Oldcoyote

I have 2.25 Flowmaster Delta Flow 50s on a 403 with manifolds. They have a very loud drone. I love them anyway.

slade69

I don't understand you guys building engine with high performance modifications and then use exhaust manifolds?!? You are leaving a big amount of power (~20hp) on the table. Does manifolds look cool for you or what?

70sgeek

I think the actual HP gain with headers is debatable - everyone has an opinion but I think few can cite guaranteed gains within the confines of any given build.


The gains from available shorty headers has been argued on this site as being minimal (if any) and long tube headers, while the preferred choice of HP seekers, have their own challenges whose trade-offs may not be worth the possibly nominal gain some people might pick up in their moderately hotter-than-stock street cruising machine.


Long-tubes are definitely a plus I think for a true high-performance build that's going to be run to the extremes it was built for, but maybe not so much for a primarily local good-weather street cruiser.

olds 307 and 403

Thorton's have never been dynoed, shorties for other makes have been, it is always 15 to 20 hp and similar torque. Good long tubes are 25+ hp but some hang low or need mini starters or both. It would be interesting to see both Thorton's with the larger openings and their new tubular manifolds tested. The Thorton manifolds probably do flow better but what it actually adds is a mystery.

RetroRanger

not to mention repro manifolds $300 ish

nice arh headers 1k plus

cutlassefi

Check out my 374 build on here. Headers were worth 30hp and 25 or so in Tq over regular Thornton’s.

olds 307 and 403

I assumed they were regular factory manifold's which might actually be even worse. I still say shorties are a good gap filler, 20 hp and 15 to 20 ft/lbs gained and allow a regular starter and better ground clearance. Great info.

slade69

Regular or Thornton's, they're still log-manifolds and they will not help engine to breath. They will mask other performance modifications very effectively. You'll never see the real benefits of raised cr and matched cam and intake with log-manifolds.

slade69

You don't have to buy low hanging leaking headers. Do your own and you get what you need.

mikejana

Block and heads all passed magna-flux.
Parts are ordered and on the way to the machine shops.
Super Big Mahalo to CutelassFI, Mark is amazing and I am blessed to have his help and advice.
Thanks ClassicOldsmobile.com for the forum and the ability to connect with such knowledgeable and talented people.

The rebuild of my Quadra jet is about the price of the Quick Fuel Slayer, so I think rochester is going on the shelf. Have a new 7111 to sit it on. Anyone know if a stock aircleaner will fit on top of a Quick Fuel slayer?

Last big decision is headers or ......
I was initially really hesitant to leave the stock manifolds, but also don't want to leave MPG's or Pony's in the shop.
Shortys seem like a better idea and Loss of ground clearance is important to me.

Desperately searching for suggestions that don't break the bank.


Thanks, Mike

slade69

Height-wise it will fit. If it's a single snorkel it will become restrictive above 300hp.

olds 307 and 403

I made my own dual snorkel air cleaner out of two air cleaners, looks very stock. I have had my Sanderson shorties for 10 years, one tube cracked near the collector. The ceramic coating held up very nicely. Great ground clearance with properly bent pipes, can use the
full size heavy duty starter and they require just RTV to seal to the motor and I use copper or aluminum collector gaskets.httpsndersonheaders.com/sanderson-o351-header-set-for-350-olds-cutlass.html?category_id=46
Hedman also makes set with slightly larger 1 3/4" primary tubes and a thinner engine flange.
https://www.hedman.com/product-detail/58166
The Sanderson gives about 2.5" more ground clearance according to both their specs and both are just over $350 uncoated. I would recommend getting the ceramic coating, I know it costs more but it really helps keep the heat inside the header. Summit Racing sells both.

mikejana

Thanks guys. Remembering this is not a big horsepower build, and in total agreement that I don't want to leave power behind.
I'm a purist when it comes to old cars. Before that, I grew up doing engine swaps when headers had to be mangled to fit, always produced leaks and way too much heat. Heat is a big factor as I've never lived very north.

olds 307 and 403- shorty Sanderson's really give that much more ground clearance over other shorty's ?

