[25stevem]

Back then with the typical street tires and 3.55 gears the level of torque the 350 made could be put to better use, especially in a factory stripped out car like the GT-37.
To this day I would love to know why and how they settled on that 37 number for the model of the car?

[77 TRASHCAN]

I agree on Dennis’ head swap thoughts.
If the OP’er is unable to make that happen, milling the original 11 heads, some, maybe .030, and zero decking the block would help a bunch.

[SD455DJ]

Originally Posted by 25stevem

Back then with the typical street tires and 3.55 gears the level of torque the 350 made could be put to better use, especially in a factory stripped out car like the GT-37.
To this day I would love to know why and how they settled on that 37 number for the model of the car?

Steve, '27' designated 2-dr post coupe cars while '37' the 2-dr hardtops for A-bodies from '68 - '72 in all the different models, with exception to the GTO's, which were only '37' hardtops '68 - '71 (not including '67' convertibles). The late-year '70 GT-37 (April '70) introduction was available in both '27' and '37' body styles, but only in '37' hardtops in '71 and '72 (Lemans GT). Pontiac replaced the Tempest name with T-37 in 1971 for both '27' and '37' body styles, just to make it more confusing. The GT-37 was the introductory low cost musclecar to compete with the Roadrunner and it's inspiration was the 'ET' prototype developed in late '68 & '69 (with the 350HO) which became the Judge after Delorean's input. Clear as mud, right?

I have a hunch that the GT-37 in '70 was to be based on the new 'T-37' Hardtop on the Tempest line, also introduced in spring of 1970, but decided to offer it on the '27' post coupe as well...but, this is pure conjecture on my part.

Dennis

[Cliff R]

"Way back in 1973/74, we were always cruising the local used car lots and found a really nice '72 Lemans GT (T-41 Sundance Orange with black top & interior) similarly equipped as the GT-37 you recall...350 2-bbl, 3-spd (M-13), 3.55 std. rear gears,"

The car I mentioned was a 350 2bbl engine, not 4bbl. It was really quick on the street for the weight of the vehicle and engine size. Something to be said for not overpowering the tires with big power and the vehicle not moving out fast on street tires.

Completely different story at the track. MY 440 powered 1970 Roadrunner ran high 7's in the 1/8th mile (low to mid-12's) way back then the second you bolted a set of slicks on it. The GT-37 on it's best day slicks or not might have been good for maybe low 9's in the 1/8th.........

[77 TRASHCAN]

Originally Posted by SD455DJ

Steve, '27' designated 2-dr post coupe cars while '37' the 2-dr hardtops for A-bodies from '68 - '72 in all the different models, with exception to the GTO's, which were only '37' hardtops '68 - '71 (not including '67' convertibles). The late-year '70 GT-37 (April '70) introduction was available in both '27' and '37' body styles, but only in '37' hardtops in '71 and '72 (Lemans GT). Pontiac replaced the Tempest name with T-37 in 1971 for both '27' and '37' body styles, just to make it more confusing. The GT-37 was the introductory low cost musclecar to compete with the Roadrunner and it's inspiration was the 'ET' prototype developed in late '68 & '69 (with the 350HO) which became the Judge after Delorean's input. Clear as mud, right?

I have a hunch that the GT-37 in '70 was to be based on the new 'T-37' Hardtop on the Tempest line, also introduced in spring of 1970, but decided to offer it on the '27' post coupe as well...but, this is pure conjecture on my part.

Dennis

LOL, I thought it might have been some guy at Pontiac, named Sheldon that came up with the "37" number

[cdoggy81]

Good info & thanks. Yes I will get a HD timing chain & the 60psi melling oil pump. Where should I look for either a factory style late model baffled oil pan and 3/4 or full length windage tray or a crank scraper?

I agree new heads would be best but due to this being low budget & wanting to keep it as original as possible plus not a big hp build we will keep the original #11.

Thanks all!

[SD455DJ]

Your #11 heads will be fine, but low on compression...maybe 8.2 to 1 one after cut for flatness. I have both #15 (360 hp YH 455) and #16 (330 hp XV 400) 1970 small valve heads, that I had the pressed-in studs pinned when they were being rebuilt, like they used to do in the olden days of yore. I rev the 400 with the #16 heads (9.94 compression) to 5600 rpm shift points and so far, so good...none pulled or broken, but I use valve springs with the lowest open pressure possible to help them survive, but not float. I use the Summit 2801 cam and it idles nice, 20 in. vacuum at idle. I would make sure to zero deck the block (new .030 pistons?) and plan for .040" quench (the Felpro 1016 head gasket has .039" compressed thickness) as that will help guard against detonation and pinging. Low compression engines can ping easily with the wrong combination of parts. With the 2800 cam (or similar) it will be a good runner.

