78 Grand Prix project

[G-Body_Vet]

Just make sure you consult someone about the ramp, and duration of a hyd. cam. Way to many guys put a fast acting cam with a large duration, that could kill the torque your large inch engine can make. It looks like you have a quality shop that you are using, they should know what to do for your engine. Don't be afraid to have a quality company like Comp. Cams custom grind one for you, the cost isn't much and its worth it. Off the shelf cams are for stock rebuilds or underpowered noise makers. I don't know anything about Pont. but some blocks require machine work for the lifter tie bar to have room to clear.

Oh believe me brother, I'm all about due diligence before I spend a dime and I'm not a young guy just getting started. The machinist is meticulous and knows what he's doing as well. We've kicked around a few ideas so far but nothing is finalized yet. I'm not trying to turn a low grunt engine into a high winding screamer, but everything is getting balanced and I've gone the extra mile for quality machine work. I'm going for a reliable, smooth running street engine with some serious balls when it's said and done.

 

[pontiacgp]

Finally have pistons! Now I'm on the fence with either a flat tappet or a hydraulic roller cam. I hope this thing will be fully built by October.

I have a roller cam in the same engine I had a hydraulic in and although the cam itself woke up the engine it was so nice starting it up for the first time not having to worry about getting it to run 20 minutes and change the revs at the right time for the right amount of time so the cam doesn't get ruined...the first time when it started with a roller cam I cracked open a beer

 

[G-Body_Vet]

I have a roller cam in the same engine I had a hydraulic in and although the cam itself woke up the engine it was so nice starting it up for the first time not having to worry about getting it to run 20 minutes and change the revs at the right time for the right amount of time so the cam doesn't get ruined...the first time when it started with a roller cam I cracked open a beer

The hardest part about going roller is the price tag, otherwise I'm already convinced. No break-in period is a nice perk too!

 

[Fox80]

Price does suck on roller anything, but you get what you pay for. I'm sure the factory didn't like changing over to roller cams either but even the " engineers" in Detroit could see the benefits

 

[SafariWagon]

Nice to see an update earlier this week. I just got my new 455 running a bout 2 weeks ago. Similar build as yours, and I am very happy with it. Big improvement over the 400 that was in it. It's a .030 over 455 2 bolt block with main studs, H beam rods, Ross flat top pistons (2 valve reliefs), 6X heads (mild port), Lunati Hydraulic flat tappet cam (Part # ends in 703), Rhoades (extra v groove for oiling) lifters, performer intake with Q-jet. The roller would be awesome, but I believe it's an extra $7-800 bucks. I am very happy tons of torque! Biggest issue for me was the oil pump. Start up 90+ psi. I damn near SH**t myself. Warm up still 80 psi. 10W40 oil. Dropped to 5W30 and start up 85 or so when warm at idle its about 40. Cruises down the highway at 65Mph at 60-65 psi turning about 3100 RPM. From what I've read Pontiac engineers knew that with a large 3.25 inch main journal they needed more oil pressure to get the oil around that large of a journal to keep it oiled. So in performance applications they used the 80 psi pump. Pontiac motors also typically run tighter clearances as well. In short don't be alarmed by the oil pressure. I run Lucas oil "engine break in" additive to get the zinc in the oil. It's about $15 a bottle and available around here at every O'Reilly's auto parts. It's advertised as Break in additive. The parts counter guy said they have to market it that way for legal purposes. It's been working great for me so far and I've run it in other cars for 3 years now.

 

[Fox80]

Sounds like a decent motor, you may want to talk to the machine shop that did the work for you to see what they set the main and rod clearances at. Dropping from a 40wt to a 30wt oil may not be a good idea. The first numbers don't so much matter that is the flow viscosity of the oil when cold. Its hard to find but we ran a 0w40 racing synthetic oil from Joe gibbs this keeps the oil pressure in check when cold but the motor still runs on a 40wt oil when warm, with a race motor or street motor with clearances in the .0018-.0024 range that is what you need. Lucas "breakin oil" is good stuff it will plug the filter almost immediately but that's not that big of a deal on a street car they can by-pass the filter. This is why I brought up the roller cam you spend $15 a quart, so that's $75 in oil $10 for a good filter=$85 for an oil change. If you change your oil twice a year call that $200 a year in oil changes compared to $3.50 for Quaker State 15w40 $10 filter= $28.00 oil change that twice a year = $56.00 a year. Saving nearly $150 a year in oil alone once you put a roller cam in and don't have to worry about the zinc content in the oil, in six years you would have offset the cost of the cam, lifters, pushrods, and dist. gear. Just some food for thought, lol maybe I'm the only one who thinks like this IDK