I appreciate the input, also don't know how ceramic coating could fit the budget.

Thanks, Mike

brownbomber77

Performance Coatings in Jonesboo, GA is a place quite a few Grand national guys use. I had them do the headers on my daily driver. 30,000 miles and no chips on the Y-pipe or anything. It was $265 to have them coat them, your choice of color, I went with black, but you can do the shiny stuff. Manifolds are probably below $200 given how much less time needs to be spent on them.


Header technology has come a long way...plus, Engine Masters PROVED that dented headers make MORE power....haha. Are you going off roading with the thing? I've never scraped headers, even on speed bumps which is why I ask.

mikejana

I have to go several miles down a narrow 2 lane road with 7 big speed "humps" to get home. Rarely at an appropriate speed.
We lost everything in a house fire several years ago. My Olds was in a mini storage, our old Mercedes and old corvette were not. It kinda changed how I think and treat things.
Some may call it sacrilege, but we love and use the Cutlass. I drive it in the rain with the top down, hang sandy waxy surfboards over the back seat, bring plants (& trees) home from Lowes and fill the trunk with hay and chicken feed for my wife's backyard chicken flock. I've been known to cross medians and curbs. No trailer queen here.
I use and enjoy this car, often to her detriment, but she is valued and loved and gives us a lot of joy.
If something is hanging low on my car, I'll find out.

Engine masters is great, that was an awesome episode.

mikejana

So here's the update:
Cylinder heads should be ready Friday. Original 7a heads with 2.00/1.60 valves, welded the exhaust and sealed the crossover. 7111 manifold on the shelf ready for assembly.

Cutlessfi (Mark) has set up the machine work on the block and should be all set next Tuesday, just waiting on the last few parts to arrive:
looks like 414 ci and lots of usable torque.
-Forged 5140 Stroker Crankshaft
-Custom Stroker pistons, rings, pins and locks all being balanced
-Forged 4340 I-Beam rods
-Mark also picked out a Custom Hyd roller cam, lifters, cam button, timing set and adjustable valves.
-Hopefully he can chime in with the specs,

Even better, maybe he can get us on the dyno.......

Decided on the Hedman shorty's.
Working on getting the 200-R4 setup so we can get back on the road like yesterday.

cutlassefi

Actually it'll be 422 c.i.(4.100 bore, 4.00 stroke)
Cam specs are 218/226@.050 on a 114, .517/.525 lift. That'll keep the overlap to a minimum and spread the tq out over a broader range.(I don't think he'll have any issue making torque) Compression will be 9.0:1, should run fine on 89. Anyone want to guess on the hp and tq?

Thanks Mike, I really appreciate the opportunity!!

olds 307 and 403

Mark, I bet 87 octane won't even be an issue. I am going say 352 hp and 454 ft/lbs of torque, betting that will be low. What piston's are going in this build?

cutlassefi

Custom from Racetec. 28cc dish, 1.00, 1.00, 2.00 ring pack.

olds 307 and 403

Those sound nice and would work even with milled heads.

OldSoldier

I'll be surprised if it doesn't break 400 HP and 450 TQ.

oldsmobiledave

My Guess


422 hp @ 5700rpm & 459 TQ @ 4600 rpm.


I look forward to the actual numbers. Good luck with the build.

olds 307 and 403

Remember he has 7A iron heads with 2"/1.625" valves and the bowls opened, not ported. That is why I put the hp 100 below the torque.

stevengerard

If you don't' want headers don't get them. There is still a cost to them and as you state how you drive the car and where matters. I'm in the same boat as you right now, 3 college payments, an engine that needs to be rebuilt, I'd love it to have more HP/TQ yet being a W30 I feel pretty firm about it looking stock from the outside.

I read years ago an article somewhere of an Olds shop in NJ trying numerous variations of exhaust systems including headers with full exhaust, open headers, and stock manifolds at the dragstrip. The car was most consistent with stock exhaust and only a tenth or so slower than open headers. I know a lot goes into that including track conditions, weather etc. but it just another point of view.