Dennis

[F ROCK]

I had a 1970 P350 with the #11 heads in my GTO as a backup engine for a few years.
It had a performer manifold w/ Qjet, unknown cam, and stock manifolds.
That engine ran fantastic, and still runs in a friends car.
It was not a torque monster, but surprisingly quick in his '72 lemans w/ t350 and 3.55 gears.
Sounds real nice with a pypes 2.5" system.

[cdoggy81]

Thanks again guys for the information. I think the engine stuff is pretty well sorted out now.

Is there anything I should be aware of when it comes to the 4spd conversion? What all will transfer over from the M 13 three speed manual that’s in there now? What new things will I need to get?
Thanks in advance!

[Shiny]

Any progress on this?

Lots of good info in this thread, curious what decisions you made and what you are experiencing.

Mike

[Schurkey]

Originally Posted by cdoggy81

Will also be adding rear disc brakes too.

Probably a mistake.

A decent rear disc conversion kit will be very expensive.

Cheap disc conversion kits usually have crappy engineering, where the caliper relies on the pins and bushings for braking thrust instead of for mere location; and often delete the park brake, making them illegal (but popular.)

It would be less expensive, safer, and easier to merely install the larger 11" drums from a mid-70s A-body. Still retain park brake, and no problems created by the disc conversion. Parts are available from the Treasure Yard at advantageous pricing. You'll probably have to replace the wheel cylinders, and brake springs in any event, but if you choose your parts carefully, you could get usable shoes, drums, adjusters, and backing plates direct from the Yard, practically for free.

[Scarebird]

Originally Posted by cdoggy81

Is there anything I should be aware of when it comes to the 4spd conversion? What all will transfer over from the M 13 three speed manual that’s in there now? What new things will I need to get?
Thanks in advance!

I do not think swapping a 3 for a 4 speed is worth it unless you get a ST10 with a lower 1st gear.

[cdoggy81]

Hi guys,
Nothing new to report sadly. Bro remodeling house so taking up all his time & $$$…
Have been keeping an eye open for cheap parts we will need like:
3.08 disc brake position rear (from a 79-81 TA)
ST10 4 spd with the lower gear
Good q-jet
68-70 iron intake
15” Rally wheels or 16” TT with gray centers

On a positive note I do see the 2800 cams are back in stock so will grab one now JTBS 👍🏻😎👍🏻

[Shiny]

Thanks for the update and no worries, just curious. I foolishly thought I had mine good to go about 15 yrs ago and am just now trying to get it running so I can relate!

I do have the engine idling, thanks to shaker455 and a new gas tank. I'm excited to keep moving towards a driver.

Mike

[cdoggy81]

Brothers birthday is this month so family is buying parts :-) Looks like we are going with:

Summit 2800 cam
Stock #11 heads milled .010" up to .020"
Block zero decked
Felpro 1016 head gaskets
HD timing chain
Melling 60psi oil pump
3/4 or full length windage tray
67-70 4bbl qjet carb (built per Cliff's specs)
Stock 67-70 Iron intake
Stock rods & crank (won't spin it over 5200)
Stock pistons but new rings
Stock internal wear parts replaced (lifters, pushrods, rockers, fuel pump)
Stock distributor but may go with an HEI (not sure yet)
Stock exhaust manifolds cleaned & opened up
Pypes 2.5 dual exhaust - probably the Race Pro mufflers
4spd - needs to have a 2.64 or higher first gear
3.08 rear posi
rear disc conversion if we can do it cheap
15x8 Rally II or 16x8 Torq Thrust with gray centers
245 or 255 width tires

Should be a fun lil build & hope to have him cruising with me late spring 2024!

[steve25]

If you have not checked the top and second ring groove clearance and confirmed that you have absolutely no more then .003” clearance only then can you say that you can reuse the stock pistons.

You have limited compression as it is with those heads and you do not want to give up cylinder pressure to worn out ring grooves, no less deal with the mess of having a blow by condition .

The rings are much harder then the cast stock pistons so you can check the groove clearance with your old top and bottom compression rings very likely.

[Cliff R]

"67-70 4bbl qjet carb (built per Cliff's specs)"

Since you aren't locked down on a year I'd go 69-70. Just bypass the 67-68's and go to the vastly improved hinge pin location so you can run a smaller float, high flow N/S assembly and higher fuel pressure w/o issues.

Nothing at all wrong with a stock type points distributor. The HEI offers nothing in improved engine power or performance and points are easy to replace if needed.......

[blueghoast]

X2 on the stock dizzy or even install a pertronx. Have one in my
original 57 ponco. As for your tranny use a sagina-4-speed with
the 350-first gear you will love it. I have one in my 64-Tempest
with a 3.31 rear gear go's down the highway great. I also run
A 235-70-R15 tire out back to, tall tire.

GT

[cdoggy81]

Very good point Steve25. Didn't even think to get the ole feeler gauges out. We will also do a compression test before teardown as well to see if there are any correlations.

Roger that Cliff, I'll look for a 69-70 core then.

Same on the distributor. He may want to do a pertronx & stick with stock.