 

[SafariWagon]

I agree the roller cam is they way to go, and in time it pays for itself, but the initial buy in is the hard part for me. I prefer to nickel and dime myself to death 😳 over a long period of time rather than do the smart thing and spend the money up front. Don't know why, just works out that way. Initially cheap I guess. There is a little more difference in the pressure once it warms up. It never got below 60 psi with the 10W40. Running the 30 weight oil I questioned, but was what most people I checked with suggested to do. As far as clearances I am not exactly sure what they set them up at, but I have been told by several Pontiac people that the clearances for a specific motor (usually SBC used for example) can not be applied to the Pontiac. This is why on the Performance Years forum you can find all sorts of threads about oil pumps, oil pressures, 400 journal size Vs. 455 journal size. etc. I don't want to high jack this build thread. I was just telling him what I ended up doing, right or wrong. I just think a guy has to read as much info as possible about this and try something because this is one of those topics different people have different opinions about. I'll bet his machine shop has a suggestion on what to do.

 

[G-Body_Vet]

Nice to see an update earlier this week. I just got my new 455 running a bout 2 weeks ago. Similar build as yours, and I am very happy with it. Big improvement over the 400 that was in it. It's a .030 over 455 2 bolt block with main studs, H beam rods, Ross flat top pistons (2 valve reliefs), 6X heads (mild port), Lunati Hydraulic flat tappet cam (Part # ends in 703), Rhoades (extra v groove for oiling) lifters, performer intake with Q-jet. The roller would be awesome, but I believe it's an extra $7-800 bucks. I am very happy tons of torque! Biggest issue for me was the oil pump. Start up 90+ psi. I damn near SH**t myself. Warm up still 80 psi. 10W40 oil. Dropped to 5W30 and start up 85 or so when warm at idle its about 40. Cruises down the highway at 65Mph at 60-65 psi turning about 3100 RPM. From what I've read Pontiac engineers knew that with a large 3.25 inch main journal they needed more oil pressure to get the oil around that large of a journal to keep it oiled. So in performance applications they used the 80 psi pump. Pontiac motors also typically run tighter clearances as well. In short don't be alarmed by the oil pressure. I run Lucas oil "engine break in" additive to get the zinc in the oil. It's about $15 a bottle and available around here at every O'Reilly's auto parts. It's advertised as Break in additive. The parts counter guy said they have to market it that way for legal purposes. It's been working great for me so far and I've run it in other cars for 3 years now.

You're not jacking the thread, so no worries. I come here to BS with other car people anyway :wink:
Hopefully mine will be night and day difference since I had a 2bbl 305 :lol: Mine is .035 over, with custom pistons from DSS Racing. I have the lightweight 4340 i-beams from RPM, 6X-4 heads with porting & SI valves. We have CR figured at 9.3 to 1. I'm still undecided on cam specs, but nothing too crazy. My plan is to take this car on the Power Tour and some other events when it's done.

From what I recall, I think the 80 psi pumps were used in the SD motors. I just went with a 60psi Melling Select from this place. http://stores.precisionoilpumps.com/-st ... Detail.bok.

What gearing are you using? Are you using headers or manifolds and what brand? I originally wanted to use RA manifolds but I'm really thinking about using the Maddog headers since they're the only ones made for g-bodies right now. I could probably have this car on the road by the fall but I'm more than likely going to save for a built 200-4R instead.

 

[SafariWagon]

I am running highly modified 66-67 GTO headers, I cut the pipes and re-welded them. Total waste of time.....way too many hours. I have the mini starter wrapped and still over heat the solenoid. I would like to buy Mad dog headers, but I am running a Super T10 4 speed and they were made for automatic cars. I am certain the factory G-body Z bar isn't going to fit. Factory Ram air manifolds I think may be the way to go since they will help the starter issues as well. I am running a 9" ford rear with 3:25 gears. Pretty short tires. Just under 26 inches tall I believe. BTW I haven't checked it yet, but gas mileage sucks! :lol:

 

[G-Body_Vet]

I was really leaning towards the RA manifolds because I've never had a good time with headers on a street car. Since flanges & gaskets have evolved in the past 10 years I'm not totally opposed to headers anymore. In the past I've used those off the shelf heat shields on solenoids and they've helped. I've thought about possibly relocating mine when the time comes, maybe the oil filter too.