'll call and go through everything I have and go from there with a tune.

Think I have changed my mind on cam... Not the XP but go with Intense S1x or stage 2 cam. I hate decisions..

what rpm range do you want to be in ?

It will be a daily driver with some track use. mainly highway driving. I do want room to add as I go, I think the S1X cam will be maxed out

........... so are you useing factory shift points????

No, I will have a custom tune talored for what components I use... I know I'm being vague, but my options are open...

TOP SWAP ARRIVED!!!!!!!!!!!!!!!!! And now I can add a N* throttle body to my list of parts!!

Just ordered XP cam with 105# springs and modified retainers, 42.5# flowmatched injectors, and Double Roller timing set.

I would only run the N* if you know for a fact you are going to outflow the stock MAF and throttle body.

With a XP cam, I think you'll be fine still. Also many people hate the pedal feel with the N*.