I will tell you one of my Cutlass' has headers and it sounds awesome. That is something else to think of, but you can get a nice sound with good mufflers and an H-pipe as well

stevengerard

[QUOTE=mikejana;1068927] hang sandy waxy surfboards over the back seat, /QUOTE]

cutlassefi

Along those same lines I’m going with 370/440.

olds 307 and 403

You are probably closer Mark. The torque numbers are going to be what make that combo a real winner. The roller cam will also no doubt make a difference and 1 3/4" shorties will be 20 hp better, I would bet than awful stock 350 manifolds.

olds 307 and 403

Mark, what lift range can safely go with a stock length valve on stock iron Olds SB heads? I see you are .525" on the exhaust.

cutlassefi

.600 is not a problem.

olds 307 and 403

Cool then a roller cam would work with my 1.72 roller rocker arms. I know others have said the Ford rocker arms are only good to .540" lift. What brand of roller rockers do you usually run? I assume a stiffer valve spring due to the faster ramps and shorter pushrods are needed due to the taller lifters with a roller cam? I will be contacting Mark for cam bearings, main bearings in .010", I may wait for the new ones and just get the roller cam itself so I can finish my stroker short block this year. Mine will be 4.390 bore with a 3.5" stroke, 424 ci. Mike's set up will be bullet proof compared to mine, the 403 is much flimsier even with a Halo.

mikejana

I'm loading the trailer, hoping to assemble end of next week so I will digress with a really technical -

Best Oldsmobile gold engine paint?

( I have searched the site, and would appreciate current opinion, Thanks)

olds 307 and 403

The universal Duplicolor gold is not the correct factory shade and thin but holds up all right. With the filled heads the paint might actually not burn on the center exhaust port.

Fun71

I'm a bit late but figured I'd throw this in for anyone reading.

I live in a warm area as well - currently in Phoenix (110+ summers) and grew up on the Louisiana Gulf Coast (similar to your area). My car has had Heddman headers since 1982 and I never had any issues with excessive heat, leaks, or ground clearance (other than one time when we jumped some railroad tracks with 6 people in the car - sparks flew on that landing!) I am a firm supporter of headers on anything but a show car.

mikejana

Thanks for all the help and sorry i haven't had much to share.
Seems my Pistons went on a walk-about, but have finally made it to the state of Florida a week late.
Due a the machine shop Thursday, so I'll update as soon as I can.

mikejana

Everything here or with Cutlassefi except heads and torque converter.
Kinda driving me crazy.
Have a great sunny day in the 80's today, so laying down some gold paint.
Do the exhaust shields and the timing bracket get the gold or another color?

olds 307 and 403

The exhaust might look best high temp black or aluminum. The timing cover is gold. I mark the TDC mark on the balancer a bright colour, numbers on the indicator are also nice in a high vis colour. Are you running the stock points distributor. Accessory brackets are black.

mikejana

Thanks Christian.
Wasn't thinking about exhaust, already painted the Hedman Shorties a cast iron- flat Blackish. Doh, guess I do't need the heat shields.
I don't do much "resto-modding". I'm usually aiming at exact factory matches, so that's what I was asking about for other parts. I even ground the "Edelbrock and Performer RPM" script off the intake before painting it Gold.
I'm running the stock distributor with a Petronix points eliminator. I use them a lot and love them.

AZ520

VHT Gold at autozone, MR. T approved!

mikejana

I ended up ordering the , it is supposed to be an exact match.

I also got several rattle cans of Duplicolor 1604, Universal Gold Engine paint. None of the auto parts stores stocked it, but NAPA was able to order it in.
(**Just My Opinion***) The finished product does not match the cap, but I believe it is pretty close to Olds Gold (**Just My Opinion***)

I'll post some pics later.

olds 307 and 403

That looks closer to the original gold than the Duplicolor, factory looks almost like butterscotch. The Por15 paint is usually a high quality paint. The Por15 silver exhaust manifold paint I could never get to cure, even after baking. I use the VHT flat aluminum extra high temp spray paint on exhaust parts, holds up pretty well.