Re: Need some opinions on if I should swap..
[Re: Fat_Mike]
#2026738
03/07/16 08:50 PM
03/07/16 08:50 PM
|
Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,376
|
The 91 318 has the 302 heads or a later casting number version. It has one of the smallest cams known to man. You are building a cruiser. Here's what I did with my '86 318, basically the same engine. 1. New rings and bearings. Very little wear visible after 115K miles, no ridge in the cylinders. 2. I swapped camshafts for a 360 roller replacement cam. Something like 200 degrees at 50 lift and .400 total lift. The 360 roller engine used the same springs, no need to change them. I actually did because I wanted to be able to run a larger cam down the road. 3. I home ported the heads. Steve Dulcich wrote a very good article about porting the 302s. If you cannot do the work yourself move up to Magnums, the 302s are not worth paying someone else to port. 4. I used the oil pan and pickup from the Poly motor because it fit the chassis and the block. 5. I bolted on a mid '70s 360 Thermoquad intake. Heavy but it works really well. For carb I used a Holley Street Avenger I had been using with the last engine. 6. I used exhaust manifolds that fit in the truck. I believe one was from a 1971 pickup and the other came on the '86 engine. I ran dual exhaust, 2.5". 7. High performance curve distributor with vacuum advance, I set total timing around 34 degrees. 8. I used the Mr. Gasket 1121G thin head gaskets.
Results: This engine increased mileage from 15 to 21 over the 318 Poly I had been driving, same vehicle. Also the distributor, exhaust system and carburetor were the same ones.
What happened bad: I had reused the '64 oil pump and it starved the engine for oil, took out the #1 rod bearing and burned the crank. DO use a new pump and DO check the pickup tube for cracks.
I was the world's third biggest Poly supporter and they're still pretty cool, but for a daily driver on a budget they'll kill you.
R.
|
|
|
Re: Need some opinions on if I should swap..
[Re: dogdays]
#2027281
03/08/16 04:41 PM
03/08/16 04:41 PM
|
Joined: Jan 2003
Posts: 75,070 U.S.S.A.
JohnRR
I Win
|
I Win
Joined: Jan 2003
Posts: 75,070
U.S.S.A.
|
I believe stock Mag pushrods will work with your earlier 318 roller cam setup.
There are a few ways to go on the intakes and the first way is to use one of the Chinese copy intakes that are not too expensive and have holes for both configurations. The second is to redrill the holes in the head using some sort of a jig. You'd fabricate this yourself, setting it up on a LA head and welding it up. The jig that was around several years ago is no more so it is out of the picture. But it was homemade in much the same way. You need a tube at the right angle to aim the drill bit. The third is to use the LA intake, elongate the holes, and make some angle spacers for the angle between bolt head and intake surface.
R. There used to be a Jig for this that was floating around the board for a few years , no idea who has it now though .
running up my post count some more .
|
|
|
Re: Need some opinions on if I should swap..
[Re: JohnRR]
#2027846
03/09/16 02:03 PM
03/09/16 02:03 PM
|
Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,376
|
" There used to be a Jig for this that was floating around the board for a few years , no idea who has it now though. "
I know who built it in his garage and know it turned out to be a hassle for him, both when he was lending it out and after he had sold it to whoever has it now. That's why I said in my post that it was no longer available.
BUT, it was built in a garage by someone who was not a metal fabricator, just smart. And whoever wanted to build one could do it with a hacksaw, a welder, and a few other tools to measure and clamp. Start with a bare LA cylinder head and work out from there.
Keep the Poly? Sure, as long as you are OK with $650 intake manifolds, $285 new camshafts and out-of-production pistons. Or, the increased fuel consumption.
R.
|
|
|
|
|